2014 Illinois Crop Management Conferences Registration Now Open

The latest research information on crop production and management issues will be discussed at four University of Illinois Crop Management Conferences this winter. These two-day conferences are designed to address a wide array of topics pertinent to crop production, pest management, and natural resource issues and provide a forum for discussion and interaction between participants and university researchers.

Certified Crop Advisers can earn up to 13 hours of CEU credit. Advance registration, no later than one week before each conference, is $130 per person. Late and on-site registration is $150. Dates and location for the four regional conferences are listed below. Links to the complete agendas and registration information for each conference are located on the Crop Sciences Research and Education Center web page here.

 

January 22-23: Mt. Vernon – Krieger/Holiday Inn Convention Center. For more information, contact Robert Bellm, (618-427-3349); rcbellm@illinois.edu . Register online at http://extension.illinois.edu/go/icmcmtvernon

January 29-30: Springfield – Northfield Inn Conference Center. For more information, contact Robert Bellm, (618-427-3349); rcbellm@illinois.edu . Register online at http://extension.illinois.edu/go/icmcspringfield

February 6:  Champaign – i-Hotel and Conference Center. For more information, contact Dennis Bowman, 217-244-0851); ndbowman@illinois.edu . Register online at http://extension.illinois.edu/go/icmcchampaign

February 12-13: Malta – Kishwaukee College Conference Center. For more information, contact Russ Higgins (815-274-1343); rahiggin@illinois.edu . Register online at http://extension.illinois.edu/go/icmcmalta


Brownstown Agronomy Research Center Field Day – July 25

The 2013 Brownstown Agronomy Research Center Field Day, presented by the University Of Illinois Department Of Crop Sciences, will be held on Thursday, July 25. Extension researchers and specialists will address issues pertinent to the current growing season. Tours will start at 8 a.m., with the second and third groups leaving the headquarters around 8:20 a.m. and 8:40 a.m. The tours will last about two and a half hours and will be followed by lunch provided by U of I Extension.

Shaded tour wagons will take participants to each stop. These topics will be addressed:

  • Nitrogen Sensors & Variable-rate N Applications – Dennis Bowman
  • Wheat Disease I.D. & Management – Dr. Carl Bradley
  • Emerging Developments in Weed Management – Doug Maxwell
  • Crop Rotation:  Another Risk Management Tool – Dr. Emerson Nafziger
  • Agronomic and Environmental Assessment of Cover Crops – Dr. Angie Peltier

 The 208-acre Brownstown Agronomy Research Center has been conducting crop research on the claypan soils of southern Illinois since 1937. More than 30 research and demonstration projects are conducted at the Center every year. Visitors are always welcome.

The research center is located south of Brownstown on IL Route 185, approximately 4 miles east of the IL Route 40 / 185 junction.

For more information, contact Robert Bellm (618-427-3349); rcbellm@illinois.edu
Visit us on the web at http://web.extension.illinois.edu/barc/


Western Corn Rootworm Hatch Confirmed in West Central Indiana

Entomologists (Christian Krupke, John Obermeyer, and Larry Bledsoe) at Purdue University have confirmed that the annual larval hatch of western corn rootworms is underway. They found the first corn rootworm larva on June 6 and believe that hatch was initiated on June 4. This event was a little later than heat-unit totals predicted. I suspect that the drought of 2012 forced much deeper egg laying in the soil contributing to the slightly later hatch this spring. Not all corn rootworm larvae hatch at once. This staggered event will occur over the next several weeks. By late June and early July, we should begin to see evidence of root injury, especially in fields where corn rootworm products may not be performing up to acceptable standards.

Mike Gray


Early Season Soybean Aphid Observations

On May 15-19, 2013, Drs. David Voegtlin (retired entomologist, Illinois Natural History Survey) and Dave Hogg (Professor, University of Wisconsin, Madison), surveyed the overwintering hosts of soybean aphids — the common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus). Their 2,000 + mile survey of these primary hosts took them across Illinois, Indiana, Michigan, Minnesota, Ohio, South Dakota, and Wisconsin. A synopsis of their observations by state are provided below.

  • Illinois -aphid colonies found in Mississippi Palisades State Park, Savannah, Illinois; Quad Cities – surveyed three sites, aphids numerous at one location, present at two remaining sites; Joliet – discovered some small colonies, overall aphids not numerous
  • Indiana – aphid colonies easy to find near LaPorte and Rome City
  • Michigan – aphids discovered near Augusta, not numerous
  • Minnesota (western) – no aphids found
  • Ohio – aphids were abundant near Toledo (Secor Park)
  • South Dakota – no aphids found
  • Wisconsin – aphids found near Prairie du Chien

The entomologists concluded that aphids were more abundant on this expedition than the exceptionally early spring of 2012. They did add a cautionary statement regarding the identification of the aphids that were collected, that is, some of the aphids observed could be a different aphid species — A. nasturtii (buckthorn aphids).

