Volume 12, Issue 17
July 16, 2004
Volume 12, Issue 17
July 16, 2004
Vegetables
Vegetable Crop Insects -
Blacklight and
Pheromone Trap Catches.
Trap catches have started to
increase, especially corn borers. Since this information can be used to make
treatment decisions on sweet corn, snap beans and peppers, you will need to
check for the most recent trap catches at least twice a week. Trap catches are updated twice a week
(generally Monday and Thursday PM late) on our website (http://www.udel.edu/IPM/traps/latestblt.html)
or on the Crop Pest Hotline (1-800-345-7544
– in state only or 1-302-831-8851 – out of state).
Cucumbers.
Continue to scout for
aphids. A treatment should be applied for aphids if 10 to 20 percent of the
plants are infested with 5 or more aphids per leaf.
Lima Beans.
The earliest planted fields with pin
pods 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. You should also start scouting the earliest planted
fields for corn earworm. A treatment will be needed if you find one corn
earworm larvae per 6 ft-of-row from late flat pod stage until harvest.
Melons.
Continue to scout all melons for
aphids, cucumber beetles, and spider mites. We continue to see an increase in
the number of fields with spider mite, aphid, and cucumber beetle infestations.
Since beetles found now can often lead to damage to rinds, be sure to watch
fields carefully and treat as soon as you see an increase in the
populations. Be sure to watch for bees
foraging in the area and avoid insecticide applications on blooming
crops.
Peppers.
In areas where corn borer trap catches are above 2 per-night and pepper fruit is
½ inch in size or larger, fields should be sprayed on a 7-day schedule for corn
borer control except in the Harrington, Greenwood and Laurel areas where sprays
are needed on a 5-day schedule. You will also need to consider a treatment for
pepper maggot. If Orthene is used for corn borer control, it will also reduce
damage from pepper maggot. Otherwise, dimethoate should be added to the mix.
You should also watch for beet armyworm (BAW) larvae. Economic damage is
starting to show up and small larvae can be readily found. No threshold is
available, so you need to watch for the first small larvae as well as their
feeding. You will also need to use a product like Spintor, Avaunt, or Intrepid
which provide BAW control.
Potatoes.
Continue to scout fields on a weekly
basis for Colorado potato beetle (CPB) adults and
larvae. We continue to find economic levels of green peach aphids. A control
will be needed if you find 2 aphids per leaf pre-bloom, 4 aphids per bloom –
post bloom and 10 aphids per leaf at 2 weeks from vine kill/harvest. If melon aphids are found, the threshold
should be reduced by ½. If green peach
aphid is the predominant species, Fulfill, Lannate, Monitor, Provado, or Vydate
will provide control. If Fulfill is used, a penetrating surfactant is needed to
achieve good coverage and achieve optimum control.
Snap
Beans.
Continue to scout all
seedling stage beans for leafhopper and thrips
activity. The thrips threshold is 5-6 per leaflet and
the leafhopper threshold is 5 per sweep. If both insects are present, the
threshold for each should be reduced by 1/3. Dimethoate,
Lannate, Asana, Capture, or Warrior will provide
control of both insect pests. At this time, all fresh market and processing
snap beans in the bud to pin stages should be sprayed for corn borer. Acephate should be used at the bud and pin stages on
processing beans. After the pin spray on processing beans, sprays will be
needed on a 5-6 day schedule except in the Harrington,
Sweet Corn.
All fresh market silking
sweet corn should be sprayed on a 3-4 day schedule throughout the state except
in the
Vegetable Crop Diseases - Bob Mulrooney, Extension Plant
Pathologist, bobmul@udel.edu
Late Blight Advisory.
Disease Severity Value
(DSV) Accumulation as of July 14, 2004 is as follows:
|
Date |
Daily DSV |
Total DSV |
Spray Recommendation |
|
4/25- 5/18 |
4 |
18 |
7-day |
|
5/19 |
4 |
22 |
7-day |
|
5/20 |
2 |
24 |
7-day |
|
5/21 |
2 |
26 |
7-day |
|
5/25 |
5 |
31 |
7-day |
|
5/27 |
3 |
34 |
7-day |
|
5/30 |
8 |
42 |
7-day |
|
5/31 |
1 |
43 |
7-day |
|
6/1 |
1 |
44 |
7-day |
|
6/4 |
17 |
61 |
5-day |
|
6/7 |
2 |
63 |
5-day |
|
6/8 |
1 |
64 |
5-day |
|
6/10-6/13 |
9 |
73 |
7-day |
|
6/14-6/15 |
3 |
76 |
7-day |
|
6/16 |
3 |
79 |
7-day |
|
6/17 |
3 |
82 |
7-day |
|
6/22 |
1 |
83 |
7-day |
|
6/23 |
1 |
84 |
10-day |
|
6/25 |
3 |
87 |
7-day |
|
6/26-30 |
0 |
87 |
10-day |
|
7/1 |
2 |
89 |
10-day |
|
7/4 |
2 |
91 |
10-day |
|
7/7 |
2 |
93 |
10-day |
|
7/11 |
1 |