C.O.R.N. Newsletter 2005-32

Tell CORN About Your Summer Experience With Aphids and Weed Control

Authors: Greg LaBarge

CORN readers please let us know what your experience was this past summer with soybean aphid and weed control issues. A survey that asks some questions related to these two summer problems and a few other issues can be found at the following link: http://www.zoomerang.com/survey.zgi?p=WEB224LWXVCMXN. If you have already responded to the survey, we thank you. If you haven’t responded to the survey, please take time to reply. The survey will only take a few minutes but provide us with valuable information on the extent of spraying for soybean aphids in Ohio and some weed control issues. The results of the survey will be used to direct research and educational activities. We will share the results in a future newsletter. The survey will be open for the next two weeks but we hope you can take time today to share your experiences with us!

Stored Grain Insecticide Options

Few insecticides are labeled for use in, on and/or around stored grain and stored grain facilities. Labels and registrations are changing or being withdrawn, thus one should be cautious as to what is being applied. Be sure to have a current label for the product you are considering, follow the label directions for appropriate rates and methods of application, and in some cases, you may need to talk to your grain purchaser before you apply a material to be sure the grain will be accepted with insecticide residues. Only a few new products have been registered for use in stored grain over the past couple of years.

Two weeks ago, an article discussing the SLAM IPM strategy for managing stored grain and grain handling facilities was presented in this newsletter (Protect Grain Quality and Profits through Storage Bin Preparation, CORN 2005-30 - http://corn.osu.edu/story.php?setissueID=103&storyID=609). In that article, empty bin insecticide treatments were presented. Three additional options for use of insecticides in stored grain are applying insecticides as entire grain mass protectants, as top-dress treatments and in fumigations.

The following are insecticides registered for management of stored grain insects, where they can be used and comments about their use.

If one knows or if there is a chance that grain is going to be stored for several months, especially if it is going to be stored into and through the following summer, the grain will often benefit from the use of a grain protectant. Protectants are materials applied to the grain as it is loaded into storage. These products should only be applied to clean, dry grain. The effective life of these products is shortened as grain moisture increases.

Chlorpyrifos-methyl (Reldan 4E) is registered for use on small grains (barley, oats, rice, sorghum and wheat). This product is not registered for use on corn or soybeans. Reldan should not be applied to grain that was dried in a high temperature drier until the grain is cooled. It can protect grain from infestation for up to 12 months if moisture content of the grain is less than 14%. It may not be effective against lesser grain borer. Reldan 4E will be sold by Gustafson until 12/31/04 to authorized distributors. Distributors will sell Reldan 4E until 12/31/05 and treated grain will be given the opportunity to move through grain channels until 2009-2010.

Chlorpyrifos-methyl and deltamethrin (Storcide II) is registered for use on small grains (barley, oats, rice, sorghum and wheat). Storcide II is the replacement product for Reldan 4E. Storcide II is effective against a broad spectrum of stored grain pests, including the lesser grain borer.

Malathion is or was registered for use on multiple grains, including corn, barley, oats, rice, sorghum and wheat. Before the application of malathion, grain should be dried to 13% or less moisture content and cooled. Malathion has never been overly effective against Indianmeal moth and lesser grain borer. The “stored grain” labels for liquid formulations of malathion have been withdrawn. Current stocks with the correct label may be used until the stock is exhausted. Some dust formulations of malathion (MAX KILL Dusta-cide 6) are still available. Malathion products that are not specifically labeled for use on stored grain should not be used.

Pirimiphos-methyl (Actellic 5E) is registered for use on corn, including pop corn and grain sorghum. Do not apply to grain before high temperature drying. There are no food or feeding restrictions on this product. Lesser grain borer is not listed as a target pest on this label.

(s)-Methoprene (DIACON II) is registered for use on corn, barley, oats, rice, peanuts, grain sorghum and wheat. DIACON II is an insect growth regulator (IGR) that prevents insects from completing their growth and development. It has a limited number of insects listed on its label which does not include weevils. See the DIACON II label for application methods and restrictions.

Silicon dioxide and/or diatomaceaou earth (DE) (Dryacide, Insecto, Perma-Guard, Protect-It and others) are registered for all grains. Select one of these products that is labeled for treating stored grain and follow label directions. Applications of these materials to the entire grain mass can lower test weight and reduce the flowability of grain. In many cases, these products are only applied to the bottom and top layers of the grain.

