Abstract
![Blueberry Basket](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/blue_basket.jpg)
Blueberry Basket
Photo by: Scott Bauer
2004 USDA Image Gallery |
Blueberries are the most widely grown fruit crop in the U.S. Blueberries
are well-suited to organic culture, and good markets exist for
organically grown blueberries. This production guide addresses
key aspects of organic blueberry production, including soils and
fertility, cultural considerations, pests, and diseases, as well
as marketing. Additional resources are provided for further investigation.
Table of Contents
Introduction
This publication focuses on organic blueberry production, specifically
the highbush and rabbiteye species, and is most relevant to production
conditions east of the Rocky Mountains. It does not go deeply into
many of the basics of blueberry culture—variety choice, planting,
pruning and training—which are largely the same under both
organic and conventional management. Such general information is
available from the Cooperative Extension Service and many horticulture
books, periodicals, and bulletins. Nor does this publication address
organic production of lowbush blueberries. The Maine Organic Farmers
and Gardeners Association (MOFGA) and K-Ag Laboratories International
in Wisconsin both have information on organic culture of native,
unimproved lowbush blueberries. (See the Electronic Resources section
of this publication for contact information.)
While anyone may choose to grow organically, the USDA National
Organic Program (NOP) now regulates the labeling, marketing, and
record-keeping procedures of all products
labeled as organic. If you have a commercial farm and plan to market
your produce as organic, you will need to be certified, unless
your gross farm income is less than $5000. To learn about organic
certification and the steps involved in it, read ATTRA’s Organic
Farm Certification & the National Organic Program.
Blueberries adapt well to organic culture. Production costs may
be somewhat higher using organic methods, but this can be effectively
counterbalanced by premium prices. Many cultural practices, such
as the use of deep mulching and sodded row-middles, work for both
conventional and organic blueberry production systems, offering
a more sustainable approach to commercial horticulture.
Back to top
Choosing a Variety
Blueberries are members of the genus Vaccinium and belong
to the Rhododendron family (Ericaceae). The Vaccinium genus
contains several species of economic importance. The highbush blueberry
(Vaccinium corymbosum) is the most widely cultivated,
grown from the Mid-Atlantic to California, Oregon, and Washington,
and from the Upper Midwest to the Mid-South. The lowbush (wild)
blueberry (V. angustifolium) is adapted to the far North
and is commercially important in Maine, Eastern Canada, and parts
of New Hampshire, Massachusetts, Michigan, and Wisconsin. Rabbiteye
(V. ashei) is a large bush well-adapted to the South,
in the region roughly south of Interstate 40. Southern highbush
(V. corymbosum x V. darrowi), a new hybrid, is adapted
to the southern rabbiteye zone as well as the coastal South. It
has a lower chilling-hours requirement, and it flowers and fruits
earlier than highbush or rabbiteye varieties.
Blueberries have fewer pest problems than most other fruits, offering
an advantage for organic production. In some areas, most insect
and disease problems can be controlled through cultural manipulation
and proper cultivar selection. Weather fluctuations and geographic
seasonal advantage are the major economic considerations for variety
selection.
The National Organic Standard is unclear on the precise requirements
for planting stock when establishing a perennial crop like blueberries.
Historically, non-organic transplants could be used to establish
perennial crops. However, if conventional planting stock were used,
most certifiers required that the plants be grown at least 12 months
under organic conditions after transplanting before any harvested
product could be marketed as organic. It is likely, but not certain,
that most certifiers are continuing that policy. Therefore, it
is important that you discuss your plans with your certifier prior
to making a purchase.
Back to top
Soils and Fertility
The Importance of Soil pH
Blueberries are distinct among fruit crops in their soil and fertility
requirements. As members of the Rhododendron family, blueberries
require an acidic (low pH) soil, preferably in the 4.8 to 5.5 pH
range. When soil pH is appreciably higher than 5.5, iron chlorosis
often results; when soil pH drops below 4.8, the possibility of
manganese toxicity arises. In either case, plants do not perform
well.
Blueberries have a relatively low nitrogen requirement and thrive
on organic fertilizers. Soil pH also plays a significant role in
nitrogen management for blueberries. Research shows that blueberries
prefer soil and fertilizer nitrogen in the ammonium form, absorbing
and using it much more efficiently than nitrate nitrogen—the
form preferred by most other commercial crop plants. Neutral and
high-pH soils favor nitrification—the rapid conversion
of ammonium nitrogen to nitrate through the activity of nitrifying
microorganisms. In an acidic soil, however, the ammonium form of
nitrogen predominates and is readily available to blueberries.
For instance, when a slow-release organic fertilizer like fishmeal
is applied, the nitrogen in the proteins is converted first into
ammonium. This ammonium—which would rapidly convert to nitrate
under neutral soil conditions and be leached out of the root zone—tends
to remain in the desired, ammoniated form and thus be held in the
soil for uptake.
Perhaps the most common method of lowering soil pH in organic
culture is by applying sulfur. Pre-plant incorporation of sulfur
to lower the pH to an optimal blueberry range of 4.8 to 5.5 should
be based on a soil pH test. Because soil pH is subject to considerable
seasonal fluctuation—especially on cropped soils—it
is advisable to do soil sampling and testing in winter or very
early spring, when biological activity is low. Table 1 provides
guidelines for sulfur or lime to raise or lower pH on different
types of soil.
Table 1. Approximate pounds per acre of sulfur or ground limestone
to change soil pH one unit. (Whitworth, 1995) |
Soil Texture |
Pounds per acre of sulfur to lower soil pH one unit (e.g., 6.0 to 5.0) |
Pounds per acre of lime to raise soil pH one unit (e.g., 4.0 to 5.0) |
Sand (CEC=5) |
435 to 650 |
1000 |
Loam (CEC=15) |
870 to 1300 |
2800 |
Clay (CEC=25) |
1300 to 1750 |
4400 |
Powdered sulfur takes about one year to oxidize and reduce soil
pH. Prilled sulfur takes somewhat longer. Limestone, used to increase
pH, requires several months to a year to effect changes in pH,
and reactive time is highly dependent on the fineness of the grind.
Single applications of sulfur should not exceed 400 pounds per
acre. Best results are obtained by applying up to 200 pounds in
spring, followed by up to 200 in the fall, for as many applications
as are required to deliver the total amount. It is advisable to
re-test the soil one year after each application to determine whether
additional acidification is necessary.(Pritts
and Hancock, 1992)
Organic growers should be conservative in the application of soil
sulfur. Sulfur has both fungicidal and insecticidal action and
can detrimentally affect soil biology if overused. Organic growers
sometimes increase their applications of peat moss at planting
time, since it too is a soil acidifier (pH 4.8), reducing the need
for sulfur. The Ozark Organic Growers Association suggests as much
as 5 to 10 gallons of peat moss per blueberry plant. While costly,
peat is resistant to decomposition and provides the benefit of
soil humus. Those seeking alternatives to sphagnum peat moss might
consider pine bark or similar amendments incorporated in the planting
rows or holes. While less desirable than sphagnum peat moss, pine
bark often can be obtained locally at a much lower cost.
It is advisable to monitor soil pH over time because production
practices can cause gradual changes to occur. Irrigation water
often contains calcium and magnesium, which may cause soil pH to
creep upwards, while repeated use of acidifying fertilizers, such
as cottonseed meal, may lower pH.(Spiers and
Braswell, 1992) Fortunately,
the presence of abundant organic materials such as peat and the
breakdown products of sawdust and woodchip mulches tend to buffer
soil pH. Several organic growers have even observed that blueberries
grown in high organic matter soils will perform well at a pH as
high as 6.0 with few apparent problems. As a result, additional
sulfur (or lime, for that matter) seldom is needed. When needed,
sulfur is usually applied as a top dressing, but delivery of soluble
sulfur through drip irrigation lines also is an option. Vinegar
or citric acid solutions may also be applied through drip lines
to provide acidity.
Blueberry Fertilization Practices
Soil-building practices prior to establishment can go a long way
toward providing the fertility necessary for a healthy blueberry
planting. High levels of soil organic matter are especially important
in blueberry culture, contributing to the soil's ability to retain
and supply moisture to the crop, buffering pH, and releasing nutrients
through decay. Soils rich in organic matter are also a desirable
environment for symbiotic mycorrhizal fungi that assist blueberry
roots in absorbing water, nitrogen, phosphorus, and other minerals.(Yang
et al., 2002) Green manures in advance of planting can play an
important part in cycling organic matter into the soil system,
as can applications of composts and livestock manures. ATTRA has
several publications that can be useful in these areas, including Overview
of Cover Crops and Green Manures, Manures
for Organic Crop Production, and Farm-Scale
Composting Resource List.
Once a blueberry planting is established, supplemental fertilization
can be applied in a number of forms and by several means. Generally,
supplemental nitrogen is the greatest concern, followed by potassium.
Blueberries have a low phosphorus requirement and typically require
little, if any, phosphorus fertilization. In fact, excessive phosphorus
has been one of the factors linked to iron chlorosis in blueberries.
High calcium levels are also undesirable.
