Disease Digest

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Deere sprayer, corn

In the fungicide world, 2007 will be memorable for its flurry of foliar fungicide applications, especially in corn, but not because diseases were rampant. No, many of these applications targeted the health of the crop.

This is just one of the key topics our in-house advice columnist, Rusty Beane, will discuss in this final installment of the Crop Protection Review series. Like Reid W. Acker and Bugsy B. Gohn, Beane is a fictional character based on a combination of almost two decades of staff background in crop protection, along with recent interviews with Extension plant pathologists and fungicide product managers.

Dear Rusty: What key diseases should we keep an eye on this year?

As always, weather will play a key role. There have been reports that 2008 will be a dry season. “According to weather experts, the drought in the Southeast in 2007 may be a precursor for drought in the Midwest in 2008,” explains Daren Mueller, Iowa State University Extension plant pathologist. “In that case, we may see a different set of diseases on corn and soybeans. For example, Aspergillus ear rot on corn and charcoal rot in soybeans can be more severe when weather conditions are dry,” he says. Charcoal rot can show up in corn, too.

“If the trends that we have seen the past few years continue, other diseases on soybeans that are more severe in Iowa are sudden death syndrome (SDS) and frogeye leaf spot,” Mueller says.

Dear Rusty: Are there any new fungicides for corn or soybeans in ’08?

There are two, both for soybeans.

Ballad Plus biofungicide from AgraQuest is registered for Asian soybean rust, powdery mildew, coercospora, and brown spot. Based on a patented strain of Bacillus pumilus, it offers broad-spectrum control or suppression of many key plant diseases and is an excellent fit in disease control programs of both conventional and organic production.

2008 New Fungicides
 Product  Company  Active Ingredient(s)
 Ballad Plus  AgraQuest  Bacillus pumilus
 Nevado  MANA  iprodione

Makhteshim Agan of North America, Inc. (MANA) received EPA approval for Nevado fungicide, which contains iprodione, the active ingredient in Rovral. While its primary targets are specialty crops, it also has been approved for use against black leaf blight in soybeans in small areas in the Western U.S.

Dear Rusty: I hear that Extension scientists are still on the fence about using Headline on corn, but then my BASF rep says the Plant Health benefits of Headline really work. What do I tell my growers?

Oh, my, now that’s a bit of a pickle. Not all Extension researchers should be painted with the same brush, but overall, many are hesitant to jump on BASF’s Plant Health program bandwagon until they see their own research results, and I can understand that. “We’re sort of unpopular for saying there isn’t much yield response, although this has been what our research has shown to date; growers don’t want to hear that,” Mueller says.

There has been minimal soybean yield response to fungicides in Iowa, for example, although individual fields responded well. The response is more mixed in Iowa corn, though. “There are fields that get yield benefit and others that have yield loss,” he says.

The potential for stronger stalks and better yields with today’s higher crop prices is especially enticing for growers with larger acreage. Narrowing down the various factors that could impact preventive fungicide benefits and increase the potential for positive economic response should be the goal of researchers, Mueller says. 

As in 2007, we can expect growers to be willing to spend input dollars to ultimately increase yield.

And BASF’s numbers appear to back its claims. The company released results of its on-farm trials in early January: In the more than 1,150 on-farm trials conducted across the U.S. in 2007, the average yield increase of Headline-treated corn ranged from 12 bushels per acre (bu/A) to 16 bu/A, while Headline-treated soybeans increased by an average of 4 bu/A to 8 bu/A. BASF estimates that in 2007, U.S. corn and soybean growers who used Headline produced an additional $450 million worth of grain.

According to BASF, that works out to an extra profit of $34 to $51 per acre for corn growers and $28 to $74 per acre for soybean growers, estimated at current commodity prices and average application costs.

Most of Headline was applied by air, and Midwestern aerial applicators called on their Southern brethren to help cover the extra acreage in 2007. “We had an astronomical increase in demand for aerial applications in 2007, from 8,000 to 80,000 acres, and I think we’ll see another big increase in 2008,” says Craig Bair with AgFlight, Inc., who services the York, NE, area.

