Volume
4 Issue 2 May
22, 2007
Corn Herbicides and Post Emergence Treatment
Guidelines
It is still early in the region for extensive post
emergent corn weed management, but it can’t hurt to think about
growth stage and weed height guidelines for post emergent herbicide
usage. In recent years, the wet weather in many areas of the region
has hampered timely post emerge applications. The recent spate of
heavy showers might disrupt a few spray plans, also.
There are several concerns with these delays, including:
- label restrictions regarding crop or weed size,
- increased sensitivity of large corn to herbicides, and
- reduced efficacy due to large weed size and/or canopy
interference with spray coverage.
The reference tables list the maximum corn size specified on
herbicide labels. As corn increases in size, the crop canopy
intercepts a significant portion of the herbicide spray. This would
reduce performance due to inadequate coverage or contact with weeds
or enhance the potential for crop injury. Drop nozzles will reduce
these risks by directing the spray to the weeds, therefore improving
coverage and reducing corn exposure.
 Table
1. Application restrictions for post emergence GRASS control in
conventional corn.
Table 2. Application restrictions for post emergence BROADLEAF
control in conventional corn.
Table 3. Application restrictions for herbicide resistant corn
hybrids.
David Nicolai
REE-Crops, Hutchinson
and
Phillip Glogoza
REE-Crops, Moorhead
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