SOME PROSPECTS OF CONTROL OF THE APRICOT CHLOROTIC LEAF ROLL DISEASE: RESISTANCE INDUCED BY THE ROOTSTOCK, ACQUIRED IMMUNITY
When this disease was considered as a virus disease the first studies were planned to look for sensitive plants of the genus Prunus which may be used for selecting healthy plant propagation material. The researches also disclosed some Prunus species which showed no symptom after inoculation of the pathogen. Most of them are only tolerant since after inoculation the pathogen is able to invade the tissues of such species and to reach to rootstock. This one when it is sensitive shows symptoms. Some of these species (P.domestica cultivar Brompton and P. americana) used as rootstock or interstock are able to confer on the apricot scion grafted on them a certain resistance to the disease. A particular clone of P. spinosa seemed immune since the pathogen after inoculation did not reach the rootstock. Yet, when such a clone is used as interstock and top worked with an apricot scion, the pathogen inoculated in the apricot scion is able to cross the spinnosa tissues and to reach the rootstock but it does it only slowly and the symptoms on the apricot scion are milder. Another case of resistance seems in reference to acquired immunty. Apricot trees were produced using budsticks picked on some trees recovered after being obviously diseased some years earlier. In spite of inoculation such trees remained healthy and strangely grew. Since there is no curative method to control such a disease now considered caused by a myeoplasmalike organism, it is urgent to look for and to analyse any case of resistance which may appear. The cases described here are examples of these possibilities.
Morvan, G. and Castelain, C. (1981). SOME PROSPECTS OF CONTROL OF THE APRICOT CHLOROTIC LEAF ROLL DISEASE: RESISTANCE INDUCED BY THE ROOTSTOCK, ACQUIRED IMMUNITY. Acta Hortic. 85, 269-277