Volume 6, Issue 12                                                                                      June 12, 1998


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

Melons. Threshold levels of spider mites (10-15 percent infested crowns) can now be found in watermelon fields, especially where every row rye has been used. Dimethoate, Dibrom, Kelthane or Agri-Mek are the insecticides available for mite control in melons. Chemical selection should be based on control success in the past as well as population levels. If you have not had success with dimethoate or Kelthane, Agri-Mek should be used first. In trials in 1997, Agri-Mek at the 8-oz/acre rate gave approximately 3 weeks control when applied in 20 gallons of water per acre and sprayed on an exploded population. Although the current label for Agri-Mek states ground application only, it is under revision to include aerial application and the new label should be available any day. In addition to mites, continue to watch for increases in melon aphid populations. Fields should be treated if 20% of the plants are infested with aphids and you can find at least 5 aphids per plant. Lannate is the only material available for melon aphid control in melons.


Low levels of aphids can now be found in fields were Admire was not used at planting. Begin sampling lower leaves for the presence of green peach aphids. During bloom, the treatment threshold is 4 per leaf. This threshold increases to 10 per leaf at 2 weeks from harvest. If melon aphid is the predominant species, these thresholds should be reduced by one-half. If green peach aphid is the predominant species, Provado or Monitor will provide control. Lannate or Provado will provide melon aphid control. Although potato leafhopper populations are being held in check by the cooler weather, fields should be watched carefully if the weather turns hot and dry. Adults have been laying eggs for almost 3 weeks and nymphs can quickly cause damage. (NOTE: The Monitor rate on potatoes is 1 qt/acre not 2 qt/acre as stated in the last newsletter).

Sweet Corn .

Continue to sample for European corn borer in whorl stage corn. Treatments can be timed for tassel emergence but must be applied just as tassels are emerging from the whorls to be effective. Also, once larvae begin to bore into the midribs you will not get control. Any early-planted fresh market silking sweet corn should be sprayed on a 6-7 day schedule for earworm control. *


Processing Crops at the National Level - Ed Kee, Extension Vegetable Crops Specialist ; kee@udel.edu

The American Frozen Food Institute reports the national intentions for planting Green Peas for freezing to be 144,294 acres, compared to 152,979 last year, of which 148,408 was actually harvested. Sweet Corn for freezing is 184, 929, which compares to 199,562 acres planted last year. Intended acreage of Green Beans for freezing is 64,039 which compares to 59,261 last year. These decreases reflect the free-market reaction of supply and demand to large inventories from last year.

Pickle packers intend to contract 95,260 acres, up from 2% last year. Current estimates indicate that 50% of that acreage is machine harvest, the balance is hand-pick. Machine acreage is increasing and may have passed the 50% mark. Delaware and Maryland’s acreage of 5,000 acres accounts for approximately five percent of the nation’s crop. Of course, our local processors handle a much larger percentage of the acreage with pickles from other areas shipped in before, during, and after our season. *


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

MELCAST for Scheduling Fungicide Sprays on Watermelon

Do not use MELCAST if there is a disease outbreak in your field, it is a preventative program.

  1. The first fungicide spray should be applied by the time the vines begin to run.
  2. Once you have applied the first spray, accumulate daily EFI units.
  3. In addition to weather based EFI, add two EFI if you apply overhead irrigation to the crop.
  4. The accumulated EFI units are the "spray counter". When the spray counter reaches 30, apply a spray of chlorothalonil.
  5. Reset the spray counter to zero. Again, accumulate the EFI units until the spray counter reaches 30.
  6. If a spray has not been applied for 14 days, apply a fungicide and reset the spray counter to zero, continue accumulating EFI.


Below are the EFI values from weather stations located on the Eastern Shore June 4 - 10.

