Will Monterrey Complete Disease Control fix this?

[JScott]

Originally Posted by estación seca

I think it's fungal, spread during high humidity. The spores overwinter on shed leaves and plant stems. They splash up onto plants the next spring. Make sure you rake up all dead leaves, and bag and remove all prunings.

Consider using a wettable sulfur powder. It is an excellent topical fungicide. Spray the canes during a good dry spell this winter with Bordeaux mixture (copper sulfate.) I would read up on your antifungals to make sure they cover black spot before using them.

We're lucky here; it's not humid enough for black spot. We do get powdery mildew during spring and fall days when it's cool with very low humidity.

I never had black spot in Oklahoma. Mine would get scale in the winter time sometimes, but a good application of horticultural oil took care of that. The disease control products I have both say that they treat black spot, but I think they all say that. I'll do some research, and probably end up doing the sulfur thing you suggested. It can't hurt.