On June 4, Dave Hogg observed soybean aphids on seedling soybeans (VC – V1) at a research farm near Madison, Wisconsin. They sampled 100 plants and discovered that 13 were infested with aphids. It’s too early to tell what type of season producers should expect from this insect pest. Mild summers tend to promote greater soybean aphid activity and injury to soybeans. Hot and dry summers tend to work against the establishment of soybean aphids. I offer my thanks to David Voegtlin and Dave Hogg for sharing these early-season observations.

Mike Gray


Armyworms Reach Impressive Levels in Southwestern Illinois Wheat

Wheat producers, especially in southwestern Illinois, should be scouting their fields for armyworms and considering the need to apply a rescue treatment. Kevin Black, Insect and Plant Disease Technical Manager, Growmark, Inc., reported on June 7 that large numbers of armyworms were leaving roadside ditches, moving into adjacent wheat fields, and inflicting heavy damage. Armyworm densities and damage in one wheat field located northeast of St. Louis was particularly impressive. Because of the heavy rains this spring and the lack of mowing, ditch banks and roadsides have thick stands of tall fescue and brome grass. These sites have served as attractive egg laying targets for migrating armyworm moths. Producers are encouraged to scout their wheat fields and pastures for potentially heavy armyworm feeding.

Below are some photographs of the armyworm infestation provided by Mr. Kyle Heimann of M & M Service Company. He indicated to Kevin Black that treatments have been applied to some fields with only marginal success.

Armyworms vacating wet ditchbanks and seeking higher ground, Photo: Courtesy of Mr. Kyle Heimann, M & M Service Company, June 7, 2013.

 

Armyworm damage to plants, north east of St. Louis, Photo - Courtesy of Mr. Kyle Heimann, M & M Service Company, June 7, 2013.

 

For more information about the identification, biology, life cycle, and management of armyworms, please consult the fact sheet on this insect pest provided by the Department of Crop Sciences, University of Illinois.

Mike Gray


Potato Leafhoppers Active in Central Illinois

On June 5, I sampled an alfalfa field in Champaign County and found potato leafhoppers by using a sweep net. These small insects have the potential to cause injury to subsequent cuttings of alfalfa. Typically, the first cutting across much of Illinois is not at economic risk to this migratory pest. Producers are encouraged to scout their fields for potato leafhoppers and recognize that very low densities of these insects equipped with piercing and sucking mouthparts can cause economic losses to alfalfa soon after the first cutting. Densities as low as 0.2 leafhoppers per sweep in stands that have plants less than 3 inches in height can cause damage. Don’t wait too long for plants to begin greening up after the first harvest only to find leafhoppers have been hard at work. For more information about the identification, biology, life cycle, and management of potato leafhoppers, please refer to the Department of Crop Sciences fact sheet regarding this insect.

Mike Gray


Armyworm Activity Reported in Corn and Wheat

Producers are encouraged to scout both corn and wheat for armyworms and potential feeding. Kevin Black, Insect and Plant Disease Technical Manager with Growmark Inc., reported that a field of corn (Putnam County) planted into a rye cover crop had received some defoliation by armyworms. Kelli Bassett, a Field Agronomist with DuPont Pioneer, observed (May 30) some armyworm feeding in scattered wheat fields across Macoupin and Montgomery counties.

For more information about the biology, life cycle, management, and economic thresholds for armyworms in corn and wheat, please refer to the Department of Crop Sciences fact sheet.

Mike Gray


Delayed Soybean Planting: Prospects for Insect Injury

The stormy spring weather across much of the nation’s mid-section continues to cause planting delays. Planting estimates (USDA NASS, May 28, 2013) indicate that approximately 40% of Illinois soybean acres have been planted. Roughly 12% of the soybean crop has emerged across the state. These percentages are well below the five-year averages for Illinois by this date – 53% planted and 28% emerged. As overwintering bean leaf beetles break dormancy and begin to seek out soybean fields, those fields that are first to emerge will be most susceptible to early season feeding. Overwintering adults typically become active in April and initially may spend most of their time feeding within alfalfa or clover. As soybean plants become available in May and June, they become a preferred host. Fields most at risk this spring would include those that were planted first within an area and are now serving as a very attractive trap crop. These fields should be scouted for signs of defoliation. Fortunately, a rescue treatment for seedling soybeans is most often not justified because densities of 16 beetles per foot of row (early seedling stage) or 39 adults per foot of row at the V2+ stage of development are necessary for economic injury.

