Finding cherry leaf spot resistant varieties

A study was recently conducted in China to identify the resistance levels of cherry cultivars in that country, and offers useful information for farmers in all cherry-growing regions.

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Cherry leaf spot (CLS), caused by Passalora circumscissa, is a fungal disease that can result in decreased fruit quality and yield due to inconsistent ripening or premature defoliation. However, there is limited information available in China about the resistance of cherry cultivars to leaf spot caused by P. circumscissa. Our study aimed to identify the resistance levels of cherry cultivars to this disease.

Fifty-two cherry cultivars, comprising 40 sweet cherry (Prunus avium), four Chinese cherry (P. pseudocerasus) and eight sour cherry (P. cerasus) cultivars, were evaluated for resistance level characterisation. Specimens of these cultivars were collected and then used to screen for P. circumscissa resistance through both detached leaf assays and natural field infection.

Our study provides a theoretical basis for cherry disease resistance breeding and rational cultivar utilisation.

BACKGROUND

Cherry production in China has risen significantly over the past decade. China now has both the largest total sweet cherry cultivation area (200 000ha) and the greatest annual sweet cherry yield (about one million tons) in the world. These increases have coincided with the rising prevalence of cherry foliar diseases in many regions of China. Leaf spot caused by P. circumscissa has emerged as a disease in cherry trees, posing a threat to sweet and sour cherry production in China. P. circumscissa primarily affects the leaves of cherry trees, resulting in early chlorosis and premature defoliation during summer. This defoliation results in the trees being more susceptible to cold-induced injury and death during winter, and also results in major reductions (about 40%) in fruit yield and fruit quality.