resistant or just hard to manage?

July 31, 2015 12:12 PM
Blog Post

Waterhemp continues to be a problem in parts of northwest Iowa.  There is a fair amount of waterhemp that survived the glyphosate and/or Flexstar applications in late June. 

There is also a new crop of waterhemp that has germinated recently.   That fact is surprising since it has been fairly dry in July for a lot of northwest Iowa.

There is not much that can be done to manage this waterhemp problem at this time of year.   Herbicides like Cobra and Ultra Blazer can be used – they have a 45 and 50 day Pre Harvest Interval.  However, they will at best – burn a few leaves off of the waterhemp and suppress it’s growth.  And the crop oil type additives that make Cobra or Ultra Blazer more effective as a waterhemp killer – will add to the leaf burn on the soybean plants.   So this is one thing that can be done this time of year, but it is not a real good option.

So if herbicide application is not a good option – what is left?  I have heard a few comments on hiring a crew – or whomever they can get – to walk the beans.  This may not be a real good option either, but many farmers are fairly motivated to do something with these waterhemp problem acres.

 

 

 20 days after Ultra Blazer application.

five days after Ultra Blazer application.

Author: 

Paul Kassel Field Agronomist in NW Iowa

Paul Kassel provides research based crop production information to area farmers and agribusiness. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors.

Areas of expertise include soil survey, crop production, soil ferti...