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Search for resistance to phytophthora root rot in West Indian avocado rootstocks in the Canary Islands 1
Author(s) -
LLOBET L. GALLO
Publication year - 1990
Publication title -
eppo bulletin
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.327
H-Index - 36
eISSN - 1365-2338
pISSN - 0250-8052
DOI - 10.1111/j.1365-2338.1990.tb01184.x
Subject(s) - rootstock , germplasm , phytophthora cinnamomi , biology , population , horticulture , inoculation , phytophthora , christian ministry , botany , demography , philosophy , theology , sociology
Avocado root rot caused by Phytophthora cinnamoni is a major limitation for avocado expansion in the Canary Islands, as it is in other producing areas of the world. To date, no germplasm with resistance potential has been found among West Indian avocados, which would convert this type into an ideal rootstock for use in infested areas such as the Canary Islands. Our aim was a thorough screening of the local West Indian population, descendants of seedlings brought to the Canaries from the Caribbean in the early 1800s. Our selection methods were based on those used by Zentmyer in California (US) since 1960 (nutritivesolution tank, with controlled aeration, pH, and temperature, to which inoculum is added), which gave rise at that time to several resistant/tolerant Guatemalan and Mexican rootstocks. We also screened using pots filled with naturally infested soil. The plant material tested was: (a) West Indian seeds from the original, local population; (b) seeds of the Guatemalan x West Indian hybrid Gema, taken from 20‐year‐old local trees growing in highly infected groves; (c) seeds of the salt‐resistant Israeli West Indian cv. Maoz. Also tested for comparison purposes were seeds of Mexican and Guatemalan avocados. Inoculations were done using the P. cinnamomi A2 strain, taken from proved diseased trees found in the Canaries. At present, one West Indian plant has survived the selection in a first trial, while 38 have survived in a second trial. One Mexican plant (cv. Topa‐Topa) has survived in a third trial. Resistant material is now being reproduced both by tissue culture and by the etiolation technique.