Nitrogen fertilizer recommendations vary somewhat from region
to region. As a general guideline, 100 to 120 pounds of nitrogen
per acre are commonly recommended on mulched berries; a reduced
rate of 50 to 60 pounds per acre is advised where little or no
mulch is used.(Clark, 1987) In conventional production, nitrogen
is often applied in three split applications—one at bud break,
followed by two more at six-week intervals. Adjustments may be
necessary for less-soluble organic fertilizers. One rule of thumb
suggests that these fertilizers be applied from one to four weeks
ahead of the recommended schedule for soluble fertilizers. This
allows additional time for the decomposition processes to make
nutrients available. Applications after mid-July are discouraged,
as they tend to promote late growth that is particularly sensitive
to freeze damage. Table 2 shows natural materials used by organic
growers for supplementary fertilization.
Table 2. Natural materials for supplementary fertilization.
(Penhallegon, 1992, and Nitron, no date) |
Material |
Estimated N-P-K |
Characteristics |
Alfalfa meal |
3-1-2 |
Slow to medium N release
Good
micronutrient source |
Blood meal |
12-1.5-0.6 |
Medium N release, 6-8 weeks |
Cottonseed meal |
6-2.5-1.7 |
Slow N release, 4-6 months |
Feather meal |
13-0-0 |
Slow N release, 4-6 months |
Fish meal |
10-4-0 |
Slow N release, 4-6 months |
Soybean meal |
7-1.6-2.3 |
Slow N release, 4-6 months |
Compost |
Variable |
Analysis depends on feed stock |
Fortified Compost |
Variable |
Analysis depends on materials added |
Current fertilization practices among organic growers vary considerably.
In one example (Moore et al., 1994), an organic blueberry grower
in the Missouri Ozarks applied ½ pound of feather meal per
mulched plant in late May of the establishment year, followed by
a similar application four to six weeks later. In subsequent years,
an additional (third) application of ½ pound of feather
meal was made earlier, in mid- to late-March. As the feather meal
products available in this region contain roughly 13% nitrogen,
this grower was applying approximately 141 pounds of actual N per
acre in the establishment year, and an annual total of 212 pounds
per acre thereafter.
Using the same schedule of split applications, another organic
grower in the Arkansas Ozarks, also growing mulched berries, applies
cottonseed meal (estimated at 7% N) at 1 pound per plant each time—that’s
two times in the establishment year and three times in subsequent
years. At these rates, this grower is applying roughly 152 pounds
per acre in the establishment year and about 229 pounds per acre
in subsequent years.(Watkins, 1988) However, it should be noted
that many sources of cottonseed meal are contaminated and will
not be allowed in organic production. Contact your certifier first.
Associate professor John Clark (1987) at the University of Arkansas
believes the fertilization rates used by many organic growers are
probably excessive. Despite the slower release of organic-based
nitrogen, the carry-over from previous seasons probably results
in roughly the same amount of nitrogen released each season as
is being applied.
Clark suggests that the best way to determine whether fertilization
rates are "on target" is to test foliar nitrogen levels
annually. This testing is done in late July or early August (in
Arkansas) by sampling leaves from the mid-shoot area on fruiting
canes and sending them to an analytical laboratory. Lab results
showing nitrogen levels below 1.6% indicate a nitrogen deficiency;
a level above of 2.2% indicates excess nitrogen. This service is
available through Cooperative Extension in Arkansas and other states.
Several commercial laboratories also provide foliar analysis. ATTRA
identifies laboratories that offer various soil and plant tissue-testing
services in its publication Alternative Soil Testing Laboratories.
Potassium for blueberries is often adequately provided through
decaying mulches. The need for further supplementation should be
determined by soil and/or tissue testing. Where additional potassium
is needed, it can be applied in a number of mineral forms—including
sulfate-of-potash-magnesia or K-Mag,™ granite meal, and greensand.
Some forms of potassium sulfate are also allowed in organic production.
See your certifier before buying fertilizer.
High-quality compost is an all-around good blueberry fertilizer.
Depending on the humus condition and biological activity in the
soil, compost may provide all the fertility needs of the crop.
Where compost is of average quality, it may still function as a
good soil conditioner. Using aged animal manures in blueberry production
also is possible, but less common.
Fertigation—the practice of injecting soluble fertilizers
through drip irrigation lines—is a common practice in conventional
blueberry production. Since fertigation is based on the complete
solubility of fertilizers in water, there are limited options among
organic fertilizers. Early attempts at fertigation with blood meal
by Arkansas blueberry growers resulted in clogged emitters and
algae growth. In the 1990s, however, researchers in California
successfully demonstrated the use of spray-dried fish protein and
poultry protein in drip systems.(Schwankl and
McGourty, 1992)
In addition, several organic liquid fertilizers—derived from
fish emulsion, seeds, kelp, or seaweed—are available.
Unlike the roots of grapes and bramble fruits, which grow well
into the inter-row area, blueberry roots are not very extensive.
As a result, all fertilizers and acid-forming amendments must be
applied under the plant canopy to assure that they reach the roots.
Foliar feeding of blueberries is practiced by some organic growers
and is especially helpful when plants are stressed. Foliar fertilization
programs usually employ seaweed and fish emulsion. The Ozark Organic
Growers Association has recommended a seaweed-fish mix applied
three times per growing season—at bud break, just prior to
harvest, and just after harvest. More detailed information is available
in ATTRA’s Foliar Fertilization publication.
Back to top
Cultural Considerations
Plant Spacing
Highbush blueberries are typically spaced 4 to 4½ feet
in the row, with 8 to 12 feet between rows. As bushes can get quite
large at maturity, many growers find that 10– to 12–foot
row spacings—approximately 900 to 1090 plants per acre—are
preferable for tractor operations (mowing, harvesting, and spraying).
Rabbiteyes are typically spaced at 5 to 8 feet within a row, with
12 to 14 feet between the rows, or 388 to 726 plants per acre.
Dr. J.N. Moore and others at the University of Arkansas have experimented
with denser within-row plant spacings for highbush blueberries,
effectively doubling the number of plants per acre. Yields during
the first five years after planting were found to be substantially
higher (a boon to the overall economics of blueberry production—especially
where growers have made high investments in drip irrigation and
bird netting).
These researchers have been careful to point out, however, that
beyond the fifth year, inter-plant competition may create problems,
requiring removal of every other plant in the row.(Pritts
and Hancock, 1992) Fortunately, highbush blueberries transplant easily, and
removed bushes can be used to establish a new field.
Inter-row Management
Blueberries do not have extensive root systems. As a result, clean
cultivation of row middles to control weeds and to incorporate
cover crops is less damaging to blueberries than it is to bramble
fruits. Still, it is wise to till no deeper than 3 inches. Similarly,
inter-row living mulches—also called sodded middles—generally
are not competitive with the crop unless the inter-row species
are aggressive and invade the rows. Fescue is commonly used in
the Mid-South for sodded middles, as are several other grass species.
Timely mowing—usually three to five times per year—is
the common means of controlling weeds and other vegetation in sodded
middles. It is most important that weeds not be allowed to produce
seed that may be scattered into the rows and germinate later.
In a Texas study, researchers demonstrated that the inter-row
area could be used to produce significant quantities of mulch for
rabbiteye blueberries. Successful winter crops of rye, ryegrass,
and crimson clover, and a summer crop of pearl millet, were grown,
cut, and windrowed onto the blueberry rows. Nitrogen proved the
major limiting factor for non-leguminous cover crops; low soil
pH and browsing deer limited the biomass production of legumes.
Pearl millet demonstrated the greatest level of allelopathic (natural
production of plant chemicals by one plant that inhibit other plants
growing nearby) weed suppression.(Patten et al.,
1990)
In some systems that employ sodded middles, a weed-free strip
6 to 12 inches wide often is maintained between the edge of the
mulch and the cover crop. The strip reduces competition between
the cover crop and berry bushes, and lessens the chance that weeds
or the cover crop itself will advance into the mulch. It has the
added advantage of discouraging cutworms, an occasional pest in
blueberries. In organic systems, this strip is maintained without
the use of herbicides.
Organic growers typically employ mechanical cultivators of various
types to maintain the weed-free strip. Gordon Watkins (1989) described
two modified "off-the-shelf" cultivators used by growers
in the Ozark region. One, referred to as the Vasluski Edger, uses
a single disc from a rice levee plow in conjunction with two shanks
from a spring-tooth chisel. These are mounted on a tool-bar that
extends past the rear tractor tire. The disc cuts a strip along
the row edge and throws soil towards the plants, while the shanks
stir soil closer to the bed. The result is a weed-free strip about
6 to 8 inches wide. The drawback of this implement is the amount
of dirt shifted by the disc and the resulting "ditch."
The second implement Watkins describes is the Lilliston Rolling
Cultivator,™ with all the heads removed except the two extending
beyond one rear tire. One head rolls in the ditch area that is
(or would be) created by the Vasluski Edger. The second extends
approximately 12 inches onto the side of the bed. Depth of penetration
is set at 1 inch, and the implement is best operated at relatively
high speeds. Since it cultivates about one-half of the bed surfaces,
only about a 2-foot strip remains for hand pulling and hoeing.
The tool works well on small weeds but does not control larger,
well-established weeds.
Flame, steam, and infrared thermal weed-control systems are other
options. In the 1980s and ’90s, flame weeding made a rapid
comeback as a non-chemical weed control technique, especially among
organic farmers. However, this technique is not always practical
or safe around flammable mulch materials. ATTRA can provide additional
information on flame weeding.
