CORN Newsletter: 2009-30, September 8, 2009

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C.O.R.N Newsletter 2009-30
September 8, 2009 - September 14, 2009

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Those 60 mph Field Surveys
by Anne Dorrance


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We have had some great weather for field scouting and now is the perfect time for a drive. The crop is just starting to turn in many areas of the state. A field that is maturing normally – will all turn yellow at about the same time, maybe a bit delayed around the edges but by far every plant will start to mature at the same time. Fields with issues, namely SCN will not. One of the key findings last year in the soybean check-off funded project was this difference in maturity in areas of the study site that had high populations of SCN at the end of the season. These are perfect spots to check for SCN. Sometimes you can see the white pearls (females) on the roots indicative of SCN and sometimes you can’t. If the females have all form that hard shell, which serves as their protective layer that can then help them survive for years in your soil, it is brown in color making them difficult to pick out.

Another caution on these “drive by’s” is that many late season diseases look the same: white mold, sudden death syndrome (SDS), brown stem rot (BSR), Phytophthora and last but not least – stem canker. In addition, often rare in these parts, charcoal rot, can also be present to and adds further insult to injury in areas which are dry. Each of these utilizes a different management strategy – so it is worth doing the “soybean crawl” to get to those spots to check it out. Some short diagnostic features:

White mold – at this point, stems are bleached white and soft like straw with sclerotia (black irregular shaped bodies) both inside and outside the stem.

SDS – leaves are quickly defoliating but some leaves with the irregular bright yellow spots and brown interveinal patters. When you split the tap root, it is gray in color and the pith of the stem is bright white.

BSR – leaves are also quickly defoliating on this one as well. On this when you look at the bottom of the stem it will have a “greasy” appearance, when the stem is cut, the pith will be chocolately brown just like a buckeye.

Phytophthora – leaves will cling to the plant and will fold down, the tell tale sign is the canker that comes from the soil line up the plant.
Stem canker – leaves will also cling, but here the canker is only at that third or fourth node of the plant, and the bottom of the plant – including root system is healthy.

Charcoal rot – some defoliation will begin and early dying of the plants but the tap root will have a peppery appearance often marked by dark lines. This can extend for a short distance up from the soil line.
And yes, you can have more than one pathogen hitting an individual plant, this is Ohio.

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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.

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

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.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868


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