Pest Pressure Watch

White Mold in Soybean

Pay attention to in-season developments. That’s the key piece of advice offered by University of Minnesota entomologist Ken Ostlie as he contemplates pest problems for the season ahead. “Each year is different. I don’t put too much stock in predicting insect problems because I’ve been humbled frequently,” he admits. But Ostlie and other insect and disease experts had a few observations to at least give dealers and growers a heads up.

Soybean Sickness

Soybeans faced some of the most startling pest outbreaks last year. Kier­sten Wise, plant pathologist at Purdue University, reports that Indiana growers had problems with white mold in the crop, thanks to cool conditions in July and August. Illinois had similar problems, and Iowa actually had a white mold “epidemic” in 2009, per X.B. Yang, Iowa State University.

Iowa also saw a surprising incidence of sudden death syndrome (SDS), says Daren Mueller, Extension plant pathologist. Selecting varieties with high levels of resistance to SDS will be the key for managing the disease, as one potential management tool — fungicide seed treatment — has not been effective in reducing SDS on soybeans. Researchers had been hoping to see some control with this strategy, but so far no good results have been reported by other states, he says.

And white mold control with foliar fungicides continues to be tough, he admits. “By the time you see it in a field, it’s often too late to get the maximum benefit from a fungicide application,” he says. Unfortunately, the fungus survives well in the soil as well as on other hosts besides soybean, adds Carl Bradley, crop scientist at the University of Illinois.

The amount of foliar diseases seen in 2009 coupled with this winter’s snow cover are cause for concern, says Mueller. Inoculums in fields have likely been well protected, and fields planted to the same crop may be especially problematic in 2010, he says. Yang agrees: “It is a mistake to plant soybean after soybean in 2010. The risk can be high unless 2010 is a dry season.”

Mueller says there’s a good chance for a wet spring — which also doesn’t bode well for disease pressure. Growers may want to consider using seed treatments on soybeans to help manage seedling diseases associated with wet soils. Growers may be forced to plant less seed per acre to save money. Yang recommends avoiding planting soybean with narrow rows (15 inches or less) in fields that had white mold in the past. And, growers should use no-till if corn is the rotation crop, as tillage can bury white mold fungus, allowing it to survive in deep soil up to seven years.

Excessive moisture in Mississippi last year delayed soybean harvest for up to five weeks in some areas and caused pod and seed diseases to dominate the entire state, says Mississippi State’s Extension Plant Pathologist Tom Allen.

Cool conditions around and after corn silking — plus late rains — favored widespread ear rots in Indiana corn fields, says Purdue’s Wise. In Illinois, diplodia ear rot was especially prevalent, with some field’s having incidence as high as 70%, reports Bradley.

Iowa’s problems included some ear rots as well as eyespot, gray leaf spot, and Northern leaf blight. Fungicides are effective at reducing many of these diseases, says Mueller, “but with the cost of application and the price of corn, some corn growers were reluctant to pull the trigger on fungicides, even when they had dramatic eyespot and gray leaf spot pressure early in the season.”

In the South, Mississippi’s Allen attributes increased foliar diseases such as gray leaf spot and Northern corn leaf blight to producers deciding to plant continuous corn — and last year in particular — to the extended cool, wet weather throughout the state.

“The likelihood that these or any other diseases will be problematic in 2010 will depend mostly on the weather,” says Purdue’s Wise. “We advise growers to take good notes about the history of disease within a field — and if they are planting back into a field that has disease problems, the best thing is to choose a hybrid that has some level of resistance to the disease that was problematic.”

Excessive Aphids

The extremely late and heavy soybean aphid population in southern Indiana last season surprised Christian Krupke, entomologist with Purdue University. Late planting and replanting due to early season rains meant this area had relatively immature beans that attracted many winged migrants from adjacent states, he says. Fortunately, most areas did not reach threshold levels and did not require pyrethroid sprays.

Even better news: “Soybean aphid numbers are expected to be low early in the season, as we found very few overwintering on buckthorn plants in fall,” Krupke says.

Erin Hodgson, Iowa State Uni­versity entomologist, says soybean aphid continues to be the state’s biggest insect problem, and last year’s cool summer temperatures certainly favored aphid development. In fact, she saw record numbers of fall migrant aphids moving to buckthorn. “We don’t know what this means for hatch numbers in the spring and subsequent movement to soybean,” she says. Spring planting may be delayed in 2010 — and this may be an advantage for the pest. “Start scouting before flowering and continue regularly until seed set,” she advises.

