Volume 8, Issue 16                                                                                          July 7, 2000

Vegetables

 

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

 

Lima Beans.

Continue to sample for spider mites on seedling stage lima beans. A treatment should be considered when you first notice the stippling and you find 10-20 mites per leaflet.  Kelthane should provide effective control. The Kelthane MF formulation is the only formulation labeled on lima beans and snap beans.  Lygus and stinkbug populations continue to increase. Be sure to sample fields as they approach the bud stage. A treatment is needed if you find 15 lygus or stinkbugs per 50 sweeps. Lannate will provide control of both insects.

 

Peppers.

At the present time, all peppers in the Dover, Frederica, Harrington, Laurel, Middletown, Milford, and Rising Sun areas 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.

 

Potatoes.

We are starting to see economic levels of green peach aphids in potatoes.  Before 2 weeks from harvest, the threshold level is 4 per leaf. Within 2 weeks from harvest, the threshold increases to 10 per leaf. If green peach aphid is the predominant species, Provado,  Monitor or Fulfill will provide control. Lannate,  Provado or Fulfill will provide melon aphid control. Monitor will not control melon aphids.  If Fulfill is used, remember it is a selective aphicide. The use rate is 2.75 oz/acre. Aphids stop feeding immediately after application; however, they may remain on the plants for 2-4 days before they die. We have also seen an increase in second generation adult Colorado potato beetle activity. If Admire was used at planting or Provado was applied on the first generation, you should switch to Spintor for adult beetle control. Depending on the population level, the use rate is 5-6 ounces per acre.

 

Snap Beans.

Leafhoppers and thrips remain active in seedling stage snap beans. A treatment is needed if you find 5-6 thrips per leaflet or 5 leafhoppers per sweep. If both insects are present, the threshold of each should be reduced by ½ the level for each insect. In the Dover, Frederica, Harrington, Laurel, Middletown, Milford, and Rising Sun areas, corn borer sprays should be applied on processing snap beans in the bud and pin stages and on all fresh market snap beans where pin pods are present. In all other areas, corn borer sprays will be needed when trap catches reach the 2 to 5 per night range.

 

Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 4-5 day schedule in all areas of the state. Be sure to watch for trap increases that usually occurs in early July. 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) or our website at  http://www.udel.edu/IPM/latestblt.html. Fall armyworm larvae can be found in later planted fields. A treatment will be needed if 15% of the plants are infested. Lannate, Spintor or Warrior will provide control. Materials must be washed into the whorls and 2 treatments are generally needed for control.

 


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

 

A new fungicide with an old (but tried and true) active ingredient was recently registered for use in Delaware. Griffin L.L.C. registered its new chlorothalonil fungicide Equus 720 on a wide range of crops. The label is the same as for Bravo Weather Stik and the same concentration of active ingredient, 720 grams /liter. Be sure to read the label for crops registered and application information.

 

Rhizoctonia pod tip rot is present in some fields of snapbeans. Pods in contact with the soil will develop reddish sunken areas and rot. Nova is registered for this disease. Apply 4-5 oz/A when pods begin to develop. Continue applications every 7-10 days.

 

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), mancozeb, or Tilt for control. Older corn will not benefit from an application.

 

Early blight is beginning to appear in potatoes at low levels on susceptible varieties. Apply Quadris at the 6.2 fl oz rate/A on a 14-day schedule. Apply mancozeb or Bravo between Quadris applications. Look on the oldest leaves first for symptoms of early blight. Early blight produces small circular, brown spots that look like target boards with concentric rings of dead tissue.

 

Cucurbits.

Maintain applications of Bravo or mancozeb for control of foliar diseases according to Melcast predictions or weekly. At the first sign of powdery mildew begin alternating Quadris or Flint with Bravo (chlorothalonil) plus Nova (5oz/A) every 7 days. Begin the powdery mildew control program with the strobilurin fungicides (Quadris or Flint).

 


Laurel Farmer's Auction Market Report

 

Opening Day  -  July 6, 2000 

 

Quantity

Produce

Price

2,393

Cantaloupes

0.50-1.00

988

Sugar Babies 

1.45-1.70

219

Honeydews

0.30-1.00

105

Watermelons  

 

 

Jade Star

 

 

               15 up

1.55

 

Sangria

 

 

               20 up

2.55

1

Peppers 

 

 

Green

10.50

85

Tomatoes

 

 

Red

12.00-13.50

364

Sweet Corn Doz. 

1.25-1.55

3

Cucumbers 

3.00-7.50

11

Squash 

 

 

Yellow

3.00-5.50

 

Green

3.00-8.00

14

Potatoes 

 

 

Red

6.00-13.00

17

String Beans

6.00-11.00

 

 


Late Blight Update - - Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

 

Disease Severity Value (DSV) Accumulations as of July 6, 2000 are as follows:

Remember that 18 DSV’s is the threshold to begin a spray program

 

Emergence

Date

DSV’s

July

5

Recommendation

April 14

143

5-day, mid rate

April 21

116

5-day, mid rate

April 27

104

5-day, mid rate

May 20

56

5-day, low rate

May 24

56

5-day, low rate

 

Accumulated 8 DSV’s since the last report.  

