Proceedings Volume 2010 (format .pdf) - SimpBTH

123. RESULTS AND DISCUSSIONSAfter mechanical inoculation, about all of tested plants presented mosaicsymptoms on leaves, associated with crinkling top leaves (Ostara, Desire, Tampaand Hermes) or with necroses and streak on leaves, veins, petioles and stemsfollowed by wilting of leaves (Koretta, Roclas and Romano). Our results confirmethe former investigations of Le Romancer and Kerlan (1992, 1994) that Y NTN ismore virulent than Y N strains. In most of the plants the virus began to multiply inthe inoculated leaves four to five days after inoculation, at the time when the firstlocal lesions appeared. We evaluated the foliar symptoms from primary infectionsin a greenhouse conditions. The virus then spread to the stem, followed by theupper, green parts of the plants and the roots at the same time. The virus multipliedvigorously in the potato cv. Koretta and Tampa similary phenomen observed to theextremely susceptible variety Hermes, the percentage of infected plants beingmaximal in these situations (table 1). As espected, the virus did not multiply in thehighly resistant cv. Sante. Excepting cv. Sante, Christian and Dacia which werevery resistent and middle resistent to mechanical inoculation, all the other varietiespresented 62.5-100% infected plants.Table 1. Frequency of infected plants (after mechanical inoculation) and of tubers withpotato ring necrotic disease (PTRND) symptoms% plants infected % tubers with symptoms**Varietyafter inoculation* At harvest After 3monthsSante 0 (0/8)*** 0 0,0Christian 50 (4/8) 0 0,0Dacia 50 (4/8) 3,3 6.6Agata 100 (8/8) 4 8,0Roclas 62,5 (6/8) 4,5 9,0Romano 87,5 (7/8) 4 12,0Ostara 62,5 (6/8) 0 22,2Tampa 100 (8/8) 10 60,0Koretta 87,5 (6/8) 53,1 87,5Hermes 100 (8/8) 62,5 95,8* ELISA test made after 3 weeks after inoculation** Tuber symptoms characterized by raised or sunken necrotic lesions, were scored at harvest andafter 3 months storage at 4-8 o C*** In the brackets, the first number represents nr of plants found infected after inoculation, thefollowing one represents the total number of plants inoculated for every variety.