The Response of Several Plum Cultivars to Natural Infection with <i>Monilinia laxa, Polystigma rubrum </i>and<i> Stigmina carpophila</i>

The response to the attack of Monilinia laxa, Polystigma rubrum and Stigmina carpophila in natural conditions of infection of 13 plum cultivars were evaluated during three years, in a commercial orchard located in North-western of Romania. The studied cultivars were: ‘Topfirst’, ‘Nectarina rosie’, ‘Tuleu timpuriu’, ‘Hangata’, ‘Toptaste’, ‘Tuleu gras’, ‘Vinete de Italia’, ‘Stanley’, ‘Vinete romanesti’, ‘Tophit’, ‘Jojo’,‘Anna Späth’, ‘Topend’. The highest degree of flower attack by Monilinia laxa was recorded for ‘Stanley’, while the lowest attacks were registered on ‘Topend’, ‘Jojo’, ‘Tophit’ and ‘Nectarina rosie’. The best response regarding the attack on fruits proved to be with ‘Topend’, ‘Jojo’, ‘Tophit’ and ‘Topfirst’. These cultivars registered small values of attack degree (0.7-3.3%). The cultivars with the lowest attack degree of red staining caused by Polystigma rubrum were ‘Top End’, ‘Jojo’, ‘Tophit’, ‘Toptaste’, ‘Nectarina rosie’ and ‘Topfirst’. A high degree of attack was calculated on ‘Anna Späth’, ‘Vinete romanesti’, ‘Vinete de Italia’ and ‘Tuleu timpuriu’. These cultivars prove to be very sensitive to the red staining disease in natural conditions of infections. Cultivars ‘Top End’, ‘Jojo’, ‘Tophit’, ‘Toptaste’, ‘Nectarina rosie’ and ‘Topfirst’ were slightly attacked by Stigmina carpophila (5.3-7.3% attack degree). The low infections levels recommend the mentioned cultivars as possible genitors in plum breeding programs, for creating new genotypes with good response to diseases attack.