From our roots to our newest blooms, we geraniums bring vibrant color and life to your gardens and homes. However, we are susceptible to various ailments that can compromise our health and beauty. Understanding these diseases from our perspective is key to ensuring we thrive. We communicate our distress through our leaves, stems, and flowers; learning to interpret these signs allows for timely and effective treatment.
We dread damp, cool, and overcrowded conditions because they invite the fungal pathogen *Botrytis cinerea*. You will first notice our older, lower leaves and spent flower clusters developing small, water-soaked spots. These quickly expand into soft, brown, rotting areas covered in a characteristic gray, fuzzy mold. The fungus can spread rapidly, killing blossoms and causing stem cankers. To help us, please improve air circulation around us, avoid wetting our foliage when watering, and immediately remove any infected plant parts or fallen debris. In severe cases, a recommended fungicide may be necessary.
This is a physiological disorder, not a contagious disease, caused by our roots absorbing water faster than we can transpire it through our leaves. This often happens during cool, cloudy weather with high humidity. The water pressure causes cells in our leaves to rupture, creating small, corky, scab-like bumps or blisters, primarily on the undersides of our leaves. To prevent this, please water us less frequently during prolonged periods of cool, sunless weather and ensure we have excellent drainage. Moving potted specimens to a sunnier, warmer location with better air flow can quickly halt its progression.
Bacteria from the *Xanthomonas* and *Pseudomonas* genera are a significant threat. They manifest as small, round, water-soaked spots on our leaves. These spots often have a yellow halo and quickly turn dark brown or black, causing the leaf to wilt, yellow, and eventually drop. The disease spreads easily through splashing water, contaminated tools, or even handling. There is no cure once we are infected. You must isolate affected plants immediately. Remove and destroy severely diseased plants. For mild cases, prune away infected leaves, sterilize all tools after use, and water us at the soil level to keep our foliage dry.
Fungi like *Pythium* and *Rhizoctonia* attack our most vital foundation: our root system. This is almost always a consequence of being planted in heavy, soggy, poorly draining soil or being over-watered. You will see us wilt, despite the soil being wet. Our lower leaves will yellow and drop, and our growth will be severely stunted. Upon inspection, our roots will be dark brown, mushy, and rotten instead of firm and white. Prevention is paramount. Always plant us in well-draining soil and pots with adequate drainage holes. If caught early, you can try to save us by carefully removing the soggy soil, trimming away any soft, rotten roots, and repotting us into fresh, sterile, dry potting mix.