Seedling soybeans, May 31, 2013, Piatt County, Illinois.

Continuing delays in soybean planting could dim the prospects for soybean aphid establishment this season. Infestations of this insect pest have become less predictable and more sporadic the last several years in many areas of the Midwest. Soybean aphids first detected in North America (Wisconsin) in July of 2000, quickly spread to 10 North Central states by September of that same year. At the conclusion of the 2003 summer, they could be found in 21 states and three Canadian provinces. Entomologists have learned a great deal about this aphid species during the past 13 years and have developed some very sound economic thresholds that can be used in the effective management of this insect pest. Currently, alate (winged) viviparous (give birth to living young, nymphs) females are flying from their primary and overwintering host (common buckthorn) to their secondary host (soybean plants). These spring migrants may have more challenges this year locating soybean fields that are ready to receive them. It’s too early to offer any kind of firm predictions for soybean aphids this year. More moderate summer temperatures would work in favor of soybean aphids. For now, it appears they may have some establishment hurdles to clear this spring.

Management questions regarding soybean aphids and bean leaf beetles are often intertwined. A paper published in 2008 by some entomologists at Iowa State University provided some helpful insights regarding the use of insecticidal seed treatments and early-season rescue treatments in soybeans. They determined that neither of these approaches that targeted early-season bean leaf beetle densities had much value for overall soybean aphid management. For more information about this 3-year investigation, I encourage you to take a look at this useful journal article.

Johnson, K.D., M.E. O’Neal, J.D. Bradshaw, and M.E. Rice. 2008. Is preventative, concurrent management of the soybean aphid (Hemiptera: Aphididae) and bean leaf beetle (Coleoptera: Chrysomelidae) possible? Journal of Economic Entomology 101(3): 801-809.

Bean leaf beetle, Warren County, June 5 - Courtesy of Angie Peltier, Commercial Agriculture Educator, Northwestern Illinois Research and Education Center, Monmouth, Illinois.

Mike Gray


Western Corn Rootworm Injury in First-Year Corn: A Diminished Threat?

The economic impact of the variant western corn rootworm that evolved in the eastern Corn Belt continues to reverberate nearly twenty years later. The overall impact includes yield losses in first-year corn and the additional input costs of Bt seed and/or soil insecticides to rotated corn. In 1995, severe root injury and punishing yield losses occurred in first-year cornfields across east-central Illinois and northern Indiana. These were fields in which the annual rotation of corn and soybeans had rigidly taken place for decades. Producers had unwittingly selected for a rotation-resistant western corn rootworm in which females were laying at least a portion of their eggs in the soil of soybean fields. This behavior enhanced the survival of their progeny the following spring in first-year cornfields. In 2012, some University of Illinois researchers determined that the variant western corn rootworm could tolerate soybean foliage to a greater extent than the non-rotation resistant population. Based on their investigations, they discovered that the variant western corn rootworm had 3 to 4 times more of a key digestive enzyme (cathepsin L-like protease) enabling them to feed on soybean foliage for longer periods of time. Consequently, these western corn rootworms spent more time in soybean fields laying eggs. The reference for this very nice contribution to the entomological literature is provided.

Curzi, M.J., J.A. Zavala, J.L. Spencer, and M.J. Seufferheld. 2012. Abnormally high digestive enzyme activity and gene expression explain the contemporary evolution of a Diabrotica biotype able to feed on soybeans. Ecology and Evolution: DOI 10.1002/ece3.331.

As mentioned previously, the economic impact of this unique adaptation continues to be sobering in the eastern Corn Belt. Prior to the evolution of the variant western corn rootworm, crop rotation was considered to be a sound pest management strategy to limit root injury and yield loss caused by this insect pest. Since the mid-1990s, producers who felt they were at risk to first-year corn rootworm damage began to use planting-time soil insecticides on rotated corn ground. Western corn rootworms began to move across the Corn Belt in the 1950s and 1960s and continuous corn was the primary sink for soil insecticides delivered during planting. After 1995, concern over potential injury to rotated corn was most common in the northern two-thirds of Illinois and northern Indiana. In 2003, Bt hybrids that offered corn rootworm protection were commercialized. Producers quickly transitioned away from soil insecticides as their primary corn rootworm control tactic. However, many of these producers who were using soil insecticides on rotated and non-rotated corn ground continued to use Bt corn rootworm hybrids across all their corn acres regardless of crop history. Recently, it has become increasingly common to use both a planting-time soil insecticide and a Bt corn rootworm hybrid in some areas of the eastern Corn Belt even though crop rotation has been practiced.

