Volume 10, Issue 11
June 7, 2002
Volume 10, Issue 11
June 7, 2002
Vegetables
Vegetable Insects
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Melons.
Economic levels of cucumber beetles, aphids and spider mites continue to be found. If Agri-mek is used for spider mite control, it should not be combined with Bravo Weather-Stik or fungicides with similar stickers. These materials prevent the material from moving into the leaves. It can be combined with Quadris. Actara or Fulfill can be combined with Bravo Weather-Stik as long as an 80:20 surfactant is also used. Since most melon fields are in bloom or starting to bloom, it will be important to exercise caution when applying insecticides to avoid bee kills. Many of the insecticides labeled for melons have the following label restriction: "Toxic to bees exposed to direct treatment or to residues on blooming crops and weeds. Do not apply or allow it to drift on blooming plants if bees are foraging in the area." So, be sure to check the label before making an insecticide application during bloom. One way to reduce exposure to bees is to make applications late in the evening when bees are not foraging in the area.
Peppers.
Although most peppers are just starting to set flower buds we should see significant bloom starting next week. Although corn borer stem tunneling has been observed, we have not seen significant damage. In general, the first corn borer sprays are needed when fruit is ˝-inch in size or larger. Sprays should then be applied on a 7–10 day schedule depending on material selection and corn borer pressure. Orthene or Address (both acephate) should be used on a 10-day schedule and will also provide pepper maggot control. Remember - only 2 applications of acephate at the 1 1/3 lb. per acre rate can now be used. If a pyrethroid or Lannate is used, sprays should be applied on a 7-day schedule and dimethoate should be added to the mix for pepper maggot control.
Potatoes.
Continue to sample potatoes for Colorado potato beetle, ECB egg masses and stem tunneling and potato leafhoppers. In the earliest planted fields, the at-planting treatments of Admire, Platinum and Tops MZ Gaucho are all starting to break at the same time for Colorado potato beetle control. If economic levels of larvae are found in these fields, Spintor or cryolite should be used for beetle control. In order to prevent the development of resistance, foliar applications of Provado or Actara should not be used if at planting treatments of Admire, Platinum, or Tops MZ Gaucho were used. In many fields, ECB sprays will be needed by the end of this week or early next week.
Snap
Beans.
We continue to see an increase in thrips activity, especially in seedling stage beans. The thrips threshold is 5-6 per leaflet. Lannate, Asana, Capture, or dimethoate will provide control.
Sweet Corn.
Continue to watch the earliest planted fields for European
corn borer larvae. A treatment should be
applied if 15% of the plants are infested. As the earliest planted fields begin
to silk, the first silk sprays will be needed as soon as ear shanks are
visible. In
Sandea For Cucumbers - Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu
A special local-needs 24c label has been approved for use of
Sandea postemergence in
It should be applied when the crop has 2-4 leaves and has not yet begun to run. The rate is 0.5 – 0.66 dry ounces per acre, with non-ionic surfactant at 0.25 percent of the volume. DO NOT USE IF ORGANOPHOSPHATE INSECTICIDES HAVE BEEN APPLIED TO THE CROP. Read the label for complete details.
Approved last year, Sandea did an excellent job in several severe nutgrass outbreaks in pickling cucumbers.
Vegetable Diseases -
Kate Everts, Extension Vegetable Pathologist,
University of
The weather based forecasting program MELCAST has begun for 2002. If you signed up to receive a report, it should have started this week. If you have not received any reports, please call Lisa Dorey at (302) 856-7303 and give us your name and Fax number or e-mail address. In addition, this information is available on the web at http://www.agnr.umd.edu/users/vegdisease/vegdisease.htm.
To use MELCAST for watermelons, apply the first fungicide spray when the watermelon vines meet within the row. Additional sprays should be applied using MELCAST. Accumulate EFI (environmental favorability index) values beginning the day after your first fungicide spray. Apply a fungicide spray when 30 EFI values have accumulated by the weather station nearest your fields. Add 2 points for each overhead irrigation. After a fungicide spray, reset your counter to 0 and start over. If a spray has not been applied in 14 days, apply a fungicide, reset the counter to 0 and start over.
Because of widespread resistance to Quadris in our area, chlorothalonil (Bravo, Equus or Terranil) is recommended when spraying according to MELCAST. If, for some reason, a serious disease outbreak occurs in your field, return to a weekly spray schedule.
In addition to MELCAST for Watermelon, we have added two models that are designed to help you make decisions on when to spray for diseases. MELCAST for Cantaloupes is a fungicide application program for Alternaria leaf blight. It can be used by anyone growing a powdery mildew resistant variety such as Athena. To use MELCAST for Cantaloupe, apply the first fungicide spray when the cantaloupe vines meet within the row. Additional sprays should be applied using MELCAST. Accumulate EFI (environmental favorability index) values beginning the day after your first fungicide spray. Apply a fungicide spray when 20 EFI values have accumulated by the weather station nearest your fields. Add 2 points for each overhead irrigation. After a fungicide spray, reset your counter to 0 and start over. If a spray has not been applied in 14 days, apply a fungicide and reset the counter to 0 and start over.
TOMCAST is a spray forecaster for leaf blights and fruit diseases of processing tomato. However, it does not work for bacterial diseases. In fields that are not rotated away from tomatoes and in late-planted fields begin sprays shortly after transplanting. In all other areas begin sprays when crown fruit are one-third their final size. Additional sprays can be scheduled using TOMCAST. Sprays should be applied after accumulating 18 DSV’s (disease severity values) since the last fungicide application. Scout fields for late blight. If late blight occurs, additional sprays are warranted (see Delaware Extension Bulletin137).
The three disease models are available at http://www.agnr.umd.edu/users/vegdisease/vegdisease.htm. In addition you can receive the models by e-mail or fax. To sign up please call Lisa Dorey at (302) 856-7303.
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. 0 2 0 0 0 2 2
Collins Farms 0 0 0 2 1 3 1
Galestown, MD 0 0 0 3 1 3 1
Glenville, MD 0 0 0 0 7 2 2
Vincent Farms 0 0 0 2 0 4 1
White Marsh 0