In-row Weed Management and Mulching
Weeds are considered by many growers to be the number one problem
in organic blueberry culture. It is especially important to control
aggressive perennial weeds such as johnsongrass, bermudagrass,
and quackgrass prior to crop establishment. Sites with
these grasses should generally be avoided for blueberry establishment.
Details of pre-plant and post-plant weed management for all fruit
plants are provided in ATTRA's Overview of Organic Fruit Production.
Some techniques, however, deserve additional elaboration.
In much of the country, blueberries are grown on mulched, raised
beds. Rabbiteyes and old highbush plantings are commonly grown
without mulch. Raised beds reduce the incidence of soil- and water-borne
diseases. Thick organic mulches provide weed and disease suppression,
soil temperature regulation, slow-release nutrients, organic matter,
and moisture conservation. The latter is especially important because
blueberry roots lack root hairs—the primary sites for water
and mineral absorption on most plants. This characteristic makes
water management of paramount concern and goes a long way toward
explaining why irrigation and mulching are recommended practices.
The importance of maintaining a weed-free zone around blueberries
was demonstrated in a Georgia study (NeSmith
et al., 1995) using
rabbiteye blueberries—which have a more vigorous root system
than highbush. Researchers determined that an optimum vegetation-free
zone during the first two to three years of growth extends roughly
1.5 to 2.5 feet from the plant. This translates to a 3- to 5-foot-wide,
weed-free row bed.
Current recommendations suggest mulching a 3- to 4-foot-wide strip
under the plants with 3 to 5 inches of sawdust, bark, wood chips,
or wood shavings. Organic growers often prefer a deeper mulch of
up to 6 inches over a strip at least 4 feet wide. Ideally, the
mulch should be sufficiently coarse to minimize crusting, and the
surface relatively flat to encourage water penetration and gas
exchange.
While the mulch suppresses many weeds, the moist organic medium
can also become a haven for annual weeds (annual ryegrass, stinging
nettle, crabgrass) as well as perennial weeds (dandelion, horsetail,
sheep sorrel) that find a niche in perennial plantings. Strategic
attention to weed control, even in mulched fields, is a major cultural
consideration. Tractor-drawn cultivation implements are impractical
for in-row weed control on deep-mulched blueberries because blueberry
roots often grow into the mulch, and significant plant damage can
result from tillage. Shallow hoeing or hand-pulling weeds are two
traditional options practiced by many organic growers.
Weeder geese can also eliminate most of the grass and many of
the tender broadleaf weeds from a planting. They are prone to eating
ripe fruit, however, and may damage some of the newly emerging
canes, so their use should be timed accordingly. Obviously, goose
stocking rates are much lower, and management easier, on clean
cultivated plantings. Investigators at the Kerr Center for Sustainable
Agriculture have used weeder geese for effective weed control in
blueberries with sodded middles. The Center’s strategy involves
using movable electric fencing and intensive grazing. One possible
drawback cited by Kerr Center researchers is the tendency of geese
to compact the soil and mulch. ATTRA can supply further information
on weeding with geese.
A promising alternative to organic mulching is the use of fabric
weed barriers. While fabric mulches may not provide all the benefits
of deep organic mulch, they are highly effective for weed control
and allow water to pass through. And, though the initial cost is
high, it may prove reasonable when amortized over the fabric’s
expected lifetime of 10 to 12 years. All fabric mulches must be
removed, however, before they deteriorate and decompose into the
soil. Have a plan in place to deal with this eventuality. Available
fabric mulches include Sunbelt by DeWitt Company (see References).
Non-porous black plastic mulches—commonly used in vegetable
production—are not recommended for blueberries. Polyethylene
plastic mulch encourages surface rooting—making the plants
more susceptible to drought stress and winter injury—and
the plastic does not allow water to pass through.
Pollination
Blueberries are insect-pollinated; thus, increasing the number
of pollinators can be quite beneficial. Blueberry flowers vary
greatly in size and shape, depending on species.(Lyrene,
1994)
Therefore, having a variety of pollinators like horn-faced bees,
mason bees, carpenter bees, bumblebees, orchard bees, and others
is important for good fruit set.
Several varieties of blueberry require cross-pollination, and
almost all varieties yield better as a result of it. In a pollination
study, the variety Patriot, and possibly Northland, benefited from
cross pollination, while the variety Bluecrop did not; therefore,
highbush blueberry planting design must be based on the pollination
requirements of the particular variety.(MacKenzie,
1997) Identify
the pollinators that are most efficient for the variety and encourage
them to remain in the area by creating insect habitats. Cover crops
and adjacent vegetation may act as habitats for beneficial insects
that provide pollination and help suppress pest insects and mites.
When crops and field borders are managed with beneficials in mind,
they often are referred to as refugia, and represent a
new approach to attracting pollinators and natural enemies of pests,
based on planned biodiversity. To learn more about refugia, see
the ATTRA publication Farmscaping to Enhance Biological Control.
Additional information on using various bees as pollinators can
be found in ATTRA’s Alternative Pollinators: Native Bees.
Back to top
Insect Pests
Rabbiteye blueberries seem more tolerant of insect damage than
highbush varieties. Although insect damage in blueberry plantings
rarely reaches economic thresholds, regular monitoring by scouting
and use of insect traps is advised. As discussed in the previous
section, the use of beneficial insect habitats along crop field
borders increases the presence of beneficial insects. If you are
releasing purchased beneficial insects, these field-edge habitats
will encourage them to remain and continue their life cycle in
that location, helping reduce the pest populations. However, pests
may also inhabit the field-edge habitats; therefore, these habitats
should be monitored along with the crop field. For additional information,
see ATTRA’s publications Biointensive Integrated
Pest Management and Farmscaping to Enhance Biological
Control.
Depending on the locations of blueberry plantings and the insect
pressure on them, sanitation, good cultural practices, vigorous
plant growth, and natural biological control will handle most pests.
However, when specific pests reach economically damaging levels,
additional action is necessary. The following discussion identifies
some common blueberry pests and allowed organic controls. This
information was taken largely from Cornell University’s Crop
Profiles: Blueberries in New York (Harrington
and Good, 2000),
where more detailed information can be found.
Blueberry maggot
![Blueberry Maggot Adult Fly on fruit](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/blue_maggot_fly.jpg)
Figure 1. Blueberry maggot adult fly
Used with permission.
G.J. Steck and J.A. Payne. |
The most common insect pest is the blueberry maggot, Rhagoletis
mendax. It attacks the fruit in midsummer before harvest
and feeds on all varieties of blueberries. It is found throughout
the eastern U.S. and Canada. This pest overwinters in the pupae
stage, buried 1 to 2 inches in the soil. The adult flies emerge
over a period of a month or two during summer. They lay eggs
in ripe berries, and the maggots eat the pulp of the fruits,
causing many to drop, spoiling the sale of others, and creating
difficulties in post-harvest care. Through degree-day calculations
based on soil temperatures, one can predict the emergence of
the flies—934.3 degree days at the low temperature threshold
of 41°F (Teixeira and Polavarapu, 2001)—and implement
appropriate measures to prevent or control maggot damage.
![Blueberry Maggot on fruit](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/blue_maggot.jpg)
Figure 2. Blueberry maggots on fruit
Used with permission.
G.J. Steck and J.A. Payne. |
The choice of blueberry varieties can influence the severity of
blueberry maggot damage. In a Rhode Island study, the early ripening
varieties Earliblue and Bluetta were found to have fewer maggots
than late maturing varieties whose ripening periods were synchronized
with the fly’s egg-laying period. Of the mid- to late-season
varieties, Northland and Herbert stood out with less damage.(Liburd
et al., 1998)
The botanical insecticides rotenone and pyrethrum can be effective
in controlling blueberry maggots, but they can also be toxic to
beneficial insects, fish, and swine. The spinosad-type insecticide
Entrust™ (Dow AgroScience) is approved for use on organic
crops including blueberries and has been reported effective against
the blueberry maggot. Additionally, disking, cultivating, and off-season
grazing by fowl can reduce pupa populations.
Blueberry stem borer
This beetle, Oberea myops, causes damage in two ways.
First, egg deposits can cause the first 3 to 4 inches of the current
season’s growth to wilt or die. This is evidenced by girdling
in two places, approximately ½ inch apart, on the injured
twig. Secondly, grubs can cause canes to die. Leaves will turn
from green to yellow and drop off, and the cane will die. Pinholes
along the shoot with yellowish strings hanging from them are indicative
of this problem.
This pest can be controlled by removing wilted tips below the
insect damage and burning them.
Cranberry fruitworm
![cranberry moth larvae](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/cranberry_larvae.jpg)
Figure 4. Cranberry fruitworm larva
Used with permission.
C.D. Armstrong |
Particularly troublesome in the eastern U.S., the cranberry fruitworm, Acrobasis
vaccinii, affects both cranberries and blueberries. It overwinters
in the soil as a fully grown larva and completes development
in the spring. Adult moths mate and lay eggs from bloom until
late green fruit, usually on unripe fruit. The eggs are very
small and difficult to see. Young larvae enter the stem end of
the fruit and feed on the flesh. They often web berries together
with silk.
![adult cranberry moth](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/cranberry_moth.jpg)
Figure 3. Cranberry
fruitworm
adult moth
Used with permission.
