Volume 11, Issue 12
June 13, 2003
Volume 11, Issue 12
June 13, 2003
Vegetables
Vegetable Insects
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Cucumbers.
All fields should be scouted for cucumber beetles and aphids. Fresh market cucumbers are susceptible to bacterial wilt, so treatments should be applied before beetles feed extensively on cotyledons and first true leaves. Pickling cucumbers have more tolerance to wilt but a treatment may be needed if you find 2 or more beetles per plant and significant damage can be found on the cotyledons. A treatment should be applied for aphids if 10 to 20 percent of the plants are infested with aphids. Actara, Fulfill, Thiodan or Lannate will provide aphid control. Be sure to watch for bees foraging in the area and avoid insecticide applications on blooming crops.
Melons.
Continue to scout all melons for aphids, cucumber beetles, thrips and spider mites. The treatment threshold for aphids is 20% of the plants infested with at least 5 aphids per leaf. Actara, Fulfill, Lannate and Thiodan are labeled on melons and will provide melon aphid control. Be sure to watch for bees foraging in the area and avoid insecticide applications on blooming crops.
Cucumber beetle populations have exploded in many fields and multiple applications may be needed to control infestations. The treatment threshold for cucumber beetles in watermelons is 2 per plant. Carefully check field margins, under plastic, and cracks in ground around the base of plants for beetles. Since cucumber beetles vector bacterial wilt in cantaloupes, treatments should be applied before adult beetles feed extensively on cotyledons and first true leaves. Actara, dimethoate or a pyrethroid will provide cucumber beetle control. Again, be sure to watch for bees foraging in the area and avoid insecticide applications on blooming crops. Also, you should avoid repeated use of pyrethroids to avoid flair ups with mites later in the season.
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 7-10 day schedule for corn borer control.
Potatoes.
Continue to sample fields for Colorado potato beetle adults and larvae. We are starting to see an increase in egg laying and hatch. The treatment threshold for adults is 25 beetles per 50 plants and 10 % defoliation. Once larvae are detected, the threshold is 4 small larvae per plant or 1.5 large larvae per plant. If multiple life stages are present, reduce these thresholds by one-half. 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. A corn borer spray will be needed when we reach 700-degree days (base 50). Currently we have accumulated 650 degree-days. The first corn borer spray will be needed by the end of this week or by early next week. Be sure to check our website (http://www.udel.edu/IPM/traps/latestblt.html) for the most recent moth catches in your area. Ambush, Baythroid, Furadan, Penncap, Pounce or Spintor will provide control. If you are scouting for infested terminals, the first treatment should be applied when 20-25% of the terminals are infested. Furadan or Monitor will provide the best control if you are waiting until you see infested terminals. Potato leafhoppers populations have started to increase. Controls should be applied if you find ½ to one adult per sweep and/or one nymph per every 10 leaves. Dimethoate, a pyrethroid, Actara or Provado will provide control.
We have also found our first green peach aphids in fields
where Admire, Platinum or Tops MZ Gaucho were
not used at planting. Before bloom, the treatment threshold is 2 aphids per
leaf. From bloom until 2 weeks from harvest, the threshold is 4 aphids per
leaf. Actara, Fulfill or Provado
will provide control.
Snap
Beans.
Continue to scout seedling stage fields 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. If plants are approaching the bud stage, Orthene will control thrips, leafhoppers and corn borers. Once corn borer catches reach 2 per night, fresh market and processing snap beans in the bud to pin stages should be sprayed for corn borer. Orthene or Address (acephate) should be used at the bud and pin stages on processing beans. Once pins are present on fresh market snap beans and trap catches are above 2 per night, a 7-10 day schedule should be maintained for corn borer. Lannate, Asana, Capture or Mustang are labeled. Acephate has a 14-day wait until harvest.
Sweet
Corn.
Corn borer whorl infestations range from 5 to 25% infested plants. A
treatment should be applied if 15% of the plants are infested. The best timing
for a treatment is just as the tassels are emerging from the whorls. In recent
years, Baythroid, Mustang, Penncap
or Warrior have provided effective control. The first
silk sprays will be needed as soon as ear shanks are visible. Treatment will be
needed on a 4-day schedule in
Field Crop Insects
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New
Registration.
On
Field
Corn.
Continue to sample no-till corn fields for true armyworm. We continue to find fields with above threshold levels. The treatment threshold for armyworms in corn is 25% infested plants with larvae less than one-inch long. A pyrethroid or Lorsban will provide effective control, but only if worms are less than one-inch long.
There have also been reports of grasshoppers feeding on small plants. A grasshopper treatment should be considered if you find 5-8 grasshoppers per square yard. Asana, Dimethoate, Lorsban, Furadan and Warrior will provide control, but multiple applications may be needed.
Small
Grains.
In most cases, aphid populations have been reduced by beneficial insects, especially syrphid fly larvae. We have had numerous questions about a "tear-shaped structure" attached to wheat heads. At this time, many of the syrphid fly larvae have begun to pupate so what you are finding are syrphid fly pupae
Syrphid Fly Larva
Syrphid Fly Pupae
Syrphid Fly Adult
We can find grass sawfly and armyworm larvae in numerous
fields throughout the state. In general, most sawfly larvae are large and have
already done their damage. However, we have had reports of small larvae and
head clipping in
Soybeans.
