CORN
Crop Observation and Recommendation Network

August 20 - 26, 2002
C.O.R.N. 2002-27

In This Issue:

A) First Sample of Sudden Death Syndrome
B) Premature Death in Corn and Stalk Quality
C) Wheat Seed Quality, Dry Soil and Preparations for Fall Plantings
D) Upcoming OSU Agriculture Technology Events

A) First Sample of Sudden Death Syndrome - Anne Dorrance CORN Questions

Soybean plants with symptoms of Sudden Death Syndrome (SDS) were sent in last week. Symptoms on the leaves had bright yellow spots; older leaves had brown necrotic (dead) areas between the veins. On the taproots were signs of the fungus, blue-green spores. The fungus, Fusarium solani f.sp. glycines, causes a root rot and crown rot. The leaf symptoms are the result of a toxin.

Fusarium solani f.sp. glycines fungus on Soybean roots

Some of the more recent analysis of management of SDS have reported a decrease in the amount and severity of the disease by increasing soil drainage. Some of the factors that favor disease development include heavy rains during the vegetative growth period prior to flowering. Once a field is infested with this fungus, it is there forever. But also, in OHIO, all of the SDS fields have been SCN fields. Our management recommendations are focused on managing the SCN in the fields. The reason is that over time, SCN will cause more economic loss than the areas of SDS. In some cases the same management tools are used. Crop rotation, for SDS this prevents a rapid build-up of the pathogen in these fields as well as starves the SCN to drop those populations. SDS can also be managed by improving soil drainage. There are a few varieties with SDS resistance, but manage the SCN first, then look for varieties with SDS resistance. More information on management can be found at: http://ohioline.osu.edu/ac-fact/0044.html

B) Premature Death in Corn and Stalk Quality - Pat Lipps CORN Questions

Early planted corn in southern Ohio is beginning to mature. Over the next few weeks corn plants will begin to die in corn fields throughout the state, especially those that have been under severe stress. Premature death of plants usually indicates significant problems with stalk quality and lodging. The extreme variability in growing conditions from one area of the state to the next and from one field to the next will certainly have an impact on stalk quality and lodging potential.

Corn stalk problems usually result from stressed conditions and I think we can all agree that this year was very stressful to the corn crop nearly everywhere. The extreme wet conditions earlier this year left a corn crop with very serious root and crown rot problems, such that the root systems have never really recovered in most areas. This shallow rooted crop then faced severe drought conditions in many areas. Nutrient deficiency symptoms have been very common because the root systems have not been healthy enough to take up nutrients even when soil water was present. Root and stalk rot pathogens like Fusarium graminearum were detected on a number of plant samples by the first week of June and anthracnose was observed on the lower leaves of plants in most reduced tillage corn fields by late May. Increased leaf damage by the flea beetle, gray leaf spot and northern leaf blight have not helped the situation is some areas where these pests have been common. Isolations from corn plants indicate a high level of Fusarium moniliforme, the cause of Fusarium stalk rot, in the lower stalks and crowns of plants. The National Weather Service has indicated that drought conditions will likely continue through October. The prognosis is for continued deterioration of the crop and corn producers should stand ready to harvest the crop as soon as it is feasible.

Scout corn fields frequently for signs of premature death of plants. Check stalk quality by squeezing the lower stalks soon after you begin to see plants start losing their green color. Waiting until physiological maturity (black layer) may be too late to see early signs of stalk deterioration. As the crop matures continue to check fields and squeeze about 100 stalks randomly throughout the field to get an idea of the level of stalk quality problems. Stalks that are easily crushed with your thumb and fingers are likely to lodge given wind or stormy weather. The name of the game this year will be harvest before the crop falls down. Stalk quality issues will be much more important in those fields that have a reasonable yield potential. Fields that have had pollination problems or have had kernel abortion due to extended dry conditions will not likely have serious stalk quality issues, but then very poor yield is not an acceptable trade off for low lodging potential.

