June 16, 1995
Hollyhock rust is caused by the fungus Puccinia malvacearum. The undersides of infected leaves show raised brown spots about the size of a pinhead. The upper leaf surfaces usually show a yellow to orange discoloration above the brown spots. Infected areas may run together and destroy large portions of the leaf. Stems may also be infected.
Successfully starting plants from leaf cuttings is an easy way to experience one of nature's miracles, totipotency. Totipotency is the ability of each and every plant cell to regenerate an entirely new plant. Leaf cuttings can be made from the leaf blade and petiole, leaf blade alone, or sections of the leaf. Many houseplants such as rex and rhizomatous begonias, African violets, streptocarpus, gloxinias and sansevierias are willing candidates.
Turf samples showing the presence of slime mold have been arriving in the Plant Disease Clinic. Slime molds are fungi that grow on decaying organic matter. During wet weather they "ooze" onto leaf blades. This growth at first may appear black, yellow, or other color, and slimy. Eventually it turns to a powdery substance (usually white or grayish). Slime molds are common on turf, strawberries, or in plant beds with high organic matter.