X-disease on stone fruit caused by Candidatus Phytoplasma pruni in the United States and Canada: Recovery plan

27 Sep 2023
1235

Donato Gerin, Stefania Pollastro, Rita Milvia De Miccolis Angelini, Francesco Faretra, Franco Nigro

Department of Soil, Plant, and Food Sciences - University of Bari Aldo Moro

The prokaryote Candidatus Phytoplasma pruni is the agent responsible for the disease in stone fruit plants known as X-disease, which is causing significant economic losses in the United States and Canada.

This phytoplasma is transmitted by at least eight species of pests to plants of the genus Prunus, but it has a wide range of host species, especially in the Asteraceae and Brassicaceae families. Furthermore, like most phytoplasmas, it can be transmitted through grafting and easily spread through propagation material.

On cherry trees, the fruits appear discolored and distorted, with a bitter or tasteless flavor. Initially, symptoms appear on a single branch or often only on a single cluster of fruits, spreading to the entire tree in subsequent seasons. During the growing season, the leaves show chlorosis, curling, reduced size, and premature shedding (Figure 1), while in later stages, bronzing or anthocyanosis along the central and basal veins is observed. The type and severity of symptoms may vary depending on the cherry variety and the strain of Ca. Phytoplasma pruni.

Figure 1. Symptoms caused by X-disease on sweet cherry (Harper et al., 2023). A, size, color, and shape of infected fruits compared to normally developed fruits; B, reduced-sized leaves with enlarged leaf stipules; C, branch dieback.

Considering the increasing incidence of X-disease observed in recent years in both the United States and Canada, an intervention plan has been published (Harper et al., 2023) with the aim of providing information on the biology of Ca. Phytoplasma pruni, the expression of the disease, host-pathogen and pathogen-vector interactions.

Furthermore, the plan includes strategies to prevent the spread of the pathogen through management programs that, as outlined in suitable phytosanitary regulations for containment, are based on the use of certified propagation material, the removal of infected plants, and the control of weed hosts, as well as vectors.

Download the full document (Harper, et al. (2023). Recovery Plan for X-Disease in Stone Fruit Caused by ‘Candidatus Phytoplasma pruni’. Plant Health Progress, 24(2), 258-295. https://doi.org/10.1094/PHP-02-23-0016-RP

Cover Photo: WSU Tree Fruit


Cherry Times - All rights reserved.

What to read next

Biocontrol of brown rot on cherry and plum: e5icacy, limitations and prospects

Crop protection

25 Jul 2025

A recent study tested the effectiveness of biopesticides and native microbial strains against brown rot caused by Monilinia laxa on cherry and plum. Promising results in pre-harvest phase, but limitations emerged during post-harvest at room temperature.

Giddings-Cerasus: the secret of success for ultra-late cherries in China

Markets

27 Mar 2024

The Chilean company Giddings-Cerasus closed the 2023-24 season once again with the Cerasina varieties 'Final 12.1' and '13.1'. The last batch of Giddings Cerasus cherries sent to the Asian market arrived on 18 March, with over 90 tonnes of product.

In evidenza

Turkey increases cherry and sour cherry production: new sustainable asphalt applications

Processed

01 Aug 2025

Turkey’s cherry and sour cherry production rises, prompting innovative ways to manage waste. Çurkova and Ege universities explore biochar from cherry residues to enhance asphalt durability and sustainability, supporting eco-friendly infrastructure.

Dried cherry production in Chile: GoodValley strategy and global markets

Processed

01 Aug 2025

Dried cherry production in Chile is growing with GoodValley, aiming to reduce waste and enhance value. From the Colchagua Valley to Asia, the strategy focuses on expanding exports and finding markets for an innovative and increasingly appreciated product.

Tag Popolari