C) Wheat Seed Quality, Dry Soil and Preparations for Fall Plantings - Pat Lipps CORN Questions

The most important decision a wheat producer can make to insure a good crop next year is to choose the best varieties for his location and to make sure the seed is top quality. The 2002 season produced some of the highest test weight wheat we have seen in Ohio (up to 64 lb/bu recorded). Usually, high test weight indicates good seed quality. Seed germination tests from Ohio grown seed indicates that the germination percentage in warm germination tests has been high, however a number of seed lots appear to have Fusarium associated with the seedlings in these tests. Where did the Fusarium come from? High levels of Fusarium infested seed usually results from head scab in the field prior to harvest. Although head scab was not a serious problem in most fields this year, there were a lot of spores present in the air and on wheat heads and leaves and these spores could have been spread to wheat seed during combining. Since infection of wheat seed would have lowered seed germination percentages, spores are likely surface contaminants on the wheat seed. Regardless of where the contamination came from, the presence of Fusarium on the seed presents a potential threat to the establishment of next years crop.

The extended period of dry conditions predicted for Ohio and neighboring states this fall indicates that wheat will likely be planted into dry soil. Seed rot and seedling blight diseases caused by Fusarium may be more important when wheat is planted into dry soil. To prepare wheat seed for the possibility of increased pressure from seedling blights it is important that wheat seed be treated with an effective fungicide prior to planting. Most of the common seed treatments have some efficacy against Fusarium. However, the broad spectrum fungicides Thiram and Thiabendazole (TBZ) give improved protection against Fusarium. The most common seed treatments used in Ohio today include Raxil-Thiram, Raxil XT, Raxil MD and Dividend XL. Of these only Raxil-Thiram includes thiram. Improved efficacy against seed borne Fusarium can be achieved relatively inexpensively by applying 0.25 fl oz/cwt LSP Flowable Fungicde (TBZ) from Gustafson in addition to the other seed treatment products. Do not try to save money by cutting back on the rates of Raxil XT, Raxil MD or Dividend XL because these products help control the smut diseases and seed borne Stagonospora nodorum.

Other key factors for insuring a good wheat crop include: 1) apply 20-30 lb nitrogen at planting; 2) plant from 1.2 to 1.6 million seed per acre; 3) plant seed from 1 to 1.5 inches deep and; 4) to plant within 10 days after the Hessian Fly Safe date for your county.

D) Upcoming OSU Agriculture Technology Events - Nathan Watermeier CORN Questions

Sponsored by OSU Precision Agriculture Team, Ohio Geospatial Program for Agriculture and Natural Resources and Ohio Agricultural Technologies Association

August 21 - Southwest Ohio Corn Growers Field Day
9:30 am registration, 10:00-3:30 pm
Program: Continuing with theme of tile drainage, ground penetrating radar (GPR) used for finding tile lines, water quality associated with tile effluent, mobile handheld GPS and using remotely sensed images to identify tile lines and a tour of our current plot research at OSU Extension farm.
Location: Fayette County Airport Rt 38 . Located 2 miles north of Washington Court House, Ohio. Detailed agenda and directions at http://fayette.osu.edu/ag/ag.htm
Reservations not necessary but encouraged. $10.00 charge for non Ohio Corn Growers Association members, members have free admission. CCA credits available.
Contact: Jim O'Brien (740) 335-1150, obrien.220@osu.edu

August 22 - Precision Agriculture Day
8:30-noon
Program: Variable rate planting corn, handheld GPS units and applications, and light bar technology.
Complete Agenda and Directions at http://precisionag.osu.edu/calendar/PADay822.pdf
Location: 8924 TR 191 South, New Washington, Ohio Crawford County
Contact: Steve Prochaska, (419) 562-8731, prochaska.1@osu.edu.

August 22 - Guidance System Workshop
10:00-3:00 pm
Program: Guidance systems and light bar technology. Other agronomic speakers will start out in the morning. The guidance systems start around 1:00 pm.
Location: Morrow County, Harmony Methodist Church/Weiler Farm located at County Rd 20 and County Rd 123. 1 mile west of I-71, State Route 95 interchange turn south on County Rd 20 and go 1 1/2 mile to church.
Contact: Matthew Sullivan, (614) 247-6286, sullivan.64@osu.edu, and Steve Ruhl, 419-947-1070, ruhl.2@osu.edu

August 29 - Guidance System Workshop
4:00-7:00 pm
Program: Guidance systems and light bar technology.
Location: Champaign county, located in wheat stubble field east side of Route 68, 1 to 2 miles south of Urbana.
Contact: Matthew Sullivan, (614) 247-6286, sullivan.64@osu.edu and Barry Ward, 937-484-1526, ward.8@osu.edu

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Past versions of C.O.R.N. can be found on the World Wide Web at: http:/www.ag.ohio-state.edu/~corn/archive/

C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Editor: Clark Hutson        Web Editor: Tom Rosati

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Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

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