With the dry conditions is there greater concern for herbicide carry over than in most years?

Yes, there is a greater chance of carry-over from certain herbicides then in a normal year.

For several residual herbicides, hydrolysis or the breakdown of herbicide molecules by water, is an important process. In the absence of water, herbicides tend to stay adsorbed to the soil particles and can be carried over and can potentially damage the next crop. Risk of carry-over is also affected by the half-life of herbicide, rate of herbicide used, application date, soil characteristics (texture, organic matter, pH), and rotational crop sensitivity.  The main management option a farmer can control in regards to carry-over and crop injury is the crop choice for the next year.  Study the herbicide label for the product used for re-cropping restrictions and avoid those crops for the specified time listed.  

What common herbicides should producers be concerned about carrying over in dry conditions?

A list of residual herbicides and the restrictions for re-cropping are mentioned in the Guide to field crop protection on pages 58-59. Please refer to them.  The link to the website is http://www.gov.mb.ca/agriculture/crops/cropproduction/pdf/gcp2012/herbicide.pdf

Also make a note that the re-cropping intervals listed may not be sufficient to prevent crop injury during periods of below average rainfall. In other words, the restriction period for planting sensitive crops will be longer under dry conditions. Further discuss with your company representative/agronomist for more specific information.



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