My Hibiscus Plant Has Yellow Dead Leaves With Spots

Types

• Hibiscus plants are susceptible to three diseases that cause yellow dead leaves with spots: fungal leaf spot, bacterial leaf spot and verticillium wilt. Fungal leaf spot caused by the parasitic fungi Alternaria alternate is a serious disease of hibiscus and several other plants. Bacterial leaf spot caused by the bacterium Pseudomonas syringae is a serious hibiscus disease. The bacteria survive on seeds, which cause perennial infections. Verticillium wilt is a serious disease that infects plants through infected soil contact. The disease infects the plant’s root system. Above-ground symptoms on the plant’s foliage indicate infection.

Symptoms

• Fungal leaf spot symptoms appear as brown, water-soaked leaf spots with a sunken appearance. As the disease progresses, yellow halos surround the leaf spots, the entire foliage yellows and leaf death occurs. Symptoms are tan-to- black lesions with a water-soaked appearance. As the disease progresses, it causes yellowing of foliage and leaf death. Dead leaves crack and have a brittle texture. Verticillium wilt symptoms are leaf wilt, premature yellowing foliage, leaf death and branch dieback. Depending on the infection’s severity of infection, plant death occurs within weeks or years of infection.

Favorable Conditions

• The fungal leaf spot pathogen favors weakened hibiscus plants from too high or low temperatures, crowded growing conditions and overhead irrigation. Bacterial leaf spot infections favor low temperatures and water on leaf surfaces for infection. Verticillium wilt fungi are soilborne and spread through the contact of infected soils, which occurs during transplanting or in previously infected soil.

Management/Control

• Avoid irrigating during the evening and avoiding overhead irrigation prevents fungal and bacterial leaf spot infections. Fungicidal sprays during the early growing season help reduce infection rates and infection severity. Planting disease-resistant hibiscus cultivators and maintaining plant vigor with regular fertilization and watering prevents and reduces infection’s severity. Avoid planting in soils where verticillium wilt infections previously occurred. Because the disease is soilborne, there are no cost-effective fungicidal controls. Always plant hibiscus plants free of verticillium wilt to prevent infections to noninfected plants. Overfertilization increases verticillium wilt’s severity. Low-nitrogen, high-potassium fertilizers prevent the fungus from spreading.