C.D. Armstrong |
A Michigan study reports that many parasites attack the cranberry
fruitworm. The most common larval parasitoid is Campoletis
patsuiketorum (Hymenoptera: Ichneumonidae); the most common
parasitoid recovered from the fruitworm’s hibernating structure
was Villa lateralis (Diptera: Bombyliidae).(Murray
et al., 1996) Therefore, maintaining refugia, by enhancing field borders
for beneficial insects, and proper sanitation are especially important
in controlling this pest. Additionally, eliminating weeds and vegetative
litter around plants helps cut down on overwintering protection
for fruitworm cocoons.
The biocontrol Bacillus thuringiensis (Bt) can effectively
control cranberry fruitworm. Make sure to use a Bt product approved
for organic production. The spinosad insecticide Entrust (Dow AgroScience)
is registered for use against the cranberry fruitworm and cherry
fruitworm on blueberries.
Cherry fruitworm
The cherry fruitworm, Grapholitha packardi, which bores into the
fruit and feeds extensively below the surface, can be very damaging
to blueberries. It causes injury within a few days of hatching.
This pest overwinters as mature larvae in hibernating structures
on the blueberry bushes, with larvae pupating in the spring. The
adults appear in about a month (this varies by seasonal conditions).
Adult moths mate and lay eggs on unripe fruit. Pruning and burning
the cut limbs helps control the cherry fruitworm, because the hibernating
larvae are contained in these limbs. The cherry fruitworm is a
lepidopteran pest, and organically approved control products include
Bt or the spinosad product Entrust.
Japanese beetle
![Japanese beetle skeletonizing a leaf.](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/japanese_beetle.jpg)
Figure 5. Japanese beetle skeletonizing a leaf.
Photo used
with permission. University of Maryland Cooperative
Extension Home and Garden Information Center. |
The Japanese beetle larvae develop in pastures, lawns, and other
types of turf, where they live in the soil. Adults emerge in early
summer and feed on blueberry foliage and berries, causing injury
to the berries, as well as decay from fruit-rotting pathogens.
Organic growers use a number of methods to control these pests.
Hand picking, trapping, milky spore disease, and/or beneficial
nematodes have all been used by growers with varying degrees of
success. The key practices are the use of milky spore (which provides
a long term approach to larvae reduction), trapping away from the
crop, and regular emptying of the traps.
Clean harvesting prevents the accumulation of overripe fruit,
reducing the attraction for beetles. In a Michigan study, fields
with tilled row-middles had significantly fewer larvae than those
with permanent sod, and larval abundance was significantly lower
on the interiors of the fields compared to the perimeters.(Szendrei
et al., 2001) Clean row middles may have fewer Japanese beetle
larvae, but they also leave the soil open to erosion, so this option
should be used only on level fields.
Some botanical insecticides—such as rotenone—can legally
be used even on the day of harvest according to current label restrictions;
however, none have proven adequate for Japanese beetle control.
Kaolin clay, available in the product Surround, can be used for
suppression of the Japanese beetle only on blueberries that will
be processed.
Leafroller
Leafrollers are the caterpillars of a few species of small moths.
These pests roll leaves (hence their name) to use as shelter during
their metamorphosis. Adults emerge, mate, lay eggs, and then repeat
the cycle at least twice each year. Larvae feed on green berries,
ripe berries, and leaves. Small numbers of leafrollers (fewer than
15 per plant) usually will not cause significant losses, unless
they are feeding on blossoms.(Elsner and Whalon,
1998)
The pesticide Bt var kurstaki can be applied when insects
are feeding. Additional organically accepted strains of Bt can be
effective at egg hatch, becoming less effective as larval size increases.
Neemix, a product containing azadirachtin, acts as an insecticide
and insect growth regulator affecting young (1 st and 2 nd instar)
caterpillar pests. It is registered for leafrollers on organic blueberries
with an “R” (regulated) status.
Leafhopper
Leafhoppers are small, mobile insects that are often found on
stems or the undersides of leaves. They feed by piercing the plant
surface to suck plant juices.(Elsner and Whalon,
1998) Leafhoppers
transmit a microorganism that causes stunt disease. In areas where
stunt disease is a known problem, leafhopper control is suggested.
The botanical pesticide sabadilla, as well as insecticidal soap
and diatomaceous earth, are reported to be effective against these
pests. Surround (for processing blueberries) and Neemix are registered
for leafhopper control on blueberries. Kaolin clay in Surround
can be used for suppression of leafhoppers on processing blueberries
only.
Aphids
Aphids, or plant lice, are related to the leafhopper. They feed
on the undersides of the youngest leaves and on tender shoots,
and reproduce very rapidly. Aphids transmit blueberry shoestring
virus, which can be very damaging to commercial blueberry producers.(Elsner
and Whalon, 1998) Aphids have many natural enemies like ladybugs,
lacewings, and parasitic wasps. Encouraging these natural enemies
with habitat plantings can keep aphids and other pests on blueberries
below economic thresholds. Remove the virus-infected plants, which
will have bright red streaks or straplike leaves. Avoid overfertilization
of the crop. Organic growers can also use insecticidal soap to
control aphids.
Back to top
Diseases
Diseases in plants occur when a pathogen is present, the host
is susceptible, and the environment is favorable for the disease
to develop. Changing one of these three factors may prevent the
disease from occurring. Pathogens responsible for blueberry diseases
include fungi, bacteria, nematodes, and viruses. If these pathogens
are present, manipulation of the environment and the host, to make
it less susceptible, help to manage diseases on blueberries in
a more sustainable manner. Check with your nursery and local Extension
office to see whether known diseases are prevalent in your area.
Then, plant tolerant or resistant blueberry varieties.
Managing soil health is key for successful control of soil-borne
diseases. A soil with adequate organic matter can house large numbers
of organisms (e.g., beneficial bacteria, fungi, amoebas, nematodes,
protozoa, arthropods, and earthworms) that in conjunction deter
pathogenic fungi, bacteria, nematodes, and arthropods from attacking
plants. These beneficial organisms also help foster a healthy plant
that is able to resist pest attack. For more information, see the
ATTRA publication Sustainable Management of Soil-borne Plant
Diseases.
The plant’s leaf surface can also host beneficial organisms
that compete with pathogens for space. A disease spore landing
on a leaf surface, for example, has to find a suitable niche for
it to germinate, penetrate, and infect. The more beneficial organisms
there are on the leaf, the greater the competition for the disease-causing
spore trying to find a niche. Applying compost teas adds microorganisms
to the plant’s surface, making it more difficult for diseases
to become established. Note, however, that there are restrictions
on the use of compost tea prior to harvest. Be sure to consult
your certifier. For more information on disease controls, see the
ATTRA publications Notes on Compost Teas and Use
of Baking Soda as a Fungicide.
A blueberry diagnostic tool from Cornell University has a step-by-step
exercise that can aid a blueberry grower in determining what diseases
may be affecting the crop. The diagnostic tool can be found at
the following Web site:
www.hort.cornell.edu/department/faculty/pritts/BerryDoc/blueberry/BBparts.htm
Diseases common to blueberries include mummy berry, Botrytis
blight (gray mold), stem blight, stem canker, phytophthora root
rot, blueberry stunt, and several viral diseases. For proper disease
identification, consult Cooperative Extension Service publications
and related literature. Many states also have plant pathology laboratories
associated with their land-grant university that can provide diagnosis.
Foliar diseases
Mummy Berry (Monilinia vacinii-corymbosi)
This fungus overwinters in mummified berries that have fallen
to the ground. Sod or moss directly under the plant will contribute
to spore production. To control this fungus, remove infested fruit
(“mummies”) from the plant, rake and burn mummified
berries, or cover the fallen berries with at least two inches of
mulch. Cultivation during moist spring weather will destroy the
spore-forming bodies. Strategies that lead to early pollination
of newly open flowers may be useful in managing mummy berry disease
in the field, since studies show that newly opened flowers are
the most susceptible to infection and that fruit disease incidence
is reduced if pollination occurs at least one day before infection.(Ngugi
et al., 2002)
The fungus survives the winter on dead twigs and in organic matter
in the soil. The disease is more severe when excessive nitrogen
has been used, where air circulation is poor, or when frost has
injured blossoms. Varieties possessing tight fruit clusters are
particularly susceptible to this disease. Remove dead berries,
debris, and mulch from infected plants during the winter and compost
or destroy it. Replace with new mulch, and do not place mulch against
the trunk of the plant.
Highbush blueberry varieties are more resistant to mummy berry
than are rabbiteye. Rabbiteye varieties that showed lower levels
of infection were Coastal, Delite, Centurion, Walker, Callaway,
and Garden Blue.(Ehlenfeldt et al., 2000) Highbush varieties that
exhibited constant resistance to mummy berry were Northsky, Reka,
Northblue, Cape Fear, Bluegold, Puru, and Bluejay.(Stretch
and Ehlenfeldt, 2000)
This fungus overwinters in dead or diseased twigs, fruit spurs,
and cankers. Spores are released in the spring and are spread by
rain and wind. Varieties in which the ripe fruit hangs for a long
time on the bush prior to picking are especially susceptible. Removal
of infected twigs by pruning and frequent harvesting are beneficial
to control. Old canes and small twiggy wood should be removed in
order to increase air circulation around the fruit clusters. Immediate
postharvest cooling will significantly reduce the incidence of
this disease.
