ISHS Acta Horticulturae 235: XIV International Symposium on Fruit Tree Virus Diseases
NATURAL CROSS PROTECTION AMONG STRAINS OF PRUNUS NECROTIC RINGSPOT VIRUS |
| Authors: | W.E. Howell, G.I. Mink |
| Abstract:
Spread of prunus necrotic ringspot virus (PNRSV) in a commercial sweet cherry (Prunus avium L.) orchard was monitored visually and serologically for eight years. Based on symptomatology, two PNRSV biotypes were observed: cherry rugose mosaic disease (CRM) biotype and a symptomless biotype (HENS = high ELISA values but no symptoms). In orchard plots the HENS isolates effectively stopped the natural spread of CRM. However, in experimental plots several protected trees challenged by inoculation with tissue grafts containing CRM in 1984 exhibited CRM symptoms by 1986. The level of protective breakdown was dependent on the combination of protective and challenge isolates. It is suggested that challenge inoculations with tissue grafts are more stringent than those imposed by the natural spread of PNRSV. | |
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