 

It is not likely that more DSV’s will accumulate over the weekend. The 5- day spray schedule is in response to the favorable weather of last week. I know that this is not possible for most growers.

I did have a confirmed report of some late blight hits on the eastern shore of Virginia. It was very minor and no losses are anticipated. Their plant pathologist is pretty sure that the source of the late blight inoculum was from volunteer plants in nearby fields and not seedborn. We have had weather that has been very favorable for late blight development but either seed treatments and/or your protective sprays are doing the job. Most importantly, seed has been free of the disease.

 


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

 

Melcast for Watermelons

EFI Values (Environmental Favorability Index)

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program.  Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu

 

Location

6/28

6/29

6/30

7/1

7/2

7/3

7/4

7/5

Bridgeville, DE

4

2

1

2

1

2

3

3

Laurel, DE

(Collins Farms)

5

2

3

2

2

4

3

4

Galestown, MD

5

2

2

1

0

0

3

2

Georgetown, DE

1

9

2

2

 

1

3

1

Hebron, MD

5

2

2

3

1

1

3

3

Salisbury, MD

6

9

3

3

1

2

3

3

Vienna, MD

5

2

3

2

1

0

3

3

Laurel, DE

(Vincent Farms)

5

1

3

1

1

1

3

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 or http://www.udel.edu/IPM/     

 


Field Crops

 

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

 

Soybeans.

Continue to sample for spider mites, grasshoppers and leafhoppers in seedling stage soybeans. If all three are present, the threshold for each should be reduced by 1/3. In addition to these 3 pests, green cloverworm populations are starting to increase in soybeans. Small larvae produce "window-pane" feeding holes in the leaves. As larvae increase in size, the damage will appear as large holes between the veins. In general, no controls are needed prebloom unless you find 15 larvae per foot of row and 30 % defoliation. A pyrethroid will provide effective control. In years past, dimethoate, Lorsban, and parathion have provided varying levels of mite control. Dimethoate is the only systemic material available for mite control on soybeans. Lorsban and Parathion only provide contact activity. In addition, parathion can only be applied by air and there are a number of setback restrictions. We have received our Section 18 for the use of Danitol 2.4EC to control spider mites on soybeans. It should be used at a rate of 11.66 to 16 ounces per acre depending on the population pressure at the time of treatment. It can be applied by ground or air. A maximum of 2 applications per acre may be applied and there is a 30-day pre-harvest interval. Note – Although Sevin is listed as a labeled insecticide for insect control in our Regional Field Crops Recommendations Book, it is no longer labeled on soybeans. 

 

 


AGRONOMIC CROPS FIELD DAY

 

TUESDAY, JULY 18, 2000

9:15 am - 1:30 pm

(includes lunch)

 

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.

New Castle County Extension and the Delaware Soybean Board invite 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 to include:

 

Small Grain 

·        variety trial results – wheat and barley 

·        Hessian Fly study 

·        disease update 

Corn

Soybeans

·        Northern Uniform soybean variety evaluation

Nutrient Management

 

We expect to have the 1999-2000 wheat and barley variety trial results for distribution and discussion.  There will be time to discuss your current cropping issues.

 

Lunch (hot dogs, hamburgers, sweet corn, dessert, and beverage) will be provided.

 

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

 

For More Information:  Contact Carl Davis at 302-831-2506 or cpdavis@udel.edu

 


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

 

June Acreage and Stocks Report Implies Large Corn and Soybean Harvest

 

Combining USDA's June crop acreage report with the current yield assumptions suggests a 2000 U.S. corn crop pre report estimate of 10.013 billion bushels and soybean production at 2.939 billion bushels. The yield estimate is based upon the June supply and demand report with an average yield for corn estimated at 137 bushels per acre and a soybean yield of 40 bushels per acre. The June 30 corn acreage planting number was placed at 79.579 million acres, just under the 80.165 million planted in 1998. Estimated harvested acreage was estimated at 73.088 million bushels, the highest number in a decade. The record year for corn production was in 1994 with production of 10.050 billion bushels, with the average yield also record high at 138.6 bushels per acre.

 

U. S. soybean production, indicated at 2.939 billion bushels, would be record high, above the 2.741 billion recorded in 1998. Plantings were pegged at 74.501 million acres. Trade is likely to be soft over the next several days with commodity price levels now too low across the board to create any interest in farmer selling. The next USDA supply and demand report will be issued on Wednesday July 12th.

 


Upcoming Events…

Irrigation Tour

Date: August 22, 2000

More Information To Follow.


                   Weather Summary

Week of June 30 to July 5

Rainfall:

0.03 inches: June 30, 2000

0.23 inches: July 4, 2000

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

Air Temperature:

Highs Ranged from 86°F on July 3 to 80° F on June 30.

Lows Ranged from 70°F on July 4 to 61° F on July 2.

Soil Temperature:

82°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:

http://www.rec.udel.edu


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.