Top-dress treatments can help protect the grain from infestations that enter the bin through the head space. They should be applied to the grain as soon as the bin is filled and the surface of the grain mass is leveled. They may need to be reapplied anytime the surface is disturbed. Reldan 4E, malathion, Actellic 5E, DIACON II, Protect-It, and DE (Insecto) can all be used as top-dress materials. However, products such as Reldan 4E and Actellic 5E can not be used as both a grain mass protectant and a top-dress treatment at the same time.

Bacillus thuringiensis (Bt) (Dipel Dust) is registered for use on all grains including soybeans. This product only protects against Lepidopteran insect pests, Indianmeal moth and Angoumois grain moth, and only impacts the larval (caterpillar) stage.

Fumigations are used for rescue treatments of grain that becomes infested with stored grain insect pests, especially pests such as weevils and lesser grain borers. Products available for grain fumigation included aluminum and magnesium phosphide (Fumiphos, Fumitoxin, Phosfume, Phostoxin, Weevilcide, and others), and sulfuryl fluoride (Profume). These products are extremely toxic, require specialized worker protection equipment and should only be applied by specially trained applicators.

One practice that we highly recommend NOT doing is loading newly harvested grain into a bin partially filled with grain from a previous harvest. Grain that has been stored for several months including summer months have a great potential for having become infested with highly destructive stored grain insects, such as weevils. Loading new grain into a bin with old grain could result in rapid infestation. However, if a situation arises where this practice can not be avoided, one should take several steps to reduce risks of developing a major problem. First, inspect the grain for infestations. If it is infested either have the grain fumigated or while moving the grain, clean it and treat it with a grain mass protectant. Remember that primary insect pests such as weevils whose larvae (grubs) develop inside of kernels of grain will NOT be killed by an insecticide applied to the surface of the grain. Only a fumigation treatment can penetrate into the larvae. Once the grain has been fumigated or cleaned and treated, consolidate this old grain as much as possible into the smallest bin that will hold the entire mass. Finally, place new grain treated with a grain protectant in with the old grain only as a last resort. Try to avoid this practice whenever possible.

Skip Rows in Soybeans

Authors: Ron Hammond, Jim Beuerlein, Anne Dorrance

Now that the summer is coming to a close, most of you are probably thankful that soybean rust did not occur in Ohio, and glad that the soybean aphid and other insect pests are behind us. For those of you who had to spray narrow row soybeans for soybean aphids or other insect problems, diseases other than soybean rust, or make a late herbicide application, you in all likelihood ran down soybean rows as the sprayer went through the field. It was very easy to travel through many parts of the state and see which fields had been sprayed in mid to late summer just by looking at the downed rows every 60 to 90 ft across the field.

This article is only to remind everybody, while fresh in your mind, of the potential that skip row planting offers. Skip rows allows space for the sprayer’s tires to travel without destroying plants. As we enter the fall and winter months and you begin thinking about potential changes to your production practices for next year, consider skip rows as a possible solution to this problem. See https://agcrops.osu.edu/soybean/research/SkipRow5%20May20-2005.pdf for a full discussion of this practice. We will also be discussing skip rows during the winter meetings. This is a practice that can increase your profits.

Sampling for Slugs in the Fall

Authors: Ron Hammond, Bruce Eisley

Although most slug problems are from juvenile slugs occurring in the spring, we have observed significant feeding by adult slugs in fall plantings of alfalfa and winter wheat when either was no-till planted. Thus, no-till growers who have planted either crop should check their fields and take corrective action if slugs are active and reducing stands.

More importantly, the coming months are the time periods when growers should begin scouting their fields for slug populations for next year. Sampling can be done both prior to and following harvest. While we do not have thresholds, sampling will indicate whether a field has a small or large slug population. A large population of slugs will help indicate which fields need extra monitoring next spring.

There are a number of ways to sample for slugs. The main technique is placing wood boards or roofing shingles on the ground across the field and checking them weekly throughout the fall and counting the number of adult slugs underneath the traps. It is best to count the slugs in the morning. Ten traps in a field would be a good number to use. Other ways of determining if fields have a lot of slugs is by visiting the fields in late evening before dusk or early in the morning during periods of heavy dew or fog. Slugs will often be crawling on the plants, especially corn, if not yet harvested. Growers are also advised to look underneath the leaves of larger weeds that are covering the ground. Numerous slugs are often found in those situations.

To repeat, although no thresholds are available, fields with large numbers of slugs should be monitored more closely next spring. Fields with low numbers, while still needing sampling next spring, can be a lower priority.