C.O.R.N. Newsletter 2010-23

Dates Covered: 
July 27, 2010 - August 3, 2010
Editor: 
Greg LaBarge
2010 Ohio Wheat Performance Results Available2010 Ohio Wheat Performance Results Available

2010 Ohio Wheat Performance Results Available

The purpose of the Ohio Wheat Performance Test is to evaluate wheat varieties, blends, brands, and breeding lines for yield, grain quality and other important performance characteristics. This information gives wheat producers comparative information for selecting the varieties best suited for their production system and market. Varieties differ in yield potential, winter hardiness, maturity, standability, disease and insect resistance, and other agronomic characteristics. Depending on variety and test site, yields varied between 52.5 and 89.7 bushels per acre, and test weight ranged from 53.3 to 60.0 pounds per bushel. Selection should be based on performance from multiple test sites and years. Results of the 2010 wheat performance evaluation are available at:  http://www.ag.ohio-state.edu/~perf

Insect Observations for Late JulySoybean Aphid

Insect Observations for Late July

Currently, we are not receiving many reports of insect problems in field crops in Ohio.   People are reporting finding soybean aphids, but only at a few aphids per plant at most.  Remember that the threshold is 250 aphids per plant with a rising population (it takes 700-800 per plant to cause economic damage), and these numbers are NOT being seen.  As we get into August and the later part of the summer, the susceptibility of soybeans to aphids goes down.  However, as in other years with low numbers aphid, we do expect the numbers of aphids to begin to rise prior to the end of the summer.  These aphids then will move to buckthorn in the fall and lay eggs, and will overwinter, possibly resulting in problems in 2011.

A few people have asked about twospotted spider mites in soybean with the hot temperatures we have been experiencing.  While mite populations might build up in dry areas, remember that the weather has also been very humid, which encourages a natural-occurring pathogen that helps to keep populations down.  Before taking action against this mite in soybeans, make sure that it is extensive enough and also an expanding problem.

Although not having received reports of abnormal defoliation occurring in soybean in Ohio, we have heard from other states in the Midwest including Michigan of defoliation occurring from various caterpillars.   Growers might want to check on their fields to make sure they are not caught off-guard.

One thing we would like to mention is that we are concerned about a few newer stink bugs that could be creeping into soybean fields in Ohio, as well as large numbers of the regular green and brown ones.  This is especially a concern in southern areas of the state.  The two new species of stink bugs are the brown marmorated stink bug, an invasive species from Asia, which is currently in eastern states, and the red banded stink bug which is causing new problems in middle and southern U.S. states.  Growers in Ohio are asked to make note of the presence of stink bugs that appear to be different than the usually green and brown ones or in unusually high populations over the next few months in soybean.  Please let your county extension educator know about any such findings.  A fact sheet on the brown marmorated stink bug is available on the Agronomic Crops Insects webpage at http://entomology.osu.edu/ag/images/Marmorated_Stink_Bug.pdf.

Peak flight has passed for Western Bean CutwormWestern Bean Cutworm Larvae

Peak flight has passed for Western Bean Cutworm

Based on our western bean cutworm counts this week, peak flight of western bean cutworm has finally ended in most areas of Ohio.  There are a few traps where counts slightly increased, but across the state catches have largely crashed from last week. 

Adults may still be found, but as most of our corn has already tasseled, egg laying should be minimal and non-economic.  Scouting should continue, although it should concentrate more on the presence of larvae rather than egg masses.  Newly hatched larvae are small with dark, black heads.  As they mature, they become tan or pink in color, with grayish-brown longitudinal stripes. 

The later instar stages are readily identified by 2 broad black stripes immediately behind the orange head.  Larvae can be found on leaves or in leaf axils ingesting pollen.  Eventually, larvae will reach the corn ear and begin chewing on silk and the developing kernels.  Entry holes and tip damage may be visible, but most often removing the husk is necessary to fully determine larval presence.

Although we have not yet heard of a field were egg masses indicated economic threshold was reached, we recommend scouting corn ears, especially in late August and September. This will provide some estimate of western bean cutworm damage and feeding and predict where overwintering may occur and where to intensify management efforts for next year.

Curious Kernels in Corn

In the July 23, 2010 issue of the Illinois Pest Management Bulletin, Dr. Emerson Nafziger describes an unusual phenomenon “in which corn kernels seem to start to develop after pollination but are empty of content.” Affected kernels appeared to contain only clear liquid with perhaps a small amount of white material--probably starch--that may later turn yellow.” An image of a corn ear showing the symptoms is included with the article at http://bulletin.ipm.illinois.edu/article.php?id=1387. The liquid in these "bubbles" eventually dries up, leaving what are essentially seed coats without an embryo or endosperm. These may flatten as kernels on both sides press in during grainfill, if there are only a few, scattered "bubble kernels" on an ear. Dr. Nafziger notes that corn ears exhibiting “bubble kernel” symptoms were associated with late glyphosate application and observes that conditions after application this year might have favored the development of the effect.

In recent years, there have been reports that pretassel applications of various pesticides and surfactants, especially non-ionic surfactants, may result in arrested ear development and poor kernel set (http://corn.osu.edu/newsletters/2009/article?issueid=282&articleid=1680). In a 2009 Ohio FSR evaluation conducted by ag educators Harold Watters and Jonah Johnson, ears with “jumbled” kernels resulted from applications of herbicides and various adjuvants at early tassel. Kernel jumbling was particularly severe in the glyphosate+AMS+NIS treatment. Shriveled, aborted kernels scattered throughout ears promoted the jumbled kernel appearance.

The “bubble kernels” remind me of another kernel development problem reported by Dr. Bob Nielsen at Purdue University several years ago, which he characterized as “translucent kernel syndrome” (http://www.agry.purdue.edu/ext/corn/news/articles.99/990903.html). According to Dr. Nielsen, “the initial symptoms of this oddity were the appearance of plump, translucent, liquid-filled kernels scattered randomly among already-dented kernels throughout an otherwise normal-looking ear.” The abnormal kernels subsequently shriveled as the kernels matured, “resulting in a shriveled kernel appearance not unlike mature sweet corn kernels.” Dr. Nielsen also did not specify a cause suggesting several possibilities from high temperatures to a possible genetic factor. However, glyphosate was not mentioned; the report pre-dated widespread use of glyphosate resistant hybrids and suggests that “bubble”- “translucent” kernel symptoms may occur as the result of several factors.

Sprayer Demonstration and Technology Day Plugged Nozzle

Sprayer Demonstration and Technology Day

On August 4 a Sprayer Demonstration and Technology Day will be hosted on the Fulton County Fairgrounds from 8:30 (Registration) until 3:15 by Ohio State University Extension. Register for the program by 9:45 to guarantee that a free lunch is available for you. The day will be a look at technology and practices to make the most effective and efficient application of herbicides, insecticides and fungicides to save money and maximize yields by controlling pest. The program will be focused on field demonstration of equipment and practices.

Topics for the day will include Hitting the target!, Delivering the right amount of product, preventing costly overlaps and vendor displays. Attendees will get a chance to see technologies that control boom stability and height, drift, application rate over a range of speeds and deliver the proper products rate under a simulated field condition. In addition updates on current pest of concern and poly tank inspection and selection will be included.

The program is free and open to anyone interested. Pesticide recertification or continuing education credits will be available for Ohio, Michigan and Indiana

pesticide applicator license holders.

Whether a new sprayer is in your farm’s future or you are looking to get a few more years out of your current sprayer, you will find some hints and tips to get the most our of your spray applications.

For more information and details of the day or call the Fulton County Office of Ohio State University Extension at 419-337-9210.
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Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.