Volume 15, Issue 3                                                                                  April 13, 2007

Agronomic Crops


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



Small alfalfa weevil larvae and pin hole feeding can be found in fields in all 3 counties. Be sure to sample fields on a weekly basis for larvae. The following Penn State website can also be used to track development (http://psu.zedxinc.com/cgi-bin/site.cgi?location=2&user=psu#)


Field Corn

With continued cold weather, black cutworm pheromone trap catches remain extremely low. As temperatures increase, be sure to check recent trap catches for increases in moth activity (http://ag.udel.edu/extension/IPM/traps/currentbcwtraps.html).


Seed treatment insecticides containing lindane will no longer be sold after July 1, 2007 - EPA has announced a phase-out period for all pesticide products containing the active ingredient, lindane. Growers need to be aware of two important dates. Cancellation date of end-use product registrations - this will affect stocks of lindane available for sale to the public. This date is July 1, 2007. The more important date is October 1, 2009. End-users holding lindane products after this date will no longer be legally able to use the products. For more details, please refer to the following link in Pesticide Briefs http://ag.udel.edu/extension/pesticide/briefs/dec2006.htm#lindaneru


Small Grains

Very low levels of cereal leaf beetle egg laying have been found in isolated areas. As soon as temperatures increase, you should watch for an increase in egg laying and hatch. Populations can increase quickly so continue to scout fields on a weekly basis.



With the increased interest in early planted soybeans, remember that seed corn maggot can be a problem, especially in no-till fields or in fields where a green manure is plowed under before planting. At this point, control options are limited to the commercial applied seed treatments, Cruiser and Gaucho.



Agronomic Crop Diseases Bob Mulrooney; Extension Plant Pathologist; bobmul@udel.edu


Soybean Rust Update

The record breaking frost on Easter Sunday morning throughout the Southeast has burnt kudzu back within four feet of the ground. Early planted soybeans in the panhandle of Florida were frosted as well, but not killed. This unusual weather event will delay kudzu development, and therefore soybean rust development in the South. Louisiana was not affected by the frost but no rust is present there. To keep up with the latest soybean rust developments visit http://www.sbrusa.net/.



The first disease of the season on wheat is usually powdery mildew. In general powdery mildew has not been a problem for several years. Once wheat reaches jointing (Growth Stage 6) it should be scouted regularly for powdery mildew. As always, planting the best yielding resistant varieties is the best control strategy, but if mildew threatens to rob yields later, fungicide control is the best control measure. Tilt, Propimax EC and Stratego are suggested for control when and if fungicides are needed. It is common for powdery mildew to infect the lowest leaves and remain there for some time. The critical time to scout for powdery mildew is GS 8-10 (when the last leaf just appears until head emergence) to determine if fungicides are needed.



Cold Weather and Corn PlantingRichard Taylor, Extension Agronomist; rtaylor@udel.edu


Other than the occasional day in March, temperatures have remained at or below normal causing the daily low soil temperatures to seldom rise above the critical 50˚ F. level needed for corn germination and growth. Reports have come in that indicate some corn has already been planted. A major concern for these planted acres is the continuing low soil temperatures and a long-term forecast showing only limited periods of warmer daytime temperatures before the latter part of April. Corn that fails to emerge after being in the ground for 3 weeks has a much higher risk of stand emergence problems and frequently shows very uneven emergence. The chance that very early planted corn will need to be replanted this year is high in my estimation, especially if the current long-range forecast holds true. Replanting certainly will impact the profitability of the corn crop even with the prices available at this time.


Stand reductions can significantly impact yield potential but so can uneven emergence. Severe uneven emergence can cause yield reductions of 10 to 20 bu/acre or greater.


Mid-April (April 21) planted short to mid-season corn can have a yield reduction of 8 to 16% when stands are reduced by 4 to 6 thousand plants per acre while full-season corn can have a yield reduction of 6 to 9%. Earlier planting will significantly increase the potential yield reduction. Very late planting also can reduce yield potential significantly but probably not as much as we will see with early April planted corn this year.


If at all possible, try to avoid planting corn until the average soil temperature goes above 50˚ F to ensure rapid and uniform germination and emergence. High yield potential fields should be planted under these conditions since they offer the chance at the highest net return per acre.



