Crop Tech

February 26, 2010 12:32 PM

A New Decade for Soy Rust

The new decade may have started with Southerners shivering, but it wasn't enough to discourage the first outbreaks of soybean rust. The state of Florida turned red with the first positive soybean rust outbreak of the year on Jan. 4. Outbreaks in Louisiana and Georgia followed a few days later. Soybean rust has also been reported on jicama in the state of Tamaulipas in Altamira municipality in Mexico.

The disease was found in kudzu, the wily weed where soybean rust prefers to overwinter. Clayton Hollier, Louisiana State University Ag Center plant pathologist, says the disease could be evolving.

"I'm not certain if rust is getting tougher, but something interesting is going on with the survival of rust during colder temps lately,” he says. He points to newly formed rust pustules with new sporulation as evidence. By collecting the fresh spores, Hollier was able to get 10% germination.

At this time of the year, kudzu that survives is generally in a protected area.

In 2009, soybean rust was found in 16 states and more than 576 counties in the U.S., and in three states and nine municipalities in Mexico. Last year, high levels of the disease spread across the Southeast and established early enough to require treatment in that region. Soybean rust spread as far north as northwestern Illinois in 2009, but arrived too late to threaten crop yields.

Hollier says fungicides have done a good job of controlling rust in Louisiana. "The growers in the southern half of the state are applying fungicides for other diseases and controlling rust too,” he reports. "Those in the mid- to upper states are applying for soybean rust as needed. There were a few incidences this past season where fungicides were applied too late and significant yield losses occurred.”

Follow soybean rust's path at USDA's Integrated Pest Management Web site:


Kick Out Kochia

Farmers who are struggling with destructive broadleaf weeds, such as wild buckwheat and ALS-resistant kochia—this one's for you.

Pulsar, a new postemergence, systemic herbicide, has received clearance for the 2010 season (some state registrations may still be pending). Available from Syngenta Crop Protection, the product combines two active Group 4 synthetic auxins.

Shawn Potter, herbicide brand manager for Syngenta, explains the premix combines the leading choice for kochia control, fluroxypyr, with dicamba, which offers broad-spectrum weed control. Two active ingredients also aid in resistance management by providing an alternative mode of action to ALS (Group 2) herbicides. Pulsar controls weeds by interfering with the plant's growth hormones (auxins), causing the disruption of normal plant growth patterns.

"Pulsar has excellent crop safety on all varieties of spring wheat, winter wheat, durum wheat and barley,” Potter says. Flexible tank-mix options offer opportunities to combine weed, disease and/or insect control.


Supercharged Fungicide Treatment

Corn growers are already familiar with pyraclostrobin in Headline fungicide. A new BASF product, Headline AMP, teams Headline with a triazole to deliver a broad-spectrum fungicide to protect yield and fight off major leaf diseases.

Nick Fassler, BASF technical marketing manager, says Headline AMP protects against anthracnose, gray leaf spot, northern corn leaf blight, southern corn rust and eyespot. "It was developed for growers who wish to have additional protection against disease by providing the plant health benefits of Headline plus the added benefits of a unique triazole,” Fassler says.

Labeled for corn only, application timing for Headline AMP is the same as for Headline. Growers should aim for the VT to R2 growth stages (full tassel to milk) or prior to the onset of disease to achieve optimum results. The VT stage begins when the last branch of the tassel is visible outside the whorl.

"Corn treated with Headline AMP doesn't waste energy fighting off disease, which leaves more energy to spend on growth and yield production,” Fassler says.


Plants Have Feelings, Too

Plants are incredibly temperature sensitive and can respond to changes as small as 1°C. A new study shows they not only "feel”' temperatures rise but also respond by activating and deactivating genes.

The report, published in a recent issue of the journal Cell, says the findings should help explain how plants will respond in the face of climate change and offer scientists new ideas to create crops that can withstand high temperature stress.

Philip Wigge of the John Innes Centre, Norwich, U.K., is one of the researchers on the project. Using a model plant, Arabidopsis thaliana, researchers found the key to the plant's temperature-sensing ability is a histone protein that wraps DNA into a tightly packed structure called a nucleosome. As temperatures rise, histones allow DNA to progressively wrap and nucleosomes to loosen.

This research suggests the degree of unwrapping may also be responsive to temperature. This basic discovery could one day prove critical for breeding temperature-resistant crops. Wigge points to wheat, in particular, as being vulnerable to hot and dry conditions.

"You can't make a temperature-proof plant, but there's a lot of scope to develop crops that are more resilient to high temperatures,” he says.


Pest Control That Lasts

When you belay in rock climbing, you literally hold your partner's life in your hands. The new insecticide, Belay, offers new control options to soybean and cotton growers facing tough-to-control insects, such as aphids, plant bugs and stinkbugs.

As a member of the neonicotinoid class of insecticide, Belay provides highly systemic chemistry, which quickly translocates through the plant. Trevor Dale, field market development specialist for Valent U.S.A., says this means farmers can expect longer residual control.

"Belay provides initial knockdown of aphids after a few hours. Then, it enters the plant to create long-lasting protection for 14 to 21 days of control,” he adds. This mode of action offers benefits for controlling primary and secondary pest populations.

Today, many similar products are marketed as being reduced risk or "soft” on beneficial predators and parasitoids, but Peter Ellsworth, an University of Arizona Extension entomologist, says Belay truly looks to be a selective material in cotton growing environments.

"We look forward to access to Belay as a rotational alternative to flonicamid [Carbine], which is fantastic on Lygus but also subject to overuse if we don't get some good alternatives,” Ellsworth explains.

According to its label, Belay can be applied 45 days after a seed treatment containing a neonicotinoid. However, increasing use of neonicotinoids has entomologists urging growers to rotate insecticides to avoid resistance issues with this important class of chemistry.

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