Crops Bulletin
August 12, 2015      
Issue 13       
 

Prepared by

Paul Kassel

Extension Field Agronomist

 

Phone: 

(712) 262-2264

Email: [email protected] 

 

 

Serving Clay, Buena Vista, Dickinson, Emmet, Hancock, Kossuth, Palo Alto, Pocahontas, Sac and Winnebago Counties

 

 

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Many materials can be made available in alternative formats for ADA clients. To file a complaint of discrimination, write USDA, Office of Civil Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964.

Soybean aphids. Continue to check early treated and untreated fields for soybean aphid activity. Soybeans will be susceptible to damage from aphid feeding until the late R5/early R6 stage - or about another 10-14 days.
 
 
Corn aphids. Corn aphids have appeared in area cornfields. There is no good threshold for corn aphid activity after pollination. Consider insecticide treatment if 500+ aphids are present at the ear leaf and above - and the corn is in the dough (R4) to early dent (R5) stage.
 
 
Yield prospects. A University of Nebraska yield model shows that northwest Iowa has an 82% probability of above normal grain yields. Recent rainfall and long term forecast of cool weather has increased the yield potential of area cornfields.
 
 
Palmer waterhemp. Palmer amaranth has not been identified in northern Iowa. However, this is the time of year when  Palmer is easier to identify.
 
Palmer amaranth will often have the following.
-  petiole is longer than the leaf blade
-  canopy is more dense than common waterhemp
-  vigorous growth and taller than common waterhemp
-  sometimes it has a leaf tip hair.
 
More descriptive guidelines for Palmer.
-  seed bract is longer than the seed capsule - use a hand lens.
-  Seed head is stiff and narrow - compared to open seed head of common waterhemp.
-  male common waterhemp plants may appear to be like Palmer, but do not have the long seed bracts or sharp seed bracts.

Prepared by Paul Kassel, Extension Field Agronomist

Phone: (712) 262-2264, Email: [email protected]