From our perspective, powdery mildew is a common fungal adversary. It manifests as a white or grayish, powdery coating on our leaves, stems, and sometimes even our flower buds. This coating is the fungal mycelium and spores, which hinder our ability to photosynthesize effectively. We struggle to produce the energy needed for strong growth and vibrant blooms. The infection often starts on older leaves, causing them to yellow, curl, and eventually drop prematurely. This weakens us significantly and leaves us vulnerable to other stressors.
This is a devastating condition that attacks us from below the soil line. Fungi such as Fusarium and water molds like Pythium thrive in waterlogged, poorly draining soil. They infect our root systems, causing them to turn brown, black, and mushy instead of remaining firm and white. With our roots rotting, we cannot uptake water or essential nutrients. Above ground, this translates to stunted growth, wilting that does not improve with watering, and a general yellowing and collapse of the entire plant, often starting with the lower leaves.
Several fungal pathogens can cause spotting and blighting on our foliage. You will see dark brown or black spots with a concentric ring pattern or a yellow halo on our leaves and stipules. As the disease progresses, these spots can enlarge and merge, causing large sections of the leaf tissue to die (a symptom known as blight). This necrotic tissue cannot contribute to photosynthesis, reducing our overall vigor. In severe cases, the disease can also cause stem cankers, which girdle and weaken our stems, potentially causing them to break.
To help us thrive organically, please provide good air circulation by spacing us appropriately and avoiding overcrowding. Water us at the soil level in the morning so our leaves dry quickly, creating an environment less hospitable to fungal spores. For mild cases of powdery mildew, a weekly spray of a solution made from one part milk to nine parts water can create an unfavorable surface for the fungus. For more persistent fungal issues, OMRI-listed products containing neem oil or potassium bicarbonate are effective organic fungicides that disrupt the fungal life cycle without harsh synthetic chemicals. For root rot, prevention is key; ensure we are planted in well-draining soil and avoid overwatering.
