Volume 10, Issue 26 September 20, 2002




Vegetable Insects - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu


Lima Beans.

Continue to watch for corn earworm and apply a treatment if you find one corn earworm per 6 foot of row. 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.



All peppers should be sprayed on a 5 to 7-day schedule for corn borer, corn earworm, and beet armyworm control until then end of September. In addition, you will need to continue to watch for aphid explosions, especially if the weather turns hot and dry. 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.

All snap beans should be sprayed for corn earworm and corn borer through September.



You will need to watch for beet armyworm and webworms through the first cutting. We have seen a significant increase in beet armyworm. Right before and after the first cutting, be sure to watch for aphids. If the weather turns warm and dry like last fall, populations could increase rapidly. In addition to Lannate, dimethoate and Provado, Fulfill (2.75 oz/A) and Assail 70WP (0.8-1.2 oz/A) now have federal labels for aphid control on spinach.


Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 3-day schedule until the end of the season.



Field Crops


Field Crop Insects - Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu



Be sure to watch for corn earworm (CEW), beet armyworm (BAW), fall armyworm (FAW) and webworms defoliating fields through the month of September. Although we have no specific thresholds for defoliators, a treatment should be considered when larvae are small and before significant defoliation occurs.



At this point, very few new corn earworm infestations are being found. You will need to continue to watch double crop beans for potential defoliation from beet armyworm until frost. Lorsban or Steward can be used for beet armyworm control.


Although we have only seen an occasional soybean looper in soybeans in Delaware this season, here is some information from Ames Herbert on what they are seeing in Virginia. Hopefully this pest will stay to the south:


"Soybean looper is showing up in several soybean fields throughout much of eastern and even central Virginia. They are readily distinguished from green cloverworm by: 2 pairs of prolegs rather than 3; tail end fatter than head end (vs cloverworms that are more uniform; can have green or black head capsules (cloverworms never black); can have black true legs (cloverworms never black); and they eat a lot more leaf area worm for worm. This late season influx of soybean looper is very unusual. We always see a few in soybean fields, but I have never witnessed, in Virginia that is, this large-scale late season infestation. We did predict it however, based on the outbreaks in North Carolina.


Four major factors must be considered when making a treatment decision for soybean looper: 1) the number of worms (the threshold is 1 per sweep, or ca. 22/15 sweeps); 2) the stage of the beans (fields that are still in the pod fill stage will have to be protected if the canopy is being seriously threatened, fields that have fully filled pods may not need protection; 3) the amount of canopy that is available (full canopies can withstand more defoliation compared with marginal canopies); and 4) the yield potential of the field. This will be a tough decision for many, but soybean looper can present a serious threat to soybean and must be dealt with accordingly.


Steward is the only product that is providing consistent control from what we are hearing from states to the south of us. Pyrethroids and Lannate/Larvin are not very effective. "


Wheat and Barley.

From plant emergence until 60 days after emergence, wheat should be sampled for aphids. It still appears that the economic value of fall spraying for aphids in wheat is dependent on the aphid population level and the amount of barley yellow dwarf present in an area. When making a treatment decision, the following factors can increase the potential of a return from a fall application of an insecticide to control aphids and to reduce barley yellow dwarf (BYD) infection:

(1) Normal summer temperatures with adequate rainfall; (2) Intensive wheat management, high fertility, etc.; (3) Use of BYD susceptible varieties; (4) Early planting, especially before the Hessian fly free date; (5) Late, warm falls; and (6) Aphid numbers greater than treatment guidelines. We are still using a threshold for fall treatment for aphids of 15-25 aphids per foot of row in combination with a known history of BYDV.


One exception to the above is when greenbugs are present in wheat and barley. Along with vectoring barley yellow dwarf, this aphid species causes direct damage to wheat and barley by injecting a toxin into plants, resulting in stunting and plant death. In the fall of 2001, we did see high numbers of green bug aphid mainly in barley and early planted wheat. Entire sections of wheat fields were killed in Maryland. If you are unable to scout or plan to use a preventative treatment, Gaucho or Cruiser treated seed work very well to control this aphid. If you choose to scout, be sure you plan to sample your fields at emergence. Although we do not have any thresholds developed in our area, thresholds from Arkansas say a treatment will be needed in the fall if you find 10 aphids per foot of row. This aphid is a very difficult one to control. The Warrior label says 3.84 oz/acre are needed and the Mustang label states only aids in control. Remember that these pyrethroids are only labeled on wheat. The other materials labeled on wheat and barley include Lannate, malathion and Penncap. Dimethoate is only labeled on wheat.



