Cytospora Canker Poses Major Threat to Colorado’s Beloved Peach Orchards
Amid the picturesque orchards of western Colorado, where the renowned Palisade peach thrives, a significant challenge looms for fruit growers: cytospora canker. This fungal disease has emerged as a formidable adversary, threatening both the economic stability and vitality of the region’s fruit industry.
According to a study by Colorado State University, every orchard surveyed in Orchard Mesa showed signs of cytospora canker infection. The presence of gummosis, the sweet-smelling sap oozing from trees, is a telltale sign of this pervasive pathogen.
Collaborating with local fruit growers, extension personnel, and researchers, efforts are underway to mitigate the impact of this disease, which is responsible for at least $3 million in annual economic losses for Colorado growers. Damage to major branches, or scaffolds, can result in a 50% reduction of peaches per tree.
Tracing its roots back to 1882 when John Harlow first planted peaches in Palisade and Grand Junction, peach farming has become an integral part of Colorado’s agricultural landscape. In 2024, the state’s peach production reached approximately 15,000 tons, valued at $34 million.
Understanding Cytospora Canker
The disease, caused by fungi within the genus Cytospora, affects over 70 species of woody plants worldwide. First identified in the U.S. in 1892, it has evolved from a disease of stressed trees to a destructive force in fruit orchards nationwide.
Typically, peach trees have a lifespan of 20 years, with peak production occurring between years 5 and 15. Cytospora canker can drastically shorten this lifespan, often killing infected trees by their fourth or fifth year.
Infection occurs through wounds in woody branches, often caused by pruning or extreme weather events. Colorado’s frequent freeze events create conditions conducive to infection, as ice formation in plant tissues causes cracks that allow fungal spores to enter and establish.
The Freeze Factor
A significant freeze event in 2020 exemplified the vulnerability of Colorado’s fruit trees. Temperatures plummeted from 65°F to below 10°F within 48 hours, resulting in the death of tens of thousands of peach trees. Surviving trees were left susceptible to new cytospora canker infections due to exposed and damaged tissues.
While management strategies include removing infected trees and protecting wounds with chemicals, the effectiveness of these measures is limited by environmental conditions. Even Palisade’s favorable microclimate is at the edge of what peach trees can endure.
Ongoing Research and Strategies
Research teams at Colorado State University are pursuing solutions to combat cytospora canker. Efforts include developing chemical treatments for various farming practices and identifying peach cultivars resistant to the disease. Understanding the pathogen’s spread, through air, insects, and irrigation, remains a priority.
The formation of a cytospora working group aims to foster collaboration among researchers, extension officers, and growers to devise effective management practices and sustain the thriving peach industry in Colorado.
For additional insights into Colorado’s agricultural challenges, explore further stories here.
Original Story at www.upi.com