Weather Playing Havoc with Herbicides


Randy Zondag expressed concerns that landscapers and nursery growers may be disappointed with the performance of a number of their herbicides this spring.  This is not to say that there is anything wrong with the herbicides, rather it is the radically changing weather that Ohio and surrounding states are experiencing.  The record setting high temperatures that occurred in March boosted a number of weed species into high gear.  Winter annuals that survived the mild winter of 2011-12 were more than impressive this spring.  Massive patches of CHICKWEED, YELLOW ROCKET, FIELD PENNYCRESS, HAIRY BITTERCRESS, HENBIT and PURPLE DEADNETTLE to name a few of the winter annuals, blanketed agricultural fields and any open disturbed area that had no other plant material growing on the soil.  Most if not all of these weeds flourished in the heat of March and in the process produce voluminous quantities of seeds.  This occurred before anyone even thought about getting out into the fields to apply herbicides…what a mess!

Then, when it was time to apply herbicides, it quit raining and turned cold.  Producers may be disappointed with their pre-emergent herbicides, not because they aren't good herbicides, but because there has been little to no rain to activate these herbicides.  These products could still be sitting on the surface of the soil in their original form.  Until the rains return, they will not be effective.  In the meantime, weeds are emerging unaffected by the presence of the herbicides.  Contact and translocated herbicides may not be faring much better.  Part of the problem in their case is the colder temperatures that have moved into Ohio over the past couple of weeks including frost and snow flurries.  Under these conditions, plant functions have slowed, tender leaves have been frosted off and translocation within the plants has slowed, none of which is good for herbicide activity.  There are going to be herbicide challenges out in the fields this year and weed control may be a bigger problem this year than in previous years, not to mention the buildup of huge seed banks.