Volume 6, Issue 20                                                                                               August 7, 1998


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

Lima Beans and Snap Beans.

Continue to watch fields for leafhopper adults and nymphs. The treatment threshold is 5 per sweep prebloom and 10 per sweep during bloom. In snap beans, Asana, Lannate or Orthene will provide control. In lima beans, dimethoate or Lannate will provide control. If lima bean fields are in bloom, Lannate would be the material of choice. Processing snap beans should still be sprayed at the bud and pin stages with Orthene for corn borer control. Since corn borer catches are still only in the 5-7 per night range, a third spray with Lannate will be needed 5-7 days from harvest. Be sure to check the Crop Pest Hotline on Tuesdays and Fridays for the most recent trap catches in your areas (in-state: 1-800-345-7544; out-of state: 1-302-831-8851).


Maintain a 7-10 day schedule for corn borer control. Aphid activity is starting to increase, especially in fields where only a pyrethoid has been used. If aphid populations are starting to increase, Lannate or Orthene should be used to provide both aphid and corn borer control.

Pickling Cucumbers.

Aphid activity has started to increase in seedling stage fields. As temperatures increase, fields should be watched for melon aphid explosions. A treatment will be needed if 20% of the plants are infested with aphids. Lannate will provide melon aphid control.

Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 3-4 day schedule throughout the state. Be sure to check the Crop Pest Hotline on Tuesdays and Fridays for the most recent trap catches in your areas (in-state: 1-800-345-7544; out-of state: 1-302-831-8851). We have also seen an increase in fall armyworm moth activity. All late-planted fields should be checked during the whorl stage for fall armyworm feeding. A treatment is recommended if 15 % of the plants are infested. In many cases, 2 applications will be needed to provide effective control. Larvin (30 oz per acre) and Warrior (3.84 oz per acre) have provided the best control in recent years. *


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

Pumpkins and Winter Squash.

Apply Bravo and a copper fungicide for control of foliar diseases. Good fungicide coverage is important for disease control. Check fields for the presence of powdery mildew. Once powdery mildew is seen, add Nova to the Bravo (chlorothalonil), the next spray 7-10 days later you can switch to Quadris alone, then repeat the Bravo plus Nova and repeat that rotation. Do not make any more than two successive applications of Quadris to prevent resistance development in the powdery mildew population. Nova or Quadris will provide excellent powdery mildew control and Quadris will also provide black rot control.

Bravo is still very good for downy mildew, and black rot, again good coverage is very important. Fungicides are important for good fruit quality including good handles.

Late Blight Update

DSV accumulations as of July 30, 1998 are as follows:

Location/Emergence Date

DSV's July 27

DSV's July 30


Baldwin - 4/20



10-day, low rate

Jackewicz - 4/20



10-day, low rate

Zimmerman - 4/23



10-day, low rate

Baker - 5/1



10-day, low rate

This will be the last late blight FAX for the 1998 season. Most potatoes are done and conditions for late blight certainly have passed for this season. The weather monitors will continue to collect data, but I will not be faxing anymore reports this season. If anyone has very late potatoes and wants the information, please give me a call. I hope digging and marketing season is successful for you. Let's hope the demand and prices increase.

Remember, if you see any potatoes with pink rot, please save me 4-5 infected tubers, refrigerate them, and let me know so I can get them. Phone: 302-831-4865, Fax: 302-831-0605. Thanks. The Late Blight Report is also posted electronically at the UD Extension IPM website: http://www.udel.edu/IPM *


Vegetable Diseases - Kate Everts, Extension Plant Pathologist, University of Maryland and University of Delaware ; everts@udel.edu, Phil Shields, University of Maryland, ps136@umail.umd.edu

MELCAST for Fungicide Application on Watermelons.

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program. Below are the EFI values from weather stations located on the Eastern Shore July 29-Aug. 5. Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu

EFI Values



















Wootten Farms, Galestown,MD









Mark Collins, Laurel, DE









U of D, REC Georgetown, DE








Vincent Farms Laurel, DE









Watermelon Fields should be sprayed with a fungicide when 30 EFI values have been 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 zero. The first and last day above can be partial days so use the larger EFI value of this report and other reports for any specific day. *


Watermelon Twilight Meeting

Wednesday, August 12, 1998

5:30 p.m.

