Healthy vs. diseased alfalfaCooperation between University of Kentucky researchers and the IPM program has encouraged seed companies to develop and market new fungus-resistant seed.
Growers in Kentucky often experience problems with establishing uniform healthy stands of alfalfa because of extended periods of wet weather. A seven-year program of applied research at the University of Kentucky determined that these problems can be avoided by using alfalfa varieties with high resistance to the root rot fungus, Aphanomyces euteiches.

Improved Alfalfa Stands Result From Local Knowledge of a Root Rot Fungus

Failure to establish a uniform, healthy stand of alfalfa after seeding can dramatically affect profitability and also expose the soil to erosion. Problems in alfalfa stand establishment routinely occur in Kentucky when extended periods of wet weather follow seeding.Field devastated by root rot disease

What has been done: A 7-year program of applied research has produced clear evidence that many of these stand establishment problems can be avoided by using alfalfa varieties with high levels of resistance to the root rot fungus Aphanomyces euteiches. During this project, we learned how widespread the fungus is in Kentucky soils, how damaging it can be to new seedlings, and how much benefit we can expect from Aphanomyces-resistant alfalfa varieties.

Companies that sell alfalfa seed in the region are now placing a high priority on developing and marketing Aphanomyces-resistant varieties for the region. I expect an ongoing shift towards the use of these varieties over the next 5-10 years. This had essentially been an applied research topic until 1997, when we began to extend our results heavily. The research program will be wrapping up in 1998 but extension efforts will continue.

Kentucky producers grow alfalfa on more than 300,000 acres of land, much of which is classified as 'highly erodible'. Any given year, 6097 acres of seeded alfalfa will be lost due to Aphanomyces root rot. Appropriate use of this information would result in the following benefits.

Economic Impact: Farmers would save the stand establishment cost of $150 and first year's yield income of $378 (at 3.5 ton/acre at $108 dollars/ton) for a total of $ 528 per acre established. On a statewide basis this represents a savings of AT LEAST ($528/ acre for 6097 acres) $3,219,216!

Water Quality: Because many alfalfa fields are on highly erodible land, and stand establishment requires inputs of agri-chemicals and tillage operations, increasing the rate of successful establishment reduces the loss of soil and agri-chemicals to lakes and streams from 6097 acres.

Non-target Species: Successful stand establishment means agri-chemicals stay in the target area reducing the chance of affecting other organisms on 6097 acres.

This work is a clear example of the Cooperative Extension Service moving research information developed by Extension Plant Pathologists into the hands of the private sector.


Paul Vincelli
Dept. of Plant Pathology
University of Kentucky
S-305 Ag Science North
Lexington, KY 40546-0091
Phone: 859/257-5675
FAX: 859/323-1961

Kentucky IPM
University of Kentucky Integrated Pest Management Program

Original document: 13 April 1998
Last updated: 14 January 2005

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