Volume 7, Issue 5                                                                                                       April 30, 1999


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


Seed corn maggot flies continue to lay eggs and will be present at the time of transplanting melons. The potential for damage will continue through May so a preventative treatment will be needed, especially in fields where manure has been used. On direct seeded fields, a seed treatment containing diazinon or chlorpyrifos should be used. On transplants, a broadcast application of diazinon will provide effective control. This application must be done close to planting and incorporated in 3-4 inches of soil to be effective. No rescue treatments are available for seed corn maggot.


Pea aphids can be found in many fields; however, beneficial insects still appear to be keeping populations in check. However, if the weather quickly turns warm, aphid populations often explode and beneficial insect activity can lag behind. Fields should be sampled from the bud-stage through harvest for aphids. On small plants, you should sample for aphids by counting the number of aphids on 10 plants in 10 locations throughout a field. On larger plants, take 10 sweeps in 10 locations. A treatment is recommended if you find 5-10 aphids per plant or 50 or more aphids per sweep. Dimethoate, Lannate or Penncap-M will provide aphid control. Be sure to check the labels for application restrictions during bloom. v

More Section 18 Labels for Vegetable Herbicides - Ed Kee, Extension Vegetable Crops Specialist, kee@udel.edu

Reflex has been granted a Section 18 Emergency label for post-emergence use on green beans to control certain broadleaf weeds. The rate is 1 to 1.25 pints/acre, with crop oil or surfactant. Read the label for directions. The regional application restriction mandated by the federal product label is also in effect on snap beans. Do not apply on the same acreage more than once every two years.

Command has received a Section 18 Emergency Label for use on watermelons as a preemergence treatment at 0.3 to 0.4 pints/acre; or as a preplant incorporated treatment at 0.4 to 0.5 pints/acre. This label has been granted for several consecutive years.

In addition, Command has a Section 24c, Local Use Permit on cucumbers as a preemergence treatment. This label has been in effect since 1996, and lasts for a total of five years. Pickle growers use it at 0.4 to 0.5 pints/acre in combination with Curbit.

The following table summarizes the Section 18 labels in Delaware for 1999.

Herbicide Crop
Sprout Nip spinach
Reflex green beans
Sinbar watermelons
Command watermelons


Field Crops

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

Field Corn.

As the earliest planted corn emerges, be sure to watch for early signs of cutworm activity. Damage can initially appear as small holes in the leaves, which eventually appear shredded. At the 1-2 leaf stage, a rescue treatment is recommended if 10 % of the plants exhibit leaf feeding, or 3% of the plants are cut off and larvae can be found. A pyrethroid will provide the most cost-effective control. During the past week, moth catches increased significantly in many locations in Delaware and Maryland (see table at the end of the newsletter). Over a 3-week period, the highest trap catches have consistently occurred in the Delmar, Milford, and Laurel areas.

Small Grains.

Cereal leaf beetle egg hatch has occurred in localized areas of Kent and Sussex Counties. Although there are hot spots of activity, beetle populations remain below normal in many locations. Aphid activity is also low, with an occasional field exhibiting high levels on the lower leaves. Although the weather has remained cool, beneficial insects are active in many fields. However, if the weather quickly turns warm; aphid populations can explode and beneficials will lag behind. Be sure to watch for aphids moving into the grain heads and treat if you find 20 to 25 aphids per head, especially if beneficial activity is low. As grain heads emerge, you should also begin to watch for grass sawfly and true armyworm larvae. A sweep net can be used to detect small grass sawfly larvae, often found in denser areas along field edges. Once larvae are detected, look for larvae in 5 linear foot of row in 5-10 areas of a field by shaking plants to dislodge larvae that feed on the plants during the day. Since true armyworm larvae are generally found at the base of the plants during the day, you will also need to look at the base of plants for armyworms. The treatment threshold for sawfly is 0.4 per foot of row. The treatment threshold for armyworm is one – two per foot of row. v

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


A recent survey of our small grain variety trials revealed that powdery mildew is present, but none of the varieties in my opinion needed a fungicide application. Many varieties had mildew on the lowest leaves and stems, but the top two leaves of the flag and the F-1 were clean. Every field will be different, but disease levels at Georgetown and Felton did not need fungicides at this time. The flag leaves were all out and one or two of the earliest varieties were in the early boot stage. Several susceptible varieties that were treated with Baytan still had very little to no mildew. The best time to apply fungicides is from early head emergence through full head emergence, Feekes growth stage 10.5. Tilt and Quadris cannot be applied after G.S. 10.5. Most wheat that I saw is approaching growth stage 10.1(first spikes just visible). Barley diseases were not present on any variety in our plots at the present time. All but one variety had heads present and one was flowering. I have not seen any indication that the bacterial kernel blight on Nomini, that was so common last year, will appear this year. Let’s hope not.  v

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

Corn Planting Progress
U.S. corn planting in the 17 key states is reported at 10 % complete as of April 25th, five points behind the five-year average of 15 %. Even though traders are beginning to keep an eye on the weather, planting delays won't become much of a factor for commodity prices until the end of May. In the mid-section of the corn belt the frost free date is approximately May 10th and corn can be comfortably planted up to June 10th, before it becomes wise to switch to beans.

