Phytophthora Nicotianae: A Cause of Zebra Disease in Agave Hybrid No. 11648 and Other Agaves

Abstract

Clinton and Peregrine [2] and Peregrine-[5] led to the distinction of three sets of syndromes: zebra leaf spot, bole rot and spike rot. The entire disease complex was called zebra disease after the marked symptoms of the leaf spot phase [3]. Although a Phytophthora was seen on infected hybrid leaves [1], it was only after considerable difficulties and by the use of specialized techniques [2] that a species of this fungus was isolated which produced the typical zebra disease symptoms upon re-inoculation into healthy hybrid plants. The fungus was identified at the Commonwealth Mycological Institute as being near P. arecae. This isolate will be referred to as Pfl. With a view to developing possible control measures more information was required on the disease, particularly on its spread and mode of infection. Since Clinton and Peregrine [1. c.] had encountered difficulties in the isolation of the causal organism, it was thought relevant first to investigate alternative isolation methods. Soon after the initiation of this work a second Phytophthora species was isolated so that a study had to be made of the distribution and importance of both pathogens.