Volume 7, Issue 26                                                                                                                 September 24, 1999



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


Cole Crops.

Although insect pressure has been lower in recent weeks, diamondback moth (DBM) adults could be found actively laying eggs in fields early this week. Check fields carefully for the presence of larvae, especially the undersurface of leaves and deep inside the heart of the plants. At this time, a control is needed on cabbage if 5% of plans are infested with larvae. With the recent cooler evenings,  Spintor will be the best choice for diamondback control. The Bt insecticides have provided good DBM control but generally need warmer temperatures to provide effective control.


Lima Beans.

Corn earworm moths could still be found laying eggs in fields after the hurricane. The rain helped to reduce the numbers of very small larvae; however, it did not totally eliminate them. Cooler evening temperatures will slow the development of corn earworm; however, fields should still be sampled for larvae until early October.



Feeding damage from webworms can be found in fields throughout the state. Many larvae have probably been killed by the heavy rains from the hurricane; however, there is still time to get additional egg laying. In addition, beet armyworm moths are actively laying eggs. The newer products, Confirm (8 oz/acre) and Spintor (3-4 oz/acre), have provided effective webworm and beet armyworm control in research trials.


Vegetable Diseases    -  Bob Mulrooney, Extension Plant Patholgist ; bobmul@udel.edu


Lima beans.

Downy mildew caused by Phytophthora phaseoli is present in Maryland and the recent wet weather has been ideal for infection of the late crop. Scouting fields is very important at this time. Downy mildew produces a flat white fungus growth on the pods that are not touching the soil. White mold caused by Sclerotinia is much whiter and fluffier that downy mildew. Sclerotinia will produce hard black sclerotia embedded in the white fungus growth. Another disease that can be confused with the previous two diseases is Pythium pod rot. Pythium infect pods that are touching the ground.  It is also fluffy and pods deteriorate rapidly once infected. As mentioned last week, for downy mildew control there is a Section 18 label for Quadris Flowable at 15.4 fl. oz./A. Tri-basic copper sulfate is also labeled, but has not been as effective as Quadris in tests conducted last season. We don’t know what fields are at risk because of the presence of a new race for which there is no resistance. You cannot presume that your variety is resistant, so scouting is very important. 


Cole Crops.

Late season Alternaria leaf spot and head rot and downy mildew can be a problem in the fall or when harvest is extended late in the fall. Preventative applications of Bravo, Ridomil Gold/Bravo, or maneb on a 7-10 day interval can protect plants from these diseases. Bacterial head rot in broccoli and cauliflower cannot be controlled effectively with chemicals. Choose varieties that are well-domed to shed water. The cool temperatures we are experiencing now are not favorable for infection.


Field Crops



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



I am still receiving samples of charcoal rot and stem canker from several areas. Even when the plant is dead, the small microsclerotia of charcoal rot can be seen in the pith of infected stems. It will look like fine powdered charcoal in the pith or embedded in the bark from the taproot and/or lower stems.


As soybean harvest approaches, try to diagnose any problems you may have had while the crop is still in the field, so you can implement the proper control strategy. For most, drought was the major problem, but it may have masked other problems such as diseases caused by soybean cyst nematode (SCN), charcoal rot, stem canker, and others. The weather was not particularly favorable for SCN late in the season, but I have seen it. Survey sampling the soil in the fall after harvest is the best way determine if SCN is present or evaluating your control program using resistant varieties or rotation. Soil sample bags are available from the county Extension offices for $10.00.


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


Harvest Pressure; Large Supplies Pressure Grain Markets
The 1999 U.S. corn harvest is speeding along. Todate, some 15 % + of the nations corn harvest is in the bin, and that number is expected to double in about a week. Soybean harvest is currently running about 6 to 8 % which is about normal for this time of year. Forecasts for frost in the upper Midwest have not garnered much attention in the commodity trading pits, with USDA reporting crop maturity for corn at 66 %, with 52 % of soybeans dropping leaves. In Minnesota, Nebraska, and Wisconsin, 45% or better of the corn crop is reported as mature. Temperatures are forecast to warm up the balance of the week and damaging cold readings will likely be limited.

November soybeans are trading at $4.80 per bushel this morning, now placing support at $4.75. December corn is currently trading at support of $2.08 per bushel. If the market trades lower today we are likely to see a move back below $2.00 per bushel for December corn futures. One trader stated this week "December corn won't be happy until it doesn't have a '2' in front of it, and Nov. beans are likely to head further south to $4.50 per bushel".

Preplant Decisions Greatly Impact Wheat Success

Richard W. Taylor, Extension Agronomist, rtaylor@udel.edu

Bob Mulrooney, Extension Plant Pathologist, bobmul@udel.edu

Joanne Whalen, Extension IPM Specialist, jwhalen@udel.edu

Bob Uniatowski, Extension Field Crops Associate, bobuni@udel.edu



In farming, we sometimes run into times when it is easier to make decisions more by default than by reasoned and thoughtful consideration.  This can be true especially in times when commodity prices are low.  Our tendency then is to fall back on old habits and to try to just make do.


