With an anticipated surge of continuous corn acres in 2007, many no-tillers are anticipating more problems with weeds, insects and diseases. There’s also a growing concern about weed resistance problems with increased use of glyphosate-tolerant corn hybrids.
Corn On Corn
Mike Weber told attendees at the recent 15th annual National No-Tillage Conference that it is essential that management of no-till continuous corn include a careful look at crop residue, fertilizer, stand establishment, hybrid selection and control of insects, diseases and weeds.
“Continuous corn will generate a tremendous amount of crop residue and the greatest risk will be with no-till,” says the Bayer CropScience senior technical service representative at Indianola, Iowa. “The yield drag with continuous corn comes from diseases, cooler and wetter soils, interference with planter row units that leads to uneven seeding depth, decreased efficacy of soil-applied herbicides and the depletion of soil moisture.”
Weber sees rootworms being a major threat to continuous corn. Earlier plantings can also lead to concerns with wireworms, cutworms, seed corn maggots and other insects.
Weed Control Strategies
Mike Leetch says Syngenta Crop Protection offers Gramoxone Inteon for faster burndown within 24 to 48 hours. “It is a breakthrough, user-friendly formulation that delivers the fastest weed control and is an important tool to manage weed resistance,” says the technical support agronomist at Adel, Iowa. “It eliminates grasses and broadleaves to speed up soil drying and warming and allows earlier planting under better field conditions.”
Leetch says Syngenta is emphasizing the impact of early-season weed control. Data from the Syngenta Learning Center at Keystone, Iowa, indicates that yield losses can run as high as 20 bushels per acre when 4- to 6-inch-tall weeds compete with corn. He recommends two-pass herbicide treatments that include Lumax and Lexar to control early-season weeds in no-tilled corn.
Leetch says Syngenta will announce a new, so far unmanned, glyphosate-tolerant herbicide this spring that will provide both season-long residual control and early-post weed control.
Bayer’s Weber says more no-tillers are relying on Radius to control escapes of late-season grass and broadleaves. The herbicide can be combined with crop oil concentrate to burn down weeds up to 2 inches tall while providing residual control of foxtails, waterhemp, lambsquarter and wooly cupgrass.
Weber says Liberty controls over 120 annual and perennial weeds and is excellent for control of ALS, triazine and glyphosate-resistant weeds.
Balance Pro can be used as an early preplant, preplant or pre-emergence for control of annual grasses and broadleaves. It can also be combined with crop oil concentrate to burndown winter annuals, he says.
With a HPPD mode of herbicide action, Laudis is a new post-emergence for broad-spectrum grass and broadleaf weed control that also offers residual weed control.
Bayer’s latest introduction is Autumn, which offers superior burndown control of tough early spring weeds. As adoption of no-till increases, Weber says, fall herbicide application is increasingly important since recent mild winters have increased winter annual weed populations. Autumn also offers a residual component not offered with glyphosate or 2,4-D.
Insect Management Strategies
Along with rootworm control traits in Syngenta’s Agrisure lineup of corn hybrids, Leetch says, another insect control option is Cruiser Extreme 250. “A combination of several seed treatment insecticides and fungicides, Cruiser Extreme 250 provides premium protection against a broad spectrum of early-season insects as well as providing enhanced disease protection against all four major fungal groups,” says Leetch.
Disease Management Strategies
Leetch says Quilt and Quadris work well to control diseases in disease tolerant corn hybrids. “Timely scouting from ear formation through black layer is critical, and Quilt should be applied beginning at silking if a disease infection is building up and environmental conditions favor disease development,” he says.
Leetch says fungicide tests across the Corn Belt indicate an average yield increase of 12.7 bushels per acre. “Some 92 percent of the time, the response was positive, and 70 percent of the time the economic threshold for return on investment was only 8 bushels per acre.”
Leetch recommends an application of Quilt at 14 ounces per acre mixed with 1 percent crop oil concentrate. Based on scouting, application should be made when disease thresholds are achieved. In the absence of scouting, an application at VT (full tassel and silk emergence) to R1 (early milk stage) is recommended.