My Calla Lily Has Dead Leaves

Viral Disease

• Calla lilies are susceptible to several pathogenic viruses that cause severe damage to their foliage. The calla lily chlorotic spot virus causes discoloration on the surface of calla leaves. The tomato spotted wilt virus, which attacks a number of commercially cultivated vegetable species, also damages calla lilies. Symptoms of an infection include declining growth, severe discoloration of leaves and deformity of green tissue. Infected plants begin to wilt as rotting lesions emerge on their leaves, flowers and stems.

Bacterial Disease

• Bacterial soft rot is a common condition caused by a number of pathogenic bacteria, including Erwinia carotovora and Pseudomonas cichorii. Initial symptoms of this bacterial infection include moist spots on leaves, roots and stems. The spots darken and expand as damaged tissue decays, causing cosmetic damage and exposing the plant to other dangerous pathogens. Bacterial soft rot destroys the consistency of stems, roots and bulbs. Plants can collapse from this structural damage in less than a day, according to the University of Illinois Extension.

Fungal Disease

• Calla lilies are vulnerable to several fungal diseases that can damage or kill their foliage. Phytophthora root rot, caused by Phytophthora cinnamomi, often infects plants in wet and warm soil, according to North Carolina State University. This fungus infects the roots of its host and causing several serious symptoms, including discoloration, deformity and death of foliage. Calla lilies can also contract a leaf spot disease caused fungal species in the Phyllosticta genus. Phyllosticta leaf spot can lead to significant defoliation and cosmetic damage, but rarely produces fatal symptoms on established plants.

Environmental Stress

• Dead leaves on a calla lily can also result from environmental stress, including unfavorable soil conditions and chemical toxicity. An excessive supply of chemicals like fluoride and chlorine in the plant's soil or water can decrease the plant's growth and damage leaves. Fertilizer with high salt content can also lead to browning of leaves and stems, according to North Dakota State University. Saturated soil can drown the roots of calla lilies, preventing them from absorbing and distributing critical nutrients.