What Is Pecan Scab – Learn How To Treat Pecan Scab Disease

Three Pecans Covered With Pecan Scab Disease
pecan scab
(Image credit: University of Georgia Plant Pathology, Bugwood.org)

Pecan scab disease is an extremely destructive disease affecting pecan trees. Severe scab can reduce pecan nut size and result in a total crop loss. What is pecan scab? For information on pecan scab disease and tips on preventing pecan scab in your orchard, read on.

What is Pecan Scab?

Pecan scab disease is caused by the fungus Fusicladium effusum. It is a disease that destroys pecan crops, especially in the southeastern United States. Scab is most severe during times of above-average rainfall. The pecan scab fungus causes its first damage in the spring, when it attacks new, young leaves. As summer arrives, the fungus moves into the nut shucks. Left to its own devices, pecan scab can kill all of the leaves on a nut tree. But that’s not all the pecan scab symptoms. As the fungus progresses, the pecan scab disease reduces the size and fill of the pecan nuts, and can even result in complete nut loss. It is possible, in rainy years, for a grower to lose an entire crop to pecan scab disease. It is quite easy for a home grower to lose to the fungus the nut crop from a handful of pecan trees.

Preventing Pecan Scab

Are you wondering how to go about preventing pecan scab in your trees? It’s easier than figuring out how to treat pecan scab. Big commercial growers spray fungicides repeatedly on their pecan trees in an attempt to reduce pecan scab symptoms. However, the best bets for home growers are to select resistant cultivars and to use good cultural practices. The cultural practices that can help in preventing pecan scab all involve ways of getting air moving around the trees to keep them dry. For example, pruning and thinning the trees encourage air and sunshine to enter the canopy, helping to dry the branches. In addition, clearing vegetation in the areas around the pecan trees also allows for faster drying. Mowing grass under the pecans does the same. If you are wondering how to treat pecan scab, the only effective means is spraying fungicides. However, pecan trees are generally too tall to allow homeowners to spray them easily., and they must be sprayed multiple times in order to combat the disease. These measures are not practical for home growers with a few trees. The cost of repeated spraying would be prohibitive. Attempting to prevent the disease is by far the better option.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.