Prune out knots during the dormant season. Make cuts four to six inches below the first sign of visible swellings. Thiophanate-methyl has proven most effective for black knot control. Chlorothalonil and captan, when used for brown rot control, may also be helpful. Do not use chlorothalonil after shuck-split.
Infection can take place in six to seven hours when trees are wet.
Occasionally mites may become a problem. If so, use insecticidal soap in two sprays spaced five to seven days apart. This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate. The information in this material is for educational purposes.