Greenhouse Note PSU
A serious disease has be<n reported on geraniums growing in certain areas of the United States. This disease was first reported in Africa and New Zealand in 1961. France reported geranium rust in 1963, Italy in 1964 and several other European countries have resorted it since 1965. * The disease attacks only zonal geraniums. There have been no re ports of it on ivy-leaved geraniums. The rust disease closely resembles other rust diseases. The first symptoms appear in 10-14 days after infection on the underside of the leaves as very small light colored spots The upper side of the leaf shows light spots that increase in size rapidly and turn yellow. The underside of the leaves give off brown powdery spores — similar to any other rust. The rust attacks zonal geraniums in all stages of development. The disease can spread very rapidly and once established can reach epidemic stages in a short time. The disease will cause severe leaf drop.
Source: • Greenhouse Notes PENNSYLVANIA STATE UNIVERSITY JANUARY 1968
Keywords: Disease ivy-leaved geraniums Zineb low humidity High temperatures