SUSCEPTIBILITY OF PLUM CULTIVARS TO RED LEAF SPOT POLYSTIGMA RUBRUM (PERSOON) DE CANDOLLE

The investigations were made with 16 plum cultivars in a fruit bearing orchard of the Institute of Agriculture in Kyustendil during the period 1997 – 1999.The trees were planted in 1994. The cultivars were grafted on P. cerasifera rootstock.
During 1997 the trees were grown without any fungicidal sprays.
Next two years the trees were sprayed with zineb only once at the end of blossoming.
All of them were surveyed and more than 80 plants were individually inspected.
The estimation of the susceptibility of the plum cultivars to Polystigma rubrum was made in September.
The method of Townsend et Heuberger was applied to estimate the rate of attack.
All the evaluated cultivars are susceptible to Polystigma rubrum but the degree of susceptibility is very different.
Cultivars ‘Lyubimtsa Hramova’, ‘Ashatan’, ‘Sofia-2’, ‘Gilej’, ‘Strinava’ ‘Stanley’ and ‘Stanley plum’ are with weak susceptibility.
Their rate of attack is about 4%. Cultivars ‘Green gage’ and ‘Cacanska najbolja’ are with strong susceptibility to Polystigma rubrum with maximum rate of attack – 34,72% and 30,8%.

VII International Symposium on Plum and Prune Genetics, Breeding and Pomology

M. Borovinova

plum, fungi disease, estimation of resistance

https://doi.org/10.17660/ActaHortic.2002.577.43