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 accumulation to 0 and start over. 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. *

Field Crops

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


Fields should be sampled on a weekly basis for potato leafhopper nymphs and adults. Adults have been laying eggs for more than 3 weeks and nymphs can now be found in fields. Remember, nymphs can quickly cause damage, especially when the weather is hot and dry. In 4-6 inch-tall alfalfa, the threshold is 50 leafhoppers per 100 sweeps. In 7-11 inch-tall alfalfa, the threshold is 100 leafhoppers per 100 sweeps. The threshold in alfalfa taller than 12 inches is 150 per 100 sweeps. As alfalfa reaches the bud stage, early harvest is a control option if the field is 60% or more in bud and you have had 35-40 days since your last harvest. Ambush, Baythroid, Pounce, or Warrior will all provide effective control.


At this time, grasshoppers continue to be the predominant insect pest in soybeans. For grasshoppers, treatment of non-crop areas may help to prevent whole field infestations at a later date. As a general guideline, non-crop areas should be treated if you find 20 or more grasshoppers per square yard. Remember, before bloom no in-field insect controls should be needed unless you find 30% defoliation and one grasshopper per sweep. Asana, Sevin, or Warrior have provided the most consistent control in recent years. *


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

"New Grain Marketing Alternatives Now Available"

The Prepaid Forward Delivery Contract

Those needing money today to fund business operations and willing to commit to future delivery of crops, may be interested in the prepaid forward delivery contract. What is it? The prepaid forward delivery contract - known as the prepay - is a physical grain purchase contract that provides immediate funds for a portion of the value of each contract written. Following application and approval, the maximum number of bushels eligible for prepayment are determined. Typically, this will be 50 percent of estimated crop production, and may be as high as 65 percent or more. Each contract will run on a 12-month cycle based on the crop year, and the minimum advance amount in most cases will be $25,000. Advances must be used within one year of approval, or a new approval must be granted.

The prepay may be used to contract bushels up to the pre-approved limit and receive funds immediately for a portion of the value of each contract. The amount received depends upon the specific contract and pricing option chosen, as well as the number of bushels contracted. A competitive, fixed interest rate will be charged on the amounts advanced until the grain is delivered.

A variety of contract and pricing options are provided. A contract can be selected with:

   *     a guaranteed minimum price

    *    a pricing window with a minimum and maximum price

    *    a predetermined fixed price

    *    a No Price Established Contract providing added pricing flexibility at a lower level of             advance

Each of these contracts differs in the level of downside price protection provided, the level of upward price movement given, and to a limited degree, the financing rate on the advance.

The Premium Offer Contract

Those wanting to enhance the price of a nearby delivery for grain and willing to commit to a firm offer to sell for deferred grain delivery may be interested in the Premium Offer Contract as a marketing alternative. What is it? With the premium offer contract, a premium is paid for a nearby delivery of grain in exchange for a firm offer to sell grain for deferred delivery at an established price.

What are the advantages of the Premium Offer Contract?

*      allows one to capture a premium on grain for nearby delivery

*      the basis may be set for the firm offer to sell deferred delivery grain on the day         of writing the contract, or wait until later

*      no obligation to deliver on the firm offer of deferred delivery grain if

       futures close below the strike price

*      an election may be made to be paid in advance in the amount of 1/2 of the         premium on the nearby delivery grain by giving a firm offer to sell deferred          delivery grain in an amount equal to 1/2 of the nearby delivery grain bushels         to be sold

What are the risks and disadvantages of the Premium Offer Contract?

*      the only time the deferred delivery grain may be priced is on the pricing date         after the market closes

*      regardless of how high futures prices may exceed the initial strike price on the         pricing date, the final cash price will be the strike price less local basis

*      the firm offer does not guarantee the sale of deferred delivery grain

*      the deferred delivery grain conditional sale might cause uncertainty when         marketing additional deferred delivery grain during a futures rally that occurs          before the firm offer pricing date

*      should futures prices rally above the strike price before the pricing date, the         deferred delivery grain committed under the premium offer contract cannot be          repriced.

