The Richmond Register

January 30, 2013

Walnut trees can cause wilting of nearby plants

By Amanda Sears
Extension Agent

RICHMOND — Have you noticed a problem with plants not growing near your walnut trees?

If so, you may be experiencing a non-infectious plant disease called walnut wilt.

Black walnut tree roots release a toxin called juglone, which can cause sensitive plants to suddenly wilt or die. Plant species vary in their sensitivity to juglone. Plants which are sensitive to this toxin include: tomato, potato, pea, cabbage, pear, apple, sour cherry, red pine, and rhododendron.

Symptoms of walnut wilt include sudden wilting of affected plants. If you cut into the effected plant, the tissue just under the outer layer will be brown.

 Toxicity from the black walnut roots does not show up every year. This compound does not persist in the soil over the winter and is only active during the growing season. The release of juglone is influenced by the growing conditions each year, so in some years conditions may not favor a high level of this chemical in the soil. In other years, the toxin may be high enough to affect sensitive plants.

Avoid this disease by planting vegetables and ornamentals away from walnut trees. How far is far enough from the tree? Plants will usually be safe it they are planted at a distance from the tree equal to the tree’s height.

Raised bed gardening class

A class on raised-bed gardening will be offered at the Madison County Cooperative Extension Office on Monday, Feb. 25, at both noon and 6 p.m. You need attend only one session. This class will cover the basics of raised-bed gardening, materials needed, soil mixtures, growing requirements and plant varieties.

If you wish to learn more about this topic, but cannot attend the class, more information can be found at this website, including videos on the subject:

If you are interested in attending, please contact us at 623-4072 or to reserve your seat and so we can prepare the correct amount of materials.

Madison County Farmers’ Market meeting

There will be and informational meeting about the Madison County Farmers’ Market on Monday, Feb. 18, from 6 to 7:30 p.m. at the Madison County Extension Office, 230 Duncannon Lane, Richmond.

Educational programs of the University of Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability or national origin.