Volume 10, Issue 19 August 2, 2002



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


Lima Beans.

We are staring to find the first corn earworm larvae in fields with pin pods. You should also continue to sample for 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.



Spider mite populations are still at threshold in many fields. As a general guideline, fields should be sprayed if 20-30% of the plants are infested with 1-2 mites per leaf. However, if hot spots are present in fields, the percentage of infested plants continues to increase and numerous eggs can be found, a spray should be considered before you find 1 per leaf. We are also starting to see an increase in aphids and cucumber beetles.



At the present time, all peppers should be sprayed on a 7-day schedule for corn borer, corn earworm and pepper maggot control. With the recent increase in corn earworm catches and the occurrence of beet armyworm, chemical selection will be important. Remember Orthene or Address will not provide satisfactory earworm control. A pyrethroid or Lannate will be needed for earworm control. Dimethoate should still be added to the mix for pepper maggot control if a pyrethroid or Lannate are used. Also, a continuous pyrethroid program should not be used to avoid aphid explosions. If beet armyworms are present, the pyrethroids have not provided effective control. Avaunt, Spintor, Confirm or Lannate will provide the best beet armyworm control. Depending on the pest complex present, a combination of products will be needed.


Snap Beans.

Processing snap beans in all areas of the state should be treated at the bud and pin stages for corn borer control. Orthene or Address should be used at the bud and/or pin stages for corn borer control. In the Rising Sun, Laurel, Bridgeville and Georgetown areas, a pyrethroid should be combined with Orthene at the pin spray for earworm control. After the pin stage, Lannate, Capture or Mustang should be used. Sprays will be needed on a 6-7-day schedule from the pin spray until harvest. Since this can change quickly, be sure to check our website for the most recent trap catches and information on how to use this information to make a treatment decision in processing snap beans (http://www.udel.edu/IPM/traps/latestblt.html and http://www.udel.edu/IPM/thresh/snapbeanecbthresh.html). You should treat 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.

Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 3-day schedule in all areas of the state except in the Bridgeville, Rising Sun and Dover areas where sprays are needed on a 2-3 day schedule. Since this can change quickly, be sure to check our website for the most recent trap catches and information on how to use this information to make a treatment decisions in fresh market sweet corn.

(http://www.udel.edu/IPM/traps/latestblt.html and http://www.udel.edu/IPM/thresh/silkspraythresh.html )



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 07/31/02 07/30/02 07/29/02 07/28/02 07/27/02 07/26/02 07/25/02 07/24/02

Bridgeville, DE 2 2 0 7 2 1 2

Charles Co. 0 0 1 9 10 4 4

Collins Farms 1 1 0 5 1 1 1

Galestown, MD 3 2 2 5 2 1 2

Georgetown, DE 0 2 1 6 1 1 4 3

Glenville, MD 0 0 0 7 4 1 4

Hebron 3 3 2 5 2 1 2

Hog Creek Rd. 0 0 0 9 10 2 4

Salisbury, MD 2 1 0 5 2 1 3

Vincent Farms 4 3 2 5 2 1 1

Westminster 0 0 0 7 9 2 4

White Marsh 0 0 0 8 10 1 4

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.


Field Crops


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



Continue to watch for spider mites, leafhoppers and defoliators in soybeans. The spider mite threshold is 20 per leaflet or 10% of plants with 1/3 or more of the leaf area damaged and the leafhopper threshold is 4-8 per sweep. If defoliators are present, the treatment threshold is 30% defoliation prebloom and 15% once bloom occurs. If a combination of insects is present, reduce the threshold for each pest by one-third. Now that most locations have received rain, you should achieve better control with applications of dimethoate plus LI-700 or AD-100 for spider mite control. Although a few diseased mites have been observed this week, in general we have not had enough consistent wet, humid weather to cause spider mite populations to crash. If mites can be found on new growth and you can observe stippling on the leaves, a treatment should be applied as soon as possible to prevent additional yield loss. Application made very early in the morning or late in the evening when leaf stomates are open will help move materials into the leaves. In many cases, at least 2 applications will be needed.




You should start sampling fields as soon as blossoms and pin pods are present for corn earworm. We have found our first corn earworm larvae in a full season soybean field in Kent County. Local moth catches in black light and pheromone traps continue to increase (108/night in Rising Sun and 75/night in Bridgeville). The 2002 Virginia field corn survey used to predict the potential for earworm outbreaks in soybeans has found significantly higher levels compared to 2001. Although the results of our field corn survey indicate low to moderate populations at this time (5-20% infested ears); a combination of resident populations and migratory populations in early August could result in podworm outbreaks in soybeans. Both full season and double crop beans will be susceptible this year since the drought has resulted in reduced canopy closure. In addition, as corn drys down early due to the drought, emerging moths will be attracted to open canopy blooming fields. If the weather remains hot and dry, we will not see fungal pathogens helping to crash populations. The weather in August will have the greatest impact on whether or not we see outbreak numbers like 1999. Therefore, it will be critical to start scouting fields for earworms as soon as blossoms are present.


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


Commodity Prices Rebound on Weather Developments


The end of last week through the first of this week saw commodity prices drift lower on trader expectations for an improvement in overall crop conditions for U.S. corn and soybeans. Rain events in part of the corn belt over the weekend resulted in a "sky is falling" reaction to commodity bidding in the markets, at the end of last week through Monday of this week, at least until the facts were in. Rain had not improved overall crop condition ratings and a realization that time is running out for rain to be of much help to several corn and soybean producing states. Commodity analysts are now beginning to lower production estimates for the 2002 corn and soybean crops with some conviction.

Marketing Strategy


Dec '02 corn futures and Nov '02 soybean futures are now expected to trade higher from current levels due to, among other things, a return to hot and dry conditions in a large portion of the corn belt, currently trading at $2.56 and $5.36 respectively. $2.70 Dec '02 corn and $5.80 Nov beans (CBT) appear to be well within reach in terms of new crop pricing objectives for advancing new crop sales.



 Pesticide Briefs Online Susan Whitney, Extension Specialist, Pesticides, Urban Entomology, swhitney@udel.edu


The latest issue of Pesticide Briefs has been posted at:http://www.udel.edu/pesticide/briefs.htm







Wicomico Farm & Home Show


Winterplace Park

RT 50 & Hobbs Road

Salisbury, MD 21804


August 15-17, 2002



    Weather Summary

Week of July 26 to August 1, 2002


July 26 th -0.03 inches

July 27th- 0.57 inches

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

Air Temperature:

Highs Ranged from 96F on July 29 & August 1 to 73F on July 26.

Lows Ranged from 77F on July 29 to 61F on July 26.

Soil Temperature:

83 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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