Question: Fall of 1997 I planted hollyhock seeds....they grew over that winter and by midspring I had flowers...quickly after that the plants were dead from rust. I pulled the plants up and threw them in a near by drainage area that is part of the garden bed. As I didn't really do anything special to cleanse the area of rust can I replant with hollyhocks this fall. Need to know what to do to prevent contamination again.
Answer: Rust can spread from plant to plant and in my experience it seems to be in every garden to some extent, so we can only hope to reduce the reinfection rate. I am not aware of any soil treatment. The best things to do are to clean up, remove and destroy all infected plant debris (burn it or put it in the trash, not in the compost) as it happens and at the end of the season; plant susceptible plants in locations with good air circulation; and avoid watering the foliage or otherwise wetting it unnecessarily. Finally, cut the plants back after blooming. If the rust is still intolerable, you might consider a fungicide containing sulphur applied according to the label instructions.
Hollyhocks are notorious for rust infections and since it is so difficult to control many gardeners will plant them in an out of the way spot or at a distance so that the rust is simply less noticeable. Hollyhocks are also usually treated as biennials, meaning they grow for a year and winter over, then bloom the second summer, then set seed and die. It may be that your hollyhocks were simply following their natural schedule rather than killed by the rust.
Q&A Library Searching Tips: