Ballistospore discharge in Tilletiopsis minor

Abstract

Ballistospore discharge in Tilletiopsis minor Nyland was studied in a growth chamber under various conditions using a Kramer-Collins Spore Sampler. Sporulation occurred on leaves of Althea naturally infected with Puccinia malvacearum, on inoculated healthy leaves of Althea, and on 11 other hosts. Under alternating dark (12 h, 90–94% relative humidity (RH)) and light (12 h, 80% RH) at 21 °C, sporulation occurred periodically, only when humidity was high. There was no evidence of an endogenous rhythm in continuous light or dark.