July 28, 2017   
  Issue 9  

Prepared by

Paul Kassel

Extension Field Agronomist



(712) 262-2264

Email: kassel@iastate.edu 



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



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Dicamba drift. The dicamba drift dilemma continues. Of concern are the lingering effects of the dicamba drift - as susceptible varieties have as many as 6 nodes with cupped leaves before a normal leaf has emerged. Also, height reduction and a narrowing of the soybean canopy have occurred.  
Several factors may be contributing to this issue
-  dicamba application rates on RR2X varieties are 0.5 lb/a versus a lot of previous dicamba drift experience has been with dicamba rates of 0.25 lb/a.
-  dicamba application timing - although within label guidelines - has been in late June and early July.
-  Dry weather and high temperatures likely limits the ability of the soybean plant to metabolize dicamba residue.
-            Aaron Hager, University of Illinois.
-            Kevin Bradley, University of Missouri.
Spider mites. Two spotted spider mites are present in some area corn and soybean fields. Spider mite populations are favored by hot dry weather. Conversely, cooler weather with rainfall/high relative humidity will limit spider mite populations.
Guidelines for treatment of spider mites in soybean consider amount of leaf damage or stippling, the presence of mites in the middle canopy and a hot dry weather forecast.
Corn silage questions. Decisions on corn silage harvest - where dry weather has reduced corn grain yield potential - involve the moisture content of the silage crop and yield potential of the drought damaged crop. The Iowa Beef Center has info on harvesting drought-damaged corn for silage, rations and emergency forage crops.

Prepared by Paul Kassel, Extension Field Agronomist

Phone: (712) 262-2264, Email: kassel@iastate.edu