Volume 8, Issue 16 July 7, 2000
Volume 8, Issue 16 July 7, 2000
Vegetables
Vegetable Insects - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Lima Beans.
Continue to sample for spider mites on seedling stage lima beans. A treatment should be considered when you first notice the stippling and you find 10-20 mites per leaflet. Kelthane should provide effective control. The Kelthane MF formulation is the only formulation labeled on lima beans and snap beans. Lygus and stinkbug populations continue to increase. Be sure to sample fields as they approach the bud stage. A treatment is needed if you find 15 lygus or stinkbugs per 50 sweeps. Lannate will provide control of both insects.
Peppers.
At the present time, all peppers in the Dover, Frederica, Harrington, Laurel, Middletown, Milford, and Rising Sun areas that have fruit ½ inch in size or larger should be sprayed on a 7-10 day schedule for corn borer and pepper maggot control.
Potatoes.
We are starting to see economic levels of green peach aphids in potatoes. Before 2 weeks from harvest, the threshold level is 4 per leaf. Within 2 weeks from harvest, the threshold increases to 10 per leaf. If green peach aphid is the predominant species, Provado, Monitor or Fulfill will provide control. Lannate, Provado or Fulfill will provide melon aphid control. Monitor will not control melon aphids. If Fulfill is used, remember it is a selective aphicide. The use rate is 2.75 oz/acre. Aphids stop feeding immediately after application; however, they may remain on the plants for 2-4 days before they die. We have also seen an increase in second generation adult Colorado potato beetle activity. If Admire was used at planting or Provado was applied on the first generation, you should switch to Spintor for adult beetle control. Depending on the population level, the use rate is 5-6 ounces per acre.
Snap Beans.
Leafhoppers and thrips remain active in seedling stage snap beans. A treatment is needed if you find 5-6 thrips per leaflet or 5 leafhoppers per sweep. If both insects are present, the threshold of each should be reduced by ½ the level for each insect. In the Dover, Frederica, Harrington, Laurel, Middletown, Milford, and Rising Sun areas, corn borer sprays should be applied on processing snap beans in the bud and pin stages and on all fresh market snap beans where pin pods are present. In all other areas, corn borer sprays will be needed when trap catches reach the 2 to 5 per night range.
Sweet Corn.
Fresh market silking sweet corn should be sprayed on a 4-5 day schedule in all areas of the state. Be sure to watch for trap increases that usually occurs in early July. Check the Crop Pest Hotline on Tuesdays and Fridays for the most recent trap catches in your areas (in-state: 1-800-345-7544; out-of state: 1-302-831-8851) or our website at http://www.udel.edu/IPM/latestblt.html. Fall armyworm larvae can be found in later planted fields. A treatment will be needed if 15% of the plants are infested. Lannate, Spintor or Warrior will provide control. Materials must be washed into the whorls and 2 treatments are generally needed for control.
Vegetables - - Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
A new fungicide with an old (but tried and true) active ingredient was recently registered for use in Delaware. Griffin L.L.C. registered its new chlorothalonil fungicide Equus 720 on a wide range of crops. The label is the same as for Bravo Weather Stik and the same concentration of active ingredient, 720 grams /liter. Be sure to read the label for crops registered and application information.
Rhizoctonia pod tip rot is present in some fields of snapbeans. Pods in contact with the soil will develop reddish sunken areas and rot. Nova is registered for this disease. Apply 4-5 oz/A when pods begin to develop. Continue applications every 7-10 days.
Be on the lookout for sweet corn rust. Look for the small red pustules. Once observed on corn in the whorl stage or earlier, apply a fungicide such as Bravo (fresh market only), mancozeb, or Tilt for control. Older corn will not benefit from an application.
Early blight is beginning to appear in potatoes at low levels on susceptible varieties. Apply Quadris at the 6.2 fl oz rate/A on a 14-day schedule. Apply mancozeb or Bravo between Quadris applications. Look on the oldest leaves first for symptoms of early blight. Early blight produces small circular, brown spots that look like target boards with concentric rings of dead tissue.
Cucurbits.
Maintain applications of Bravo or mancozeb for control of foliar diseases according to Melcast predictions or weekly. At the first sign of powdery mildew begin alternating Quadris or Flint with Bravo (chlorothalonil) plus Nova (5oz/A) every 7 days. Begin the powdery mildew control program with the strobilurin fungicides (Quadris or Flint).
Laurel Farmer's Auction Market Report
|
Quantity |
Produce |
Price |
|
2,393 |
Cantaloupes |
0.50-1.00 |
|
988 |
Sugar Babies |
1.45-1.70 |
|
219 |
Honeydews |
0.30-1.00 |
|
105 |
Watermelons |
|
|
|
Jade Star |
|
|
|
15 up |
1.55 |
|
|
Sangria |
|
|
|
20 up |
2.55 |
|
1 |
Peppers |
|
|
|
Green |
10.50 |
|
85 |
Tomatoes |
|
|
|
Red |
12.00-13.50 |
|
364 |
Sweet Corn Doz. |
1.25-1.55 |
|
3 |
Cucumbers |
3.00-7.50 |
|
11 |
Squash |
|
|
|
Yellow |
3.00-5.50 |
|
|
Green |
3.00-8.00 |
|
14 |
Potatoes |
|
|
|
Red |
6.00-13.00 |
|
17 |
String Beans |
6.00-11.00 |
Late Blight Update - - Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
|
Emergence Date |
DSV’s July 5 |
Recommendation |
|
April 14 |
143 |
5-day, mid rate |
|
April 21 |
116 |
5-day, mid rate |
|
April 27 |
104 |
5-day, mid rate |
|
May 20 |
56 |
5-day, low rate |
|
May 24 |
56 |
5-day, low rate |
Accumulated 8 DSV’s since the last report.
It is not likely that more DSV’s will accumulate over the weekend. The 5- day spray schedule is in response to the favorable weather of last week. I know that this is not possible for most growers.
I did have a confirmed report of some late blight hits on the eastern shore of Virginia. It was very minor and no losses are anticipated. Their plant pathologist is pretty sure that the source of the late blight inoculum was from volunteer plants in nearby fields and not seedborn. We have had weather that has been very favorable for late blight development but either seed treatments and/or your protective sprays are doing the job. Most importantly, seed has been free of the disease.
Vegetable Diseases - Kate Everts, Extension Vegetable Pathologist, University of Delaware and University of Maryland; everts@udel.edu
EFI Values (Environmental Favorability Index)
Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program. Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu
|
Location |
6/28 |
6/29 |
6/30 |
7/1 |
7/2 |
7/3 |
7/4 |
7/5 |
|
Bridgeville, DE |
4 |
2 |
1 |
2 |
1 |
2 |
3 |
3 |
|
Laurel, DE (Collins Farms) |
5 |
2 |
3 |
2 |
2 |
4 |
3 |
4 |
|
Galestown, MD |
5 |
2 |
2 |
1 |
0 |
0 |
3 |
2 |
|
Georgetown, DE |
1 |
9 |
2 |
2 |
|
1 |
3 |
1 |
|
Hebron, MD |