Volume
11, Issue 16
July 11, 2003
Volume
11, Issue 16
July 11, 2003
Vegetables
Vegetable Insects
-
Lima
Beans.
As soon as pin pods are present, scout fields for lygus bugs and stinkbugs. Treatment should be considered if you find 15 adults and/or nymphs per 50 sweeps. Lannate, Capture or Warrior can be used if both species are present. A higher rate of Capture (4 oz/A), Mustang (4.3 oz/A) or Warrior (3.84 oz) will be needed if stinkbugs are the predominant insect present.
Melons.
Continue to scout all melons for aphids, cucumber beetles, and spider mites. A treatment will be needed for spider mites if you find 20-30% of the plants infested with 1-2 mites per leaf. If populations of mites have exploded and adult mites are the predominant life stage, Capture or Danitol should be used. If the population is a mixture of eggs, immature mites and lower levels of adult mites, Agri-Mek should be used at 8 oz/acre. A second miticide application may be needed in 3-7 days depending on the population level at treatment time.
Peppers.
Even though corn borer catches are low, a spray should be applied as soon as 1/2-inch fruit is present. As soon as corn borer trap catches are above 2 per night and pepper fruit is ˝ inch in size or larger, fields should be sprayed on a 7-10 day schedule for corn borer control. Pepper maggot sprays are needed as soon as fruit are present. If you are using acephate (Orthene or Address), it will provide pepper maggot control. Otherwise, dimethoate is the best control option.
Potatoes.
Continue to sample fields for Colorado potato beetle adults and larvae. Remember Actara or Provado should not be used in fields where Admire, Platinum or Tops MZ-Gaucho were used at planting to avoid the development of resistance. You will need to use Spintor, cryolite, or Avaunt plus PBO. We are still finding threshold levels of green peach aphids in fields where Admire, Platinum or Tops MZ Gaucho were not used at planting. The threshold at this time is 4 aphids per leaf. Once we are 2 weeks from harvest, the threshold increases to 10 per leaf. Provado, Fulfill, Monitor or Vydate will provide green peach aphid control. Vydate CLV formulation is now labeled on potatoes and should be used at 1.5-2 pts/acre. Provado is only labeled for ground application for aphid control. A penetrating surfactant ( e.g. LI-700 or AD-100) should be used with Fulfill.
Snap
Beans.
Seedling beans should still be watched carefully for thrips and leafhopper 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. Even though corn borer counts remain low, a treatment should be applied if defoliators are feeding on pin pods. Lannate, Asana, Warrior or Capture will provide the best control of defoliators. Corn borer sprays should be applied at the bud and pin stages on processing snap beans.
Sweet
Corn.
When you look at the corn earworm trap catches for the last seven days, fresh market silking sweet corn should be sprayed on a 3-4 day schedule throughout the state. Be sure to check the IPM website for the most recent BLT catches in your area (http://www.udel.edu/IPM/traps/latestblt.html).
Vegetable Crop
Diseases –
Update on Disease Control
on Pickles.
Last week in my attempt to provide disease control
recommendations I made a few omissions. In addition to the other strobilurin fungicides available for powdery mildew control
add
is recommended an alternative is Flouranil (mefanoxam plus chlorothalonil).
Snapbeans.
If this wet, humid weather pattern continues, look for Rhizoctonia tip rot to become a problem on snapbeans where the pods touch the soil. Growers now have
an option for control with Quadris which was labeled
after the Vegetable Recommendations Book was published. Quadris
is labeled on snapbeans, including foliar Rhizoctonia with zero days to harvest. Apply 6.2- 15.4 fl.
oz./A before the pods touch the soil. A small test
conducted here several years ago in addition to a test in
Dual Magnum Receives Special Local Need Label (Section
24c) for Use on Transplanted Cabbage and Peppers -
Dual Magnum has received a renewal of the Special Local Need
Label (Section 24c) for use on Transplanted Cabbage and Bell Peppers in
Language from the Waiver of Liability form includes, “Neither the Vegetable Growers Association of Delaware (VGAD) nor Syngenta Crop Protection Inc. recommends the use of Dual Magnum on transplanted cabbage and transplanted bell peppers. The decision to use or not to use this herbicide must be made by each individual user and/or grower on the basis of possible crop injury from Dual Magnum, the severity of weed infestations, the cost of alternative weed controls, and other factors.”
On cabbage, Dual Magnum may be applied with ground application equipment prior to transplanting or a broadcast application within 48 hours after transplanting cabbage. Use 0.5 to 1.33 pints per acre, according to soil type in a minimum of 10 gallons of water. Do not incorporate, do not use on direct-seeded cabbage, and do not use in combination with Goal. Crop maturity may be delayed.
On Bell Peppers, apply as a broadcast application with ground application equipment within 48 hours after transplanting bell peppers. Use 0.5 to 1 pint per acre according to soil type in a minimum of 10 gallons of water per acre.
