farmgate: If Creating New Corn Revenue, Try Creative Weed Control
If falling commodity prices have pushed you toward producing non-GMO corn under contract, you may have some additional production choices to make in cultivating a weed-free corn crop. Your non-transgenic seed will not be glyphosate resistant, so brushing up on alternative weed control programs will be your priority, and our service for you today.
With the help of Ohio State University weed specialist Mark Loux we’ll focus on pre-emergent and post emergent weed control outlined in Vol. 3 of the C.O.R.N. newsletter from OSU agronomists. He says recent advances make PRE and POST weed control for non-GMO corn about as economical as glyphosate on commodity GT corn. Loux divides the strategy into Pre-emergent, Pre- and Post-emergent, and Post-emergent, which he says any can provide effective weed control, depending on your typical crop of weeds.
Pre-emergent strategies can be effective where weed pressure is low to moderate, and generally void of perennials or late germinating weeds. And Loux warns that a pre-emergent herbicide program depends on rain within a week after application, or your post-emergent program may become more expensive.
The Pre and Post strategy provides the most consistent control of weeds that emerge throughout the season such as ragweed, waterhemp, annual grasses and other perennials. He says it works better than the other choices in fields that have very heavy weed pressure. Loux rhetorically asks, “Am I better off spending money on a broad-spectrum total PRE program, or spending the same amount or a little more on a PRE + POST program that can provide more consistent control of the weeds that I am dealing with?” He says the keys to success include:
1) Use a PRE herbicide treatment that includes a true “grass” herbicide, and use a rate equal to at least 75% of a normal full-season PRE rate.
2) Use a POST herbicide treatment with activity on both grass and broadleaf weeds.
3) Apply the POST treatment when corn is not more than 12 to 14 inches tall, or before weeds exceed about 3 inches in height. Where the PRE herbicides have controlled weeds well, so that none are evident in 14-inch corn, it is possible to delay POST applications. However, corn is competitive with weeds once it reaches a size of about 20 inches tall, and POST herbicides should be applied before this size.
The total Post-emergent program may not protect yields quite as well as the Pre- and Post-, and it is less effective in fields with perennials and late emerging weeds. Loux says success depends on:
1) It is essential that weeds are no more than 1 to 2 inches tall at the time of POST herbicide application, to ensure that they are not a yield-limiting factor.
2) Include broad-spectrum residual herbicides, and take a similar approach with rates as indicated above the PRE + POST program. Reducing rates too much or failing to use a broad-spectrum approach can result in weed problems later in the season.
3) Make sure that the herbicides applied will effectively control the weeds present in the field.
Summary:
The need for creative weed control need not scare you away from growing non-GMO corn as a potential new profit center. While conventional wisdom may say glyphosate applied to glyphosate tolerant corn will produce revenue, the cost for conventional herbicides can be as economical if used judiciously. Such herbicide programs would be either a pre-emergent program, a post-emergent program, or one that combines the two.
Posted by Stu Ellis on February 11, 2009 12:51 AM to farmgate