Joseph D. Postman, Shawn A. Mehlenbacher
Apple mosaic virus (ApMV) has been reported in hazelnut in several European countries but is not known to occur in commercial plantings or in the wild in the United States. Since 1985, 255 hazelnut clones have been imported from around the world and are being maintained and evaluated at the USDA National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon. The germplasm is used by the hazelnut breeding program at Oregon State University (OSU). All imported Corylus accessions are tested for ApMV by ELISA. The virus was detected in 44% of 48 clones imported from Spain, 15% of 34 clones from Turkey and 8% of 65 clones from Italy. One infected German cultivar (imported from England) and one infected cultivar from the Republic of Georgia were also detected. No infected plants were detected among 163 clones from Australia, Azerbaijan, Bulgaria, Canada, China, Czechoslovakia, Denmark, Finland, France, Hungary, Japan, Korea, Nepal, New Zealand, Pakistan, Poland, Romania, Russia, Switzerland, Ukraine, and Yugoslavia. Most infected clones were symptomless.

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.

Postman, Joseph D. and Mehlenbacher, Shawn A. (1994). APPLE MOSAIC VIRUS IN HAZELNUT GERMPLASM. Acta Hortic. 351, 601-610
DOI: 10.17660/ActaHortic.1994.351.66

Acta Horticulturae