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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #323576
Title: Effects of Phytophthora cinnamomi isolate, inoculum delivery method, flood, and drought on vigor, disease severity and mortality of blueberry plants

Author
item Smith, Barbara
item Miller Butler, Melinda
item CURRY, KENNETH - University Of Southern Mississippi
item Sakhanokho, Hamidou

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2016
Publication Date: 4/4/2016
Citation: Smith, B.J. and Miller-Butler, M.A., Curry, K.J., Sakhanokho, H. F. 2016. Effects of Phytophthora cinnamomi isolate, inoculum delivery method, flood, and drought on vigor, disease severity and mortality of blueberry plants. Abstract Book XI International Vaccinium Symposium, University of Florida Gainesville, FL. Page 180.

Interpretive Summary:

Technical Abstract: Four studies evaluated the effects of cultivar, inoculum delivery method, flood, and drought on plant vigor, disease severity, and mortality of blueberry plants grown in pots in the greenhouse. Phytophthora cinnamomi isolates were obtained from the root zone of blueberry plants displaying symptoms of Phytophthora root rot. 'Tifblue', 'Star', and 'Biloxi' plants were inoculated with 11 P. cinnamomi isolates using inoculum delivered as a mycelial slurry, zoospore suspension, or grown on rice grains or vermiculite. Flood conditions were evaluated by submerging pots in water for 0, 24, or 48 hr every 3 or 6 weeks. To evaluate drought conditions, plants were watered 4 or 7 days a week. In each study, there were significant differences among isolates in plant vigor, mortality and disease ratings; and inoculated plants were less vigorous, received higher disease ratings and had a higher mortality rate than plants that were not inoculated. 'Biloxi', a southern highbush cultivar, was less vigorous, received higher disease ratings, and had a higher mortality rate than 'Tifblue', a rabbiteye cultivar, or 'Star', a southern highbush cultivar. The drought conditions evaluated resulted in high mortality rates in both inoculated and not inoculated plants. Based on the results of these four studies, we determined that inoculating rooted cuttings of ‘Biloxi’ with a virulent P. cinnamomi isolate grown on rice grains and subjecting the plants to either a 24 or 48 hr flood every 6 weeks provided the best protocol for future studies evaluating chemical and biological root rot controls or studying environmental effects on the development of Phytophthora root rot on blueberries.