Answer: Rhubarb leaf spot is caused by a fungus, and it needn't be cause for alarm. Removing the infected leaves and spraying every 3 weeks or so with compost tea should take care of it. In the fall, be sure to clean up any debris, and next spring apply a good helping of rotted manure to the soil.
To make compost tea, mix one part mature compost that contains some manure with five parts water. Let the mixture sit in the shade for 2 weeks, then filter through cheesecloth and spray on the plants. You can then spread the residue around the base of your plants. Good luck.
Q&A Library Searching Tips