Botrytis Blight (Botrytis cineria)
Anthracnose (Collectotrichum acutatum and C.
gloeosporioides)
![Anthracnose Infected fruit](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/anthracnose1.jpg)
|
|
![Orange spores oozing out of berry](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/anthracnose2.jpg) |
Figure 11.
Anthracnose Infected fruit |
|
Figure 12. Orange
spores oozing out of berry |
Photos courtesy
of Dr. P. Bristow, Washington State University, Puyallup,
WA.
www.agf.gov.bc.ca/cropprot/blueberry.htm |
Stem Blight (Botryosphaeria dothidea)
Stem blight shows up as a wilting, browning, or reddening of the
infected leaves, which frequently precedes the death of the plant.
This is a vascular disease that most often starts from a wound
infection site. The most typical symptom would be a flag (limbs
killed by the disease that do not drop their leaves). The stems
can be cut open to reveal a light-brown discoloration.
![Symptoms of Botryosphaeria Stem Blight](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/blight1.jpg)
|
|
![Symptoms of Botryosphaeria Stem Blight](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/blight2.jpg) |
Figures 13 & 14.
Symptoms of Botryosphaeria Stem Blight |
Photos
used with permission. Bill Cline, Plant Pathology Extension,
North Carolina State University. |
Removal of infected wood, pruning about 12 inches below the discolored
part of the limb, is the only practical control for Botryosphaeria stem
blight. Since infection can spread throughout the growing season,
growers should prune during dormancy. Fertilizer management is
necessary to prevent the formation of succulent shoots late in
the season. Infection of cold-injured shoots around the base of
the bush is a primary way for this fungus to enter the plant. The
worst cases of stem blight occur on soils that are extremely sandy
or on heavy peat soils that promote excessive growth. Clove oil
inhibits fungal growth and spore germination of Botryosphaeria
dothidea and could be effective in controlling this disease
on several woody plant species such as blueberry.(Jacobs
et al., 1995) Be certain any clove oil product you use is properly formulated
and allowed in organic production.
Rust (Pucciniastrum vaccinii)
Rust is a serious leaf-defoliating problem for southern highbush
varieties. The first yellow leaf-spot symptoms appear in late spring
to early summer. The yellow spots turn reddish-brown as yellow-to-orange
pustules show up on the bottom sides of leaves. Finally the infected
leaves turn brown and drop off prematurely. Remedial action includes
removing and burning infected vegetation. Multiple reinfestations
are possible during one growing season. Native evergreen berries
(but not hemlock) are suspected as the overwintering source and
a necessary alternative host for completion of the fungus life
cycle. It may be beneficial to remove native species in the Vaccinium genus—which
include sparkleberry, huckleberry, gooseberry, and bearberry—from
areas adjacent to cultivated bushes.
Phytophthora Root Rot (Phytophthora cinnamomi)
Root rot occurs more often on southern highbush plants than on
rabbiteyes. The first symptoms are general unthriftiness leading
to yellowing and reddening of leaves. Necrosis will appear on small
rootlets and progress to a discoloration on the main roots and
crowns. Eventually the plants will drop their leaves and die. Controls
include use of clean nursery stock and good field drainage. Heavy
soils that become waterlogged or have a high water table should
be avoided. Plants can be grown on raised beds to reduce risks.
Varieties resistant to Phytophthora include the rabbiteye
varieties Premier and Tifblue and the highbush variety Gulf Coast.(Smith
and Hepp, 2000)
Blueberries’ shallow roots may benefit from the soil-disease
suppressive qualities of an organic mulch.
Phomopsis Twig Blight (Phomopsis species)
![Phomopsis Twig Blight symptoms.](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/phomopsis1.jpg)
|
|
![Phomopsis Twig Blight symptoms.](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/phomopsis2.jpg) |
Figures 15
& 16. Phomopsis Twig Blight symptoms. |
Photos
used with permission. Highbush Blueberry Production Guide,
NRAES, Cooperative Extension, Ithaca, New York. |
Tip browning and dieback are classic symptoms of this disease.
Then elongated brownish cankers up to 4 inches long appear on stems.
The fungus overwinters in infected plant parts. Spores are released
from old cankers in the spring; rain is necessary for spore release.
Temperatures ranging from 70 to 80°F encourage infections,
and moisture stress predisposes the plant to infection. The disease
is most severe after winters in which mild spells are interspersed
with cold periods. Growers should prune and destroy infected plant
parts. Avoid mechanical damage such as that caused by careless
pruning and cultivating. Avoid moisture stress by using irrigation
during dry periods. A fall application of lime sulfur after the
leaves have dropped helps reduce disease spores. Spring application
of lime sulfur should be made early before warm weather occurs,
to avoid injury to plants. Refer to your state's spray guide for
recommended rates and timing. Careful variety selection can greatly
reduce the severity of twig blight. The varieties Elliott and Bluetta
have proved resistant to Phomopsis twig blight. (Baker
et al., 1995)
![Fusicoccum Canker (Fusicoccum species)](https://webarchive.library.unt.edu/web/20090305002706im_/http://attra.ncat.org/images/blueberry/fusicoccum.jpg)
Figure 17. Fusicoccum Canker (Fusicoccum species)
Photo used with permission. Highbush
Blueberry Production Guide, NRAES, Cooperative Extension |
Fusicoccum Canker
Fusicoccum is a stem disease causing
dieback and general plant decline. This fungus overwinters in
cankers. Spores are largely disseminated by rainwater, and cold
stress may play a part in increasing disease damage. Removal of
infected plant parts is essential for control. Varieties differ
in their resistance to this disease.
Viral diseases
Control of vectors, like aphids and leafhoppers, and sanitation
of pruning and propagating materials are important steps in controlling
viral diseases. Once a plant is infected, diagnosing it and culling
it from the field is critical to prevent the virus from spreading.
Shoestring Disease
Symptoms appear as red discoloration in the midvein of a leaf,
which then develops abnormally into wavy, distorted, or crescent
shapes. Other than buying disease–free plants, destroying
wild plants near the planting, and removing diseased plants, control
does not exist. Some cultivars possess genetic resistance or tolerance.
Stunt
With this disease, plants lose vigor and become yellowish and
dwarfed. The yellow-tipped leaves remain small, rounded, and often
puckered. The only known carrier is the sharp–nosed leafhopper,
though other vectors probably exist. Diseased bushes cannot be
cured. They must be removed from the field as soon as they are
diagnosed. Agitation of the bush during removal will dislodge the
leafhoppers, causing them to move to a neighboring healthy bush.
Scorch virus
This virus causes severe dieback, blossom blighting, and significant
yield reduction on susceptible varieties, eventually killing its
host. First, the flowers turn brown and fade to a greyish color
before they fall off, though with the West Coast strain of the
virus, the dried flowers can be retained on the bush for more than
a year. Production drops off and the plants do not recover. The
virus is spread by aphids or by planting infected stock. The first
line of defense is to plant virus-free stock obtained from a nursery
that undergoes regular virus testing. Otherwise, remove infected
plants when symptoms appear and after the disease has been diagnosed
by testing. Also, control aphids in the blueberry field. Replant
with virus-free stock. Most University Extension Service State
offices have a disease diagnostic service for plant samples.
Bacterial disease
Bacterial Crown Gall (Agrobacterium tumefaciens)
The crown gall bacterium does not grow well in an acidic environment,
so this disease is uncommon where soil pH is maintained in the
optimum range for blueberries.
Back to top
Bird and Rodent Control
Birds are a common pest of blueberries. Their impact varies, depending
on location and bird density. Oregon reported up to 60% crop loss
from birds.(Main et al., circa 2000) In a Florida
study(Main
et al., circa 2000), blueberries protected with bird netting
yielded the same as those unprotected. Various methods of control
have been tried—including "scare-eye" balloons,
Mylar reflective tape, and sonic devices—with varying levels
of success. The problem with most repellents or scare tactics is
that birds become habituated to the stimulus, rendering it ineffective
after a short time. Sometimes, growers overcome this problem by
changing the stimulus frequently—e.g., switching from balloons
to Mylar tape, or moving the balloons from one site to another.
Properly applied bird netting has provided consistent and predictable
control, but it is expensive to purchase and set up. At the time
of this writing (2004), the cost for ¾-inch bird netting
14 feet wide by 100 feet long is $85 plus shipping; 14 feet by
200 feet is $175, plus shipping; while a 5000 foot roll of 14-foot
wide netting runs $1800 plus shipping. For a Web site that sells
bird netting, see www.bird-away.com.
An Illinois study (Anon., 1991) found that the yield increase
on net-protected blueberries paid 80% of the costs of installation
at a problem site. As growers report a 10-year life expectancy
for netting, the investment proved profitable by the second year.
Rodents, primarily voles, can be a problem in blueberries, because
they inhabit mulches and feed on roots and bark. Several other
soil dwellers such as moles and shrews may also be present. Shrews
are carnivores that feed on grubs and worms; however, their tunneling
can harm the plants. Rodent problems are largely confined to plantings
that are mulched and those with permanently sodded middles. Clean
cultivation provides little shelter and disturbs burrows, but it
also creates an erosion hazard. Organic alternatives include trapping,
encouraging predators (e.g., setting out perches to attract hawks,
and owl boxes for barn owls), frequent mowing of sodded middles,
and managing fencerows and adjacent areas to discourage migrants.(Hauschild,
1995)
For details on options for rodent control, please refer to ATTRA's Overview
of Organic Fruit Production. This publication also discusses
management of bird problems. Cooperative Extension and the U.S.