2008 Label Changes
 Product  Company  Label Change(s)
 Bumper  MANA  Added Asian soybean rust, frogeye leaf spot, brown spot, anthracnose, aerial web blight in soybeans.
 Domark Valent U.S.A. Corp. Received full Section 3.
Headline BASF Corp. At the VT stage or later in corn, may be used with adjuvant; do not use adjuvant prior to full tassel stage; application rate reduced for corn; eyespot added to 2(ee) label; REI shortened to 12 hours.
Headline BASF/Monsanto Agreement created between BASF and Monsanto to co-promote.
Laredo Dow AgroSciences Full Section 18 label.
Quilt Syngenta Rate reduced for aerial application; REI now 12 hours.
Punch DuPont Crop Protection Continued Section 18 label.
Stratego Bayer CropScience Updated label in soybeans, corn.

What does all of this mean to your business? At least some of your grower-customers will use Headline or another foliar fungicide this year, so why not use that to your advantage? Do some test plots of your own to get a better sense of which soils, weather factors, hybrids, production practices, etc. take to a crop health system best in your service area. Be sure to follow up at grower meetings and in one-on-one planning sessions next winter.

Dear Rusty: Our dealership is in the Midwest and Asian soybean rust has yet to affect our soybean yields. Is there any reason to be very concerned about it this year?

Asian soybean rust is a disease we’re still getting to know, and 2007 proved beneficial to the learning curve because rust became more widespread. “Last year, we learned a lot about how well we can predict rust,” says Mueller.
But you’re right, what yield loss there’s been has been in the South and Southeast, where soybean rust has built a stronghold the past three seasons. For others, by the time rust made it to their fields, the soybeans were past the reproductive stages, their pods were set, and yields were not affected.

Many fingers point to the lack of moisture for the fairly quiet invasion. Remember, an Asian soybean rust epidemic will require three elements: leaf wetness from rainfall or high humidity; susceptible host plant (usually kudzu and soybeans); and spores that are still viable when they land on the soybean plant.

“My fear is that we’ve had three extremely unusual years environmentally, especially when you look at the drought in the Southeast,” says Anne Dorrance, Ohio State University Extension plant pathologist. “That drought in the Southeast really kept things quiet last year.” If it turns out to be a wetter-than-average year in the wrong places, more areas could well have soybean fields with rust-induced yield losses.

One of the smartest things you can do for your growers is to never let your guard down and monitor USDA’s impPIPE (Integrated Pest Management-Pest Information Platform for Extension and Education) Web site throughout the season at www.sbrusa.net.

The key is not if soybean rust shows up in fields, but when and how much inoculum the wind brings into an area — and the Southeast and South hold the key for everyone else. “You have to have a certain quantity of rust in the South before it’s going to economically impact the northern states,” she says. There are two major wind patterns that will move rust northward, so states along the Eastern part of the U.S. need to watch what happens in states like Florida, Georgia, and Alabama; while those in the rest of the Midwest should keep an eye on Mexico and adjacent states.

“Certainly any inoculum buildup in areas like Texas, Louisiana, and Mexico does not bode well for soybean strongholds like Iowa,” adds Mueller.

Dear Rusty: My grower-customers like using fungicide seed treatments. Anything new on that front?

BASF just received registration for Stamina fungicide in late February. Derived from pyraclostrobin, the same active ingredient used in BASF’s Headline, Stamina will be marketed for corn seed.

The company tells me that seed and seedlings are better protected from key diseases such as Rhizoctonia and stress tolerance is improved. According to BASF, this is particularly important because of the earlier planting that we’re seeing more of and the increased use of no-till production systems may lead to slower emergence of seedlings in the cool, wet soils. “This delivers healthy plants right out of the ground as corn seedlings have a strong start, resulting in increased yield potential,” says Craig Lindholm, marketing manager, seed treatments at BASF U.S. Crop Protection Products.

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