At the University of Delaware Research & Education Center

Route 9, Georgetown, Delaware

Sponsored by the Universities of Delaware and Maryland

The twilight meeting this year will include:

3 A 25 variety seedless watermelon variety trial. Red and yellow flesh varieties as well as icebox and large, oblong seedless are included in the trial.

3 MELCAST, a weather-based fungicide application model for control of gummy stem blight and anthracnose on watermelon trial. This model was evaluated on research stations and growers fields in Maryland and Delaware in 1996, 1997 and 1998. Environmental favorability indices (EFI) were determined from current weather data. Sprays are applied when EFI accumulate to the threshold value of 30. Compared to plots sprayed weekly, plots sprayed according to MELCAST received two and three fewer fungicide applications in 1996 and 1997, respectively. Despite receiving fewer sprays, disease severity was the same in plots sprayed weekly or according to MELCAST where on site weather was used. Weather stations have been set up in grower's fields for the 1998 growing season and EFI data collected three times per week. Growers can access this information by fax, phone or the internet. The EFI Values are also posted each week in the Weekly Crop Update Newsletter. As researchers, we are very interested in your thoughts on this system. We would like to know if you are using the system, and what you like and dislike about the model.

3 In recent years, spider mite management in watermelons has become increasingly difficult due to improper timing of pesticide applications, lack of effective miticides and the use of cultural management systems which favor mite development. The following topics will be highlighted: mite populations under different management systems (every row rye, windbreak rye, and no rye), timing of miticide applications, and promising new materials for mite control.

Universities of Delaware and Maryland Specialists and Agents will be on hand to answer questions concerning problems you may be experiencing this year. We invite you to visit the plots and join us for dinner.

The meeting will begin at 5:30 p.m. followed by an "Emings" dinner at 6:00 p.m. Please call Edna Marvil at 302-856-7303 by August 10, 1998 to register for the meeting. We will need to verify the number for dinner by the 10th .

Laurel Farmer's Auction Market Report

July 30 - August 5, 1998

Quantity Produce Price
66,883 Cantaloupes  



Super Star







2098 Honeydews 0.45-1.65
523 Crenshaws 0.60-1.30
11549 Sugar Babies 0.50-1.50
  Seedless Sugar Babies 1.20-2.15
341,463 Watermelons  

Crimson Sweet


12 up


15 up


20 up


25 up


30 up




12 up




20 up


25 up


30 up


Royal Majesty


12 up


15 up


All Sweet


20 up


25 up




20 up


Royal Sweet


15 up


20 up


Royal Star


15 up


20 up


25 up




Yellow Dolls

117 Peppers  






3103 Tomatoes  





Plum Tomatoes

299 Sweet Corn Doz. 0.75-1.55
9 Stringbeans 7.00
54 Lima Beans 14.00-31.00
90 Cucumbers 3.00-12.50
88 Squash  




15 Potatoes  


1 Eggplant 9.00
36 qts. Blackberries 1.80
54 Peaches 5.00-8.00
78 Nectarine 5.50-8.00

Field Crops

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


Potato leafhopper adults and nymphs are still active in many fields. Fields should be scouted from one week after harvest until 60% of the field is in the bud stage. Ambush, Baythroid, Dimethoate, Pounce or Warrior will provide effective control. If fields are treated after a cutting, the best control will be achieved if there is at least 1-2 inches of regrowth before application.


Spider mites can readily be found in many fields, although infestation levels range from a few patches in a field to high populations throughout fields. In areas of the state that recently received rain, many fields are actively growing and dimethoate will have the best chance of working under these conditions. If threshold levels are present – that is 20-30 mites per leaflet and/or 10% of the plants exhibiting mite damage (light stippling not severe damage) over more than one-third of the leaves, a treatment should be applied. If dimethoate has worked in the past, then it will be worth using again this year. The addition of a vegetable oil or an organosilicone can improve control, especially if egg populations are high at the time of application. If you did not get control with dimethoate last year and/or you have already sprayed dimethoate this year and it has not worked, the Section 18 material Danitol, at 16 oz per acre, should be considered. Parathion can still be used but it can only be applied by very few aerial applicators. You should also begin sampling your earliest planted soybeans during the next week for podworm activity. No controls will be needed until you find 3 earworms per 25 sweeps in narrow row beans or 5 per 25 sweeps in wide row beans. A pyrethroid or Larvin will provide control. *


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

Private Crop Forecaster "Sparks" Market

With USDA's release of the August crop report just one week away, commodities are struggling to find a reason, any reason to bid higher. Spark's Companies, Inc. has estimated U.S. corn production at 9.410 billion bushels for their August estimate, as compared to USDA's July estimate of 9.625 billion bushels. This number is viewed as slightly supportive because it is under USDA's previous figure. Of course, the official estimate will be released by USDA on August 12th.

