Volume 10, Issue 16                                                                                                    July 12, 2002



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



Continue to scout for aphids. A treatment should be applied for aphids if 10 to 20 percent of the plants are infested with aphids.


Lima Beans.

Be sure to watch for economic levels of leafhoppers in fields throughout the state. Remember, most labeled insecticides will only provide 7-10 days of control.  In fields with pin pods, you should sample for earworm, lygus and stinkbugs. A treatment should be applied if you find one corn earworm per 6 foot of row or 15 tarnished plant bugs and/or stinkbugs per 50 sweeps. Lannate, Mustang or Capture can be used to control all 3 insects on lima beans.



At the present time, all peppers that have fruit ½ inch in size or larger should be sprayed on a 7-10 day schedule for corn borer and pepper maggot control. We are also starting to see an increase in aphid populations in peppers. Remember a continuous pyrethroid program should not be used to avoid aphid explosions.


Snap Beans.

In areas where we have started to see an increase in corn borers moth catches - Bridgeville, Dover, Harrington, Milford , Laurel and Seaford ---a corn borer spray will be needed at the bud and pin stages on processing snap beans.  Orthene or Address should be used on processing snap beans for corn borer control at the bud and/or pin stages. After these stages, Lannate, Capture or Mustang should be used.  In these same areas, you should begin treating fresh market snap beans for corn borers on a 7-day schedule from the pin stage until harvest. Lannate, Capture or Mustang should be used. Continue to watch for defoliators feeding on the pin pods. A treatment should be applied if defoliators are feeding on pin pods.  Lannate, Asana, Mustang or Capture will provide the best control of defoliators. Be sure to check for the most recent trap catches in your area by calling 1-800-345-7544(in-state), 1-302-831-8851(out of state) or checking our website - http://www.udel.edu/IPM/traps/latestblt.html.Trap catches are updated on the IPM website three times per week. We have also included a new link on this page for ECB moth trap thresholds for processing snap beans.


Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 4-day schedule except in the Harrington and Seaford areas where sprays are needed on a 3-day schedule.  The first spray should be applied as soon as ear shanks are visible. Be sure to also sample late-planted fields for fall armyworm larvae. No controls will be needed until 15% of the plants are infested.  Spider mites have also been reported in fresh and processing sweet corn. If numbers are increasing and plants are yellowing, a treatment should be considered. Metasystox-R is the only insecticide labeled for sweet corn in our area. Capture is not labeled for coastal counties. Be sure to check for the most recent trap catches in your area by calling 1-800-345-7544(in-state), 1-302-831-8851(out of state) or checking our website  at  http://www.udel.edu/IPM/traps/latestblt.html.  Trap catches are updated on the IPM website three times per week. We have also included a new link on this page for ECB and CEW moth trap thresholds for silking sweet corn. In many years, dry weather conditions often lead to quick increases in corn earworm populations so be sure to check trap catches frequently.




Pickling Cucumber Yields and Quality -Ed Kee, Extension Vegetable Crops Specialist; kee@udel.edu


The varieties used for the machine harvest pickling cucumbers are female (gynoecious or predominantly female) hybrids.  The typical ratio in a mixture of seed is 88% female hybrid and 12% male variety to provide the pollen for fertilization and subsequent fruit set.  The use of the female hybrids at high populations (50-60,000 plants per acre) helps achieve a concentrated set of fruit, which facilitates the once-over mechanical harvest.


High temperatures will induce male flower development in the female hybrids.  This is aggravated by long days and any moisture stress.  We have seen examples of this in some non-irrigated corners of fields or in fields where mechanical problems have hindered irrigation.  Other stresses, such as fertility, herbicide injury, or soil compaction can also cause a change in sex expression.


Yield reductions obviously occur under such situations, but increased deformed fruit, known as crooks and nubs also occurs.   Pickling cucumbers that are blossoming, setting fruit, and planted in high populations for mechanical harvest are using over ¼ inch of water per day when temperatures are in the 90s.


Good irrigation management is needed to maximize the investment in production and in bee rentals and to achieve good yields and quality.



Laurel Auction Market Opens  - Tracy Wootten, Extension Associate – Vegetable Crops, wootten@udel.edu


The Laurel Auction Market officially opened on July 8, 2002.  Current prices reflect a strong market for sellers.  Daily prices at the Auction Market, can be accessed at the following website:


 or by phone at (302) 875-3358.







