Preventing pesticide resistance
Most weeds are hard enough to battle as is. When you learn that they have become pesticide resistant you may think that you have entered a bad sci-fi movie, where the enemy mutates and becomes resistant to your weapons. You can prevent this scary movie from happening to you!
There are two principles that must be followed if herbicide resistant weeds are to be managed. First, specific herbicide selection pressure must be minimized. Secondly, resistant individuals must be controlled before they contribute to the seed bank.
There are practices which you can implement in order to prevent and/or slow down herbicide resistance. The most important thing to remember is rotation of your crops and herbicides. Decrease the use of herbicides with similar modes of action and avoid repetitive use of herbicides with similar modes of action. Try to avoid pesticides with long residual activity. Use mixtures or split application of pesticides with different modes of action. When using herbicides, make sure to follow the label directions.
You can also consider using pest resistant crop varieties. Keep accurate records of crop rotation and pesticide use. Cultural or non-selective control (minimum tillage and pasturing) can help reduce your use of pesticides. Use good sanitation practices and procedure to avoid spreading crop seed, weed seed, crop residues or manure from suspicious fields.
Herbicide resistance is generally a single dominant gene that is hereditable. When resistant crops are developed, remember that the resistant trait can be passed onto closely related weeds. This means that last years resistant crop may become this year’s resistant volunteer weed.
It is important to identify weed resistance. Monitor the effectiveness of all herbicide applications. Notice weeds that aren’t controlled by the herbicide. For the weeds that were not controlled, rule out the possibility of misapplication. Also determine the following.
Were the other weeds on the label controlled? Are unaffected weeds patchy in the field? Are there any symptoms of herbicide injury (resistant plants will not have symptoms)? Has the field received the same or similar herbicide treatment over a number of years?
The best way to battle resistant pests is to prevent them. Contact your Agricultural Fieldman Kelly Malmberg at 485-3103 for more information.
Shilo Andrews February 02, 2005