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Etiology of a newly described root rot of guar (Cyamopsis tetragonoloba) in Australia caused by Phytophthora cryptogea
Author(s) -
STIRLING A. M.,
IRWIN J. A. G.
Publication year - 1986
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.1986.tb02051.x
Subject(s) - cyamopsis , biology , zoospore , guar , inoculation , hypocotyl , sunflower , damping off , plant disease resistance , phytophthora sojae , phytophthora , botany , horticulture , agronomy , seedling , spore , biochemistry , gene
An isolate of Phytophthora obtained from diseased roots and stems of guar ( Cyamopsis tetragonoloba ) growing in waterlogged soil from Dalby. Queensland. was identified as Phytophothora cryptogea ( P. drechsleri ). Sex organs were not observed, Pathogenicity to guar seedlings was established under glasshouse conditions either by using a hypocotyl‐wound inoculation technique, or adding motile zoospores to seedlings growing under saturated conditions. This appears to be the first report of this disease. Seven isolates of P. drechsleri from hosts other than guar were shown to be pathogenic to guar following hypocotyls‐wound inoculation. The host range of the guar isolate was studied using both hypocotyl‐wound inoculation and zoospores. After hypocotyl inoculation, the following species were found to be susceptible : cantaloupe. cowpea, cucumber, mungbean, pea. pigeon‐pea, safflower. sunflower, tomato and watermelon. Slight symptoms were observed on bean and chickpea. When zoospores were used as the inoculum, only pea. pigeon‐pea, sunflower and safflower were highly susceptible. A range of guar cultivars and breeding lines were screened for resistance using zoospore inoculum, and although no genotypes were highly resistant, there were significant differences between disease reactions.