Vegetable Diseases -  Kate Everts, Extension Vegetable Pathologist, University of Delaware and University of Maryland;  everts@udel.edu


MELCAST for Watermelons.

From the University of Maryland and University of Delaware

Latest EFI values from local weather stations

Any questions please call (410) 742-8788


EFI Values (Environmental Favorability Index)

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program. 

  Location              07/10/02     07/09/02     07/08/02     07/07/02     07/06/02     07/05/02     07/04/02     07/03/02

  Bridgeville, DE                1               0               1               1               1               1               1

  Charles Co.                    2               0               0               0               0               0               0

  Collins Farms                 2               0               1               1               0               1               0

  Galestown, MD              2               0               1               1               0               2               1

  Georgetown, DE             0               1               1               0               1               2               4               3

  Glenville, MD                  2               0               0               0               0               0               0

  Hebron                          2               0               1               1               0               1               0

  Hog Creek Rd.               1               0               0               0               0               0               0

  Salisbury, MD                3               0               2               0               0               1               3               0

  Vincent Farms               2               0               1               1               2               3               0

  Westminster                  2               0               0               0               0               0               0

  White Marsh                  2               0               0               0               0               0               0

  The first fungicide spray should be applied when the watermelon vines meet within the row.  Additional sprays

  should be applied using MELCAST.  Accumulate EFI (environmental favorability index) values beginning the

  day after your first fungicide spray.  Apply a fungicide spray when 30 EFI values have accumulated by the

  weather station nearest your fields.  Add 2 points for every overhead irrigation.  After a fungicide spray, reset

  your counter to 0 and start over.  If a spray  has not been applied in 14 days, apply a fungicide and reset the

  counter to 0 and start over.  The first and last day listed above can be partial days so use the larger EFI value

  of this report and other reports for any specific day.


  If, for some reason, a serious disease outbreak occurs in your field, return to a weekly spray schedule.


More detailed information concerning MELCAST and sample data sheets are available on the web at http://www.agnr.umd.edu/users/vegdisease/vegdisease.htm.



Vegetable Diseases -  Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Potato Disease Advisory.


Late Blight Advisory


Disease Severity Value (DSV) Accumulations as of July 9, 2002 are as follows:

Location: Joe Jackewicz Farm, Magnolia, DE. Greenrow: April 10, 2002

Remember that 18 DSV’s is the threshold to begin a spray program for late blight.



Total DSV

Spray Recommendation






 5 days, low rate



10 days, low rate



10 days low rate



10 days low rate



7 days, low rate



7 days, mid-rate



10 days, mid-rate



7 days, high-rate



10 days, high-rate



5 day mid- rate



10 day mid-rate



7 day high rate



10 day high rate



10 day high rate



10 day high rate


Late blight has not been a problem here in Delaware for many years and unless you have seed from an unknown source the risk of late blight is very low.


NOTE: For this greenrow date and location we have accumulated 644 P-days as well. P-days are a measure of potato plant growth somewhat similar to growing-degree-days. When 400 P-days have been exceeded conditions for early blight infection are more favorable and disease may begin to show up 5-7 days later. Continue fungicide sprays for early blight.


The hot, dry weather is not conducive for foliar diseases except early blight.

With harvest underway I have seen the first samples of pink rot. Look for darkened lenticels and infection from the stem end. When infected tubers are cut the infected creamy white but firm potato flesh turns pink in 10-15 minutes depending on conditions. Grade carefully to remove infected potatoes. Leave any areas in the field and harvest after the potatoes have decayed. Pink rot favors low areas or compacted areas.


Sweet Corn.

Be on the lookout for foliar diseases on irrigated sweet corn. We have seen some isolated outbreaks of gray leafspot and Northern corn leaf blight on processing sweet corn. Unfortunately, there is not much information from our area on the impact of these diseases on quality or yield. Under most circumstances fungicides are not warranted but Tilt, Quadris, and mancozeb are labeled for control of most foliar diseases of sweet corn. Bravo (chlorothalonil) is not labeled for processing sweet corn.

Also be on the lookout for sweet corn rust. Look for the small red pustules, once observed on corn in the whorl stage or earlier, apply a fungicide such as Bravo (fresh market only), Quadris, Tilt or mancozeb for control. Older corn will not benefit from an application.





Field Crops


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


Field Corn.