Fish and Wildlife Service also have information on rodent and
bird control.
Back to top
Marketing
There are a number of marketing options for organic blueberries.
Fresh blueberries can be marketed directly through roadside stands,
U-Pick operations, on-farm sales, and farmers’ markets. There
are also well-established wholesale markets for both fresh and
frozen blueberries.
While highbush blueberries are grown for both fresh fruit and
processing markets, “nearly half of the cultivated blueberries
grown are sold as fresh blueberries,” according to the North
American Blueberry Council.(Anon, no date) Since returns to the
grower usually are higher for fresh berries, most organic growers
choose that option.
As local retail markets become saturated, many growers will also
sell their berries wholesale through growers’ cooperatives.
This is a common option for organic growers, especially where organic
collectives have helped to identify premium markets. Some value-added
processing options include frozen berries, jams, and juice.
A breakthrough in value-added marketing came in the late 1990s,
when scientific research indicated special health benefits associated
with blueberry consumption.(Staff, 2000; Anon,
1999; Lazarus and
Schmitz, 2000) More farmers are now looking at marketing blueberries
as a healthy “functional” food that contains flavonoids,
vitamin C, anthocyanins, and phenolic acids.(Medders,
2001) Among
the selling points are that blueberries are a good source of antioxidants
and vitamin C, that the tannins in blueberries can help prevent
urinary tract infections, and that ½ cup of blueberries
contains only 40 calories.(Anon., 2002)
For more information about marketing options, see the ATTRA publications Direct
Marketing, Farmers' Markets, and Adding Value
to Farm Products: An Overview. On-farm, value-added blueberry
products usually require setting up a rural enterprise besides
farming, and may entail considerable additional planning, management,
and start-up expense. Co-packers are an alternative to doing
your own processing.
Blueberries are a popular “U-Pick” crop. When acreage
exceeds the capacity of U-Pick customers, whether 5 or 15 acres,
hired labor becomes necessary. One rule of thumb suggests that
10 to 15 pickers per acre are required during the height of the
harvest season.
For a good article on marketing blueberries from a New Jersey
blueberry farm, see www.newfarm.org/features/0803/NJ%20blue/index.shtml.
For more information, see Blueberry Marketing Options,
from the Northwest Berry & Grape Information Network, available
on-line at http://berrygrape.orst.edu/fruitgrowing/berrycrops/blueberry/mopt.htm.
Additionally, the Wild Blueberry Association of North America
(WBANA) Web site, www.wildblueberries.com,
promotes marketing and is an excellent source of information on
production practices.
Back to top
Economics
Organic blueberries typically sell for about 20% more than conventionally
grown blueberries. Nationally, a survey conducted by the Organic
Farming Research Foundation showed that organic blueberry growers
received between $1.00 and $3.50 per pound for fresh berries in
1997 and that wholesale prices for fresh organic blueberries were
20% to 100% higher than for conventional blueberries, depending
on supply and demand.(Krewer, 2001)
Highbush blueberries typically start producing in the third season,
and yields increase annually for the next four years. At full capacity,
blueberries yield about 3 tons per acre. As blueberries are expensive
to establish and maintain, growers often do not realize a return
on their capital investment until the seventh year. Well-maintained
blueberry bushes remain productive for at least 15 to 20 years.
Blueberries ripen fairly predictably, according to the region
in which they are grown. In heavy bearing years, market prices
can drop dramatically, with early-bearing regions faring well and
late-bearing regions doing poorly. Harvest patterns follow a sequence
beginning with rabbiteyes from Georgia and Texas, followed by highbush
berries from North Carolina and the Southern Interior Highlands
(Arkansas, Tennessee, Kentucky, and Missouri). These are followed
by the Northern Interior Highlands, New Jersey, and so on. In years
of overproduction, harvest prices do not even cover the cost of
picking. Therefore, factors affecting local supply (such as late
spring frost and the number of blueberry farms in your area) can
play a major role in profitability.
Blueberries are a highly perishable crop, and efficient post-harvest
handling is critical. Berry flats should be quickly refrigerated
following harvest. For the commercial grower, a walk-in cooler
is a must, as is a grading and packing shed. The Mississippi State
University Extension Service publication Costs & Returns
Associated with Producing Commercial Blueberries, available
on-line at http://msucares.com/pubs/publications/p2159.html,
provides more detailed information on the economics of blueberry
production, including costs for irrigation, fertilizer, yields
based on plant age, labor requirements, field operation costs for
establishment, and more. While cost and return estimates will vary
by state, the publication can serve as a useful planning guide.
For a budget showing establishment and maintenance costs for
blueberry production, see this highbush blueberry budget from Penn
State: http://agalternatives.aers.psu.edu/crops/highbush_blueberry/highbush_blueberry.pdf.
(PDF / 145 KB) Download
Acrobat Reader
Below are two of their budgets for conventional highbush blueberries
(Table 3 and 4).
Table
3. Per-acre Cost Estimates for Fresh-market Highbush Blueberries* |
Costs |
Land Preparation |
Your Estimate |
Planting year 0 |
Your Estimate |
Mature year 4+ |
Your Estimate |
|
|
|
|
|
|
|
Variable |
|
|
|
|
|
|
Custom operations |
74.60 |
|
34.80 |
|
6.00 |
|
Fertilizer |
311.00 |
|
16.00 |
|
32.00 |
|
Weed control |
0.00 |
|
129.64 |
|
212.10 |
|
Insect control |
0.00 |
|
10.88 |
|
74.85 |
|
Disease control |
0.00 |
|
0.00 |
|
103.24 |
|
Seed |
48.00 |
|
60.00 |
|
0.00 |
|
Plants |
0.00 |
|
2001.00 |
|
0.00 |
|
Irrigation |
0.00 |
|
620.00 |
|
120.00 |
|
Mulch |
0.00 |
|
250.00 |
|
0.00 |
|
Bee rental |
0.00 |
|
0.00 |
|
25.00 |
|
Labor |
8.00 |
|
400.05 |
|
5526.19 |
|
Fuel |
0.00 |
|
4.23 |
|
7.32 |
|
Maintenance |
0.00 |
|
3.12 |
|
8.07 |
|
Interest |
22.62 |
|
188.13 |
|
16.87 |
|
Total Variable |
464.23 |
|
3717.84 |
|
6131.63 |
|
|
|
|
|
|
|
|
Fixed |
|
|
|
|
|
|
Equipment |
0.00 |
|
6.22 |
|
14.71 |
|
Land |
100.00 |
|
100.00 |
|
100.00 |
|
Total Fixed |
100.00 |
|
106.22 |
|
114.71 |
|
Total Costs |
564.23 |
|
3824.06 |
|
6246.35 |
|
* Demchak, K., J.K. Harper, and G.L. Greaser. 2001. Highbush Blueberry
Production. Agricultural Alternatives. Pennsylvania State University
College of Agricultural Sciences.
Table
4. Returns above total costs for various prices and yields* |
Price |
Yield – pounds/acre |
|
4000 |
6000 |
8000 |
10,000 |
Dollars/pound |
$ |
$ |
$ |
$ |
0.75 |
-646 |
-446 |
-246 |
-46 |
1.00 |
354 |
1054 |
1754 |
2454 |
1.25 |
1354 |
2554 |
3754 |
4954 |
1.50 |
2354 |
4054 |
5754 |
7454 |
1.75 |
3354 |
5554 |
7754 |
9954 |
2.00 |
4354 |
7054 |
9754 |
12,454 |
2.25 |
5354 |
8554 |
11,754 |
14,954 |
* Demchak, K., J.K. Harper, and G.L. Greaser. 2001. Highbush Blueberry
Production. Agricultural Alternatives. Pennsylvania State University
College of Agricultural Sciences.
Back to top
Photo Credits
Figures 1 and 2. Steck, G.J., and J.A. Payne, No date. Blueberry
Maggot, University of Florida Institute of Food and Agricultural
Science.
http://edis.ifas.ufl.edu/IN198
Figures 3 and 4. Armstrong, C.D. No date. University of Maine,
Cooperative Extension.
www.umaine.edu/umext/cranberries/fruitworm.htm
Figure 5. University of Maryland Cooperative Extension Home and
Garden Information Center.
http://plantdiagnostics.umd.edu/level3.cfm?causeID=385
Figures 6, 7, and 8. Nova Scotia Agriculture and Fisheries Agriculture
Center. Delbridge, Rick. 1995. Monilinia Blight of Lowbush Blueberry.
8 p.
www.nsac.ns.ca/wildblue/facts/disease/monilini.htm
Figures 9 and 10. Delridge, Rick. 1995. Botrytis Blight of Lowbush
Blueberry. Nova Scotia Agriculture and Fisheries, Agriculture Center.
3 p.
www.nsac.ns.ca/wildblue/facts/disease/botrybli.htm
Figures 11 and 12. Dr. P. Bristow, Washington State University,
Puyallup, WA. In: Bristo, P. 2002. Blueberry Anthracnose.
Crop Protection Factsheet, British Columbia, Ministry of Agriculture,
Food and Fisheries. 5 p.
Figures 13 and 14. Cline, W.O. No date. Stem Blight of Blueberry.