Wheat and Freezing InjuryRichard Taylor, Extension Agronomist; rtaylor@udel.edu


Although our wheat is still not far enough along to be too concerned with freezing injury, I thought it might be worthwhile to include here some information from the University of Kentucky about freeze injury on wheat. Reprinted below is Table 1 from an article by Chad Lee and Jim Herbek, Extension Grain Crops Specialists with the University of Kentucky and originally printed in Wheat Science News, Vol. 11, Issue 1 for April 2007 and published by the University of Kentucky College of Agriculture Cooperative Extension Service. Wheat losses from cold temperatures depend on the growth stage of the wheat, the air temperature in the canopy, the duration of the temperature, and possibly the sensitivity of the wheat related to the amount of nitrogen (N) applied (the higher the N rate, the more tender the tissue). Our long-range forecast includes periods of cold weather over the next two weeks. It is important for growers to scout frost-susceptible small grain fields to keep abreast of yield potential for their marketing plans.


Table 1. Freeze injury to wheat


Growth Stage

Approximate Injurious Temperature

(two hours duration)

Primary Symptoms

Yield Effect

Tillering (1-5)a

12˚ F.

Leaf chlorosis; burning of leaf tips; silage odor; blue cast to fields

Slight to moderate

Jointing (6-7)

24˚ F.

Death of growing point; leaf yellowing or burning; lesions, splitting, or bending of lower stem; odor

Moderate to severe


28˚ F.

Floret sterility; spike trapped in boot; damage to lower stem; leaf discoloration; odor

Moderate to severe

Heading (10.1-.5)

30˚ F.

Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration


Flowering (10.51-.5)

30˚ F.

Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration



28˚ F.

White awns or white spikes; damage to lower stems; leaf discoloration; shrunken, roughened, or discolored kernels

Moderate to severe

Dough (11.2)

28˚ F.

Shriveled, discolored kernels; poor germination

Slight to moderate

a Numbers in parentheses refer to the Feekes’ scale.



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


Commodity Prices Down But Not Out

Dec '07 corn futures, currently trading at $3.87 per bushel, are actually 7 cents per bushel higher than one week ago. Nov '07 soybean futures, currently trading at $7.85 per bushel, are down 20 cents per bushel from a week ago. It is now time for planting to begin in the Corn Belt. So far, it has been cold and too wet to plant corn. Although not considered late at this point in time, U.S. corn planting needs to get underway in the very near future in order to get somewhere between 87 to 90 million acres of corn in the ground. Next week mid-April shows up on the calendar and commodity traders will be taking a hard look at planting progress reports. They will be deciphering whether it is possible for all of the corn acres to get in the ground that the U.S. needs to plant this year.


Corn and Wheat Exports Termed Bullish

U.S. corn exports were nearly double (52.2 million bushels) what is needed to keep up with USDA's projected sales for the year. U.S. wheat export sales are also far ahead of USDA's projected level, reported at 25.5 mb, and are nearly three times what's needed this week to stay on pace with USDA's projection. U.S. soybean exports, reported at 5 mb, were just ahead of the 3.7 mb needed to stay on pace with USDA's revised projection of 1.08 billion bushels for the '06/'07 marketing year.


Marketing Strategy

Due to several unknowns, including the necessity to make planting progress, and the eventual size of the U.S. corn crop it appears advisable to hold up on advancing sales at this point in time. For technical assistance on making grain marketing decisions contact: Carl L. German, Extension Crops Marketing Specialist 



Weather Summary

Carvel Research and Education Center Georgetown, DE

Week of April 5 to April 11, 2007

Readings Taken from Midnight to Midnight



0.01 inch:  April 7


Air Temperature:

Highs Ranged from 53 on April 11 to 41°F on April 7.

Lows Ranged from 36°F on April 5 to 27°F on April 11.


Soil Temperature:

47°F average.

(Soil temperature taken at a 2" depth, under sod)

Additional Delaware weather data is available at http://www.rec.udel.edu/TopLevel/Weather.htm



Weekly Crop Update is compiled and edited by Emmalea Ernest, Extension Associate – Vegetable Crops



Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Delaware Cooperative Extension, University of Delaware. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age or national origin.