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Corn+Soybean Digest

Protect Vulnerable Seed

Yield potential is determined early in a plant's life, says Tim Maloney, farmer and research agronomist from Janesville, WI.

That's why he advocates seed treatments that protect corn and soybean plants in their earliest, most vulnerable stages. For years he's tested different seed treatments and seed treatment/inoculant combinations. Rating in “real-world” conditions, he has generally found they're worth the investment.

Maloney continually contends with phytophthora and pythium, seedcorn maggot, wireworm, white grubs and cold, wet soil in the spring. He puts treatments to the test with these pests and conditions.

This spring he planted various combinations of treated corn on April 14 in 51° soil. Planting was followed by cold, damp weather and corn emerged 23 days later. Almost a month later it had more than a good head start.

Maloney has tested Gaucho, Cruiser and the recently labeled Poncho on corn, as well as ApronMaxx and Rival on soybeans. He has found them all to perform well against early season pests.

In four years of testing, Maloney has found it takes a yield of just two more bushels of corn per acre for both Gaucho and Cruiser to pay for themselves (at $3.50-4/acre). He has more than covered costs by averaging a 6.7-bu./acre yield advantage with low rates of either treatment on corn.

Over the same period, the Wisconsin agronomist has tested ApronMaxx fungicide with Cell-Tech 2000 inoculant on soybeans, averaging a 4-bu./acre yield advantage. Using the fungicide alone, he's seen a 2- to 2.5-bu./acre yield bump, and with inoculant alone he's averaged a 1.5- to 2-bu./acre advantage.

John Wedberg, University of Wisconsin-Madison (UW) entomologist, has seen a steady interest in seed treatments. “In corn, it has been driven primarily by increased frequency of wireworm and seedcorn maggot incidence in crop rotations where farmers aren't using corn rootworm soil insecticides,” he says. “Those insecticides also provide control of other soil-dwelling insects.”

That factor, plus this year's introduction of Bt corn rootworm hybrids that have no activity against other soil insects, has driven interest in treatments. And the loss of some old planter-box seed treatments that no longer have EPA registration has led to a need for alternatives, says Wedberg.

The systemic activity of newer seed treatments has captured some attention as well. UW research shows such treatments hold promise for soybean aphid control, he adds, but the university has just one year of data for this insect when present in heavy numbers.

“We need data in terms of yield protection from direct feeding damage, but also in terms of protection from the viruses the soybean aphid is capable of transmitting,” Wedberg says.

Craig Grau, UW plant pathologist, has seen greater interest in soybean seed treatments as systemic activity has advanced to control disease long past the seed rot stage. But insecticidal seed treatment is attracting the most interest because growers want to control the bean leaf beetle, known to transmit bean pod mottle virus. Unfortunately, Gaucho has received only a Section 18 emergency exemption in some states and registration of any type is pending for Cruiser.

Grau adds that soybean seed treatments are now showing yield advantages in well-drained soils as well as those that are more poorly drained. Fungicide seed treatments have allowed no-till production to grow as well. And they will reduce the risk of pathogen-related yield losses in both soybeans and corn, says Grau. He has seen yield increases, primarily in the 4- to 8-bu./acre range, for treated soybeans.

Corn has been treated for quite some time, but Grau has observed a change in the type of treatments. Captan, for example, is being replaced by active ingredients with greater efficacy. Some of the newer insecticide seed treatments also help control flea beetles, which help reduce the amount of Stewart's Wilt bacterium.

Although newer compounds have rootworm activity, they don't consistently control heavy populations as well as granular soil insecticides, says Wedberg. They show activity against wireworm and seedcorn maggot, but he's occasionally seen wireworm damage even when a seed treatment was used. He's also seen unacceptable levels of wireworm damage when soil insecticides are used.

Maloney also has tested biologicals such as Yield Shield, which was just granted EPA approval for use on commercial soybeans. The naturally occurring bacteria contained in Yield Shield colonize on the plant's root surface and stimulate its natural defenses against disease organisms.

Maloney has compared Yield Shield-treated soybeans to untreated checks and has found a 1- to 1.5-bu./acre yield increase for the former. In tests with chemical fungicide treatments, soybeans average 2- to 2.5-bu./acre better than untreated checks.

An advantage of the biological is that carryover seed can be returned or reintroduced into commercial grain-trading channels. This is because the bacteria occur naturally in the environment.

Regardless of the product, Maloney sees the use of seed treatments growing. They're convenient, especially for large-acreage growers who have narrow planting windows. If they don't have to periodically stop and fill up their hopper boxes with insecticide they save time in the field.

While Maloney conducts seed treatment research that helps seed treatment and seed companies evaluate products, he keeps growers foremost in mind.

That means planting and managing treated seed in real-world conditions. And paying close attention to economics, agronomics and convenience factors. Seed treatments are standing up to these requirements, making them a good investment not only for Maloney, but for other growers as well.

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