Plant Pathology Extension, North Carolina State University, Fruit
Disease Information Note 9. 3p.
www.ces.ncsu.edu/depts/pp/notes/Fruit/fdin009/fdin009.htm
Figures 15 and 16. Highbush Blueberry Production Guide, NRAES-55,
published by NRAES, Cooperative Extension, P.O. Box 4557, Ithaca,
New York 14852-4557.
www.nraes.org
Figure 17. Highbush Blueberry Production Guide, NRAES-55, published
by NRAES, Cooperative Extension, P.O. Box 4557, Ithaca, New York.
14852-4557.
www.nraes.org.
Back to top
References
Anon. 2002. Remind customers of blueberry’s benefits. The
Seasonal Marketer. July. p. 8.
Anon. 2000. Blueberry elixir reverses age-related symptoms. Agriculture
Research (USDA). February. p. 23.
Anon. 1999. Blueberries may provide anti-ageing boost. Earth Save.
www.earthsave.org/news/rxhealth.htm
Anon. 1991. Cost-effectiveness of anti-bird netting for blueberries.
HortIdeas. April. p. 42.
Anon. No date. The cultivated blueberry market. North American
Blueberry Council.
www.blueberry.org
Baker, J.B., J.F. Hancock; and D.C. Ramsdell. 1995. Screening
highbush blueberry cultivars for resistance to Phomopsis canker.
HortScience. Vol. 30, No. 3. p. 586-588.
Clark, John. 1987. Associate Professor of Horticulture, University
of Arkansas at Fayetteville. Personal communication. March 18,
1997.
Cox, K.D., and H. Scherm. 2001. Oversummer survival of Monilinia
vaccinii-corymbosi in relation to pseudosclerotial maturity
and soil surface environment. Plant-Disease. Vol. 85, No. 7.
p. 723-730.
Delbridge, Rick. 1995. Monilinia Blight of Lowbush Blueberry.
8 p. Nova Scotia Agriculture and Fisheries Agriculture Center.
www.gov.ns.ca/nsaf/elibrary/archive/hort/wildblue/disease/monilini.htm
DeWitt Company. 8 DeWitt Drive, Sikeston, MO 63801. 573-472-008,
800-888-9669
www.dewittcompany.com/
Ehlenfeldt, M.K., and A.W. Stretch. 2000. Mummy berry blight resistance
in rabbiteye blueberry cultivars. HortScience, Vol. 35, No. 7.
p. 1326-1328.
Harrington, Eric, and George Good. 2000. Crop Profile for Blueberries
in New York. Cornell University. March 9. 18 p. Available from
http://pestdata.ncsu.edu/cropprofiles/docs/nyblueberries.html
Hauschild, Karen I. 1995. Vole management in small fruit plantings.
Northland Berry News. December. p. 22–24.
Jacobs, Karel A., J.C. Locke, and M. Carter. 1995. Inhibition
of Botryosphaeria dothidea mycelia growth and conidial
germination by botanical extracts, insecticidal soap and clove
oil, 1994-5. Agricultural Research Service, USDA TEKTRAN.
http://photon.nal.usda.gov/ttic/tektran/data/000006/49/0000064970.html
Kerr Center for Sustainable Agriculture P.O. Box 588 Poteau, OK
74953. 918-647-9123.
Krewer, Gerald. 2001. Suggestions for Organic Blueberry Production
in Georgia. University of Georgia. Fruit Publication 00-1. May.
www.smallfruits.org/Blueberries/
Lazarus, Sheryl A., and Harold H. Schmitz. 2000. Dietary flavonoids
may promote health, prevent heart disease. California Agriculture.
September/October. p. 33-39.
Liburd, O.E., S.R. Alm, and R.A. Casagrande. 1998. Susceptibility
of highbush blueberry cultivars to larval infestation by Rhagoletis
mendax (Diptera: Tephritidae). Environmental Entomology. Vol.
27, No. 4. p. 817-821.
Lyrene, P.M. 1994. Variation within and among blueberry taxa in
flower size and shape. Journal of the American Society of Horticulture
Science. Vol. 119, No. 5. p. 1039-1042.
MacKenzie, K.E. 1997. Pollination requirements of three highbush
blueberry (Vaccinium corymbosum L.) cultivars. Journal
of the American Society of Horticulture Science. Vol. 122, No.
6. p. 891-896.
Main, Martin B., T.A. Obreza, and Ginger Allen. circa 2000. Comparison
of ‘Gulf Coast’ blueberry yields in southwest Florida
with and without bird exclusion netting. University of Florida
Extension Service. EDIS. 6 p.
Medders, Howell. 2001. Let food be thy medicine and medicine
thy food. Arkansas Land and Life. Summer. p. 8-11.
Menge, John. 2002. Biocontrol of Phytophthora cinnamomi.
3rd California Conference on Biological Control, Davis, CA.
Moore, J.N., M.V. Brown, and B.P. Bordelon. 1994. Plant spacing
studies on highbush blueberries. Arkansas Farm Research. July-August.
P. 8-9.
Murray, D.A., R.D Kriegel, J.W. Johnson, and A.J. Howitt. 1996.
Natural enemies of cranberry fruitworm, Acrobasis vaccinii,
(Lepidoptera: Pyralidae) in Michigan highbush blueberries. Great
Lakes Entomologist. Vol. 29, No. 2. p. 81-86.
NeSmith, D. Scott, and Gerard Krewer. 1995. Vegetation-free area
influences growth and establishment of rabbiteye blueberry. HortScience.
Vol. 30, No. 7. December. p. 1410–1412.
Ngugi, H.K, H. Scherm, and J.S. Lehman. 2002. Relationships between
blueberry flower age, pollination, and conidial infection by Monilinia
vaccinii-corymbosi. Phytopathology. Vol. 92, No. 10. p. 1104-1109.
Nitron. No date. Nitron's Product Guide for Natural Fertilizers & Soil
Conditioners, published by Nitron Industries, Fayetteville, AR.
Patten, Kim, Gary Nimr, and Elizabeth Neuendorff. 1990. Evaluation
of living mulch systems for rabbiteye blueberry production. HortScience.
Vol. 25, No. 8. August. p. 852.
Penhallegon, Ross. 1992. Organic Fertilizer NPK Values. January.
In Good Tilth. p. 6.
Pritts, Marvin, and James Hancock (ed.). 1992. Highbush Blueberry
Production Guide. Northeast Regional Agricultural Guide. Northeast
Regional Engineering Service, Ithaca, NY. 200 p.
Sampson, B.J., and J.H. Cane. 2000. Pollination efficiencies of
three bee (Hymenoptera: Apoidaea) species visiting rabbiteye blueberry.
Journal of Economic Entomology. Vol. 93, No. 6. p. 1726-1731
Schwankl, Lawrence J., and Glenn McGourty. 1992. Organic fertilizers
can be injected through low volume irrigation systems. California
Agriculture. September–October. p. 21–23.
Smith B.J., and R.F. Hepp. 2000. Susceptibility of southern highbush
blueberry cultivars to phytophthora root rot. Proceedings of the
Seventh International Symposium on Vaccinium Culture , Chile. Acta-Horticulturae.
No. 574. p. 75-79.
Spiers, J.M., and J.H. Braswell. 1992. Soil-applied sulfur affects
elemental leaf content and growth of 'Tifblue' rabbiteye blueberry.
Journal of American Society of Horticulture Science. Vol. 117,
No.2. p. 230-233.
Staff. 2000. Blueberry elixir reverses age-related symptoms.
Agriculture Research (USDA). February. P. 23.
Stretch, A.W., and M.K. Ehlenfeldt. 2000. Resistance to the fruit
infection phase of mummy berry disease in highbush blueberry cultivars.
HortScience. Vol. 35, No. 7. p. 1271-1273.
Szendrei, Zsofia, Nikhil Mallampalli, and Rufus Isaacs. 2001.
Effect of cultural practices on Japanese beetle in Michigan blueberries.
Paper from the Entomological Society of America Annual Meeting,
San Diego.
Teixeira, L.A.F., and S. Polavarapu. 2001. Postdiapause development
and prediction of emergence of female blueberry maggot. (Diptera:
Tephritidae). Environmental Entomology. Vol. 30, No. 5. p. 925-931.
Watkins, Gordon. 1989. Non-toxic weed control in blueberries.
Ozark Organic Growers Association newsletter. May. p. 6–7.
June–July. p. 6–7.
Watkins, Gordon E. 1988. Organic Blueberry Culture. Proceedings
of the Seventh Annual Oklahoma Horticultural Industries Show. January
28–29. p. 45-51.
Whitworth, Julia. 1995. Blueberry helps: fertilizing blueberries.
Issue 1. In: Horticulture Tips. Oklahoma State University
Cooperative Extension. Stillwater, OK. March. 1 p.
Yang W.Q., B.L. Goulart, K. Demchak, and Y.D. Li. 2002. Interactive
effects of mycorrhizal inoculation and organic soil amendments
on nitrogen acquisition and growth of highbush blueberry. Journal
of the American Society for Horticultural Science. Vol. 127, No.
5. p. 742-748.
Back to top
Additional Resources
Baker, M.L., and K. Patten (eds.). 1990. Texas Blueberry Handbook.
Texas A&M, Overton, TX. 100 p.
