Volume 10, Issue 25 September 13, 2002
Volume 10, Issue 25 September 13, 2002
Vegetables
Vegetable Insects
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Cabbage.
Continue to scout for diamondback (DBM), cabbage looper (CL) and beet armyworm(BAW). DBM and CL populations have significantly increased this past week. If DBM and CL are both present, Avaunt (3.5 oz/acre), a Bt, Proclaim (3 oz/acre), or Spintor (4-5 oz per acre) will provide control. If cabbage looper is the predominant species, a pyrethroid or Confirm (8 oz/acre) will also provide control. If beet armyworm is the predominant, Avaunt, Confirm or Spintor should be used.
Lima Beans.
Be sure to continue to sample fields carefully for corn earworm. A treatment should be applied if you find one corn earworm per 6 foot of row. Since lima beans are still blooming, we continue to find small larvae at threshold levels. If possible, you should wait to treat when 1/3 of the population is 3/8-inch long. If Lannate is used, be sure to use the high rate of 2 -3 pts/acre if mixed larval sizes are present at treatment time.
Peppers.
At the present time, all peppers should be sprayed on a 5 to 7-day schedule for corn borer, corn earworm, and beet armyworm control. We can still find newly hatched beet armyworm larvae in fields. In addition, aphid populations are starting to increase in peppers. If populations increase, Lannate, Actara, Fulfill, or Provado will provide aphid control. Actara and Provado have a 0-day wait until harvest, Lannate a 3-day wait until harvest, and Fulfill a 14-day wait until harvest.
Snap Beans.
Processing snap beans in all areas of the state should be treated at the bud and pin stages for corn borer control. At the pin stage, a corn earworm spray will also be needed. After the pin stage, sprays will be needed on a 5-6 day schedule from the pin spray until harvest. You should treat fresh market snap beans for corn borers, corn earworm and beet armyworm on a 5-7 day schedule from the pin stage until harvest.
Spinach.
Continue to sample recently emerged spinach for beet armyworm and webworms. Both insects can be found at this time. Controls should be applied when worms are small and before they have moved deep into the hearts of the plants. Confirm or Spintor will be needed for beet armyworm control. If webworms are the predominant species, Ambush, Pounce, Confirm (6-8 oz/acre) or Spintor (4-8 oz/acre) should be used.
Sweet Corn.
Fresh market silking sweet corn should be sprayed on a 2-3-day schedule in all areas of the state.
Field Crop Insects
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Soybeans.
We are finally starting to see a decrease in corn earworm egg laying; however, we have seen very few diseased "worms". In general, most larvae are medium to large in size. However, we have had a few reports of economic levels of small corn earworms in soybeans planted behind sweet corn. In most cases, you should be able to make a final treatment decision by the end of this week or early next week. On the other hand, we can easily find beet armyworm egg masses and small larvae. Although we have not seen significant increases in defoliation, you will need to watch double crop beans for potential defoliation from beet armyworm until frost. In an aerial trial last week, Lorsban did give excellent control of beet armyworm when applied at 2 pts/acre of product and 5 gallons of water/acre. So at least we have another option if economic levels are still encountered. However, we are still not clear on how it works on corn earworm.
Soybean aphid can now be found in full season and double crop soybeans in all 3 counties. As of this date, it has been detected in low levels in 12 fields. Although populations are light, we can find individual plants within fields with up to 100 aphids per plant. Since late season controls have not shown an economic return and the populations are light, no controls should be needed for aphids this season. After speaking with a soybean aphid expert from the Mid-West, we are still convinced that these populations are migratory. Although the data indicates that soybean aphids need common buckthorn to overwinter, studies are being conducted with ornamental species to see if they can overwinter and reproduce on alternative hosts. We will keep you posted on the progress of this research.
Forages and Small
Grains.
Corn earworm (CEW), beet armyworm (BAW), fall armyworm (FAW) and true armyworm (AW) continue to be found in alfalfa and forages grasses. In addition, we have also found garden webworms mixed in the population. Be sure to sample all forages for these insects. Although we have no specific thresholds for defoliators in these crops, a treatment should be considered when larvae are small and before significant defoliation occurs.
Wheat.
