The ongoing wet weather prevented many cornfields from being treated with planned postmergence treatments. The growth of corn during this period has eliminated many of the herbicide options that were planned for these fields. Table 1 shows products cleared for use on corn larger than 12 inches in height. Keep in mind that just because a product is labeled for use in large corn does not mean it will control large weeds that may be present in these fields. Also, the risk of crop injury increases with corn size for many products, especially when the corn is under stress. Before deciding to treat large corn, consider the impact of the weeds on the crop if they are left untreated, the likelihood of achieving good weed control, and the potential for crop injury. Equipping the sprayer with drop nozzles reduces the potential for crop injury and provides better weed control.
Table 1. Herbicides cleared for use on corn larger than 12 inches in height.
Product
sizea |
Maximum corn |
Comments |
| Accent |
36 inches |
Use drop nozzles on corn 20 to 36 inches in height or 10 collars |
| Aim |
8 leaf
collars |
Good on large velvetleaf. |
| Banvel |
36 inches |
Use directed application when 1) corn leaves prevent proper spray coverage, 2) sensitive crops are grown nearby, or 3) tank mixing with 2,4-D. Should not be applied to corn greater than 24 inches if soybean is grown in the area. |
| Basagran |
none |
Basagran is a contact herbicide that generally does not control large weeds. |
| Buctril |
tasseling |
Buctril is a contact herbicide that generally does not control large weeds. |
| Callisto |
30 inches
or 8 leaves |
Labeled for weeds 5 inches or less in height. |
Celebrity
Plus |
24 inches |
Combination of Accent and Distinct. |
| Clarity |
36 inches |
Use directed application when canopy prevents spray coverage. |
| Distinct |
24 inches |
Use 4-ounce rate. Contains dicamba. |
| Hornet |
36 inches |
Drop nozzles must be used on corn 20 to 36 inches in height or with more than six collars. |
| Liberty |
36 inches |
Requires Liberty-Link corn. Use drop nozzles on corn 24 to 36 inches in height. |
| Lightning |
45 days
before harvest |
Requires IMI-corn. Drop nozzles must be used on corn taller than 20 inches. |
| Permit |
layby |
Refer to label for maximum weed heights controlled. |
| Resource |
10 leaf |
Good on large velvetleaf. Use drop nozzles when corn leaves interfere with spray penetration. |
Roundup
Ultra |
eight leaves or 30 inches |
Requires Roundup-Ready corn. |
| Sencor |
depends on
tank mix
partner |
Sencor can be tank mixed with the following products at rates of 1.6 to 3.0 ounces:
with Basagran: 30-inch corn
with Banvel: Use drop nozzles on corn 8-36 inches in height
with Buctril: Apply before corn canopy closes over row
with Resource: Up to 10-leaf corn
with Tough: Up to 30-inch corn. |
| Tough |
68 days
before harvest |
Tough is a contact herbicide that generally does not control large weeds. |
2,4-D
amine |
tasseling |
Use drop nozzles on corn greater than 8 inches. Product labels may vary. |
2,4-D
ester |
tasseling |
Use drop nozzles on corn greater than 8 inches. Product labels may vary. |
aThere is no standardized system of specifying crop stage within the herbicide industry, thus resulting in a variety of descriptions for label restrictions.
This article originally appeared on page 123 of the IC-486(15) -- June 25, 2001 issue.
