Symptoms and signs
|LCD infected Bing on right (A. Bixby-Brosi)|
Infection of sensitive cultivars of sweet cherry results in the development of small fruit with poor color. Some cultivars develop fruit with high shoulders and angular shape. The difference in size between fruit from healthy and from little cherry disease-infected trees first becomes evident approximately 2 weeks before harvest. The fruit remains light in color after the normal ripening period of non-infected cherries, and it fails to develop significant sweetness or acidity. The abundance of unmarketable and/or poor quality fruit that results from infection can have a severe economic impact on the industry.
The use of visual symptoms as a diagnostic tool is not a reliable indicator of LCD infection for multiple reasons (discussed below), therefore molecular diagnosis is most reliable and recommended. Trees may be non-symptomatic for several years after acquiring LCD, but serve as a reservoir during that time. The degree of disease expression is dependent on the cherry variety and the weather. ‘Bing’ and ‘Sweetheart’, the two most widely planted varieties in Washington, are among the least symptomatic in response to infection. In these two varieties, after initial shock symptoms that may last for one or two years, the fruit size and color will recover to a certain extent, but flavor is never regained. Visual diagnosis of LCD is made difficult by partial recovery in the appearance of fruit, and the potential confusion of symptoms with those of other pathogens occurring in sweet cherries and certain types of nutrient deficiencies.
|Western X infected Bing cherries on the left (N. Page)|