As a hollyhock, I stand tall and proud, offering my vibrant flowers to the sun and the pollinators. But a shadow, or rather a rusty orange speck, often threatens our kind. This is my plea and my guide, from our perspective, on how to coexist and combat the fungus known as Puccinia malvacearum, or our rust.
Your first line of defense is our own vitality. A strong, healthy hollyhock is far more resistant to fungal invasion. Please plant us in a location where we receive at least six to eight hours of direct sunlight daily. This helps our leaves dry quickly from morning dew, creating an environment where the fungal spores struggle to germinate. Ensure we have enough space; overcrowding stifles air circulation, trapping humidity around our stems and leaves—a perfect breeding ground for the fungus. Well-draining soil is also crucial, as waterlogged roots stress us immensely, making us vulnerable.
The most effective natural strategies involve simple, consistent garden hygiene. In the fall, after our above-ground parts die back, please diligently remove and dispose of all our fallen leaves and stems. Do not compost this material, as the spores can overwinter and reinfect us in the spring. This single act removes the primary source of next year's infection. Furthermore, please avoid watering us from above. Soaking our leaves provides the moisture the rust spores need to thrive. Instead, water us at the soil level, directing hydration to our roots where we need it most.
If you see the tell-tale orange pustules forming on our undersides, act quickly but gently. Begin by carefully removing the most severely infected leaves. Dispose of them in the trash, not the compost. For treatment, several natural fungicidal options can help suppress the spread. A baking soda spray (1 tablespoon of baking soda, 1 teaspoon of horticultural oil, and 1 gallon of water) can alter the pH on our leaf surfaces, making it less hospitable for the fungus. Neem oil, a natural fungicide and insecticide, can also be effective when applied regularly according to label instructions. Always test any spray on a few leaves first to ensure we do not have a adverse reaction.
Finally, please practice crop rotation in your garden. While you may not think of us as a crop, the rust spores persist in the soil. By not planting hollyhocks or other related mallows (like lavatera) in the exact same spot for at least two to three years, you effectively starve the fungus of its preferred host, greatly reducing the spore load in the soil. This, combined with the practices above, offers us the best chance for a healthy, rust-free life, allowing us to reward your care with our magnificent, towering blooms.