Aphid Data

At the University of Illinois, Michael Gray was surprised that soybean aphids came on very strong late in the growing season, especially across the southern part of the state. In fact, some growers actually described the aphid densities as “swarms.” Late summer/early fall flights to buckthorn were heavy, but an unexpected fungal disease infection helped to suppress aphid numbers. The result: Spring flights may be lower than many would have guessed, says Gray.

Hodgson has found that foliar insec­ticides are very effective in reducing populations if the coverage is sufficient. “Getting proper coverage is essential to contact aphids feeding on the undersides of leaves in the lower canopy,” she emphasizes, and making timely foliar treatments after aphids exceed the economic threshold (250 per plant) will protect yield.

Minnesota’s Ostlie warns that premature (below threshold) insecticide applications for soybean aphid may lead to resprays, as products only supply about a five- to 10-day window of control. “Be careful on your timing,” he says.

Minnesota ran into two-spotted spider mite problems as well, even in cool drought conditions. Ostlie says growers need to be careful about insecticide choice here, as pyrethroid products provide poor control — and may actually flare mite populations, leading to resprays in a couple of weeks or less, if the drought persists. He says insecticides containing chlorpyrifos and bifenthrin provide good control of both mites and soybean aphid.

Purdue’s Krupke saw few insect problems on Indiana corn last year, with late planting and excessive rain acting to reduce rootworm pressure in most of the state. He notes, though, that Western bean cutworm continued to rise in severity in northern counties, with some fields showing economic damage levels.

For this season, “rootworm numbers should again be low to moderate, although the historical high pressure areas will probably remain so, while Western bean cutworm will likely continue to expand its range eastward across Indiana and into Ohio,” Krupke says. Late, wet planting — common in Indiana — will exacerbate problems such as grubs and wireworms, he notes.

In Illinois last season, European corn borer populations reached historic low levels, reports Gray. Even densities of the Western corn rootworm were very low, and he suspects the very wet spring did not favor establishment of larvae.

To the north in Minnesota, slightly drier conditions during corn rootworm hatch and establishment enhanced pest survival and increased pressure. Across the state, Ostlie saw unexpected rootworm injury to triple-stack corn. “The performance issues with Bt (Bacillius thuringiensis)-RW corn were unprecedented,” he says. “There seems to be a fundamental shift in either the corn rootworm tolerance of the proteins or their levels in the plant were lower under the unusual weather conditions in 2009.”

Ostlie recommends growers pay attention to corn rootworm populations, especially in corn following corn fields where the same transgenic traits have been used for several years. And, producers should not neglect insect refuge management requirements in transgenic fields.

Leave a Reply

Fungicides Stories

Soybean field
FungicidesValent Launches New Seed Protection Fungicide For Soybeans
July 16, 2014
The INTEGO SUITE System contains the first new, novel seed protection fungicide chemistry registered in 30 years by the EPA for protection against Pythium and Phytophthora. Read More
FungicidesNew Players May Make Pest Headlines In Corn, Soybean
April 1, 2014
The usual insects and diseases took a bit of a break in 2013, but other culprits surfaced — and could return. Read More
Frog eye leaf spot on soybean
FungicidesMake The Case For Fungicides In 2014
February 3, 2014
New products are looking good, but will growers bite with lower crop prices? Read More
FungicidesMANA Introduces Custodia Premix Fungicide For Row Crops
January 14, 2014
New fungicide for corn, soybeans, and wheat contains the two most complementary systemic active ingredients available today in an optimized ratio to deliver both preventive and curative disease control. Read More

Trending Articles

Green Valley Ag facility
Retail FacilitiesGreen Valley Ag Adopts A.J. Sackett’s Precision Fertilizer Blending® Technology At New Facility
July 8, 2014
Sackett's Precision Fertilizer Blending® Technology is making huge strides around the world. Green Valley Ag adopts the technology at its new facility to support its advancing agronomic needs. Read More
Retail FacilitiesWaconia Manufacturing Builds Facility Designed For Speed, Efficiency
July 7, 2014
To make its new hub facility more efficient, Cooperative Elevator enlisted the aid of Waconia Manufacturing. Read More
EquipmentSummer Show Preview 2014: Superior Sprayers Take The Field
July 3, 2014
In this final installment of our coverage of the major categories of Big IRON that retailers can expect to test-drive at this summer’s events, here is a look at 19 sprayers. Read More
Scouting a soybean patch at Green Valley Ag.
EmployeesCropLife Compensation Survey: Battling Talent Drain
July 2, 2014
Retailers too often lose employees to companies outside of agriculture, while recruiting efforts are most often limited to competitors and other ag-focused organizations. Read More
HerbicidesDow AgroSciences Introduces SureStart II Herbicide
June 16, 2014
The enhanced formulation has improved viscosity and increased stability under heat and controls more than 60 high-anxiety grasses and broadleaf weeds found in corn fields. Read More
HerbicidesBASF Investing $270 Million To Expand U.S. Herbicide Production
June 11, 2014
BASF has invested more than $270 million to expand herbicide production capacities in the U.S., including more than 20 new products to be launched over next two years. Read More

