North Dakota State University
NDSU Extension Service
No. 176, July 1999
http://www.ext.nodak.edu/extnews/snouts
1999 Field Days Scheduled at NDSU Research Extension Centers
MSIDA Annual Irrigation Tour on July 13
Irrigation Scheduling is Important in July and August
Analyzing Plant Problems
Microirrigation for Row Crops?
Disease Control Under Irrigation
These field days showcase the latest research being carried out by scientists with the North Dakota Agricultural Experiment Station and the NDSU Extension Service. Each station has various tours planned so call to find out the day's events.
Hettinger Research Extension Center
(701) 567-4323July 6 3 p.m. MDT Dickinson Research Extension Center
(701) 483-2348July 7 all day Williston Research Extension Center
(701) 774-4315July 8 8:30 a.m. Carrington Research Extension Center
(701) 652-2951July 13 9 a.m. Minot North Central R&E Center
(701) 857-7679July 14 9 a.m. Langdon Research Extension Center
(701) 256-2582July 15 8:30 a.m. Sidney, Montana Eastern Ag Research Center
(406) 482-2208July 21 9 a.m. MDT Casselton (rescheduled - call for Information) Agronomy Seed Farm
(701) 347-4743Late July Oakes Irrigation Research Site
(701) 742-2189Aug. 17 9:30 a.m.
The Missouri Slope Irrigation Development Association's (MSIDA) annual irrigation tour will leave Kist Livestock in Mandan on Tuesday, July 13 at 8:30 a.m. (Central Time). Transportation will be by air conditioned motorcoach. The tour will be to the Karlsruhe area to view irrigated alfalfa, corn, potatoes, and potato storage and irrigation water pumping systems. The cost of the tour will be $30, which includes refreshments, lunch and an evening meal. The tour will return to Kist Livestock about 9:30 p.m.
For those who want to join the tour on the way to Karlsruhe, the bus will stop at the Cenex station in Washburn at 9:15 am, the Cenex station in Turtle Lake at 9:45 am and at Strawberry lake at 10:15 a.m.
Throughout this spring, practically all of North Dakota has been receiving a steady supply of rainfall, which has generally negated the use of irrigation. Some areas have too much water on the ground, which has caused either delayed planting or no planting at all. However, variable rainfall events can fool you into thinking that there is enough water in the root zone and delay starting the irrigation system until it is too late.
July and August constitute the high water use period for irrigated crops. For average weather conditions, most irrigated crops will use between 0.25 and 0.3 inches of water each day. To determine when to turn on the irrigation system and schedule irrigation, it is important to know how much rain is received at each field and have some estimate of the daily water use of your irrigated crop. To measure rainfall, I recommend having two accurate rain gages (at least 2 inch diameter opening). One should be in the southwest corner of the field and one should be located in the northwest corner. I recommend these locations because during the summer about half the rain comes from the south and half comes from the west.
There are two easy ways to obtain daily estimates of crop water use. The first is to visit your local county Extension Service office and get a copy of AE-792, Irrigation Scheduling by the Checkbook Method. This circular contains tables that allow you to estimate the daily water use of most crops by knowing the maximum air temperature. The second method involves the Internet. If you have an Internet account and can browse the web, more accurate estimates of daily crop water use can be found at this web site:
Even with accurate measurement of rainfall and crop water use, you still need to check the soil moisture in the field periodically during the season. Checking the soil moisture at several sites in a field about every two weeks is a highly recommended practice.
Tom Scherer, (701) 231-7239
NDSU Extension Agricultural Engineer
tscherer@ndsuext.nodak.edu
The NDSU Plant Diagnostic Lab operates within the Extension Service on the campus of NDSU. The function of the lab is to offer campus based support to county agents and regional centers across the state, as well as provide advice on plant health problems to the citizens of North Dakota. There is a fulltime plant diagnostician on staff, as well as a lab technician and clerical support staff in the summer.
Services offered include insect and plant identification, disease diagnosis, visual herbicide injury diagnosis, limited chemical residue testing, cultural information, and control recommendations. To submit a sample, collect as much of the living plant as possible. If possible, send several plants showing similar symptoms and include a "healthy" plant for comparison. For tree samples, send one or several branches showing the symptoms of concern. If possible, take a branch with both injury symptoms and some green, healthier material. Leaves from any plant should not be wrapped or packed with wet paper toweling of any kind. Simply place the leaves between pieces of paper. Root masses are the only part of a plant that may be wrapped in plastic, but never seal a plastic bag. Insects are best sent in vials of alcohol or placed on loose packing material in a box. Please don't send live insects in the mail for identification.
