VegNet Vol. 12,
No. 14.
On the WEB at: http://vegnet.osu.edu
If experiencing problems receiving this
fax, Call 614-292-3857
In This Issue
1. Powdery Mildew and Downy Mildew
Spotted on Pumpkins
2. Correction to the Web Location of the Pumpkin Field Day 2005 Flyer
3. Squash bugs and Squash vine borer on
the rise
3. Crop Reports
Powdery
Mildew and Downy Mildew Spotted on Pumpkins in
Pumpkins planted in mid May as a trap crop for cucumber beetles
are now showing symptoms of both Downy and Powdery Mildew.
Symptoms of Downy Mildew are very similar to Powdery
Mildew. Downy mildew will cause the upper sides of leaves to yellow and
brown out and produce grayish/white fungal masses only on the underside of
leaves.
Downy mildew of pumpkin. Symptoms on upper leaf surface (left), and olive grey lesions
underside of leaf (center) and typical symptoms in field on (right).
Powdery Mildew will produce white fungal masses on the upper and
lower leaf surface and the stem ruining quality if left uncontrolled. Also if
downy or powdery mildew cause high defoliation the fruit exposed to direct
sunlight on hot summer days may begin to show symptoms of sunscald. Powdery
Mildew will be more prevalent during drying weather; Downy Mildew will begin to
show up more often during cool, wet weather. If downy
mildew comes in, probably not before mid-late August, then the weekly
program should include a fungicide such as Tanos/Manzate,
Previcur Flex + Bravo, or Gavel + Bravo alternated
with Ridomil Gold Bravo or other fungicide with a
different mode of action (different Fungicide Group).
Powdery mildew pustules on upper leaf surface (left),
and pustules growing together on upper leaf surface (right).
The first signs of powdery mildew are pale yellow spots on leaves,
vines or petioles. These spots enlarge and become covered with white spores
that appear powdery. Scout your fields by looking at the older leaves first
although these symptoms can be found on younger leaves. Fields in low lying
areas where mist forms and remains for long periods during the night are
usually affected first. Make the first application when powdery mildew is
detected in the area or is detected by scouting (one lesion on the underside of
45 old leaves). Once powdery mildew
shows up, a good powdery mildew product should be included such as Amistar, Procure or others. Nova is also recommended for
control and rotation.
Consult the OH Vegetable Production Guide, Bull. 672 for recommended fungicides for pumpkins and other vine crops.
Correction
to the Web Location of the Pumpkin Field Day 2005 Flyer by Jin Jasinski
An incorrect web address for the pumpkin field day flyer was given
last week.
The correct address is below:
http://www.ag.ohio-state.edu/~swest/ipm/Documents/Pumpkin_20052.pdf
For more information, contact Jim Jasinski
at 937-484-1526 (office), 937-462-8016 (research station), or Jasinski.4@osu.edu.
Squash bugs and Squash vine borer on the rise...by Jim Jasinski
and C. Welty
Squash bug adults have been increasing in vine crops over the past
few weeks. Female squash bugs have been laying eggs over this same time
frame. Squash bugs eggs are rusty red in color and laid in a loose mass
of 10 - 20 eggs per cluster on the petioles and leaf undersides (see pictures
below). These egg masses are often parasitized and killed by tiny
wasps. The current threshold of greater than 1 egg mass per plant at the
time of early flowering usually justifies treatment. Insecticides are
most effective against younger and smaller nymph stages, but unfortunately may
also kill beneficial wasps and other insects in the canopy. The pyrethroids (Ambush, Asana, Capture, Danitol,
or Pounce) are good for controlling this pest if directed against stems and the
underside of leaves.
Moths of squash vine borer were detected in pheromone traps in
central
Squash
bug colony (left and center) and squash bug eggs on upper leaf surface (right).
Adult
Squash vine borer (left) and larva damage to stem (center) and uniform
yellowing of leaf caused by stem feeding (right).
Crop
Reports
Trap Counts
European corn borer: 0 for
corn ear worm: 1 for
Beet armyworm: 1 for
Water: Letart, Oh is still dry, less
than1 inch in 7 weeks. Irrigation guns and trickle going strong. Pomeroy got
4.5 inches the evening of
Tomato, pepper, eggplant and cucumber fruit under irrigation is
beautiful. Tomato harvest started with large pickings
Muskmelons are very sweet but size is somewhat smaller than normal
due to heavy water demand and lack of rain. Those under trickle are normal
size.
Sweet corn is very good where it has been irrigated but not in
un-irrigated land.