CHARACTERIZATION OF PLANTS OF 19 OPEN-POLLINATED APPLE TREE SPECIES (Malus spp) INTRODUCED FROM POLAND DUE TO THEIR VEGETATIVE DEVELOPMENT AND INCIDENCE OF MILDHOOD (Podosphaera leucotrieha)

Abstract

After stratification for three months, apple seeds of 19 species introduced from Poland, germination ranged from 1.27% (M. arnoldiana) to 72.41% (M. baccata var. sibirica). Six months later transplantation the growth of the plants fluctuated since 6.4 cm (in M. sieboldii var. colocarpa) until 39.5 cm (in M. purpurea). The leaves were different in shape and size among the same species, they developed from 7 to 48 by plant, presenting color green and/or purple. At the end of the winter 1980-1981, the falling of the leaves was heterogeneous, whereas some species mantained great part of the foliage (M. arnoldiana, M. baccata and M. baccata fructus lutea) the defoliation in other ones was almost complete (M. prunifolia, M. prunifolia var. sicora y M. rajek). Likewise at the begining of the spring the sprouting of the plants varied from 0 (in M. floribunda) to 72% (in M. bacca­ta var. sibirica).
On the other hand, the attack of mildew (Podosphaera leuco­tricha) to the plants also was very variable. The fungus was present in the seedlings in sorne plants since the first 45 days. After six months and to apply different fungicides were species that presented 100% attack by this disease (M. floribunda var. arnoldiana, M. prunifolia var. sicora A, M. purpurea y M. sil­vestris cv. Antonovka) whereas were species with 0 and 41% of attack (M. arnoldiana and M. robusta USA respectively).