Samples may be submitted with a Plant Diagnostic Lab Form (if you would like copies, please contact the lab). If a form is not available, include your name, address, phone number, email address (if appropriate), and a written narrative that contains field or planting history, pesticides and fertilizers applied, age of the plant, when symptoms were first observed, and any other information that may be relevant. A more complete history and narrative will make it possible for the lab to provide a more thorough and specific response.
The fee schedule is:
Visual/Microscopic diagnosis ND Residents
Via a County Agent
Out-of-State$15
$10
$20Culture or Special test $25 (Includes DED samples*)
*5 or more DED samples submitted at one time$15 /sample Soil Test for Pursuit Residue $125 Roundup Residue Testing $150
The lab is located in Waldron Hall, room 206. Samples may be delivered directly to the lab or sent to: NDSU Plant Diagnostic Lab, Walster Hall 306, Box 5012, Fargo, ND 58105.
Cheryl Ruby, (701) 231-7854
Plant Pest Diagnostician
diaglab@ndsuext.nodak.edu
Can microirrigation systems be used on row crops in North Dakota and be economical to install, maintain and operate? That is a question that is often asked. The answer is, it depends on what crop you want to grow, its value per acre, and the quantity and quality of your water source.
Microirrigation systems operate at low pressure and use small diameter, flexible plastic lateral pipes to apply low amounts of water through emitters or microsprinklers directly to the root zone of the crop. These systems require a lateral pipe the full length of the row, and a lateral is required for each row or every other row. Smaller volumes of water are typically applied to a field than conventional irrigation systems because less soil area is watered, thus the term "low volume" irrigation system.
Microirrigation systems are classified by the way they deliver water to the soil. The most common are drip irrigation systems (another name is trickle), but microsprinkler (also called microspray) and bubbler systems are also used extensively. Drip systems can be designated as either surface or subsurface systems. A subsurface drip system is buried anywhere from 2 to 24 inches below the soil surface. Microsprinkler and bubbler systems are always on the surface and are used primarily in orchards or landscape plantings.
Almost all components used for microirrigation systems are made from either polyvinyl chloride (PVC) or polyethylene (PE) plastic. For row crops, surface drip systems commonly use PE tubing of various diameters with either individual emitters or in-line emitters spaced equally along the tubing. Subsurface drip systems for row crops almost exclusively use drip tape. It is called tape because it comes off the roll flat and becomes round when filled with water. The most common spacing distances of emitters on the tape are 2, 8, 12, 18 and 24 inches. On the roll most tape looks similar, but tape is classified according to its wall thickness. A thicker wall means a stronger and longer lasting tape. Wall thickness is measured in "mils" where 1 mil is equal to 0.001 inch. Very thin-walled drip tape (4-mil = 0.004 inch) is only used in "throw-away" systems, which means it is replaced every year. The most popular drip tape has an 8, 10 or 12-mil wall thickness. Even thicker (15 mil or greater) tape is preferred by some growers because the cost increment is small and it provides the flexibility to use higher pressure, is less sensitive to high temperature and has reduced damage from rodents and insects.
Growers who have successfully expanded to large drip irrigation acreage have almost always begun with small 5- to 20-acre trial plots. The primary justification for most growers to shift to row-crop drip irrigation is the increased flexibility in farming operations, field access, and significant improvement in yield and quality. Although there are many benefits associated with row crop drip systems, there are still many questions that remain to be answered. What are some of the crops reported to be ideal for cultivation with microirrigation? What crops do not work well with drip irrigation? Does improvement in yield, quality, flexibility of operations and cultural costs outweigh capital and operational investment? Can drip irrigation provide improved control of diseases and pests? Based on discussions with growers throughout the western U.S., some practical observations on using drip irrigation with various crops (Table 1) have been com-piled by the Irrigation Training and Research Center in California.
Table 1. Observed crop responses to large-scale row crop drip systems.
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Type of
Response Selected Crops Comments
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Historical Strawberries Used for 20 plus years. Yield and
Successes flexibility improvements well
documented. Higher beds can be
used to aid harvesting.