Actually, when commodity prices are low is a good time to give every aspect of our farming operation a close inspection to ensure that each management decision we make will return more dollars to the bottom line than it costs.  Let’s review some small grain management decisions and discuss important aspects of these decisions.


Crop rotation—Wheat after wheat invites a number of potential problems among them take-all disease, leaf and glume blotch, tan spot, and soil-borne viruses.  Certain of these problems can worsen when wheat is no-tilled following wheat (as in continuous wheat/double-crop soybean).  This rotation also favors Hessian fly problems.  When wheat follows corn, especially no-tilled after corn, there is an increased potential for disease problems, in particular scab.  Crop rotation is effective in reducing grain crop pest problems when a particular crop is out of the rotation for two years or more and when the crops rotated are dissimilar (soybeans or vegetables versus corn as opposed to corn versus wheat or grain sorghum).


Seed quality and seed fungicide treatments—High quality seed always should be used to plant.  If you save your own seed, be sure to select your best field on which to grow the seed crop; manage it to minimize weed competition, disease incidence, and insect damage; harvest the crop as soon as it’s ready; and properly store, clean, and treat the seed.  For saved seed, if loose smut is a concern, treat the seed with a smut-effective fungicide such as Raxil or Baytan.  A small amount of loose smut in a seed production field can result in a serious yield loss when that seed is planted the next fall for grain.


Broad-spectrum seed treatments are an ideal risk management tool.  These seed treatments do not always enhance stands or increase yields or even eliminate the need of a spring applied fungicide treatment but they can protect stands from seed and seedling diseases should soil conditions become stressful due to adverse weather or planting conditions.


Variety selection—Variety trial results from the 1999 Small Grain Variety Performance Trials are now available either from your county agricultural Extension agent or online at http://bluehen.ags.udel.edu/ncc/carl.html (logon, go to the site and look under wheat variety trials for 1999).  Varieties differ in their disease resistance levels and in their ability to yield at different locations.  Look for those varieties that have good resistance or have been treated with a broad-spectrum fungicide and have performed well across locations and across at least two years.  This year the trial report features a pooled yield across location plus a pooled yield rank across location in addition to the long-term yield averages.  These numbers will let you effectively evaluate the performance of the varieties.


Planting date—Yield trials indicate that planting wheat as near to the Hessian fly-free date as possible is important for the best yields.  Fly-free dates are Oct. 3 for New Castle County, Oct. 8 for Kent County, and Oct. 10 for Sussex County.  For wheat as opposed to barley, weather conditions significantly influenced yield based on planting date.  Over a four-year period, the average reduction was 25 percent (21 bu/A) when planting in late-November versus mid- to late-October.  This varied from only a 9 percent reduction to a 51 percent reduction.  Trials also have not shown a yield boost from increasing the seeding rate for late-planted wheat or from increasing the seeding rate above 20 to 22 seeds per foot of row (7-inch rows).


Barley yields were highest when planted the first 11 days of October.  September-planted barley yield was about 10 bu/A lower than that from early October.  By the third week of Oct., yields fell 17 bu/A but fell only another 5 bu/A during the remainder of October.  November-planted barley (before Thanksgiving) decreased another 20 bu/A.  A 2.5 bu/A seeding rate maximized barley yield although the difference in yield between a 1.5 bu/A and 2.5 bu/A seeding rate was less than 5 bu/A.  Increasing the seeding rate up to 3 bu/A only increased yields for late-planted barley in only one year out of five (at the 10 percent probability level).


Fall Fertilization—Your yearly or biennial soil test report will specify the recommended amount of lime, phosphorus (P), and potassium (K) for the next cropping system.  Generally, all of the required P and K needed by both the small grain and the crop to follow (usually soybeans or grain sorghum) can be applied to the fall small grain crop. 


The critical question this year is how much nitrogen should be applied.  Following a severe drought, a significant amount of nitrogen (N) remains in the soil after corn so no fall N fertilization is needed for the small grain crop.  However, the large amount of rain received so far this fall has leached much of the nitrogen out of small grain’s rooting zone.  A response to fall nitrogen does not occur every year but, when little N is expected to remain in the top 6 to 8 inches of soil, a small amount of N (20 to 30 lbs N/A) should be applied.  On light sandy soils, sulfur also may be in short supply and can be applied by using ammonium sulfate as the N source or by blending liquid ammonium sulfate with UAN solution.  This can be applied either as part of or the whole fall N requirement or by using it as part of the first late winter/early spring N split.


What about using some of the root stimulating products such as ACA or Asset.  Of the research work in the region that evaluates one or more of these products, most although not all report zero yield response.  Work in Delaware using as many as 12 replications, also found no response at all.  Yield decreases have not been noted either.  With wheat prices very low, even inexpensive inputs that do not significantly increase your bottom line should be evaluated with a critical eye.


Text Box: Weather Summary





Week of Sept. 17 to Sept. 22


1.91 inches: September 21

0.03 inches: September 22

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

Air Temperature:

Highs Ranged from 77°F on Sept. 20 to 63° F on Sept. 22.

Lows Ranged from 55°F on Sept. 21 to 47°F on Sept. 22.

Soil Temperature:

68 °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 University 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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