APPLE MOSAIC VIRUS IN HAZELNUT GERMPLASM
In the OSU breeding program, seedlings of infected cultivars Negret and Tombul (synonym = Extra Ghiaghli), and progeny from pollen of infected cultivar Mortarella were tested for ApMV by ELISA. Infected female parents produced an average of 6.2% infected progeny (range 1.2% to 11.8%) in 516 tests of four to seven year old seedlings from several crosses. No infected progeny were detected in 241 tests of seedlings from crosses with infected pollen parents. All progeny from crosses between two non-infected parents tested negative. Seedlings testing positive for ApMV were nearly all symptomless.
Heat therapy of infected plants for 21 or more days at temperatures alternating every 4 hours between 30 and 38 C, followed by shoot-tip grafting onto healthy Corylus rootstocks resulted in the elimination of ApMV from 26 infected European hazelnut cultivars.