Morphology of spore forms and heteroecism of the giant bamboo rust, Dasturella divina

Abstract

1. Dasturella divina (Syd.) Mundkur & Kheswalla is a heteroecious eu-form with uredia and telia on the giant bamboo (Dendrocalamus strictus Nees), and pycnia and aecia on Randia dumetorum Lam. (Rubiaceae). The causal connection between the stages of the life-cycle on Randia and on the giant bamboo was first surmised from the continuous association of the two rusts in bamboo forests and was later confirmed by inoculation experiments. 2. Infections on Randia produce marked hypertrophy and formation of witches' brooms following systemic invasion of the host. The pycnia are subcuticular and conoid, borne on haploid mycelia. The aecia are cupulate and peridiate, and the aeciospore chains lack sterile intercalary cells. 3. Uredia and telia occur on the leaves of giant bamboo. The sori are striate, and morphological details of these two spore forms have been given by Mundkur and Kheswalla. The telia, which occur in flabelliform erumpent crusts, are, however, contrary to their description, composed of one-celled, catenate spores produced in basipetal succession. The accommodation of the genus in the tribe Ochrosporae of Dietel is suggested. Aeciospores from Randia were found to infect the leaves of the giant bamboo, inciting the rust on the bamboo. The period of incubation ranged from 27 to 34 days. The urediospores spread the disease by secondary infection.