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AgAlerts 2005 From Griggs County
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Issue # 1, May 24, 2005
The cool wet conditions
of the last week could have affected green ash trees that were just beginning to
leaf out. These conditions favor the infection of ash anthracnose which is
caused by a fungus called Gnomoniella fraxini. Besides premature leaf
drop, symptoms include deformed and discolored leaves. Leaves may show
brown to black lesions, often associated with leaf veins; and the leaves may
curl along the main vein. While premature leaf drop is dramatic, it is not
usually detrimental to the tree since a flush of new growth will follow.
If defoliation occurs over a number of years, this could have an affect and
cause early decline.
The best management for this disease is to rake up and
destroy all the fallen leaves. This will reduce the amount of pathogen
available to cause new infection. Fertilizing with nitrogen to promote
growth will provide for optimal refoliation. The treatment with a
fungicide is not practical and expensive for large well established trees.
However, smaller, newer trees will benefit from these applications.
Treatments with a chlorothalonil product (Daconil Ultrex, Ortho Multipurpose
Fungicide Daconil) after the first infection can reduce subsequent infection.
Asian soybean rust, Phakopsora pachyrhizi, has been observed only in four Florida counties and one Georgia county this spring thus far. The disease has not been progressing outside of these areas as of this date. In order to help growers and crop consultants to keep up to date with the spread and severity of this disease, websites have been established to track soybean rust progress. The following sites can be used to keep up to date.
This disease appears as rings of dark green grass surrounding areas of dead or light-colored grass. The rings are produced by any one of over 50 different kinds of fungus. The dying grass inside a ring is caused by lack of water penetration. Conditions that favor fairy rings are soils that contain undecomposed, woody organic matter, such as dead tree roots or old construction materials. To control fair rings is difficult. Applying adequate fertilizer will try to hide the problem. Aerate rings and use a wetting agent to improve water penetration. In extreme cases, you can dig up the entire area of the ring and find the undecomposed organic matter and replant. The following link will provide more information on Fairy Rings.
(Click on picture to enlarge)
Current conditions are favoring tan spot development in HRSW and HRWW. Early season application with fungicides in combination with herbicides have given good disease reduction in past years. The following NDSU Extension publication provides more information and pictures of tan spot. Tan Spot of Wheat, PP-766
Forecasts for tan spot, Stagonospora nodorum blotch, leaf rust, and Fusarium head blight (scab) are available for 32 locations in MN and ND. To use this forecasting system requires the station location and the stage of the small grain crop. Click on the following link to use the system. http://www.ag.ndsu.nodak.edu/cropdisease/
Please Contact Our Office For Additional Information
E-mail: john.swenson@ndsu.edu
Go to the 2005 AgAlert Index Page