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Extension > Minnesota Crop News > June 2012

Monday, June 25, 2012

Small Grains Disease Update

While a 11-plus inch deluge made for national headlines in Duluth, much smaller but timely rains have helped stave a worsening of the drought stress in parts of northwest Minnesota. Drought stress is pretty evident is many fields as evidenced by differences in plant height across the field. On June 19, the majority of northwest Minnesota is still rated to be in a moderate drought while a large portion of west central Minnesota is still considered abnormally dry. Timely rains will be needed to allow grainfill not to be impacted by drought as the crop needs nearly a 0.25 inch of water daily at the beginning of grainfill.

Monday, June 18, 2012

Update on Goss's Wilt in Minnesota

By Dean Malvick, Department of Plant Pathology

The fact that Goss's wilt is was a widespread corn disease in Minnesota in 2011 is broadly known. The question of how much Goss's wilt will develop in 2012 is dependent in part on field and weather conditions. As of June 13, 2012, Goss's wilt had been confirmed over the previous week in several counties in Iowa and Nebraska. Thus it could also start to appear soon in Minnesota. This article summarizes key points about this disease, including where it has been confirmed in Minnesota, factors that favor its development, and how to recognize it.

Thursday, June 14, 2012

Small Grains Disease Update

06/14/2012

The spring wheat in many parts of the state is now fully headed or pretty close to it. The drought stress has been partially abetted with some timely rains over the weekend. Yield potential, however, of the most drought stricken fields has been greatly reduced as tillers and lower leaves were aborted. This is very visible as the canopy opened up. Some of the worst field will likely not yield much over 35 to 40 bushels.

As far as diseases are concerned, these are some of our own observations and those of the scouts that are paid for through a grant of the Minnesota Wheat Research & Promotion Council. Tan spot is still the most prevalent disease, closely followed by stripe rust. Both diseases have progressed to the middle of the canopy, particularly on more susceptible varieties, as is the case for Faller and stripe rust

BYDV like symptomology can be readily found in barley, particular in the southern half of the state. Disconcerting in these cases is the high incidence and the severity; very seldom, if ever, have we seen such a widespread infection across fields, and the severe stunting. Fields have actually been abandoned and replanted with soybeans in the past week.

Now is the time to scout the fields to assess yield potential and the presence of any foliar diseases such as tan spot and leaf or stripe rust. With the increase in precipitation, disease risk models have, and will likely continue to trend higher, especially for the foliar diseases such as tan spot and stripe rust.

The decision to apply a fungicide at Feekes 10.51 will not be easy this year. Given the weather forecast for the next 5 to 7 days, we don't expect the risk models for FHB to increase dramatically. The decision therefore will hinge as much on the presence of foliar diseases as on the risk for FHB. The lower yield potential further complicates the matter.


Tuesday, June 5, 2012

Small Grains Disease Update

The Minnesota Wheat Research and Promotion Council funded a disease survey in small grains in 2012. This is a summary of what the scouts have found in the past few days:

The winter wheat is mostly at or just past anthesis is looking very good overall. The spring wheat is not far behind and is more variable. Drought stress is evident in the central and northern portions of the Red River Valley with the area around Crookston being the hardest hit by drought. Available soil moisture at the NWROC is between ~ 2.7 to 3.3 inches in the top 5 ft of three soils series that were sampled last week (or less than 25% of field capacity), with less than 0.5 inch in the top two feet of two of the three samples.

Crop Water Usage, Available Soil Moisture and Irrigation for Small Grains.

Jochum Wiersma, Small grains specialist

For high yields, small grains need 14 to 17 inches of water depending on weather conditions and length of growing season. The water used for optimum growth is a combination of stored soil moisture, rain and irrigation. Small grains require about six inches of water as a threshold for grain yield. Each additional inch of water will provide four to five bushels per acre. In deep well-drained soils, the roots of small grains will extract water to a depth of three feet. Small grains are most sensitive to water stress in the boot to flowering stage of growth.

Monday, June 4, 2012

Abundant Rainfall in Some Areas May Increase Soybean and Corn Seedling Disease

By Dean Malvick

With most of the soybean and corn crop emerged and growing across Minnesota - it is a good time to assess fields for seedling disease problems and the potential benefits or failures of seed treatments. The recent fluctuating temperatures and abundant rainfall that resulted in surplus topsoil moisture in about 21% of the state last week (USDA-NASS data) have created good conditions for seedling diseases and root infection by a complex mix of pathogens in many fields. Scattered problems with seedling diseases have been reported.

Seedling infection can result in dead plants before or after emergence, stunted and discolored plants, wilting, and complete or partially rotted and discolored roots. The problems often occur in a circular or random pattern in the field. Seedling infection can also lead to damage that may not be seen until mid to late summer, as is common with Phytophthora rot and sudden death syndrome. Disease is just one of many stresses that seedlings are encountering in fields. Close inspection and thorough diagnosis are often required to accurately identify the cause.
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