Volume
10, Issue 13
June 21, 2002
Vegetables
Vegetable Insects
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Lima Beans.
Be sure to watch for spider mites on seedling stage lima beans, especially in areas of the state that have not been receiving adequate rainfall. Both field interiors as well as field edges should be examined for mites. Look for the white stippling along the veins on the underside of the leaves. A treatment should be considered when you first notice the stippling and you find 10-20 mites per leaflet. Kelthane or Capture (6.4 oz/A) have provided the best control in lima beans. The earliest planted field should be scouted for lygus bugs and stinkbugs. Treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. Lannate, Capture or Mustang can be used if both species are present. The higher labeled rates of Capture (4 oz/A) and Mustang (4.3 oz/A) will be needed if stinkbugs are the predominant insect present.
Peppers.
Corn Borer catches have dropped below 2 per night in all
areas of the state except the Harrington,
Potatoes.
As we approach harvest on the earliest planted potatoes, be sure to continue to sample for potato leafhoppers and aphids. Both potato leafhopper adults and nymphs can be found in fields. The treatment threshold is 0.5 - 1 adult per sweep or 1 nymph per 10 leaves. Actara, Provado, Furadan or a pyrethroid will provide control. Aphid populations are still low. If fields are greater than 2 weeks from harvest, the threshold is 4 aphids per leaf. Within 2 weeks of harvest, the treatment threshold increases to 10 aphids per leaf. In general, Colorado potato beetle populations are moderate in most fields. If Admire, Platinum or Tops MZ Gaucho were used at planting be sure to alternate to cryolite, Agri-Mek or Spintor when threshold levels of larvae or newly emerged adults are detected.
Snap Beans.
In the Harrington,
Sweet Corn.
Fresh market silking sweet corn should be sprayed on a 5-6
day schedule in all areas of the state except in the Harrington,
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Pea Enation Mosaic Virus - Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu
Many pea fields exhibit the pea enation virus disease on some small percentage of plants, but it is noticeable. Stunted plants, distorted leaves, and the small, distorted pods, with only one or two peas are the typical symptoms. Some fields may have as much as 3-5% of the plants showing these symptoms.
The virus is spread by aphids. Aphids have not been a huge problem this year, but the symptoms indicate the presence and spread of the virus.
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Licensed and Bonded Produce Buyers and Dealers - Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu
Licensed and Bonded
Produce Buyers and Dealers.
The State of
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Cold Weather
Affects Fruit Set of Early Watermelons –
Some early planted watermelons havelittle to no crown fruit set due to cold growing conditions. Cool weather conditions early in the growing season may result in female flowers opening several days before male flowers, resulting in delayed fruit set.
Watermelons produce separate male and female flowers on the same vine. A female flower can be easily recognized by the swelling of its base which resembles a tiny watermelon. Normally a female flower may be found at every seventh to tenth node. Thus, plants usually produce about 10 times more male flowers than female flowers.

Female (left) and male
(right) flowers
(Photo taken from
For successful pollination to occur, both female and male flowers must be open on the same day. The minimum temperature for the opening of watermelon flowers is 59° F.
Optimum growth of watermelon plants is achieved at temperatures of 68-86°F.
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Vegetable Diseases - Kate
Everts, Extension Vegetable Pathologist, University of
Watermelons.
From the
Latest
EFI values from local weather stations
Any questions please call (410) 742-8788
EFI Values (Environmental Favorability Index)
Do
not use MELCAST if there is a disease outbreak in your field, it is a preventative program.
Location
Charles Co. 1 0 0 1 9 9 2
Collins Farms 1 1 3 1 3 4 1
Vincent Farms 1 2 2 1 3 7 1
White Marsh 1 2 0 1 6 7 3
The first fungicide
spray should be applied when the watermelon vines meet within the row. Additional sprays