Volume 6, Issue 23                                                                                      August 28, 1998


Vegetables

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

Cabbage.

Cabbage looper egg laying and larval activity has increased significantly. If loopers and diamondback are both present, a Bt plus a pyrethroid should be used. If Spintor is used for looper control, the higher rate (4-6 oz/acre) is needed.

Lima Beans.

With the recent increase in corn earworm moth flights, we are starting to see more corn earworm larvae. Controls are needed if you find one larva per 6 foot of row. The rate of Lannate will depend on the larval size at the time of treatment. If worms are small, 1.5 to 2 pts per acre will be adequate. However, if the worm size is mixed at the time of treatment, 3 pts/acre will be needed.

Peppers.

All peppers should be sprayed on a 7-10 day schedule for corn borer, fall armyworm and aphid control except in the Bridgeville area where sprays are needed on a 5-7 day schedule. Lannate or Orthene are the preferred materials at this time.

Snap Beans.

Processing snap beans should still be sprayed at the bud and pin stages with Orthene for corn borer control. With the recent increase in corn earworm moth catches in pheromone traps, Asana should be combined with Orthene at the pin spray. In most areas, sprays are needed on a 6-day schedule from the pin stage through harvest. In the Bridgeville area, sprays are needed on a 4-day schedule from the pin stage through harvest. Be sure to check the Crop Pest Hotline for the most recent trap catches in your area. Maintain a 5-7 day spray schedule on fresh market snap beans from pin through harvest. Whiteflies can also be found in a number of fields. In most cases, Orthene should provide adequate control. However, if populations are extremely high then a treatment with Thiodan may be needed.

Spinach.

As soon as plants emerge, begin scouting small plants for webworms and beet armyworm larvae. Controls should be applied when worms are small and before they have moved deep into the hearts of the plants. Since Lannate can not be applied before plants are 3-inches in diameter, Ambush, Pounce or a Bt insecticide should be used. Generally, at least 2 applications are needed to achieve control of webworms and beet armyworm. Spintor is also labeled for spinach and should provide very good webworm and beet armyworm control. The use rate is 4 to 6 ozs per acre.

Sweet Corn.

Fresh market silking sweet corn should be sprayed on a 3-day schedule throughout the state. Be sure to check the Crop Pest Hotline for the most recent trap catches in your area. If Ambush, Asana or Pounce are being used, you should combine the mid-range rate of these pyrethroids with Lannate or Larvin to control the complex of corn borers, earworms, and fall armyworm. If fall armyworm pressure is high in your area, you will need to alternate the high rate of Baythroid or Warrior with Lannate or Larvin at this time. *

 

Update of Downy Mildew in Lima Beans on Delmarva - Dr. Tom Evans, University of Delaware, tomevans@udel.edu

Downy mildew of lima beans continues to be a sporadic but important disease of lima beans in Delaware and Maryland. In recent years we have seen a number of small epidemics of the disease and some important changes in its pathogen, Phytophthora phaseoli. The pathogen is known to have some variability and historically this variability had been designated by four distinct races (A, B,C,D) of the fungus. Over the past four years, there have been changes in this Race picture. Prior to 1994, Race D was the most prevalent, if not the only race of the fungus, known to be present on Delmarva. In 1995 and 1996, a few isolates of a slightly different race of the P. phaseoli was detected and designated as Race D-2. In 1997, epidemics of downy mildew occurred in a number of lima bean fields in Delaware. These fields were planted to Packer and Easton, both cultivars resistant to Race D. Detailed analysis of the isolates from these fields have led us to believe that a new race of P. phaseoli, Race E, has evolved here on Delmarva.

The best method for control of downy mildew remains resistance and the only labeled chemical control is copper sulfate. Fortunately, isolates of Race E have already been shared with California breeders and cultivars with resistance to Race E are already in our evaluation blocks on Delmarva this summer. Additionally, there are a number of new fungicide materials on the market that are being tested this summer and fall in trials at the Research and Education Center that may provide us with some additional control alternatives in years to come. In the mean time, copper sulfate remains the only labeled chemical material. Downy mildew time is rapidly approaching, with cooler evening temperatures of late August and early September being the fungus' best time for infection and spread. Farmers can get an estimate of the potential for disease severity using the predicative formula in the Commercial Vegetable Production Recommendations, E.B. # 137. Using rainfall and temperature it is possible to predict the likelyhood of the occurrence of downy mildew. It should be noted however, that Race E was not known when this predictive formula was developed and it may not have the same temperature requirements for infection. *

 

Vegetable Diseases - Kate Everts, Extension Plant Pathologist, University of Maryland and University of Delaware ; everts@udel.edu ; Phil Shields, University of Maryland, ps136@umail.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 August 17- 24. Any questions please call Phil Shields at (410) 742-8788 or e-mail: ps136@umail.umd.edu

EFI Values

Location

8/17/98

8/18/98

8/19/98

8/20/98

8/21/98

8/22/98

8/23/98

8/24/98

U of M, LESREC
Salisbury,MD

5

4

3

1

1

     
Wootten Farms, Galestown,MD

6

6

2

0

0

2

4

1

Mark Collins, Laurel, DE

7

5

3

1

1

4

5

2

U of D, REC Georgetown, DE

5

4

1

0

0

1

1

0

Vincent Farms Laurel, DE

6

4

3

0

1

2

5

1

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.  *

 

Pumpkin Twilight Meeting

Thursday, September 24, 1998

4:30 - 7:00 p.m.

