Seed-applied nematicide helps protect vital young roots



By Vicky Boyd

Editor

Applying one or more fungicides and possibly even an insecticide to seed to protect it from soil-borne pests has become standard practice for the seed industry.

Now Syngenta Crop Protection is banking on the same philosophy for nematodes and wants to change the way growers and consultants think about soil-borne problems.

With the recent federal registration of Avicta, Syngenta is now offering growers a seed-applied nematicide that protects seedlings from early-season nematode feeding.

It will only be available if you also purchase the FarMore Technology Pak, which is Syngenta’s vehicle for delivering fungicide seed treatments. Neither Avicta nor the FarMore Pak is registered in California.

Company representatives are quick to point out that Avicta is not a stand-alone nematode treatment or a replacement for soil-applied fumigants, such as methyl bromide or Telone. Instead, they say the seed treatment will provide growers and consultants a different tool. The active ingredient in Avicta is abemectin.

“This is a completely different concept,” says Ole Becker, a University of California, Riverside, Cooperative Extension specialist and nematologist. “In the past, the concern was about reducing the nematode population. That is not the case with this product.

“This protects the seedling and young plant against nematode attack, much like a fungicide seed treatment where you expect to have protection against a pathogen for a few weeks.”

Traditional fumigants or soil-applied nematicides, on the other hand, kill or stunt nematodes, thereby reducing the numbers that could potentially feed on plants.

A third strategy involves planting nematode-resistant cultivars. The nematodes may still attack the plants, but the pests may not be able to feed and aren’t reproducing nearly as much on susceptible hosts.

Although the tolerant plants reduce nematode reproduction, they may still be affected by secondary pests, such as bacteria and fungi, that take advantage of nematode attacks. Using a seed-applied nematicide along with resistant cultivars may produce healthier plants altogether, Becker says.

“If you stop the initial attack, you also reduce the secondary micro-organisms,” he says.

Avicta is registered for use on small-seeded vegetables, which include fruiting vegetables, leafy vegetables, cucurbits, brassicas, and bulb and root vegetables. It is labeled for use only with direct seeding and cannot be used on transplants.

Trials: Plants look visibly stronger

Becker has conducted laboratory, greenhouse and field trails with Avicta on cucumbers during the past four years. The plants were exposed to artificially high populations of rootknot nematodes that might represent the worst-case scenario a grower would encounter.

Because this is a new concept, Becker says it is difficult to compare the Syngenta product’s performance.

“This is a new technology, and there hasn’t been a nematicide seed treatment in the U.S. market,” he says. “And even worldwide, this is only the second attempt where we are trying to protect plants with a nematicide seed treatment. So there’s really no standard.”

In rootknot-nematode-infested field trials, Becker notes that the plants from Avicta-treated seed appeared to push out of the ground faster. After four weeks, the treated plants were visibly larger than the untreated plants.

The root masses of the treated plants also were larger, and the treated plants yielded significantly more than the untreated ones.

With a short-season crop, such as cucumbers that are only in the ground about eight weeks, the product should provide enough protection so another nematode treatment typically won’t be needed, Becker says.

But in longer-season crops and especially those grown in warmer climates where nematodes may have two to three generations, the Avicta seed treatment may not provide a season-long benefit in severely infested fields, he says. But the same is often true of non-fumigant soil nematicides that require at least 100 times the application rates per acre.

Pitting the newcomer against a grower standard

In trials in a cantaloupe field about 60 miles west of Phoenix, Ariz., Syngenta Seed Treatment territory manager Tom Harris and consultant Mike Arbogast saw no differences visually between plots treated with the FarMore Technology Pak with Avicta and the grower’s standard, Telone EC run through drip irrgation plus a Thiram seed treatment.

“Visually, they were identical,” says Arbogast, who is with Verde Agricultural Services of Phoenix. “If it wasn’t marked, you probably wouldn’t be able to spot it. Of course, in our area, we don’t have a lot of seedling diseases in the spring crop, so I wasn’t expecting to see much out of the fungicide.”

Because of the way the trials were set up, Arbogast says they didn’t take actual yield. But they did count melons before harvest and didn’t see any statistical differences between melon numbers, sizes and quality from the Avicta plots and the grower standard.

The grower’s field averaged 1,337 boxes per acre, which he considered excellent.

Both Harris and Arbogast say the lack of differences between the two treatments is encouraging.

Arbogast says he doesn’t view the new seed treatment as a Telone replacement. But he does believe it has a place.

"I think perhaps people who are growing, in particular, furrow-irrigated melons, where they are not able to put a fumigant down or have some ground that doesn’t have a serious [nematode] problem or they just want an insurance policy, I think they would be very happy with this,” he says. “But to go in and actually replace Telone on something other than a trial, I wouldn’t do that yet.”

A package deal

Syngenta is including Avicta with its FarMore Technology Pak, which currently comprises mefenoxam and fluidioxinil fungicides applied to the seed at specific rates. The company plans to add azoxystrobin to the mix on some vegetable species next summer Among the early-season soil-borne pathogens controlled are Aspergillis, Fusarium, Helminthosporium, Penicillium, Pythium, Rhizoctonia and seed-borne Sclerotinia.

FarMore Technology Pak is currently available throughout the United States, including California, on all small-seeded vegetables including fruiting vegetables, leafy vegetables, cucurbits, brassica, root and bulb crops.

Although you can purchase seed treated with only the FarMore package, you cannot buy seed treated with only Avicta. If you want the nematicide, you must also purchase the fungicide package.

Syngenta has been working with three seed-treatment technology providers—Incotec, GTG and Seed Dynamics—during the past few years to perfect Avicta applications, Harris says.

The FarMore is relatively easy to apply,” Harris says. “But the Avicta, because of some of its physical characteristics, is much more difficult to apply.”

If you’re interested in buying seed treated with the fungicide and nematicide package, Harris says you’ll still deal with the same seed sales people you always have. All you need to do is tell them you want the seed treated with FarMore Technology Pak with Avicta, and the seed company takes care of the rest.