Vinca major, or big leaf periwinkle, is a shade loving ground cover that thrives in warm, moist climates. It is larger and more open than vinca minor and grows to heights of 8 to 18 inches high. It is rarely affected by diseases, but is prone to fungus outbreaks in very wet weather.
Few diseases bother Vinca major with the exception of the fungi Phoma sp. and Phomopsis sp. These funguses cause the plant to wilt and turn black or brown, dying back to the soil. Affected stems may develop black, raised growths.
Proper watering practices prevent most outbreaks of vinca major disease. The plant is drought tolerant and rarely needs to be watered, except in very dry conditions. Soaker hose irrigation and early morning waterings allow leaves to dry quickly, avoiding the spread of disease.
Removal of all diseased plants will minimize the spread of the disease. Additionally, copper and mancozeb fungicides are sprayed on diseased plants monthly to destroy the fungus.
Compact nursery plants with healthy looking stems and green leaves are better able to resist disease. Yellowed leaves indicate the plant may already be infected. These plants should be avoided.
Vinca major thrive in moist, humusy soil in partial to-full shade. They are evergreen and hardy to USDA plant hardiness zones 6 through 9. Vinca major may become invasive and should be thinned to improve plant health.