We can still find Japanese beetles and corn rootworm adult beetles feeding on silking corn. As a general rule, a treatment is recommended on silking corn if you can find 4-5 Japanese and/or corn rootworm beetles per plant and they are clipping silks to less than ½ inch long before 50% pollination.



Continue to watch for spider mites, leafhoppers and defoliators in soybeans. A treatment for leafhoppers is recommended when you find at least 4 per sweep in drought stressed beans or 8 leafhoppers per sweep in actively growing soybeans. If defoliators are present, the treatment threshold is 30% defoliation prebloom and 15% once bloom occurs. If a combination of insects is present, the threshold for each pest should be reduced by 1/3.



Field Crop Diseases -  Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu



Soybean cyst nematode can be seen on plants that are 32-35 days from planting. The dry weather will accentuate the damage from SCN. Look for areas in the field which are yellow and/or stunted. The small yellow or white cysts can be seen easily at this time if you have a 10X hand lens and carefully dig up the plants and not pull them from the soil. If you do not find the cysts, and/or to confirm their presence if you are not sure, soil sampling is encouraged. Soil sample bags are available from the county Extension offices.



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


Commodity Markets Driven By Weather Market

The market for U.S. corn, wheat, and soybeans is expected to take today's release of USDA's July crop report with a grain of salt. Commodity traders are expected to immediately turn their attention to weather developments affecting the nation's corn belt as corn pollination is taking place later and over a larger time span than normal. Ending stocks estimates were reduced for U.S. wheat and soybeans, with ending stock estimates being raised slightly for U.S. corn as compared to last month's report. Overall the report can be viewed as price positive.


Ending stocks for U.S. wheat are now projected at  520 million bushels, 35 million bushels less than last month and 252 million bushels less than last year. World wheat stocks were also reduced and are now projected at 147.08 mmt. The world wheat stocks estimate represents a reduction from last month and last year.


U.S. ending soybean stocks, now projected at 230 million bushels, are also 35 million bushels less than last month and 20 million bushels larger than ending stocks for the last marketing year. World ending soybean stocks were reduced only slightly from the June report.    


U.S. ending corn stocks, projected at 1.466 billion bushels are 165 million bushels greater than last month's estimate. However, ending stocks for U.S. corn are currently projected to be 155 million bushels less than the carry in of 1.621 billion bushels. World ending stocks for corn at 114.74 mmt represent a reduction of almost 8 mmt from this time last year.


General Comments

The weather market is expected to extend over a longer period of time this summer and it is likely for us to see some better pricing opportunities yet to come for both corn and soybeans. For wheat, the short crops peak early syndrome should make wheat a good sell for the remaining '02 sales at harvest. Further price rallies can be used to price a portion of the new '03 crop.



Ag Fact


Fifty years ago, Delaware farmers planted 174,000 acres of corn, which yielded 49 bushels/acre with an average price of $1.55 per bushel.  54,000 acres of wheat yielded 21 bushels/acre at $1.97 per bushel.  The demand for soybeans was just beginning.  68,000 acres were planted, yielding 17 bushels per acre at $2.62 per bushel.  19,600 acres of lima beans were planted, yielding 1,400 pounds per acre.








6:00 pm - dusk


Location: Marl Pit Road (Rd. 429, approximately ½ mile east of the intersection with Del. Rt. 71/U.S. Rt. 301 (Armstrong’s Corner).  Look for the University of Delaware signs on the left.


University of Delaware Cooperative Extension invites you to join your fellow farmers and other members of the agricultural community as our Extension Specialists lead discussions of this year’s field trials and other in-season issues related to corn, soybeans, and small grains. Other topics will include both grain marketing and farm bill highlights. We expect to have the 2001-2002 wheat and barley variety trial results for distribution and discussion.  There will be time to discuss your current cropping issues.

We will wrap-up the evening with an award presentation and ice cream treat!


CREDIT toward Delaware pesticide license recertification (Ag Plant category) and CCA (Certified Crop Advisor) CEUs will be awarded.


The meeting is free and everyone interested in attending is welcome.  For more information or for special consideration in accessing this meeting, please contact us at 831-2506.



Carl P. Davis

Extension Agent, Agriculture



                    Weather Summary

Week of July 3 to July 10, 2002


July 9 – 0.01 inches

July 10 – 0.01 inches


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

Air Temperature:

Highs Ranged from 97°F on July 4 to 83°F on July 10.

Lows Ranged from 73°F on July 3 & 4 to 56°F on July 7.

Soil Temperature:

85°F 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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