Answer: The fungus Guignardia bidwellii f. sp. parthenocissi causes distinct, angular, tan, spots to form on Boston ivy leaves in the spring and summer. A dark brown halo or margin along the edge of the spot is usually present. Within the tan areas, small black dots (fungal fruiting structures where new spores develop) can be observed soon after the spot reaches full size. Branch dieback occurs if the disease is very severe. You can use a copper based fungicide to protect unaffected foliage and stems. Be sure to read the label - some copper based products can stain sidewalks, bricks and siding. Good luck with your ivy!
Q&A Library Searching Tips