Caruso, Frank L., and Donald C. Ramsdell. 1995. Compendium of
Blueberry and Cranberry Diseases. APS Press, St. Paul, MN. 87 p.
Doughty, C.C., E.B. Adams, and L.W. Martin. 1981. Highbush Blueberry
Production. Washington-Oregon-Idaho Cooperative Extension Service
Bulletin. PNW 215.
Eck, P., 1988. Blueberry Science. Rutgers University Press, New
Brunswick, NJ. 284 p.
Eck, P. and N.F. Childers (ed.). 1966. Blueberry Culture. Rutgers
University Press, New Brunswick, NJ. 378 p.
Elsner, Erwin A., and Mark E. Whalon. 1998. Common Blueberry Insect
Pests and Their Control. Michigan State University Extension. September.
www.msue.msu.edu/vanburen/e-1863.htm
Galletta, Gene J., and David G. Himelrick (eds.). 1990. Small
Fruit Crop Management. Prentice Hall, Englewood Cliffs, NJ. 602
p.
Gough, R.E. 1995. The Highbush Blueberry and Its Management. Food
Products Press, NY. 272 p.
Johnston, S., J. Mouten, and J. Hull, Jr. 1969. Essentials of
Blueberry Culture. Michigan State University Extension Bulletin.
E-590.
Moore, J.N. 1976. Adaption and Production of Blueberries in Arkansas.
Arkansas Agricultural Experiment Station Bulletin. No. 804.
Highbush Blueberry Production Guide. NE Regional Ag Engineering
Service, Ithaca, NY. 200 p. NRAES-55, published by NRAES, Cooperative
Extension, 152 Riley-Robb Hall, Ithaca, NY 14853-5701. 607-255-7654.
Scott, D.H., A.D. Draper, and G.M. Darrow. 1978. Commercial Blueberry
Growing. USDA Farmers' Bulletin No. 2254. US Gov. Printing Office,
Washington, DC. 33 p.
Back to top
Blueberry Electronic Resources on
the World Wide Web
2002 Blueberry Cultivar Trial–Quicksand
http://fp1.ca.uky.edu/robinsonstation/Horticulture/blueberry02.htm
Alternative Opportunities for Small Farms: Blueberry
Production Review
http://edis.ifas.ufl.edu/AC008
The Berry Basket Newsletter
http://mtngrv.missouristate.edu/newslet.htm
Blueberry Bookmarks, Michigan State University
www.msue.msu.edu/msue/iac/agnic/blueberry2.html
The Blueberry Bulletin
Rutgers Cooperative Extension
www.rce.rutgers.edu/pubs/blueberrybulletin/
Blueberry Citation Database
Michigan State University
Extension
www.msue.msu.edu/msue/imp/modbb/modbbb.html
The Berry Diagnostic Tool
by Dr. Marvin Pritts
Cornell University, Ithaca, NY 14853 www.hort.cornell.edu/department/faculty/pritts/BerryDoc/blueberry/BBparts.htm
A companion to the NRAES Production Guides for strawberries,
raspberries and blueberries.
Blueberry gall midge, Featured Creatures
http://creatures.ifas.ufl.edu/fruit/blueberry_gall_midge.htm
Blueberry Gardener's Guide
http://edis.ifas.ufl.edu/MG359
Blueberry Information links
www.citygardening.net/blueberryinfo/
The Blueberry News
www.hos.ufl.edu/jgwweb/BBnews_202.htm
Summer Issue, 2002 Official Newsletter of the Florida Blueberry
Growers' Association.
Blueberry Page
AgNic and MSU
www.msue.msu.edu/msue/iac/agnic/blueberry.html
Commercial Fruit Crops Advisory Program, Blueberry Module
http://mtngrv.missouristate.edu/workshops/highbush_blueberries.htm
Common Blueberry Insect Pests and Their Control
Michigan
State University
www.msue.msu.edu/vanburen/e-1863.htm
Crop Profile for Highbush Blueberry in New Jersey
http://www.pestmanagement.rutgers.edu/njinpas/CropProfiles.htm
Disease resistance in blueberry cultivars commonly grown
in Kentucky
www.uky.edu/Agriculture/kpn/kpn_02/pn020128.htm#fruit
Florida's Commercial Blueberry Industry
http://edis.ifas.ufl.edu/BODY_AC031
Paul Evans Library of Fruit Science: Small Fruit Links,
Blueberry Links
http://library.missouristate.edu/paulevans/frtlinks.shtml
Fruit and Nut Review: Blueberries
Mississippi
State University Extension Service.
http://msucares.com/pubs/infosheets/is1448.htm
Highbush Blueberry Production
Pennsylvania State
Agricultural Alternatives
http://agalternatives.aers.psu.edu/crops/highbush_blueberry/highbush_blueberry.pdf
(PDF / 145 KB) Download
Acrobat Reader
Highbush Blueberry Council
www.ushbc.org
The History of the Lowbush Blueberry Industry in Nova
Scotia, 1880–1950
www.nsac.ns.ca/wildblue/hist/kinsman1880/
The History of the Lowbush Blueberry Industry in Nova
Scotia, 1950 - 1990
www.nsac.ns.ca/wildblue/hist/kinsman5090/index.htm
Jammin’ with Kentucky Blueberries
http://fp1.ca.uky.edu/robinsonstation/jammin.htm
K-Ag Laboratories International
2323 Jackson St.
Oshkosh, WI 54901
920-426-0002
920-426-2664 FAX
info@kaglab.com
www.kaglab.com
Comparison of 'Gulf Coast' Blueberry yields in Southwest
Florida with and without bird exclusion netting
By M.
B., T. A. Obreza Main, and G. M. Allen
http://edis.ifas.ufl.edu/BODY_UW141
Maine Organic Farmers and Gardeners Association (MOFGA)
P.O.
Box 170
Unity, ME 04988
207-568-4142
207-568-4141 FAX
mofga@mofga.org
www.mofga.org
Managing Plant Diseases with Biofungicides
By
C. Thomas
www.ext.vt.edu/news/periodicals/commhort/2002-11/2002-11-02.html
November 2002. Vol. 1, Issue 11. Integrated Pest Management
Program, Pennsylvania Department of Agriculture.
Massachusetts Berry Notes, University of Massachusetts
Fruit Advisor
www.umass.edu/fruitadvisor/berrynotes/index.html
Michigan Blueberry Growers Association
www.blueberries.com
Michigan State University Extension Blueberry Site
www.msue.msu.edu/vanburen/bluebweb.htm
Midwest Small Fruit Pest Management Handbook
Ohio
State University
http://ohioline.osu.edu/b861/b861_39.html
Bulletin 861, Chapter 3, Highbush Blueberries.
The New York Berry News—Tree Fruit & Berry
Pathology
www.nysaes.cornell.edu/pp/extension/tfabp/newslett.shtml
North American Blueberry Council
www.blueberry.org
Northwest Berry & Grape Infonet
Oregon State
University
www.orst.edu/dept/infonet/
Library of Fruit Science
By Paul Evans
http://mtngrv.missouristate.edu/BBack.htm
Back issues
Plant Profile for Vaccinium angustifolia
USDA-NRCS
Database
http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=VAAN
Small Fruit—Tree Fruit & Berry Pathology
www.nysaes.cornell.edu/pp/extension/tfabp/smallfr.shtml
Small-Scale Fruit Production
http://ssfruit.cas.psu.edu/Blueberries.htm
The Southern Region Small Fruit Consortium
North
Carolina State University
www.smallfruits.org/Blueberries/index.htm
Suggestions for Establishing a Blueberry Planting in Western
North Carolina
North Carolina State University
www.ces.ncsu.edu/depts/hort/hil/hil-201.html
Transition to Organic Highbush Blueberry Production
By
Bill Sciarappa, G. Pavlis, N. Vorsa
http://hortweb.cas.psu.edu/extension/vegcrops/vegetable_gazette/
2003/may2003.htm#transition
2003.
In: The Vegetable and Small Fruit Gazette, Vol. 7, No. 5. May.
Pages unknown.
Transitioning to Organic Blueberries
www.rcre.rutgers.edu/pubs/blueberrybulletin/2003/bb-v19n08.pdf
(PDF / 305 KB) Download
Acrobat Reader
In: The Blueberry Bulletin, June 6, 2003. p. 6.
U.C. Fruit & Nut Research and Information Center
University
of California, Davis
http://fruitsandnuts.ucdavis.edu
Wild Blueberry Page
University of Maine
www.wildblueberries.maine.edu/default.htm
University of Maryland Cooperative Extension Home and
Garden Information Center
http://www.hgic.umd.edu/diagn/flow/jap_beetle.html
USDA Crop Profiles: Pest Management
http://pestdata.ncsu.edu/cropprofiles/cplist.cfm?org=crop
Weed Management in Blueberries
http://edis.ifas.ufl.edu/WG016
Wild Blueberry Association of North America
www.wildblueberries.com
Wild Blueberry Fact Sheets
www.wildblueberries.maine.edu/TOC.htm
Wild Blueberry Network Information Centre
www.nsac.ns.ca/wildblue/
By George L. Kuepper and Steve Diver
Revised
2001 by Katherine Adam
Revised 2004 by Martin
Guerena and Preston Sullivan
NCAT Agriculture
Specialists
Copyright © 2004
National Center for Appropriate Technology
IP021
Slot 30
Version 073004
Back to top |