This week Diplodia leaf streak in corn (left) was confirmed for the first time in Nebraska; (right) the silver spotted skipper caterpillar is one of several insects that can cause defoliation damage in soybeans., which has surprised some growers, but is not new to the state.
CropWatch July 28, 2017
Soybean Production
Figure 1. Wilted and stunted soybean plant due to phytophthora in an otherwise healthy field. (Photo taken in Hall County by Sarah Schlund)
As conditions heated up the last two weeks, the fungus causing phytophthora root and stem rot became active in irrigated fields and those fields that received significant rain over the past couple weeks. Growers are encouraged to scout for this disease and, if found, manage through seed selection and treatment for the next crop.
Frogeye leaf spot is occurring in Nebraska soybeans, particularly in the eastern third of the state. While some fields have minor levels, some have significant levels and a fungicide treatment may be needed.
The persistent hot weather this growing season may be conducive to the development of charcoal rot disease in soybean and scouting is urged. Although charcoal rot is most severe in hot dry conditions, it can also cause losses when ample moisture is present, making it a hidden threat to yield.
Growers are reporting finding painted lady caterpillars and silver spotted skipper caterpillars in soybeans. This guide can help estimate leaf defoliation in soybean, key to determining whether treatment is necessary.
Figure 1. Cropping systems specialist Rodrigo Werle covers the latest research and technology to assist soybean producers during a 2016 Soybean Management Field Day near Cordova. (Photo by Deloris Pittman)
The 19th annual Soybean Management Field Days will key in on how producers can manage operations to increase profits and better compete in a global economy. Speakers will look at effects of early season crop stress on production; insect, disease, and weed management challenges; impacts of new herbicide formulations, crop water use, and many other factors affecting yield this year.
Warm, wet conditions across Nebraska the past two weeks created optimal conditions for crop diseases. This update looks at identification and management of three diseases in corn: southern rust, which is expanding in the state, bacterial leaf streak, and diplodia, which is new to Nebraska.
Map of counties where southern rust had been confirmed as of Aug. 3, 2017
As of Aug. 3 southern rust had been confirmed in 26 Nebraska counties by the University of Nebraska Plant and Pest Diagnostic Lab. This map is updated as new confirmations are made.
Twospotted spider mites. Almost microscopic in size, the spider mites may be imperceptible on a leaf, but become more visible against its silk-like webs. (Photo by Jim Kalisch)
Spider mite populations are increasing in Nebraska. Fields should be scouted and the species correctly identified to provide proper management. Population levels should also be considered when treating fields with other insecticides that may knock out all natural predators, leading to population explosions of spider mites.
In response to the growing area of drought in Nebraska, emergency haying and grazing of CRP acres is being allowed in most counties. Other drought-based resources now available include haying of highway rights-of-way and the Hay and Forage Hotline.
Figure 1. After the corn was cut for silage, little plant material remained in this southwest Nebraska field to protect the soil from wind or water erosion or to capture snow moisture. The corn had been planted in a field with little wheat residue.
Drought conditions across much of Nebraska will limit grain yields in dryland corn this year, leading growers to look at other options for harvesting value from these fields. In some cases, harvesting this plant material may contribute to nutrient and water removal from the soil and may not be the best solution for your rotation or cropping system.
Archived CropWatch articles for managing crop production during drought conditions, including articles related to corn and sorghum, soybeans, sorghum, dry beans, forages, silage and wheat production.
With recent and predicted rains, soil moisture conditions may improve some in western Nebraska while eastern Nebraska may continue to dry down, says climatologist Al Dutcher.
With dicamba injury reports surging during the past few weeks, we want the public to be aware that historical data is available to research whether climatic conditions were a contributing factor.
Cover Crops
Figure 1. A new two-year study led by researchers from the University of Nebraska–Lincoln will focus on the benefits of cover crops. (Photo by Chris Proctor)
A new, multi-state, two-year study led by researchers at the University of Nebraska-Lincoln will focus on the benefits of cover crops in soybean cropping systems, including finding the balance between lower soybean yields from shorter-season varieties and increased cover crop biomass after early soybean harvest.
Youth ages nine to 14 years old and adults are invited to the 2nd annual Agronomy Youth Field Day at the campus of the Nebraska College of Technical Agriculture on August 9. Participants will gain important life skills while discovering the science behind Nebraska crop production.
Figure 1. Participants can view crop nitrogen sensors and high-clearance nitrogen equipment in action at Project SENSE update sessions in August. (Photos by Laura Thompson)
