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Anthracnose of Shade Trees  

Symptoms and Diagnosis
Anthracnose is group related fungal diseases that infect shade trees, oaks, ash, walnuts and sycamore. Each fungus is specific to its host tree it affects. For example, the oak anthracnose fungus affects only oak and will not spread to other genera of trees or plants.

Ideal conditions for anthracnose is cool wet weather conditions of spring and early summer. Leaves develop irregular shaped leafspots which often coalesce to form large blotches which cover much of the leaf surface and are limited only by the midvein. Anthracnose diseases generally infect the leaf veins and cause death of the vein and surrounding tissue, which becomes papery thin and falls away, giving the leaves a tattered look. Defoliation occurs particularly on ash and red oaks which is characteristically drop a large number of affected leaflets. 

Anthracnose outbreaks subside with the onset of warmer summer temperatures and reduced moisture. Serious damage does not occur on well established trees since occasional defoliation seldom has a long-lasting impact on tree health. Trees will produce a second flush of leaves with out experiencing severe stress. Repeated defoliation for several years in succession may weaken trees and result in limb dieback. In most cases, active disease management practices are not warranted since the disease does not occur every year and the health impact is minimal.

Rake up and destroy (burn) or properly dispose of infected leaves in the spring and well as the fall leaves since the fungi over winter of infected leaves. Prune to remove diseased twigs and branches and open up the canopy for better air circulation and light penetration. Remember sterilize pruning tools with a Clorox solution of one part water or ammonium chloride, Consan 20, a triple action microbial disinfectant. Avoid wetting tree foliage with sprinklers by reducing the spray height.

Maintain good tree vigor by proper watering practices during dry periods, mulching and also periodic fertilization when necessary.

Spray with a copper sulfate fungicide, Daconil, or Banner Maxx  for preventative, not curative measures and apply according to label instructions, when the leaves are beginning to enlarge at bud break. Reapply spray application  7 - 10 day intervals for two or three more times.  

          Disclaimer This article contains pesticide recommendations that are subject to change at any time. These recommendations               are provided only as a guide. It is always the pesticide                               applicator’s responsibility, by law, to read and follow all current               label directions for the specific pesticide being used. If any                       information in these recommendations disagrees with the label,               the recommendation must be disregarded. No endorsement is                   intended for products mentioned, nor is criticism meant for                       products not mentioned. The Writer assumes no liability resulting           from the use of these recommendations.      

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