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

FungicidesSudden Death Syndrome, Brown Stem Rot Reported In Indiana Soybeans
September 3, 2014
Farmers and retailers should be watching for symptoms of these two diseases over the next few weeks as they are best managed through preventative methods. Read More
FungicidesResearchers Target Soybean Disease With Genetic Resistance Study
August 6, 2014
University of Illinois researchers will share new information on controlling sudden death syndrome through genetic resistance at this year's Agronomy Day. Read More
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

Trending Articles

Crop InputsPlatform Specialty Products To Acquire Arysta LifeScience
October 20, 2014
Once the acquisition is complete, Platform Specialty Products will combine Arysta LifeScience with previously acquired companies Agriphar and Chemtura Crop Solutions. Read More
Seed/BiotechMonsanto Offers New Support For Ferguson, Area Communities
October 8, 2014
Monsanto Co. has committed $1 million in new support for several collaborative efforts in Ferguson, MO, and surrounding communities in North St. Louis County. Read More
Seed/BiotechUnapproved Genetically Modified Wheat Found In Montana
October 3, 2014
USDA reports that one year after discovery of Monsanto's unapproved wheat in a single Oregon field disrupted U.S. wheat export sales, the GMO wheat has again been found in Montana. Read More
Equipment2014 Product Of The Year Voting
September 19, 2014
The deadline to vote for the 2014 CropLife IRON Product of the Year is October 31. Please cast your vote today to help us determine the winner. Read More
FertilizerFall Fertility 2014: Forecasting Fertilizer Use
September 7, 2014
Great crops this year have tapped the soil, and fall work is definitely called for, but how challenging will that get? Read More
CropLife 100CHS To Build $3 Billion Fertilizer Plant In North Dakota
September 5, 2014
The fertilizer plant in Spiritwood will be the single largest investment in CHS history, as well as the single largest private investment project ever undertaken in North Dakota. Read More

Latest News

InsecticidesValent U.S.A., MGK Form Marketing Agreement
October 24, 2014
Valent has formed an agreement with Minneapolis-based MGK to manage the marketing and sales of MGK’s crop protection line of insect control products within the U.S. beginning April 1, 2015. Read More
StewardshipFlorida’s 4R Advocate Keeps Improving
October 24, 2014
Florida farmer Alan Jones uses the 4R principles of nutrient stewardship as the core of his fertility program, which allows him to maximize production and keep costs in check. Read More
Seed/BiotechMonsanto Named One Of The World’s Best Multinational …
October 23, 2014
Monsanto ranked No. 8 in the world’s largest annual study of workplace excellence that identifies the top 25 best multinational companies in terms of workplace culture. Read More
Crop InputsArysta Hires Former Agri-Chem, CPS Employee For Delta S…
October 23, 2014
New Territory Sales Manager Mark Peel’s primary role will focus on working with growers regarding fungicides in Louisiana, Mississippi, Arkansas and Tennessee. Read More
CropLife 100GROWMARK Announces Appointments In Plant Food Division
October 22, 2014
GROWMARK, Inc. has announced the three key staff changes in its Plant Food Division. Read More
CropLife 100GROWMARK Appoints New VP Of Finance And Risk Management
October 22, 2014
Wade Mittelstadt has been named GROWMARK Vice President, Financial and Risk Mangement, effective December 1, 2014. Read More
FungicidesEPA Approves BASF In-Furrow Corn Fungicide
October 22, 2014
Field trials show Xanthion In-furrow fungicide provides more rapid emergence, extended residual control and improved seedling health than untreated crops. Read More
EquipmentAgraScout App Available At No Cost To Universities
October 21, 2014
AgraScout, a fast and easy to use mobile crop scouting app, is now available at no cost to University students, Read More
LegislationNew Farm Bill Program To Provide Relief To Farmers Affe…
October 21, 2014
The USDA has implemented a new Farm Bill initiative that will provide relief to farmers affected by severe weather, including drought. Read More
ManagementGreenfield Scholars Program Aims To Sustain Agronomy Wo…
October 21, 2014
The program encourages talented students to study agronomy, crop and soil sciences while cultivating networks to develop the necessary workforce to sustain the profession. Read More
Paul SchrimpfPrecision Ag: Taking It To The Hill
October 21, 2014
A new coalition took the good news message of precision agriculture to Washington, DC, last month. Read More
ManagementUSDA Awards $18 Million In Small Business Research Gran…
October 21, 2014
The grants will provide high quality, advanced research and development that will lead to technological innovations and solutions for American agriculture. Read More
FertilizerCF Industries Terminates Merger Discussions With Yara I…
October 21, 2014
CF Industries Holdings and Yara International have terminated their discussions regarding a potential merger of equals transaction. Read More
Seed/BiotechSyngenta Ranked A Top 10 Biotech Employer For Third tim…
October 20, 2014
Syngenta ranked in the top 10 among the world’s top biotech employers, according to an annual survey conducted by Science magazine. Read More
CropLife 100Wheat Growers Break Ground For New Facility At Kennebec
October 20, 2014
Wheat Growers has broke ground for a state-of-the-art shuttle loader grain handling, fertilizer and agronomy facility in Kennebec, SD. Read More
FertilizerVerdesian Life Sciences Signs Agreement With Los Alamos…
October 20, 2014
Verdesian Life Sciences has signed a licensing agreement with Los Alamos National Laboratory to develop and market LANL’s latest nitrogen enhancement technology for plants. Read More
MicronutrientsStoller Group Announces Groundbreaking At New Office Bu…
October 20, 2014
Jerry Stoller, founder and president of Stoller Group, announced the groundbreaking at the site of the company’s future headquarters in Read More
Crop InputsBioSafe Systems Opens New Production Facility In Nevada
October 20, 2014
BioSafe Systems has completed construction of a state-of-art production facility in Sparks, NV, for its line of activated peroxygen products. Read More