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Crop Roundup: Corn Root Digs

Corn rootworms are one of the most damaging pests in the Corn Belt. According to the USDA, they are responsible for up to $2 billion in lost revenues each year. The best way to scout for this pest is by digging up plants and inspecting roots for larval damage. 

Identifying damage in corn roots after pollination can help growers evaluate current management practices and plan ahead for next year. Jeff Housman, Mycogen Seeds customer agronomist, outlines six steps for a successful root dig. 

  1. Start with a plant from a refuge strip or untreated area. Dig 6 to 8 inches around the plant so as to not harm the existing roots. Untreated plants typically have a smaller root mass, making it easier to pull the plant out of the ground.
  2. Look for larvae in the soil and on the roots. Damaged roots may appear rotted and will have pinhole markings where corn rootworms have entered the plant’s roots. “Larval damage sacrifices root mass and limits the plant’s ability to stand upright,” Housman says.
  3. Survey plant silks for adult beetles. Corn rootworm damage appears primarily in the roots of the plant, but adult beetles can prevent full ear fill near the silks after pollination. Identifying corn rootworm adult beetles is a clue that root damage was, in fact, caused by this pest and can help you evaluate if an insecticide is needed.
  4. Examine overall plant and stalk health. Damaged roots restrict the amount of nutrients that can be delivered to a plant. The resulting nutrient deficiency leads to a poor crop and ear development and sacrificed yield at harvest.
  5. Dig plants from three other areas. Housman recommends examining roots and overall plant health from at least three other plants in the field for an accurate sample. Treated plants and plants with less corn rootworm damage will be sturdier, with larger root masses, and they'll be more difficult to dig up.
  6. Wash roots. Soak the plant roots in buckets of water for 30 minutes. This will allow you to examine clean roots and identify larvae that float to the top of the water. Housman uses the Iowa State University Node-Injury Scale to assess the severity of root damage.

“Root digs are helpful in evaluating the success of current corn rootworm management practices, but prevention during planting is the best way to combat this yield-robbing pest,” Housman says.

If root digs reveal rootworm damage, Housman recommends growers adjust management for those fields next year. Options include rotating crops, avoiding continuous corn rotations, as well as not planting Bt-traited corn with the same single mode of action for more than two years in a row.

New NK soybean varieties for 2015

NK soybeans are offering 21 new varieties for the 2015 season. These varieties address various growing conditions across the country and were developed using the Syngenta Yield Engineering System (Y.E.S.).  
“We know that no two fields are alike,” said Doug Tigges, soybean genetics product manager at Syngenta. “Our new varieties feature the latest herbicide technology traits and address a wide range of needs, including maturity, standability, stress tolerance, and disease and pest resistance. Whether you have poorly drained soils, high pH levels, or escalating problems with soybean cyst nematode, NK soybean varieties offer the needed built-in defensive traits with higher yield potential.”
The 21 new NK soybean varieties offer a wide range of agronomic benefits, such as strong emergence, standability, stress tolerance, and resistance to numerous yield-limiting diseases and pests. These resistances include soybean cyst nematode, sudden death syndrome, white mold, iron deficiency chlorosis, root knot nematode, and Phytophthora root rot. In addition to providing industry-leading traits, these new 2015 offerings are available for soybean growers in a wide range of choices, from maturity groups 00 through V.
As farming operations continue to become more efficient and profitable, so do the genetics and technology found in NK soybeans. Growers can speak with their local NK retailer or Syngenta Seed Advisor to learn which of the 21 new NK varieties is best suited for their fields so they can grow more soybeans in 2015.

To conserve water, look to drip

Greenley Field Day will feature demo of a drip irrigation system for soybeans.

Lack of water hasn’t been a prominent issue in most of Missouri this year, but in the past decade we have seen a precipitation rollercoaster.

Center pivot overhead irrigation systems have been a go-to for providing water. But groundwater reserves are being depleted and more landowners need to be better stewards of the land. In order to get more crops per drop of water, producers can turn to precision irrigation for the best water-use efficiency.

Studies at Greenley Research Center in northeast Missouri have found that tile drainage systems have been a solution, but not all farmers have the luxury of a level field for easy installation. A possible alternative is the use of drip irrigation — which has long been used in vegetable production, plant nurseries, and horticulture plantings — that can be implemented for commodity crops such as soybeans.

At Greenley Research Center’s free Field Day starting at 7 a.m. on August 5, a demonstration on the installation of a drip irrigation system will be featured in addition to educational talks and tours at the center operated by the College of Agriculture, Food and Natural Resources (CAFNR) at the University of Missouri.

Three separate tours geared toward livestock farmers and crop producers will include topics of managing nematodes in corn and soybeans, an overview of the new dicamba and 2,4-D soybeans, and recommendations for controlling horseweed and waterhemp. For cattle ranchers, beneficial talks will be offered covering utilization of cover crops for grazing and an update of fixed-time AI Field Trials. Row-crop farmers can learn about nitrogen management in flooded corn and impregnated fertilizers.

“This is a diverse program of applicable material that will be provided on these tours,” said Dana Harder, new superintendent at Greenley Research Center. “All this information has the potential to impact your take-home dollar.”

Another hands-on demonstration will feature ultrasonic forage management by Rob Kallenbach, MU professor and forage specialist. Kallenbach’s work involves mounting ultrasonic sensors on an all-terrain vehicle and scouting pastures to collect data on forage growth and effects of fertilization.

“It’s exciting to have cutting-edge research available for people, and this is a great time to get it in a single setting,” added Harder. “These demos are showcasing new ways we can operate more efficiently.”

Research professor Kelly Nelson will be demonstrating the installation of the drip-irrigation system at one of the center’s fields.

“We are looking at being about 90% to 95% efficient with our water while using this drip irrigation,” said Nelson. “We have to keep conservation more in our minds if we want to keep continuing production in the long run.”

The drip-irrigation system is a subsurface setup with main water lines feeding into plastic hoses placed 12 to 18 inches into the soil. Holes along the hoses allow water to slowly seep into the ground. The goal isn’t to necessarily use less water, but to get more production with the water that is available and waste less. With center pivot irrigation, growers are able to achieve 80% efficiency. Furrow irrigators reach only 50% efficiency, meaning half of the water is lost to evaporation.

Subsurface drip irrigation also allows producers working with rolling terrain — such as the 4% grade in the field Greenley Research Center is installing on — to provide efficient use of water.

“There is concern about the installation costs, but our research will help determine the economics of these systems,” said Nelson.

An optional tour of Greenley’s Drainage and Subirrigation fields will be offered with information on how managed drainage systems affect crop production and improve water quality.

The 37th annual Field Day will start with breakfast and registration at 7 a.m. Tours will start at 8 a.m. and conclude at noon when lunch will be served.

The Field Day is an opportunity to connect with local farmers, researchers that are doing world-class studies in your own backyard, and those involved with making agriculture decisions for the state. Newly appointed director of the Missouri Department of Agriculture, Richard Fordyce, plans to attend as well.

For more information about Greenley Research Center, visit its new website at From Highway 63 in La Plata, head east on Highway 156 for 17 miles. The center will be on the left, just east of Novelty.

Sources: Mycogen Seeds, Syngenta, and University of Missouri

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