VIEW ARTICLE

Development of Kabatiella caulivora in Plants of Trifolium subterraneum ‘Yarloop’ of Different Ages. Katie Helms, Division of Plant Industry, Commonwealth Scientific and Industrial Research Organization, Canberra City, 2601, Australia; Phytopathology 65:197-201. Accepted for publication 30 August 1974. DOI: 10.1094/Phyto-65-197.

Time-course development of infections of Kabatiella caulivora, the incitant of scorch or northern anthracnose of clover, was examined under specified environmental conditions in plants inoculated 4 weeks after sowing. Following inoculation, 90-100% of the leaves that were expanded at the time of inoculation, developed lesions. The disease did not spread to leaves which expanded after inoculation. A maximum of 25-30% of leaves present at the time of harvest, were recorded as diseased 9-13 days after inoculation. Evidence suggested that slight injury promoted disease development. The effect of plant age on susceptibility was examined in plants inoculated 1-5 and 8-10 weeks after sowing. In plants inoculated one week after sowing, 89% of cotyledons and 73% of unifoliolate leaves became diseased. Susceptibility of these organs decreased rapidly with seedling age. The percentage of trifoliolate leaves recorded as diseased increased from 19% for plants inoculated 2 weeks after sowing, to 33% for plants inoculated at 5 weeks. It was only 15% for plants inoculated at 8-10 weeks after sowing. The percentage of inflorescences recorded as diseased increased from 3% for plants inoculated at 8 weeks to 9% for plants inoculated at 10 weeks. The percentage of inflorescences recorded as dead either due to the disease, or to environmental conditions being unfavorable for development of inflorescences, increased from 20% for plants inoculated at 8 weeks to 32% for plants inoculated at 10 weeks.