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

Golden Harvest Corn healthy leaves
FungicidesArysta Launches New Corn And Soybean Fungicide
November 17, 2015
Arysta LifeScience North America has recently launched ZOLERA FX Fungicide. The highly systemic, powerful fungicide delivers broad-spectrum disease control with Read More
FungicidesFMC Launching New In-Furrow Combo Insecticide/Fungicide
November 9, 2015
FMC is launching Ethos XB insecticide/fungicide, the first of its kind, integrated in-furrow product for insect and disease control. Formulated Read More
FungicidesNew Corn Disease Confirmed In Illinois
October 7, 2015
Symptomatic corn leaf samples from Champaign County, IL, have been confirmed positive for the bacterium Burkholderia andropogonis (Pseudomonas adropogonis (Smith) Read More
Poor wheat stand diminished by diseases
FungicidesThe Importance Of Wheat Seed Treatments
September 18, 2015
Fungicide seed treatments help to reduce losses caused by seed transmitted and soilborne fungal diseases of wheat, according to the Read More
Top 100 Articles
CropLife 100United Cooperative Acquires Four ADM Wisconsin Facilities
November 12, 2015
United Cooperative, based out of Beaver Dam, WI, recently acquired four grain and agronomy locations from Archer Daniels Midland (ADM) Read More
CropLife 100BRANDT Car Makes NASCAR Xfinity Series
October 29, 2015
BRANDT will join JR Motorsports with driver, Justin Allgaier, for the 2016 NASCAR Xfinity (NXS) Series season. Allgaier will pilot Read More
CHS Building exterior
CropLife 100CHS Leaders Help Shape Succession Report
October 22, 2015
Succession planning was listed as a main concern of cooperative leaders at this summer’s 15 regional CHS owner town hall Read More
Fall Harvest
CropLife 100Pinnacle Purchases Eight Regional Seed Companies
October 12, 2015
Pinnacle Agriculture Holdings has announced the purchase of eight regional seed companies to advance its seed business. Pinnacle has acquired: Read More
MRM Agricultural Service
CropLife 100Pinnacle Acquires CropLife 100 Ag Retailer
October 8, 2015
Pinnacle Agriculture Holdings, LLC has successfully acquired the Missouri-based agronomy business of MRM Agricultural Service, LLC and its affiliates (MRM). Operating Read More
Eric Jenks, Wilbur-Ellis
CropLife 100Wilbur-Ellis Opens Dry Fertilizer Storage And Blending Facility In Washington
October 8, 2015
Wilbur-Ellis Co., ranked No. 4 on the CropLife 100, has constructed and opened a 22,000-ton dry fertilizer storage and blending Read More
Latest News
HerbicidesBREAKING: EPA Pulls Registration On Dow’s Enlist …
November 25, 2015
EPA on Wednesday withdrew approval of a controversial new weed killer to be used on genetically modified corn and soybeans, Read More
FertilizerYara Tampa Ammonia Terminal Garners ResponsibleAg Honor…
November 25, 2015
Yara has received its first ResponsibleAg Certification for its Tampa, FL, Ammonia terminal location. This achievement demonstrates Yara’s commitment to Read More
ManagementReviewing The Top Ag Stories For 2015
November 24, 2015
Editors Eric Sfiligoj and Paul Schrimpf discuss the most noteworthy events from this past year in agriculture. Read More
EmployeesAgriculture Jobs May Be Plentiful, But New Grads Are Sc…
November 24, 2015
Close to 60,000 jobs are set to open up in agriculture each year for the next five years, but there's not enough grads to fill them. Read More
Radish cover crop
StewardshipCover Crops Guide Helps Growers Improve Water Quality
November 23, 2015
A publication that teaches growers the advantages of using cover crops to improve soil health and crop yields has won Read More
Crop InputsThe Andersons’ Products Receive California Organi…
November 23, 2015
The Plant Nutrient Group of The Andersons, Inc. announced today that its Humic DG and Black Gypsum DG products are Read More
Eric SfiligojNew European Study Seems To Support Glyphosate Safety
November 23, 2015
Looking at any international news over the past few years, it might seem as if the European Union (EU) is Read More
Toggle Biostimulant corn roots
Crop InputsTwo New Biostimulants Added To United Suppliers’ …
November 20, 2015
Winfield US announces the launch of two new products in the United Suppliers portfolio for the 2016 crop season, Optify Read More
StewardshipNRDC Report: Cover Crops Contain Vast Benefits
November 19, 2015
As harvest season ends and farmers in the United States ready themselves for winter, one small change could make a Read More
Fall Harvest
Seed/BiotechArysta Launches New Seed Protectant
November 19, 2015
As spring wheat growers begin planning for a strong start to their season, Arysta LifeScience North America announces RANCONA V Read More
Crop InputsInocucor Receives U.S. Patent For Microbials
November 19, 2015
Inocucor Technologies Inc., the Montreal-based agriculture biotech company, was issued patent No. 9,175,258 by the U.S. Patent and Trademark Office to protect Read More
ManagementSyngenta Rumors and ARA 2015 Preview
November 19, 2015
CropLife Editor Eric Sfiligoj looks at the latest rumors involving Syngenta selling its crop protection business and talks about events Read More
EquipmentAGCO Announces Finalists For Operator Of The Year Honor
November 19, 2015
AGCO Corp. has announced the four top operators chosen as finalists for AGCO’s 10th Annual Operator of the Year program, Read More
High Plains Aquifer
StewardshipStudy: High Plains Aquifer Overall Usage In Decline
November 18, 2015
A new Kansas State University study finds that the over-tapping of the High Plains Aquifer’s groundwater beyond the aquifer’s recharge Read More
Golden Harvest Corn healthy leaves
FungicidesArysta Launches New Corn And Soybean Fungicide
November 17, 2015
Arysta LifeScience North America has recently launched ZOLERA FX Fungicide. The highly systemic, powerful fungicide delivers broad-spectrum disease control with Read More
Young corn plants in soil
Crop InputsBioAg Alliance: Microbials Targeted For 250-500 million…
November 17, 2015
Monsanto and Novozymes have announced a new 2025 acreage target that will guide the companies’ microbials business for the next Read More
Syngenta Sign
Crop InputsSyngenta Still Being Eyed For China Takeover
November 16, 2015
China National Chemical Corp. approached sovereign wealth funds including China Investment Corp. to help pay for a potential acquisition of Read More
Cedar Country Cooperative
Eric SfiligojCooperative Consolidation Continues
November 16, 2015
As I put this enewsletter column together, we’ve just put the finishing touches on our magazine’s annual CropLife 100 report. Read More