ASSESSMENT OF INFECTION AND SPORULATION PROCESSES OF PUCCINIA-MENTHAEON PEPPERMINT IN CONTROLLED CONDITIONS

The effects of environmental factors on components of the life cycle o f Puccinia menthae on Menthaxpiperita cv. Todd's Mitcham were examined . Urediniospore germination required at least 6 h leaf wetness and las ted 4-6 h at temperatures of 5-25 degrees C. Appressoria, substomatal vesicles, and haustoria were produced 6, 6, and 24 h after inoculation , respectively, at 20 degrees C. The latent period of infection ranged from 50 days at 5 degrees C to 10 days at 22 degrees C. Sporulation o ccurred over a wide range of temperatures (5-27 degrees C), the optimu m being 15-20 degrees C. The minimum, optimum, and maximum temperature s for infection were <5, 20, and 27 degrees C, respectively. Teliospor e formation required a minimum of 9 days of cold treatment (4 degrees C) and the ratio of teliospores to urediniospores produced was inverse ly proportional to the duration and intensity of light received.