$40 no-till weed control is doable
Keeping tight crop budgets in mind, this fourth Q&A series article tackles herbicide costs, Russell McLucas, a Pennsylvania No-Till Alliance board member, and Del Voight, Penn State Extension grain-crop specialist, address concerns and what works. McLucas, past chairman of the Pennsylvania Corn Growers Association and a 30-year veteran no-tiller, farms near McConnellsburg, Pa. Questions may be directed to Voight at email@example.com and McLucas at russmclucas@
• Low-cost herbicide options aren’t necessarily the most cost-effective.
• Count hybrid “tech fees” as an herbicide expense, not a seed cost.
• Take out small-grain cover crops between 6 and 9 inches tall.
Q: What are the most economical no-till herbicide options for 2010?
McLucas: I simply can’t go with a “low-cost” control option. The absolute most imperative piece of information needed is missing.
First, ID your target weed species! That’ll determine your most cost-effective programs. Second, maintaining a good soil pH (6.5 to 7) is the cheapest way to make certain herbicides can work effectively.
Third, the “tech fee” on seeds must be considered as a part of chemical costs, not a seed expense.
Today, three very good postemergence programs, coupled with a preplant burndown with some residual, can be extremely effective — and cost-effective. I try to use a one-third, one-third, one-third rotation on corn hybrids. For instance, Clearfield on all first-year corn gives way to Lightning in year two.
Then I follow with two alternatives. One is Roundup Ready hybrids, chosen according to where they’re a best fit for soils and surface residues. Some hybrids are very poor in corn-on-corn conditions. The other is a LibertyLink hybrid package. The Herculex Extra package has performed very well for me on rootworms.
I strongly suggest that in any multiyear corn program, the rootworm control package be given serious thought. It tends to “pencil out.” Buying genetics on a per-acre basis is slightly more cost-effective than soil-applied insecticides — at least for me, here.
My program probably wouldn’t travel well. But up front, I use the following: 1.5 quarts of generic glyphosate, 1 quart generic atrazine (where permitted by label) as a preplant burndown. Then for post-applications, I use 1.1 ounces of Lightning on Clearfield-tolerant hybrids, Liberty per label rate (varies due to weed spectrum and weed sizes), and Prowl at two-thirds of labeled rates.
Watch Prowl, as there are several different formulations still on the market. All have slightly different labeled rates.
As far as glyphosate, I use 1 quart of a 4-pound-per-gallon material. And again, be sure to follow the rates according to formulation percentages. I’ll try to get fields with known high levels of deep-rooted perennial weeds into a RR hybrid.
Voight: Identify your necessary weed-control tactics now so the necessary products can be obtained and ready for use. Many different scenarios require specific weed-control measures.
Typical crop budgets should reflect a $40-per-acre total weed-control cost. Two custom applications at $10 per application will spend $20 an acre just for application, leaving $20 for products.
A typical upfront burndown [glyphosate for this scenario at $3 an acre], plus a half-rate of residual [Lumax could be used, as well as many others] at $9 an acre, will bring total product costs to $12 an acre.
A second pass, then, should cost about $10 an acre to stay within budget. This is possible, with the drop in glyphosate costs. It might be slightly higher if you include another half-rate of a residual or other partner.
The prescribed scenario leaves many options for the grower with respect to specific field-weed complexes. For instance, if you have a field with a history of bur cucumber, a second pass could include atrazine and/or Spirit products known to be effective. Allow [perennial] weeds to grow to a size conducive to elimination with proper systemic herbicides. In corn, that would be 12 to 18 inches tall.
Q: When should I burn down cover crops and weeds, and with what products?
McLucas: Burndown time frame will vary as much as the cover crop itself. I try to take down small grains at the 6- to 9-inch height and before boot. Barley can be an interesting project if it heads.
Watch cereal rye carefully, and be aggressive. With this one, I try to err on the early side. It can quickly get enough late spring growth to cause planting equipment problems.
Depending on time frames, weather conditions and cover-crop size, a quart per acre of a 4L glyphosate product would be a minimum.
I’d be more comfortable with 1.5 quarts of a 4L material, especially with a good surfactant. With extreme heavy growth and good growing conditions, 2 pints of Gramoxone with 10 gallons of 30% nitrogen as a carrier might be a good idea.
Take it down and keep it down! I like, if at all possible, to have a seven- to 10-day window between burndown and planting.
Voight: For no-till, the burndown and residual applications take the place of tillage. Most growers prefer the two-pass system of a residual followed by a cleanup application in the crop. The key is to control weeds before they are the size of a dollar bill.
Bill Curran, Penn State Extension weed specialist, demonstrated this through his replicated research. Spray too early without residual control, and you’ll suffer from new weeds emerging after application. Spray too late, and the weeds have already hurt the corn. In this study, spraying when weeds were 6 inches tall was as good as two applications.
Baker is a consultant for the Pennsylvania No-Till Alliance.
This article published in the February, 2010 edition of AMERICAN AGRICULTURIST.