You should continue using a seed treatment for seed corn maggot control. We have also seen slugs feeding extensively on early-planted no-till fields. The only available options in soybeans are the metaldehyde baits-- TrailsEnd LG and Deadline M-Ps.
Watch all emerged fields for bean leaf beetles and grasshoppers. A treatment for bean leaf beetle will be needed from plant emergence to the second trifoliate when you find 2 beetles per ft. row and a 25% stand reduction. A pyrethroid, dimethoate or Lorsban will provide control. The treatment threshold for grasshoppers is 1 per sweep and 30% defoliation. Asana, Furadan, Lorsban, or Warrior will provide grasshopper control.
Grain Marketing Highlights -
Situation and Outlook
for
USDA is projecting
Global coarse grain supplies are reported to be reduced this
month as a result of smaller prospective crops and expanding use.
The initial calls for the release of the June 11th crop
report were bearish. It is important to note that the
Global oilseed production for the '03/'04 marketing year is
projected at a record 344 million tons, an increase of 17 million tons from
'02/'03. Foreign production is projected to increase 13 million tons from the
'02/'03 marketing year and is now forecast at 257 million tons. Global trade
estimates were also increased for soybeans this month as compared to the May
estimate.
The projected season average soybean price for '03/'04 is
unchanged from the May estimate of $4.45 to $5.45 per bushel, as compared to
$5.50 per bushel last year. Soybean meal prices for '03/'04 are projected at
$150 to $180 per short ton and soybean oil prices at 18 to 21 cents per pound, both
unchanged from last month.
The wheat situation and outlook in the June report is being
viewed most negative by commodity traders with the production estimate for
'03/'04 now placed at 2.176 billion bushels for all wheat, a 63 million bushel
increase. Carry in stocks from the '02/'03 marketing year were also increased
by 20 million bushels, imports were increased by 10 million bushels raising
total supply projections by 93 million bushels from May to June.
With no change in use projections, USDA raised the carry out
projection for the '03/'04 marketing year by 93 million bushels, now placed at
604 million bushels.
World wheat stocks tightened further this month, with
projected production dropping below year earlier levels. World wheat output for
'03/'04 was cut by 8 MT, but ending stocks were increased by 2 MT.
The season average farm price for all U.S. wheat was
decreased from last month and is now projected at $2.90 to $3.50 per bushel,
representing a 15 cent decline on both the high and low end of the price
estimate.
Marketing
Strategy.
Although this report was viewed as negative on today's open,
corn is trading very strong as we near today's close. Dec '03 corn futures are
trading at $2.43 per bushel, Nov '03 soybeans are trading at $5.81 per bushel,
with July '03 wheat trading at $3.30 per bushel. This market will continue to
stay focused on new crop development.
Old crop soybean basis is currently bidding at 15 over into
Be Sure to Scout Corn -
It is important to start to get over the corn ground to
check if there are weed breaks, particularly since we have had so much rain,
and that we have not had much shading due to the slow growing corn. Crabgrass is also one that worries me since
it is very difficult to control with a postemergence
spray. Most of the postemergence
grass herbicides (Basis Gold, Steadfast, or Option) will not control crabgrass
over 1 to 2 inches tall.
Herbicide-resistant corn (Liberty Link or Roundup Ready) gives you a
wider window for crabgrass control.
However, other weeds are likely to start emerging as well so be sure to
check your fields soon.
Field Crop
Diseases –
Wheat.
Head Scab or Fusarium head blight is being seen now in wheat. Infected heads are straw-colored and often have the pink discoloration on the glumes during wet weather. Infected seed is white and moldy appearing. Occurrence will depend more on weather conditions during the flowering period. Check when you see whole heads that are white to straw-colored. Some white heads are due to insect clipping at the base of the plant. It looks like 2003 will be a scab year which we have not had for some time. It is too early to guess how much we will see, but it will vary.
Septoria glume blotch is now evident as well. Glume blotch will cause discolored heads and reduced test weights. Sepotria leafspots have really moved up susceptible plants during the week with the rise in temperatures and steady rainfall.
Weeks of June 5 to
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Rainfall: |
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0.01 inches: June 5 2.54 inches: June 7 0.01 inches: June 9 0.20 inches: June 11 0.03 inches June 12 |
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Air Temperature: |
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Highs Ranged from 88°F on June
12 to 68°F on June 8 |
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Lows Ranged from 68°F on June
12 to 54°F on June 6 |
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Soil Temperature: |
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72°F average for the week. |
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(Soil temperature taken at a 2 inch depth,
under sod) |
Web Address for the U of D
Compiled and Edited
By:
Extension Associate -
Vegetable Crops
Cooperative Extension Education in Agriculture
and Home Economics, University of Delaware, Delaware State University and the
United States Department of Agriculture cooperating. Distributed in furtherance
of the Acts of Congress of May 8 and