Tuesday, April 17, 2012

Watch for Cereal Leaf Beetle in Wheat.

There have been reports of cereal leaf beetle (CLB) larvae actively feeding in wheat. This is not unexpected for this time of year. Generally this pest is not of great importance, but can always be problematic and should be monitored. This pest’s unpredictability is usually what gets producers in trouble. Often the first indication of the pest’s presence is “white” flag leaves waving in the air. This is NOT a good scouting procedure as one cannot put the leaf material back on the flag leaf!

Cereal leaf beetle can be active anytime from April to maturity. This year populations are likely to be out early, though not necessarily in larger numbers. The reports that I have received are all larval feeding, indicating that the emerging overwintering adults have already been out for some time.

CLB adults are shiny black beetles with red legs and thorax, about 1/2” long. They emerge first, usually in March and lay eggs on wheat plants.
Cereal Leaf Beetle

Larvae are pale yellow and soft bodied. They may “glue” small pieces of trash and leaf on their backs as a type of camouflage. They can look very much like bird “droppings”.

Both adults and larvae feed on the leaves and
Damage from Cereal Leaf Beetle
both may appear in the field at the same time. Both feed by removing the leaf surface tissue from between the leaf veins. This often leaves a very diagnostic scaring that looks like giant flea beetle scratches.

Scout by examining the upper leaves on 10 tillers per site and a total of at least 100 tillers per field. Be especially observant of the flag and F1 & F2 leaves. Treatment should be considered if, on average, you find ½ larva or adult per stem (1 larvae or adult for every two stems).

CLB are not particularly difficult to control. Generally the problem is that most producers do not find the pest until it is too late to protect the three important upper leaves. If a pesticide application is warranted, refer to ENT-47, Insecticide Recommendations for Small Grains - 2012, available from your County Extension Office or online at: http://pest.ca.uky.edu/EXT/Recs/ENT47-SmallGrain.pdf

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