Volume 9, Issue 14 June 29, 2001
Volume 9, Issue 14 June 29, 2001
Vegetables
Vegetable Insects - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Lima Beans.
Continue to scout fields for lygus bugs and stinkbugs. Treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. Lannate or Capture can be used if both species are present. A higher rate of Capture (4 oz/A) will be needed if stinkbugs are the predominant insect present. You should also watch for an increase in green cloverworm populations. A treatment will be needed if defoliation exceeds 20% prebloom or 10% during podding. Lannate or Capture will provide control.
Melons.
Although spider mites can still be found in most fields, economic levels are not widespread. As the temperatures increase, be sure to watch for increases in populations. A treatment will be needed if you find 20-30% of the plants infested with 1-2 mites per leaf. Agri-Mek and Capture have both provided effective control this season. Aphid populations continue to be at economic levels in many fields. A treatment is needed if 20% of the plants are infested with 5 or more aphids per leaf. Actara (3 oz/A) Fulfill (2.75 oz/A) or Lannate LV (1.5 pt/A) will provide control.
Peppers.
Since corn borer catches remain low, corn borer controls will not be needed until trap catches increase to above 2 per night and pepper fruit is ½ inch in size or larger. However, pepper maggot sprays are still needed. Dimethoate will provide control.
Potatoes.
Continue to sample for potato leafhoppers and aphids. The treatment threshold for leafhoppers is 0.5 - 1 adult per sweep or 1 nymph per 10 leaves. Provado, Furadan or a pyrethroid will provide control. The treatment threshold for aphids is 4 per leaf before 2 weeks from harvest and 10 per leaf within 2 weeks of harvest. Colorado potato beetle populations are moderate in most fields. If Admire was used at planting, be sure to alternate to Agri-Mek or Spintor when threshold levels of larvae or newly emerged adults are detected. If Admire was not used, then Provado, Leverage or Actara can be used.
Snap Beans.
Once corn borer catches start to increase again, fresh market and processing snap beans in the bud to pin stage will need to be sprayed for corn borer. Seedling beans should still be watched carefully for thrips and leafhopper activity. We continue to see an increase in leafhopper and thrips activity. If both insects are present, the threshold for each should be reduced by 1/3. The thrips threshold is 5-6 per leaflet and the leafhopper threshold is 5 per sweep. There have also be reports from consultants of increases in green cloverworm activity. In addition to feeding on the leaves, they are also feeding on the pin pods. A treatment will be needed if defoliation exceeds 20% prebloom, 10% during podding or if pin pod damage is observed. If populations are high, a pyrethroid or Lannate should be used.
Sweet Corn.
Although corn earworm catches have dropped significantly, fresh market silking sweet corn should still be sprayed on a 5-6-day schedule throughout the state except in the Seaford area where sprays are needed on a 3-4 day schedule. 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 the IPM website which is updated three times per week at http://www.udel.edu/IPM/traps/latestblt.html.
True Armyworms Still Active.
We are still finding economic levels of true armyworms
present in a number of unusual situations: peas, lawns, later planted field and
sweet corn and grass hay mixtures. Although true armyworm activity is usually
over by now, the higher and longer than normal flight period of the first
generation has resulted in extended feeding activity. Be sure to watch fields
and treat if economic damage is occurring.
Vegetable Diseases
- - Bob Mulrooney,
Extension Plant Pathologist; bobmul@udel.edu
Potatoes.
Late Blight Update
|
Date |
Total DSV |
Spray Recommendation |
|
5/16 |
0 |
|
|
5/17 |
11 |
|
|
5/20 |
29 |
|
|
5/30 |
51 |
5-day, low rate |
|
6/3 |
57 |
5-day, low rate |
|
6/5 |
57 |
5-day, low rate |
|
6/7 |
57 |
7-day, low rate |
|
6/11 |
59 |
10-day, mid rate |
|
6/13 |
60 |
10-day, mid rate |
|
6/17 |
76 |
7-day mid rate |
|
6/20 |
76 |
7-day high rate |
|
6/24 |
88 |
7-day high rate |
|
6/27 |
88 |
7-day high rate |
Growers should be applying a fungicide for foliar diseases. The current weather pattern will not be favorable for late blight, but early blight will continue to be favored.
There have been no reports of late blight on potatoes from our region.
To control pink rot caused by Phytophthora erythroseptica and P. nicotianae, and leak caused by Pythium apply Ridomil Gold MZ, Ridomil Gold /Bravo, or Flouronil between the time the potatoes are nickel-sized until flowering, and repeat 14 days later.
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 David Armentrout at (410) 742-8788 or e-mail: da88@umail.umd.edu
|
Location |
6/20 |
6/21 |
6/22 |
6/23 |
6/24 |
6/25 |
6/26 |
6/27 |
|
Bridgeville, DE |
2 |
1 |
2 |
2 |
2 |
2 |
2 |
1 |
|
Laurel, DE (Collins Farms) |
3 |
2 |
3 |
1 |
5 |
2 |
3 |
2 |
|
Galestown, MD |
2 |
2 |
3 |
2 |
3 |
1 |
2 |
1 |
|
Georgetown, DE |
2 |
2 |
4 |
|
7 |
1 |
2 |
1 |
|
Hebron, MD |
3 |
2 |
3 |
1 |
4 |
2 |
3 |
2 |
|
Salisbury, MD |