Read the restrictions and further instructions for use on the label.
While I Was Away…-
As many of you know, I was in the
As a result, most vegetable crops are ten to fourteen days later than normal. Many of you have dealt with weed control problems or fertility problems as a direct result of the weather conditions.
The first several plantings of crops such as pickling cucumbers and sweet corn, even if the cultural practices were able to be followed are experiencing relatively low yields, quality problems, and in the case of sweet corn, small ears. This is a result of stress from cool temperatures, excess moisture, compaction, and extended periods of poor sunlight. Fortunately, as we move into the next group of plantings, yields and quality are improving.
All of us probably tire of blaming the weather on
everything, but its impact cannot be underestimated.
Field Crop Insects
-
Field
Corn.
Although European corn borer larvae can be found feeding in whorl stage corn, in many cases third instar larvae are the predominant stage and have already begun to borer into the midribs. Once 1/3 of the plants have larvae boring into the midribs of leaves and stalks, rescue treatments will not be very effective.
As the earliest planted corn begins to silk, watch for Japanese beetles and corn rootworm adult beetles feeding on silking corn. The decision to treat should be based on the number of beetles per silk as well as how far you are in the pollination period. In recent years, large numbers of rootworm beetles feeding on silks before 50% pollination have resulted in yield losses, especially along field edges. Under normal conditions only late planted corn fields are at risk of poor ear fill because of silk clipping by corn rootworm and Japanese beetles. However, since plant growth and development is behind this year, more fields may be at risk. A treatment is recommended on silking corn if you can find 4-5 rootworm beetles per plant or 3 or more Japanese beetles per plant and they are clipping silks to less than ˝ inch long before 50% pollination. Once brown silk is present, silk clipping will not affect ear fill.
Soybeans.
Continue to scout for grasshoppers and spider mites in seedling stage beans. We are starting to see an increase in grasshopper activity. Grasshoppers can be controlled with Asana, Baythroid, Dimethoate, Furadan, Lorsban or Warrior. Spider mites can be managed with Dimethoate, Lorsban or Parathion. With both pests, multiple applications may be needed. In addition to grasshoppers and spider mites, Japanese beetles and green cloverworm populations are starting to increase in the earliest planted soybeans. Although we rarely see economic losses from Japanese beetle feeding, losses have occurred in recent years from green cloverworm, especially on double-cropped soybeans. Small cloverworm larvae produce "window-pane" feeding holes in the leaves. As larvae increase in size, the damage will appear as large holes between the veins. In general, no controls are needed prebloom unless you find 15 larvae per foot of row and 30 % defoliation. No controls will be needed prebloom for Japanese beetle unless you find 7 beetles per foot of row and 30% defoliation. If a combination of insects are present, the threshold for each pest should be reduced by 1/3. A pyrethroid or Lorsban will provide effective control of cloverworms and Japanese beetles.
UPCOMING
EVENTS:
Farm and
Home Field Day Set for August 13
Take
a day to enjoy summertime in the country at the
Field
tours by wagon will highlight agronomic and vegetable crops. Farmers can consult with Extension
specialists about the latest research and pest control strategies.
Visitors
to Field Day can drop by the Master Gardener demonstration garden to view the
wide array of plantings. What began
several years ago as a yearly one-day display for Farm and Home Field Day has
blossomed into a large permanent exhibit for plants, including herbs,
shade-loving plants, annual flowers, perennial ground covers, decorative
grasses, a problem garden, a bog garden,
a children’s garden, and a container garden.
Children,
parents, and caregivers will learn about keeping their young children safe
during the summer months. This portion
of the program will include many interactive exhibits and demonstrations plus
costumed characters, children’s aerobics, face painting, finger printing, a
petting zoo, and car seat check. Local
4-H clubs will set up a petting zoo and food booths. Consumer, environmental and commodity groups
will staff informational booths in the Grove.
Carriage and pony rides will round out the morning’s activities.
Farm
and Home Field Day is free and open to the public, and plenty of free parking
is available. Tickets for a traditional
barbecued chicken luncheon at
For
more information, call
|
http://www.rec.udel.edu/TopLevel/Weather.htm |
Weeks of July 3 to
|
|
Rainfall: |
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0.61 inches: July 3 0.17 inches: July 6 0.02 inches: July 7 0.93 inches: July 9 |
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|
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Air Temperature: |
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Highs Ranged from 93°F on
July 6 & 9 to 75°F on July 10. |
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Lows Ranged from 75°F on July
5 to 67°F on July 3. |
|
Soil Temperature: |
|
79°F average for the week. |
|
(Soil temperature taken at
a 2 inch depth, under sod) |
Web Address for the U of D
Compiled and Edited
By:
Cooperative Extension Education in Agriculture
and Home Economics, University of Delaware, Delaware State University and the
United States Department of Agriculture cooperating,