May 7, 2007

 

ALFALFA

Alfalfa Weevil

I have received no reports of significant alfalfa weevil injury.  However, it would be wise to continue to monitor alfalfa for this pest.  For details on scouting for and managing this insect, see pages 22-23 of the April 19, 2004 Integrated Crop Management (ICM) Newsletter http://www.ipm.iastate.edu/ipm/icm/2004/4-19-2004/. Also, watch http://www.extension.iastate.edu/Pages/eccrops/insect.html for updated information on the development of this and other insects during 2007.

 

 

CORN

 

Planting

 

There are still many acres of corn to plant.  We normally think that the ideal planting time is now at an end.  However, yields generally do not begin to drastically decline until planting is delayed until after May 15 - 20.  It is not necessary to consider switching to a shorter season hybrid until about May 25.  And be sure to avoid “mudding in” the crop; wait for good soil conditions.  For more information see the ISU Extension Corn Production web page: www.agronext.iastate.edu/corn and Iowa State University publication PM-1885  “Corn Planting Guide” at http://www.extension.iastate.edu/Publications/PM1885.pdf.

 

 

Scout for Black Cutworms

 

Black cutworms do not over winter in Iowa. Rather, if black cutworm moths fly in from the south and if they stay around long enough to lay eggs, young corn plants may be injured. A series of black cutworm moth traps is set up around Iowa and Illinois to monitor moth flights.  Significant flights occur very regularly, but damage at a treatable level generally occurs less than once per decade. If eggs are laid, the hatch date can be fairly closely predicted by monitoring temperatures.

 

Based on moth captures and temperatures, cutting, if it occurs, should begin very soon along and south of Interstate 80; I have received one report of black cutworm leaf feeding.  North of Interstate 80, See pages 105 – 106 of the May 1, 2006 ICM Newsletter or http://www.ipm.iastate.edu/ipm/icm/2006/5-1/cutworms.html for scouting and management details.  Additional information is at http://www.extension.iastate.edu/Pages/eccrops/blackcutworm.html.

 

 

Corn Flea Beetles

 

The mild temperatures of most of last winter suggest potential problems with corn flea beetles attacking seedling corn further north than normal; the two sharp cold spells may have done a good job of killing them, however.  Monitor corn for this pest from emergence through V5.  See pages 90 – 91 of the April 17, 2006 ICM Newsletter or http://www.ipm.iastate.edu/ipm/icm/2006/4-17/stewarts.html and pages 63 - 64 of the May 7, 2001 ICM Newsletter or http://www.ipm.iastate.edu/ipm/icm/2001/5-7-2001/fleabeetleexpect.html for scouting and management details.

 

 

SOYBEAN

 

Bean Leaf Beetles

 

Very few soybean fields were planted early this year.  However, as any early-planted soybeans emerge, be sure to scout for bean leaf beetles.  Marlin Rice notes that the later general planting of soybeans decreases the likelihood of widespread issues with overwintering bean leaf beetles.  See pages 81 – 82 of the May 27, 2002 ICM Newsletter or http://www.ipm.iastate.edu/ipm/icm/2002/5-27-2002/manageblb.html for scouting, threshold, and management information.  In addition to the management strategies offered there, remember that Gaucho 480 and Cruiser 5FS seed treatments offer good protection.  Additional information can be found at http://www.extension.iastate.edu/Pages/eccrops/blb3.html.

 

 

 

Note:  See also Jim Fawcett’s update on late applications of herbicides, late applications of nitrogen, and corn planter setup at http://www.extension.iastate.edu/Pages/eccrops/jfcu070507.html.