A journal article was published recently (February 2013) by Mike Dunbar and Aaron Gassmann, entomologists at Iowa State University, that clearly pointed out the viability of crop rotation as a corn rootworm management strategy for northern and western corn rootworms in eastern Iowa. They indicated rotation resistant western corn rootworms were present in eastern Iowa at very low levels. By comparing their data with previous surveys, they reported no measurable expansion of this behavior in the last 5 years. They concluded their paper by recommending that growers scout, familiarize themselves with economic thresholds, and consider crop rotation as a viable corn rootworm management strategy in eastern Iowa. Based upon their findings, it would seem reasonable to suggest that producers in eastern Iowa could potentially save on their input costs for corn rootworms in rotated corn. The citation for this research is provided.

Dunbar, M.W., and A.J. Gassmann. 2013. Abundance and distribution of western and northern corn rootworm (Diabrotica spp.) and prevalence of rotation resistance in eastern Iowa. Journal of Economic Entomology 106(1): 168-180. DOI: http://dx.doi.org/10.1603/EC11291

What do the densities of western corn rootworm adults look like in Illinois soybean fields? In 2011 (late July and early August), we conducted a statewide (47 counties) survey of both corn and soybean fields for various insect pests. In each county, five soybean and five cornfields were selected randomly and sampled. In each soybean field, 100 sweeps were taken with a sweep net. In corn, 20 consecutive plants were examined for western corn rootworm adults. In both corn and soybean fields, western corn rootworm densities were exceedingly low. With one exception (Ford County, 25 western corn rootworm adults per 100 sweeps), on average, fewer than 10 western corn rootworm adults were recovered after 100 sweeps per field in all 47 counties. Historically, 10 adults captured per 100 sweeps was considered the benchmark that indicated the presence of variant western corn rootworm adults in a soybean field. For the vast majority of Illinois soybean fields sampled in 2011, this threshold was not even approached. In fact, it was exceeded only once (Ford County) and nearly reached in Vermilion County (9.4). In 28 counties, no western corn rootworm adults were found in soybean fields that we sampled. It’s worth noting, that Ford County still has the greatest density of variant western corn rootworms. Many will recall that Ford County was the epicenter of the outbreak that erupted in 1995.

Western corn rootworm densities (per 100 sweeps) in Illinois soybean fields, 2011.

Our data collected in 2011, look far different from survey results of western corn rootworm densities in soybeans collected approximately 1 decade ago (2002 and 2003). State surveys (2002 and 2003) conducted by Dr. Joe Spencer, an entomologist with the Illinois Natural History Survey, revealed densities of western corn rootworm adults that commonly went well beyond the 10 per 100 sweep threshold mentioned previously. Western corn rootworm densities such as those observed 10 years ago in soybean fields, would likely justify the use of a planting-time soil insecticide or a corn rootworm Bt hybrid on first-year corn. Can the same argument be made today even at the higher commodity prices? Unfortunately, most producers are no longer scouting for western corn rootworms in soybean fields (or cornfields) and assume the input costs will be worth the investment. In many instances, this may not be a wise decision with these very low western corn rootworm densities observed in Illinois soybean fields in recent years.

Western corn rootworm densities (per 100 sweeps) of soybean fields, 2002 and 2003, Courtesy of Dr. Joe Spencer, Illinois Natural History Survey.

Why are the densities of variant western corn rootworm adults so low in Illinois and Iowa soybean fields in recent years? I have stated previously that I believe three key factors are involved: 1) excessively wet springs and saturated soils (2012 being an exception) over many successive years leading to significant larval mortality during the spring hatch, 2) continued significant use of Bt corn rootworm hybrids in first-year corn and continuous corn production systems, and 3) popular broadcast applications of tank-mix treatments (fungicide/insecticide) to corn and soybean fields across a large swath of the Corn Belt. With increasing concern over emerging western corn rootworm resistance to the Cry3Bb1 protein expressed in some Bt hybrids, the use of crop rotation, along with a non-Bt hybrid in first-year corn would seem to make increasing sense. This would reduce the selection pressure on various Cry proteins targeted at corn rootworms. Ultimately, in order for management decisions to be optimized, they should be made on a field by field basis and rely upon scouting inputs the previous season and knowledge of rootworm densities and economic thresholds.

Is the variant western corn rootworm threat diminished as compared with the threat it posed 10 to 15 years ago? Recent data would suggest this to be the case. We should not expect this reduced threat to be permanent. Instead, producers are encouraged to scout soybeans for western corn rootworm adults and to make more informed management decisions regarding this insect pest in first-year cornfields. By more carefully targeting inputs (Bt hybrids, soil insecticides), their longevity can be enhanced.

Mike Gray