Specialized cultural operations;
difficult to transfer technology
to other row crops.
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Favorable Bell Peppers Excellent response to drip.
or Excellent Yields are higher. Problems with
Responses disease control are reduced. This
is one of the most popular crops
with drip.
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Broccoli & Excellent yield response to drip.
Cauliflower
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Celery Excellent response to drip. Some
problems with root intrusion with
buried tape.
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Onions and Improvements in quality have been
Garlic substantial.
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Tomatoes Dramatically improved yields.
Reduced disease problems. On heavy
soil, subsurface tape depth may
need to be deeper to reduce soil
surface moisture.
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Watermelons Greatly improved flexibility in
entering fields. Water can be
applied during harvest.
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Variable Cantaloupe Some growers are absolutely
Responses convinced about benefits, others
have not had good results. It is
unclear what conditions cause
success or failure. Increased
flexibility for spraying and
harvesting. Fields can be
harvested multiple times while
irrigating. Ground spraying can
be done readily.
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Sweet Corn Biggest problem is that the corn
leaves a lot of trash in the
field that is difficult to
incorporate. Growers have
reported significant problems
with mice chewing the tape.
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Potatoes Some growers have reported
successes. Other growers will not
use drip on potatoes anymore.
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Lettuce Similar to cantaloupe in terms of
mixed success. Lettuce irrigation
scheduling still requires a high
degree of art. Easy to hurt the
plant by over-watering. Problems
with vigorous growth on some
varieties.
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Moderate Chives Good response to drip if holes
Responses and tapes is spaced closely.
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Cucumbers Flexibility of harvest increased.
Harvesters can enter fields while
irrigating.
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Special Alfalfa Almost no production acreage.
Cases Biggest problem is the fear of
compaction due to the number of
times harvest equipment needs to
move into the fields. "Row"
alfalfa (on beds) may be required
to limit tape/hose compaction by
having controlled wheel traffic
patterns.
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Asparagus Biggest problem is that the
fields are normally burned off
once per year. The tape must be
deep enough not to be damaged.
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Grain Grain is grown as a rotation crop.
By itself, it is uneconomical to
farm with drip.
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For more information on the basics of drip irrigation, contact your local county Extension
office and request bulletin AE-889, Trickle Irrigation for Home Gardens or give me a call.
Aung Hla, (701) 652-3194
Area Irrigation Specialist
Aung@daktel.com
Potato. The foliar diseases late blight and early blight are of particular concern under sprinkler irrigation. Avoid frequent shallow irrigation, if possible. Scout frequently, especially in wet weather. Look for late blight around the center pivot, since the crop in this area stays wet the longest. Early blight is more severe under irrigation. It also is more common on senescent foliage, with early planted or long season potatoes at greatest risk. One or two fungicide applications are needed before the rows close over to establish a fungicide residue on lower foliage that is hard to reach later on.
Several fungicides are available for late blight control, including chlorothalonil (Bravo, Terranil, Echo), mancozeb (Dithane, Manzate, Penncozeb), Polyram, tin (Super Tin, Agri Tin), Acrobat MZ, Curzate and Quadris. Tattoo C can be used in North Dakota and Minnesota under a section 18 and provides good protection to vigorously growing plants because it moves into new foliage. Curzate must be used with a protectant fungicide for purposes of resistance management and also because Curzate has a very short residual. Curzate has two days of post-infection activity. Quadris is another systemic fungicide that is effective against late blight. The plant absorbs systemic fungicides when it is vigorously growing, which makes this type of fungicide most effective when good growth is occurring. Protectant fungicides are best used early in the season, in rotation with the systemic fungicides when late blight is present or threatening, and near the end of the season when the plants are no longer actively growing. Acrobat MZ is a good anti-sporulant.
Many of the same fungicides, except for Curzate, also can be used against early blight. Quadris is especially effective against early blight. Last year it was noted that Quadris applied for early blight control also reduced tuber infections of Rhizoctonia, black scurf and silver scurf.
Potato Blight Hot Line. The potato blight hot line provides information on the status of late blight in various areas of North Dakota and adjacent Minnesota. The information is from 13 non-irrigated and seven irrigated NDAWN weather stations. It is updated three times a week and provides information on the status of late blight, whether conditions have been favorable for its spread, and what measures should be taken to control late blight. The hot line is available nationally at 1-888-482-7286. It is also available through the NDSU Plant Pathology Web site or directly at: http://www.ndsu.nodak.edu/instruct/gudmesta/lateblight/.
