May 18, 2005
number of black cutworm moths captured in black cutworm moth traps this spring
has been generally low. To view the numbers, go to http://www.ent.iastate.edu/trap/blackcutworm/.
A significant catch is considered to be eight or more over two consecutive
nights. It is important to remember that catching moths only indicates
they were there; it does not mean they stayed long enough to lay eggs or
that survival will be great enough to cause a problem. However, if there
are eight or more caught, there may be enough eggs laid to cause a
problem. By knowing when the moths arrived and by monitoring
temperatures, we can fairly accurately predict when cutting will start if eggs
were laid and larvae survived.
Three traps in southern
If you work off the Fruitland /
May 22 +/- one day along Highway 34
May 24 +/- one day along Interstate 80
May 25 +/- one day along Highway 30, and
May 29 +/- one day near Dubuque.
Cooler than normal temperatures will push the dates back while warmer than normal temperatures will move the dates forward.
Remember, it is wise to begin scouting for this pest a couple of days before cutting is predicted to start. A small amount of cutting by black cutworms has already been observed in
Preliminary data from Iowa State University suggests that the low rates of seed-applied insecticides (Cruiser, Poncho) are not effective in managing black cutworms; see http://www.ipm.iastate.edu/ipm/icm/2005/5-9-2005/seedtreat.html or page 76 of the May 9, 2005 ICM Newsletter. Cruiser was not tested at the high rate, but Poncho 1250 was effective in controlling black cutworms.
Granular insecticides claiming black cutworm control are not always effective.
So it is wise to scout all corn fields for black cutworm injury until the corn reaches the five-leaf stage, when it is too large to be significantly damaged by black cutworms.
When cutworms average less than 0.75 inch in length, an insecticide should be considered if 2 or 3 percent of the plants are wilted or cut. If cutworms are longer than 1 inch, treatment should be applied if 5 percent of the plants are cut. If the field has a poor plant population, 20,000 or less, these thresholds should be lowered.
An article on scouting for black cutworms will appear in a few days at http://www.ipm.iastate.edu/ipm/icm/.
Also, watch http://www.extension.iastate.edu/Pages/eccrops/insect.html for updated information on the development of this and other insects during 2005.
moderate population of flea beetles was observed in an early planted corn field
Although alfalfa weevil numbers have generally been well below threshold, continue to monitor alfalfa fields. Scouting, threshold, and management information is on pages 48 - 49 of the April 11, 2005 Integrated Crop Management (ICM) Newsletter. Also, watch http://www.extension.iastate.edu/Pages/eccrops/insect.html for updated information on the development of this and other insects during 2005.
ASIAN SOYBEAN RUST UPDATE
extensive scouting, there still have been no reports of Asian soybean rust on
soybeans or kudzu outside of
FOR YOUR CALENDAR
Brush up on Your Soybean Disease Identification Skills and Earn CCA Credits - Crawfordsville - June 23
If you have any questions, please feel free to contact the Iowa State University Extension Office.
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