USDA to Decide on LDPs
The marketing loan program and the loan deficiency payment (LDP) are being debated in USDA. A decision is expected this week. Several options are being considered, including setting a national LDP rate which would be adjusted by the individual county loan rates so as to base payments. We can expect an update from the Farm Service Agency in the near future.

Marketing Strategy
Volatility in commodity prices across the board (corn, wheat, and soybeans) remains very low. This essentially eliminates the use of many of the marketing tools that are typically available to consider, specifically, futures and options. On a positive note, the loan rates effectively provide a put option and a floor price for corn, wheat, and soybeans without having to pay the premium. Therefore, continue holding on making further sales until the opportunity is presented. v

Pesticide BriefsSusan Whitney, Extension Pesticide Educator; swhitney@udel.edu

Public Input To The OP Risk Assessments

The Food Quality Protection Act requires new procedures for registering and reregistering pesticides. The OP's are the first group of pesticides to go through the new process. EPA and USDA have formed a committee, the Tolerance Reassessment Advisory Committee (TRAC), that is charged with gathering public comment as the OP risk assessments and risk mitigation strategies are prepared. Preliminary risk assessments are completed for 27 OP's and under development for 12 more. The TRAC plans to write "Overview Summaries" of the preliminary risk assessments. According to EPA, these summaries, "...will aid public participation because they will provide stakeholders with clear, 'plain English' descriptions of the assessments." Delaware growers can get copies of the summaries from Extension Specialists and Agents as soon as they are available. The last step in the comment process will be public meetings, "Technical Briefings." Meeting notices will be published 2 weeks in advance of the Technical Briefing date. At the Technical Briefings, EPA will describe how risk assessments were calculated and growers will have opportunity to ask questions. Watch the Weekly Crop Update for announcements of Overview Summaries and Technical Briefings. v

Upcoming Meetings…

Strawberry Twilight Meeting

University of Maryland, Wye Research and Education Center, Cheston Lane, Queenstown, MD

Thursday, May 13, 1999

6:00 p.m.

What you will see:

Annual Plasticulture: 7 named varieties, 3 N.J. selections, 22 breeding lines from MD and USDA

June Matted Row: 12 named varieties and 11 N.J, breeding lines

Lime Sulfur Renovation Trial

Who will be with us:

Dr. Joseph Fiola, Rutgers; Dr. Stan Hokanson, USDA; Curt Massey, Special Strawberry Researcher; Dr. Harry Swartz and other University of Maryland Specialists

For more information, call 410-827-8056.

                    Weather Summary

Week of April 22 to April 28

0.04 inches: April 22, 1999
0.74 inches: April 23, 1999
Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 80F on April 22 to 58 F on April 24.
Lows Ranged from 51F on April 23 to 35F on April 25.
Soil Temperature:
63 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.

Black Cutworm – Pheromone Trap Catches1999 Season

Data Provided by Terra Inc., Bridgeville, DE

Trapping Period : April 18 - 24, 1999

NOTE: Moth catches ranging from 7 to 15 moths per 7 day period have been associated with a moderate to high potential for cutworm outbreaks. Once moth catches in an area reach this level, the first larvae are generally seen within 300-degree days (using a temperature base of 50 degrees F). Since April 4, 84 degrees days have accumulated at the Research and Education Center located in Georgetown, DE.




# Moths/7Days

American Corner, MD


Lewistown, MD


Argos Corner, DE


Magnolia, DE


Atlanta, DE


Mardela Springs, MD


Bayard, DE


Marydel, MD


Berlin, MD


Milford, DE #1


Bethel, DE


Millsboro, DE


Bridgetown, MD


Milton, DE


Bucktown, MD


Newark, MD #1


Burrisville. MD


Newark, MD #2


Cambridge, MD


New Church, VA


Clarksville, MD


Oak Orchard, DE


Dagsboro, DE #1


Pocomoke, MD #1


Dagsboro, DE #2


Pocomoke, MD #2


Delmar, DE


Preston, MD


Denton, MD


Public Landing, MD


Easton, MD


Redden, DE


Eldorado, MD


Reeds Grove, MD


Ellendale, DE


Reliance, MD


Farmington, DE


Rhodesdale, MD


Federalsburg, MD


Ridgely, MD


Georgetown, DE


Seaford, DE #1


Goldsboro, MD


Seaford, DE #2


Greenwood, DE


Selbyville, DE #1


Hurlock, MD #1


Selbyville, DE #2


Hurlock, MD #2


Snow Hill, MD #1


Laurel, DE # 1


Snow Hill, MD #2


Laurel, DE # 2


Snow Hill, MD #3


Laurel, DE # 3


Trappe, MD


Leipsic, DE


Vernon, DE


Lewes, DE


Wyoming, DE


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