Pink rot also is a greater problem under irrigation. Ridomil can be applied in furrow at planting to provide suppression of pink rot and leak. It also can be applied as a spray. The first application should be made at hooking up to when the tubers are the size of a nickel. A second application should be made seven to 14 days after the first.
White mold is a problem in the Pacific Northwest under irrigation but has not been a problem in North Dakota, Minnesota or South Dakota.
White mold is a serious problem on dry beans, especially under irrigation. University of Minnesota trials at Staples, MN have demonstrated that proper irrigation management is very important. In research trials on plots irrigated when soil water tension (SWT) reached either 30 centibars (CB) or 65 CB, the best treatment, in terms of disease and yield, was irrigation when SWT reached 65 CB from planting throughout the season. For this treatment, there was a yield loss of just under 10% for unsprayed plots and about 2% for plots sprayed with a fungicide. A soil water tension of 65 CB means the soil is much dryer than a 35 CB soil water tension. A treatment that was almost as good was irrigation when the SWT reached 65 CB during the planting to 10 days into bloom stage of growth. Then, for the rest of the season, irrigation was initiated when the SWT reached 30 CB. For this treatment, yield losses were about 28% for the unsprayed and over 9% for plots sprayed with a fungicide. Unsprayed plots irrigated when SWT reached 30 CB throughout the season sustained yield losses of nearly 55%.
Other University of Minnesota research trials measured the total water (rainfall plus irrigation) that plots received from June 10 until 10 days into bloom (near the end of July). When total water during this period was 3-5 inches, the use of a fungicide on pinto beans was economic 20% of the time. When total water during this period was 5-7 inches, the use of a fungicide on pinto beans was economic 65% of the time; and when total water during this period was over 7 inches, the use of a fungicide on pinto beans was economic 85% of the time.
Benlate and Topsin M are registered for white mold control on dry beans. Although they may be applied through the irrigation system, one of the most economic and effective ways of using a fungicide is to use ground application with a directed spray, a modification of what is thought of as a band spray. Drop nozzles are used between the rows, and a nozzle is also used over the top. This provides maximum coverage of the entire plant and is most effective when nozzle pressures are 150 psi or more. The full rate should be used in the band, but if a 15-inch band is used on a 30-inch row, only half of each planted acre is sprayed, cutting fungicide costs in half. This approach works well on 30 inch rows, but it is very difficult to use drop nozzles on 22-inch rows; in this case it may be necessary to use a broadcast application. Use of broadcast air assist sprayers has been as effective as use of drop nozzles on 30-inch rows; we have no data on their effectiveness on 22-inch rows. Aerial application also has been effective for white mold control. Use of 7-10 gal/A appears more effective for aerial application of white mold fungicides than 5 gal/A.
Timing of white mold sprays is important. Data from Dr. Dick Meronuck, University of Minnesota has consistently shown that the best response from the use of Benlate or Topsin M has been application at four to 10 days after the onset of bloom. My only precaution is that waiting until nearly 10 days can cause problems if the weather turns rainy at that time, since application after 10 days is less effective.
Rust is less of a threat that it used to be, because many of the new pinto varieties are resistant to the prevailing races of rust in our area. Fields planted to susceptible pinto varieties, as well to pinks or small red beans, should be monitored routinely for rust. If two pustules are found before the lower pods are striping (have full sized beans), or if one or two hot spots develop in a field, a fungicide should be applied. Bravo and Maneb are registered for bean rust control. Bravo provides seven to 10 days of protection and Maneb provides five to seven days of protection. Both are effective as protectant fungicides, but will not stop established infections. Tilt has a section 18 emergency exemption in both North Dakota and Minnesota. Tilt is locally systemic, provides 14 days of protection and can kill infections up to four days old.
Art Lamey, (701) 231-7056
Extension Plant Pathologist
alamey@ndsuext.nodak.edu
Water Spouts, No. 176, July 1999
NDSU Extension Service, North Dakota State University of Agriculture and Applied
Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director,
Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June
30, 1914. We offer our programs and facilities to all persons regardless of race, color,
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orientation; and are an equal opportunity employer.
This publication will be made available in alternative formats for people with
disabilities upon request, 701/231-7881.
North Dakota State University
NDSU Extension Service