The Spark's August estimate for U.S. soybean production was 2.819 billion bushels, as compared to USDA's July estimate of 2.830 billion bushels. Commodity trader's were very cautious in describing the impact of this number on the soybean market. The reason being, although this number is under the USDA July estimate, it falls at the high side of what the market is trading, a U.S. soybean crop size of 2.7 to 2.85 billion bushels.

Corn, soybean and wheat markets have been making new life of contract lows this past month. As of this writing, new crop December corn futures were trading at $2.22 per bushel. This translates into a local farm price of $2.30 to $2.38 per bushel (the price the farmer receives, locally). November soybean futures, trading at $5.46 per bushel translates into a local farm price of $5.32 to $5.37 per bushel. At the current price levels, only sell when and if necessary. *

Attention Delaware Farmers

Irrigation Field Day

Managing Irrigation for Crop Performance and Efficient Water Usage

Date: Wednesday, August 26, 1998

Place: T.G. Adams & Sons farm, Road 583, between Greenwood and Bridgeville, DE

Time: 9:00 A.M. to noon

Meal: A barbecue pork and chicken picnic lunch will be provided

All Delaware farmers interested in irrigation are invited to attend a field day on managing irrigation for crop performance and efficient water usage. This field day, sponsored by the University of Delaware Cooperative Extension, will be held on Wednesday, August 26,1998 at T.G. Adams & Sons farm, Road 583, between Greenwood and Bridgeville, DE from 9:00 A.M. to noon. A picnic style lunch will be provided at noon. This meeting will focus on large overhead irrigation systems (pivots, guns, laterals) and best management practices for irrigation. Topics will include:

*  Water use and irrigation strategies for field crops and vegetable crops

*  Water quality concerns in irrigated crop production

*  Managing water application rates

*  Irrigation scheduling by the checkbook method, using tensiometers and resistance meters, and computer assisted scheduling

*  Nutrient management in irrigated crops

*  Fertigation

* Water conservation concerns

* Irrigation management assistance

Talks and demonstrations will be presented by University of Delaware researchers, specialists, and agents. We will also have Paul Bodenstine an irrigation consultant with Ag Systems Consulting, Norfolk, VA to talk about his experiences with irrigation management.

Please register in advance (so we know how many meals to provide) by calling the Kent County Cooperative Extension Office at (302) 697-4000. Anyone that is interested is welcome to attend. For additional information or special assistance in accessing this meeting contact Gordon Johnson at the above number.

Hope to see you there.

Gordon Johnson - Extension Ag Agent, Kent County

Carl Davis - Extension Ag Agent, New Castle County

Derby Walker - Extension Ag Agent, Sussex County

Upcoming Events…

August 12, 1998

Farm & Home Field Day

Time: 8:30 a.m. - 1:00 p.m.

Location: U of D Research & Education Center, Georgetown

For More Information: Contact the REC at 303-856-7303.


August 12, 1998

Watermelon Twilight Meeting

Time: 5:30 p.m.

Location: U of D REC

For More Information Contact Edna Marvel at 302-856-7303.


August 26, 1998

Irrigation Field Day

Time: 9:00 a.m. - Noon.

Location: Thurman Adam's Farm

For More Information: Contact Mabel Hough at 302-856-7303.

September 15, 1998

Recycling of Pesticide Jugs

Time: 1:00 p.m. - 4:00 p.m.

Location: Sussex County Soil Conservation District Equipment Yard

For More Information: Contact DDA Pesticide Section at 1-800-282-8685

Weather Summary

Week of July 31 to August 6

Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 83 F on Aug. 3-4 to 78 F on July 31.
Lows Ranged from 65 F on July 31 to 54 F on Aug. 5.
Soil Temperature:
79 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 College and the United States Department of Agriculture cooperating, John C. Nye, Dean and Director. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. 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.