Anyone interested in pursuing the use of either of the above mentioned marketing alternatives can contact Carl German at 302-831-1317 or clgerman@udel.edu for further information.  *



Straw Harvest - What Do You Lose? - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

What do you lose when you remove the straw from wheat and barley fields. The most obvious answers are residue cover and potential organic matter/humus. The loss of crop residue can be good if there is so much there that your planter or drill will have a difficult time properly placing the next crop’s seed in contact with the soil or can be bad if after removal there will be so little cover left that it’s not able to reduce evaporation from the soil or inhibit weed germination. The lost of organic material that can be cycled through the soil system into humus is a negative and must be balanced against the profits earned from selling the straw.

What else can be lost? Using averages from nationally-developed nutritional tables [Nutrient Requirements of Dairy Cattle, 6th Revised Edition (1989) and the Atlas of Nutritional Data on United States and Canadian Feeds published by the National Academy of Sciences], I calculated how much nitrogen (N), phosphorus (P2O5), potash (K2O), calcium (Ca), magnesium (Mg), and sulfur (S) is lost in each ton of straw. For barley straw, each ton removes 12 to 14 lb N, 2 to 4 lb of P2O5, 35 to 55 lb of K2O, 4 to 6 lb of Ca, 4 to 6 lb of Mg, and 3 to 4 lb S. For wheat straw, each ton removes 10 to 12 lb N, 2 to 3 lb of P2O5, 25 to 35 lb of K2O, 3 to 5 lb of Ca, 2 to 4 lb of Mg, and 3 to 4 lb S. As you can see, the greatest nutrient removal is for potash and on soils low to medium in potash this can be significant. Generally for double-crop soybeans, enough potash is applied to the small grain crop to carry the soybeans. You also should do this when planting double-cropped grain sorghum since potash will help the crop withstand stress better.

So when you’re making the decision to remove the straw, keep in mind that not all the dollars that come in from straw sales should be credited to the profit line. Some of those dollars will need to be allocated back into fertilizer purchases and into an occasional cover/green manure crop to help improve the soil tilth. If we use 15 cents per pound for nitrogen, sulfur, and potash; 20 cents per pound for phosphorus; and 30 dollars per ton for dolomitic limestone and the mid-point of the range for nutrient removal, each ton of straw removes $10.33 or $7.90 worth of nutrients for barley or wheat straw, respectively.  *


Small Grain Nutrient Removal - Richard W. Taylor, Extension Agronomist ; rtaylor@udel.edu

In the previous article, I discussed the loss of nutrients when barley and wheat straw are baled and sold off-farm. But, what is lost when the grain crop is harvested and sold. Based on nutrient content of the grain as reported in the Atlas of Nutritional Data on United States and Canadian Feeds published by the National Academy of Sciences, each 10 bu of wheat removes 10.66 lb nitrogen, 0.78 lb magnesium, 4.4 lb of phosphorus (as P2O5), 2.8 lb potash (as K2O), 1.1 lb of sulfur, 0.5 lb calcium, and small amounts of iron, copper , and manganese. If we use 15 cents per pound for nitrogen, sulfur, and potash; 20 cents per pound for phosphorus; and 30 dollars per ton for dolomitic limestone, each 10 bushels of wheat removes $3.12 worth of nutrients.

For barley, the numbers are similar. Each 10 bu of barley removes 8.9 lb nitrogen, 0.62 lb magnesium, 4.4 lb of phosphorus (as P2O5), 2.8 lb potash (as K2O), 0.7 lb of sulfur, 0.34 lb calcium, and small amounts of iron, copper , and manganese. If we use the same costs for nutrients, each 10 bushels of barley removes $2.78 worth of nutrients.  *

                Weather Summary 

Week of June 6 to June 11

0.10 inches: June 10
Readings taken for the previous 24 hours at 8 a.m.
Air Temperature:
Highs Ranged from 84 F on June 6 to 70 F on June 8.
Lows Ranged from 58 F on June 5 to 46 F on June 9.
Soil Temperature:
67 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:



* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

The Kent County Extension Office Has Moved…

The new address for the University of Delaware Kent County Extension Office is:

69 Transportation Circle

Dover, Delaware 19901

Phone: 302-697-4000

Fax: 302-735-8130 (NEW)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

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.

Hit Counter