Grain Marketing Highlights - Carl German, Extension Crops Marketing Specialist; clgerman@udel.edu


Harvest Pressure Impacting Corn and Soybean Prices

The anticipation and arrival of the U.S. harvest, along with soybean planting getting underway in the Southern Hemisphere, is impacting commodity prices. The U.S. corn and soybean harvest is slated to be short this year. The September crop report viewed as neutral to bullish by the trade did not have a bullish effect upon new crop corn and soybean futures prices. The reason being the pre-report run up in prices, amounting to 70 cents per bushel for Dec. corn and $1.20 per bushel for Nov. soybeans. It is not generally considered good news for the commodities market to ignore rewarding, what some viewed as, a price positive report. However, an old adage among commodity traders "Buy the Rumor - Sell the Fact" took precedence over bidding in the corn and soybean pits this past week.


The trend for new crop corn and soybean prices is still up, however, we are now in the upper one-third of the expected price range for the year. One private grain analyst estimates the average price for new crop corn ranging from $2.30 to $2.80 per bushel. The estimate for the average soybean price ranges from $5.30 to $6.00 per bushel.


Market Strategy

The current price level, $2.76 CBT price for new crop corn and $5.73 for new crop soybeans, suggests a market that must be rewarded with making a sale. It is not known for a fact whether corn and soybean prices have room for a last leg up. That depends primarily on how close actual 2002 production comes to the September crop size estimates.




Seedling Small Grains Early - Richard W. Taylor,Extension Agronomist, rtaylor@udel.edu ; Bob Uniatowski, Associate Scientist, bobuni@udel.edu


With much of the corn maturing earlier than normal, many growers are getting a head start on small grain planting, especially for barley. In a four year study, we found that planting in late September resulted in a five percent yield loss as compared with planting between October 5 and 10. The yield loss was fairly consistent across varieties and was not affected by seeding rate. When considering whether to get an early start on barley planting, keep in mind that you will experience about a five percent yield penalty.


Another potential problem especially for barley that has already been planted is the excess growth that can occur with early planting and especially in this drought affected year with high levels of available nitrogen in the soil. The excess growth can be a problem if the winter temperatures are extreme with winter damage a potential serious concern. This will also be true for wheat if it is planted too early and more than adequate available nitrogen is present.


Finally, there are potential insect interactions that may occur. Weve not seen as much damage (lodging problems) on barley compared with winter wheat with planting before the Hessian Fly-Free date, but it still could potentially impact the standability of the crop during grain fill. Certainly with winter wheat, early planting can significantly increase the risk of stalk lodging if Hessian flies lay eggs in the crop. You will need to keep an eye on all early plantings as they grow this fall to scout for foliage feeders and aphids that might cause problems.




Upcoming Events:


Pumpkin Twilight Meeting

October 3, 2002

4:30-7:00 p.m



University of Marylands Wye Research & Education Center, Queenstown, Maryland


4:30 p.m. Plots available for viewing,

5:30 p.m. Comments from the Pumpkin Team


For More Information: Contact Caragh Fitzgerald at 410-313-2710 or cf80@umail.umd.edu .





Next Week Last Issue for Weekly Crop Update 2002 - Tracy Wootten, Extension Associate-Vegetable Crops, wootten@udel.edu


Next week will be the last issue of Weekly Crop Update for 2002. It will contain a survey asking for input on the usefulness of the publication and suggestions for improvements. Please take a few moments to provide this important feedback. Your comments help us to improve the newsletter, as well as justify the time spent on this important project. Your comments are important to us positive or negative.




Thank you.





Weather Summary

Week of September 13 to September 19, 2002


0.95 inches: September 15.


Readings taken for the previous 24 hours at 8 a.m.

Air Temperature:

Highs Ranged from 83F on September 14 to 80F on September 15 & 19.

Lows Ranged from 71F on September 15 to 50F on September 13.

Soil Temperature:

73F average for the week.

(Soil temperature taken at a 2 inch depth, under sod)


Web Address for the U of D Research & Education Center:




Compiled and Edited By:

Tracy Wootten

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 June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, sex, disability, age or national origin.

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