RESPONSE OF APPLE PROGENIES TO INFECTION WITH APPLE WITCHES-BROOM ANDAPPLE MOSAIC-VIRUS

Progenies (F1) from the cross 'Golden Delicious' x 'Clivia' were infec ted with apple witches' broom (AWB) and apple mosaic virus (ApMV) and studied for the course of disease. 'Golden Delicious' is quite suscept ible to the two diseases, whereas 'Clivia' is rather unsusceptible. Th e chi(2) test of goodness of fit, correlation analysis and rank correl ation analysis were used for the mathematical-statistical analysis of results. In AWB, symptoms intensity declined from the 1st to 3rd years p.i. Few idiotypes did not show any symptoms throughout the test peri od, but in some idiotypes symptoms increased. Over the three test year s, distinct deviations from the normal frequency distribution of score s were observed, especially for score 9 (no symptoms). A different cou rse of disease was found for ApMV: idiotypes with stronger symptoms in creased in the second year p.i., and the portion of idiotypes with wea ker symptoms decreased. In ApMV, too, no normal distribution of score frequencies was found, deviations having been greatest in score 8 (ver y weak symptoms). One idiotype did not produce symptoms after infectio n with both of the pathogens. It was proved by means of correlation an alysis that the two diseases occur in the phenotype independently of e ach other and that they do not interfere with each other. For the purp ose of resistance testing, the symptoms of the two diseases can be exa mined simultaneously on one and the same tree.