Response to economically important fungal diseases of plum cultivar-rootstock combinations

Abstract

The present study was conducted during the period 2020–2023 under the agroecological conditions of the Troyan plum-growing region, with the aim of assessing the susceptibility of plum cultivar–rootstock combinations to three economically important fungal diseases: rust (Tranzschelia pruni-spinosae), shot hole disease (Stigmina carpophila), and red leaf spot (Polystigma rubrum). Four widely grown plum cultivars (Сacanska Lepotica, Hanita, Jojo, and Stanley), grafted onto six rootstocks (Brompton, GF 655-2, SJ A, Wavit, Wangenheim, and Prunus cerasifera), were evaluated under natural infection conditions.

Climatic parameters were recorded annually to determine their influence on pathogen development. Significant differences in disease severity were observed among cultivars and rootstocks. The highest incidence of shot hole disease was recorded in the Hanita/Wavit combination (44.66% in 2022), while the cultivar Stanley showed pronounced susceptibility to rust when grafted on Brompton and Wavit rootstocks (31-37%). In contrast, combinations Cacanska Lepotica involving GF 655-2 and Wavit rootstocks exhibited the lowest overall disease susceptibility.

These results highlight the critical role of rootstock selection in reducing disease pressure and improving the resilience and sustainability of plum orchards under changing climatic conditions.

Highlights

This study presents a comprehensive multi-year evaluation of the response of plum cultivar–rootstock combinations to major fungal diseases under variable climatic conditions.

Rootstock selection significantly influenced disease severity and yield stability across all studied cultivars.

Integration of long-term climatic data with disease assessments provides new insights for climate-resilient plum production.