University of Maryland, Wye Research & Education Center

Queenstown,Maryland

Twenty-two varieties of pumpkins, sprayed and non-sprayed, no-tilled into hairy vetch will be on display. Other topics of discussion include: nutrient management, plant spacing, disease, insect and weed IPM, pollination and irrigation. For further information directions, contact Bob Rouse at 410-827-8056. *

 

Laurel Farmer's Auction Market Report

August 20 - August 26, 1998

Quantity Produce Price
15744 Cantaloupes  
 

Athena

0.25-1.60
 

Super Star

0.25-1.15
 

Eclipse

0.25-1.35
 

Cordele

0.40
1067 Honeydews 0.60-1.10
4969 Sugar Babies 0.30-1.25
  Seedless Sugar Babies 0.60-0.75
327,502 Watermelons  
 

Crimson Sweet

 
 

12 up

0.40-0.70
 

15 up

0.50-1.50
 

20 up

0.60-1.65
 

25 up

0.65-1.85
 

Sangria

 
 

12 up

0.45-0.80
 

15up

0.50-2.05
 

20 up

0.60-2.75
 

25 up

1.60-2.65
 

All Sweet

 
 

12 up

0.60
 

15 up

0.70-2.30
 

20 up

1.25-2.10
 

25 up

1.25-3.20
 

Royal Star

 
 

20 up

0.75-1.85
 

25 up

2.35
 

Jubilee

 
 

15 up

0.50-0.95
 

20 up

1.00-1.50
 

Royal Majesty

 
 

20 up

1.20-2.20
 

Stars-N-Stripes

 
 

15 up

0.75
 

Royal Sweet

 
 

20 up

1.30
 

Seedless

0.30-2.45
 

Yellow Dolls

0.75
  Sample Sales  
 

All Sweet

 
 

25 up

10.10 (cwt)
118 Peppers  
 

Cherry

4.00
 

Green

2.00-7.50
 

Red

4.00-10.50
857 Tomatoes  
 

Red

3.00-12.00
 

Pink

3.00-8.00
325 Sweet Corn Doz. 0.75-1.85
39 Cucumbers 3.00-10.00
278 Squash  
 

Yellow

3.00-8.00
 

Green

3.00-8.50
23 Potatoes  
 

Red

3.00
10 Eggplant 3.00-7.00
353 Mexican Hats 0.55-0.90
130 Peaches 4.00-9.00
20 Apples 4.00
5 Nectarine 7.50
4 Stringbeans 6.00-6.50
6 Lima Beans 16.00-36.00

Field Crops

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

Soybeans.

Along with low levels of corn earworm, be sure to watch for defoliators, especially green cloverworms. In some cases, plants have been completely defoliated in spots in fields. Although the current humid weather will eventually result in a crash in the population, this will not occur until you see at least a few diseased caterpillars. During the pod-fill stage, a treatment should be applied if you find 15% defoliation and 5-10 caterpillars per sweep. A pyrethroid will provide effective control. If both defoliators and podworms are present, you may need to reduce the threshold of each by one-third.   *

 

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

Commodity Prices Erode Further to Make New Lows

Grain and soycomplex futures have moved to new life of contract lows, with the December corn future closing at $2.08 and November soybeans at $ 5.23 per bushel on August 26, 1998. Concerns over deflationary factors in world markets, overall weakness in demand (particularly for corn), and bearish supply outlooks are converging simultaneously to drive corn and soybean prices even lower. Other factors weighing heavily upon price direction include loans coming due at harvest and the general psychology in the market that keeps buyers at bay, waiting for bargain prices. One Chicago grain analyst stated this morning that export sales are dismal, with only pedestrian sales (those needed to keep the pipeline functioning) being made. It may become prudent to consider the use of options on corn and soybean sales, to gain price protection and perhaps to be in position to benefit from potential higher prices later on.  *

 


Weather Summary

Week of August 21 to August 28

Rainfall:
None. *
Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 96 F on August 25 to 84 F on August 21.
Lows Ranged from 75 F on August 25 to 55 F on August 21.
Soil Temperature:
82 F average for the week.
(Soil temperature taken at a 2 inch depth, under sod)

*Bonnie has arrived on Delmarva, bringing much needed rainfall . (Thursday, a.m.).

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.


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