Charcoal rot of fir and spruce

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

A disease with which Christmas tree growers may be unfamiliar could be emerging in some Michigan plantations. Charcoal root rot, caused by Macrophomina phaseolina, may be appearing in field and nursery beds this spring and summer and could have been responsible for poor transplant stand establishment last summer.

This fungal pathogen can infect more than 300 different plant species including alfalfa and soybean. Planting seedling conifers after crops of alfalfa or soybean have been removed may increase the risk of conifer infection. This disease is normally found in southern states, and it manifests after hot, dry episodes. Last summer was extremely hot and dry in Michigan, and if you have planted seedlings of fir, spruce or other conifers in the last two years, and many of the trees died last summer, it is possible that the roots were infected with Macrophomina phaseolina. The disease is usually associated with young seedlings in nurseries or new transplants on plantations. Symptoms include chlorosis, stunting, blackening of the roots, lack of new root growth and death.

Healthy looking plants can be found in the same field depending on the population of the pathogen in the soil. Plants in light, dry soils may be more affected than plants in heavier, moisture retaining soils. If you know of fields with poor stand establishment after transplanting last year and think charcoal rot may be the cause, please contact .(JavaScript must be enabled to view this email address) or Jill O’Donnell.

Dr. Fulbright’s work is funded in part by MSU‘s AgBioResearch.

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