Although we have not seen Hessian fly problems for a few years, you should still consider this pest as you make plans to plant wheat. Be sure to use a combination of the following cultural practices because there are no cost-effective chemical controls for Hessian fly: (1) Complete plowing of infested wheat stubble, (2) Crop rotation (do not plant wheat in the same field 2 years in a row), (3) Eliminate volunteer wheat before planting to prevent early egg laying, (4) Do not use wheat as a fall cover crop near fields with infestations, (5) Plant after the fly free date (Oct 3 – New Castle County; Oct 8 – Kent County; Oct 10 – Sussex County) and, (6) Plant resistant varieties – You should consider using varieties that have resistance to Biotype L.
Grain Marketing Highlights -
USDA's September Crop Report Called Neutral
This month's crop report is being called neutral to
commodity prices due primarily to the recent run up in corn, soybean, and wheat
prices at the Chicago Board of Trade. Commodity traders are now likely to turn
their attention to anticipating how close the September forecast comes to
estimating the actual size of this year's corn and soybean crops, whether there
are any crop quality problems, and whether exports keep pace with expectations.
World coarse grain ending stocks were reduced slightly from
the August report. World corn ending stocks were also reduced slightly, with
about a 2 million metric ton reduction indicated.
Marketing Strategy
The basis for new crop corn in
Forage Stand Evaluations Following Severe
Stress Conditions – Part II
Richard W.
Taylor,Extension Agronomist, rtaylor@udel.edu
As discussed in last
week’s articles, most grass fields and especially pastures had to tolerate a
prolonged hot, extremely dry summer. I
suspect that all of us have been amazed at how grasses that we thought were
dead have begun to recover since the rain we received around Labor Day. The most severely injured fields will be
pastures that were overgrazed during the drought and often grazed right down to
the soil level. It is these severely
injured fields where the following guidelines may be useful in deciding whether
to do a partial renovation before the end of this month.
Partial renovation
will consist of no-till seeding a reduced rate of grass seed into the pasture
to aid in stand recovery. In addition to
adding seed of the dominant grass, you should also add a minimal amount of nitrogen
(20 to 30 lbs N per acre) and some phosphorus and potash if soil test levels
are not at optimum. The phosphorus will
encourage strong root growth and the potash will help the plant prepare for the
stress of winter weather and regulate water use if the dry weather continues.
Last week I
suggested you take some stand counts across the pasture or hay fields in
question. In just walking over the
fields, you probably came away with a feel for whether the field will need help
from partial renovation or not. But for
those of you who prefer numerical values, I will offer some guidelines for
minimal stands below. Please keep in
mind that these are guesstimates on my part and are not based on research since
little if any has been done on this topic.
With that limitation
in mind, obtain an average count of the number of new tillers per square foot
for grasses that are coming back from underground rhizomes such as Kentucky
bluegrass, reed canarygrass, smooth bromegrass, and perhaps tall fescue. For the other species such as ryegrass,
timothy, and orchardgrass, obtain an average count of the number of plants (a
single plant will hopefully have a number of new tiller buds developing) per
square foot and compare them with the guidelines below.
Kentucky
bluegrass: 15 to 20 tillers or new
shoots per square foot
Smooth bromegrass
and reed canarygrass: 8 to 10 new shoots
per square foot or, if you can distinguish plants or plant crowns, 3 to 5
crowns showing renewed tiller growth
Tall fescue: For fields established within the past two
years, 5 to 8 plants showing new growth per square foot. For old established pastures,
Orchardgrass:
Timothy:
Ryegrasses:
In summary, I want
to again emphasize that these are my best guess of the counts you need for your
stand to recover. They can not replace
your experience or that of someone who has worked in pastures for many
years. If you’re not comfortable with the
stand you see when you walk the field to take stand counts, then it is highly
likely the pasture will respond to overseeding or partial renovation. Another possible guideline to use is the
amount of ground coverage the desirable species provide. If you can see bare soil on 50 percent of the
pasture area, then adding seed of the dominant desirable grass is likely to
help improve the stand.
Week of September 5 to
|
|
Rainfall: None. |
|
|
|
Air Temperature: |
|
Highs Ranged from 85°F
on September 9 to 77°F on September 6. |
|
Lows Ranged from 70°F
on September 10 to 52°F on September 7. |
|
Soil
Temperature: |
|
75°F average for
the week. |
|
(Soil temperature
taken at a 2 inch depth, under sod) |
Web Address for the U of D
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, Robin Morgan, Dean and Director.
Distributed in furtherance of the Acts of Congress of May 8 and