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Wheat producers should watch fields closely for insects

May 9, 2008 9:52 AM

Insect pressure on wheat has been relatively light so far in Kansas this year, a Kansas State University entomologist said, but there are three pests to watch for in wheat during May.

Those pests, said K-State Research and Extension entomologist Jeff Whitworth, include:

* Army cutworm has been found in canola fields in Kansas within the past few weeks, and could be a problem on wheat, too. The army cutworm is a problem on wheat somewhere in Kansas almost every year. Normally, it infests wheat in late winter and spring. This year, the wheat crop is developing later than normal in most areas so it is a good idea to continue looking for this insect. Symptoms include irregular spots in the field that may turn brown after green up. Look for brownish worms hiding in soil near the base of the plants during the day. Army cutworms prefer to feed on new spring growth.

* True armyworm often shows up in wheat about this time of year. Infestations can persist from now until harvest. True armyworm is most common during wet periods in eastern Kansas. Look for black, green, and yellow striped worms. Like army cutworms, true armyworms can also be found just beneath the soil at the base of the plants during the day. They feed at night, and can strip the foliage and beards.

* Bird cherry-oat aphid can infest wheat in the spring. This insect is a vector for barley yellow dwarf disease, which does more damage to yield potential when it infects wheat in the fall than spring. We didn´t used to worry too much about direct feeding damage from the bird cherry-oat aphid until last year. Last year, we did find many cases in which bird cherry-oat aphid populations were high enough to cause direct damage from feeding. These insects should be controlled in the spring if populations reach 30 to 50 per tiller.

More information on these and other insect pests, including critical thresholds and control options, are available in the publication: Wheat Insect Management 2008, available at county and district K- State Research and Extension offices or online: http://www.oznet.ksu.edu/library/entml2/MF745.pdf.