From our perspective as Calla Lilies (Zantedeschia spp.), we are generally resilient plants, but our beauty can be compromised by various pests and diseases. Understanding these threats from our point of view is key to maintaining our health. We will detail the common ailments that affect us and the treatments that can help us recover.
We often fall victim to small, sap-sucking insects that find our lush leaves and flower stalks irresistible. These pests weaken us by draining our vital fluids.
Aphids: These tiny, soft-bodied insects, often green or black, cluster on the undersides of our leaves and on our young, tender shoots. As they feed, they excrete a sticky substance called honeydew, which can attract ants and lead to the growth of sooty mold, further blocking sunlight from our leaves. A strong spray of water from a hose can often dislodge a mild infestation. For more persistent problems, insecticidal soap or neem oil applications are effective and gentle on our systems.
Spider Mites: These are nearly microscopic pests that thrive in hot, dry conditions. They are not insects but arachnids. They pierce our leaf cells, causing a characteristic stippling or speckled yellow appearance. A severe infestation will cover our leaves in fine, silky webbing. Increasing humidity around us and regularly rinsing our leaves can deter them. Miticides or horticultural oils are necessary to control significant outbreaks.
Thrips: These slender insects rasp the surface of our petals and leaves, causing silvery streaks and distorted growth. They are particularly damaging to our beautiful flowers, leaving them scarred and discolored. Blue sticky traps can help monitor them, and consistent applications of neem oil or spinosad can help keep their populations in check.
Fungal and bacterial pathogens often attack our roots, rhizomes, and foliage, especially when our growing conditions are too damp.
Root and Rhizome Rot: This is one of our most serious threats, typically caused by overwatering or poorly draining soil. The fungi (like Pythium or Phytophthora) attack our root system, causing it to become soft, brown, and mushy. Above ground, you will see our leaves turning yellow, wilting, and collapsing. The best treatment is prevention by ensuring we are planted in well-draining soil and not left sitting in water. If caught early, you can dig us up, carefully cut away all the rotten parts of the rhizome with a sterile knife, and replant us in fresh, dry soil.
Botrytis Blight (Gray Mold): This fungal disease appears as a gray, fuzzy mold on our flowers and leaves, especially in cool, wet weather. It causes buds to rot and petals to develop spots. Improving air circulation around us is crucial. Remove and destroy any infected plant parts immediately. Fungicidal sprays can be used if the problem is widespread.
Bacterial Soft Rot: This is a foul-smelling, wet rot that affects our rhizomes, often entering through wounds. The rhizome turns into a soft, watery mess. Unfortunately, there is no cure once this disease takes hold. The infected plant must be removed and destroyed to prevent the bacteria from spreading to other plants. Prevention through careful handling of rhizomes and avoiding overwatering is essential.
Viruses are systemic problems that affect our entire being and have no cure.
Calla Lily Chlorotic Spot Virus and Dasheen Mosaic Virus: These viruses cause a range of symptoms, including yellow streaks, mosaic patterns, ring spots, and distorted or stunted growth on our leaves and flowers. They are typically spread by aphids or through contaminated tools. There is no treatment for a viral infection. An infected Calla Lily should be removed and destroyed to protect the health of other plants in the garden. Purchasing virus-free rhizomes from reputable sources is the best defense.