Latest News

Crop InputsSoybean Checkoff Produces Big ROI
July 30, 2014
Under the soy checkoff program, all U.S. soybean farmers contribute a small percentage of their gross soybean sales for research and marketing projects that maximize their profit potential. Read More
CropLife 100Learfield Sports, CHS Agree To Football-Centric, Colleg…
July 30, 2014
CHS Inc. will embark on a highly integrated collegiate sports sponsorship platform with 24 Division I universities in 19 states designed to reach the farmer-owned cooperative's rural owners and customers. Read More
LegislationUSDA Implements Key Farm Bill Crop Insurance Provision
July 30, 2014
The new Supplemental Coverage Option, available through the federal crop insurance program and set to begin with the 2015 crop year, is designed to help protect producers from yield and market volatility. Read More
CropLife 100Wilbur-Ellis Forms New Organizational Structure For Its…
July 30, 2014
The new structure will provide more responsive internal support and will allow regional vice presidents and area managers to spend more time with customers, on talent development and on operational excellence across branches. Read More
Palmer pigweed in cotton
HerbicidesNew Training Modules On Herbicide Resistance Now Availa…
July 30, 2014
The Weed Science Society of America has announced the availability of three new education modules on herbicide resistance in weeds. Read More
HerbicidesWillowood To Market Glufosinate
July 28, 2014
Willowood USA recently announced that Federal EPA has approved its technical registration for glufosinate. Read More
InsecticidesHow To Scout For Corn Earworms In Corn
July 28, 2014
In her weekly report, University of Missouri Agronomy Specialist Jill Scheidt discusses what to look for when scouting for corn earworm. Read More
Crop InputsDuPont Pioneer, Weyerhaeuser Enter Technology License A…
July 28, 2014
The agreement brings together agricultural and forestry know-how to sustainably improve crop productivity for corn growers around the world. Read More
EquipmentAGCO Launches Global iPad App
July 28, 2014
The free AGCO Global iPad App can be downloaded from the Apple iTunes Store and features the full family of RoGator self-propelled sprayers and TerraGator high-floatation spreaders. Read More
Eric SfiligojYuma Centennial Ag Supply Earns 2014 National Environme…
July 28, 2014
Colorado-based ag retailer receives top trophy in 24th annual DuPont Crop Protection/CropLife ceremony. Read More
CropLife 100Pinnacle Forms Alliance With Wildlife Managment, Seed O…
July 25, 2014
The strategic alliance will provide Tecomate with key wildlife products, processing facilities, distribution centers and sales through Pinnacle’s ever-growing retail network. Read More
ManagementFranken Presses White House On RFS Support
July 25, 2014
Al Franken and a group of Senate democrats recently met with senior White House official John Podesta to urge the administration to change its position on an EPA proposal. Read More
ManagementASA, FarmLink To Launch ‘Operation Benchmark̵…
July 25, 2014
The American Soybean Association (ASA) and FarmLink are teaming up to help farmers close the $11 billion gap between what they harvested in 2013 and what they could harvest annually. Read More
StewardshipNorthey: Farmers Commit $1.4 Million to Try New Water Q…
July 25, 2014
The practices that are eligible for funding include cover crops, no-till or strip till and using a nitrification inhibitor when applying fall fertilizer. Read More
Precision AgFarmers Learn How Changing World Will Impact Iowa
July 24, 2014
Technology and understanding global consumer demand for Iowa farm products brought hundreds of farmers and agribusiness leaders to Ames recently for the annual Iowa Farm Bureau Federation Economic Summit. Read More
HerbicidesPurdue: Late Season Weeds May Require Manual Removal
July 24, 2014
Hand-rouging and pulling late season weeds by hand may be the best way to remove them, more so than using a herbicide, a Purdue Extension weed scientist says. Read More
Soybean Field
InsecticidesTransform WG, Closer SC Insecticides Receive R&D 10…
July 23, 2014
Dow AgroSciences has received the award from R&D Magazine for Transform WG insecticide and Closer SC insecticide with Isoclast active. Read More
EquipmentKinze, Raven Team Up On 4900 Planter Monitor
July 23, 2014
Kinze Manufacturing announces a partnership with Raven Industries to develop a standalone monitor solution for the Kinze 4900 series planter. With this new Read More