C.O.R.N. Newsletter 2011-35

Dates Covered: 
October 10, 2011 - October 17, 2011
Editor: 
Curtis Young
Soybean Aphids on Buckthorn

Soybean Aphids on Buckthorn

Soybean aphids are now being observed on buckthorn, their overwintering host in Ohio.  Various natural enemies are present, including multicolored Asian lady beetles and syrphid fly maggots.  A few eggs have been laid on the buckthorn near the buds for next year's growth.  The egg is the life stage in which the soybean aphid overwinters.   

In most years that are considered “soybean aphid” years such as 2011, we would not expect to see large numbers of soybean aphids on the buckthorn nor eggs being laid; aphids on buckthorn in the fall usually happens during “non-aphid” years which provides the aphid populations for the following year.  However, in 2009, our last “aphid” year, we also experienced aphids colonizing buckthorn which was a surprise and made us wonder if the 2-year cycle had been broken.  However, aphid populations were high that fall when an apparent pathogen came in, causing severe aphid mortality and resulting in 2010 being a non-aphid year keeping the 2-year cycle.  You can read a series of articles on this occurrence at  http://corn.osu.edu/newsletters/2009/article?issueid=324&articleid=1928; http://corn.osu.edu/newsletters/2009/article?issueid=329&articleid=1948; and http://corn.osu.edu/newsletters/2010/2010-10/soybean-aphid-populations-not-being-found-on-buckthorn.   

Whether aphids now on buckthorn lay sufficient numbers of eggs that successfully overwinter will not be known until next spring and summer.  Will we see a repeat of 2009-2010, and maintain our two-year cycle and have a low aphid year next year, or will we have aphids next summer in 2012?  That will need continued observations through next spring and summer to answer these questions.

Fall Weed Control in Corn and Black Cutworm

Fall Weed Control in Corn and Black Cutworm

We like to remind growers that fall weed control of winter annuals in corn is an excellent preventive management tactic for black cutworm the following spring.  By providing a weed-free seedbed in the spring, the likelihood of black cutworm problems in the spring will be lower.  Adult moths migrate from the south each spring and lay their eggs on weeds, with chickweed perhaps the most well-known host for eggs.  Black cutworm caterpillars then move to corn when weeds are killed.  Thus, a fall herbicide application not only rids the field of the weeds, but also removes potential sites for egg laying.  When considering the benefits of a fall herbicide application, do not forget the added benefit of black cutworm management.

Correction on Burndown Information for No-till Wheat

In the September 13 C.O.R.N. article, “Burndown herbicides for wheat” (C.O.R.N. Newsletter 2011-31 (http://corn.osu.edu/newsletters/2011/2011-31)), we stated that Ignite could be used prior to wheat emergence for burndown of emerged weeds.  We forgot to review the Ignite label prior to making this suggestion.  The label indicates that 70 days must elapse between Ignite application and planting of wheat or other small grains.  This is not due to concerns about the soil residual activity of Ignite, since it has none, or the possibility of injury to wheat.  Bayer sources informed us that they have not yet conducted the plant residue studies to establish tolerances for Ignite in wheat.  The 70-day restriction is the result of this lack of residue studies.

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About the C.O.R.N. Newsletter

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.