The disease is most common during rainy weather. Infected plants should be discarded. No chemical control is listed. Several fungi cause leaf spots on periwinkle. No chemical control is listed.
Root rots cause decay of roots and stems.
In wet weather a cobwebby growth forms on the lower stems. The lower leaves rot and the upper part of the plant dies. No chemical control is listed. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.