In western Colorado, home to Precious Palisade peachesCytospora canker is one of the vital economically consequential fungal diseases faced by growers.
A recent one Survey conducted by Colorado State University In orchards Mesa found that 100% of orchards had trees infected with Cytospora canker. In some orchards, you may smell the sweetness of gummosis, the sweet oozing of sap from a tree brought on by injury, stress, pathogen infection or insect damage.
We are a part of a team of fruit tree growers, Extension Officers And The researchers who’re developing tools to scale back Cytospora canker in fruit tree orchards in Colorado and Utah.
In a study we published, we assessed the final result of this disease At least US$3 million in annual economic loss For growers in Colorado. Infected larger branches, called scaffolds, may lead to damage. 50% loss of peaches per tree.
Peaches were first planted at Palisade and Grand Junction in 1882. John Harlow, one of the first white settlers in the area. Peaches and other fruit trees have been a Colorado staple ever since. Colorado farmers produce about 15,000 tons of peaches in 2024 Which is worth 34 million dollars..
However, fruit tree production within the Intermountain West, which covers Colorado, Utah and Idaho, is threatened by reduced water supplies, spring frosts, variable winter temperatures and soils above the perfect pH range for peach trees. Adding to environmental pressures are pest problems and protracted Cytospora canker disease.
What is Cytospora canker?
Cytospora canker is brought on by a fungus inside the genus. These are pathogens. It is found worldwide and affects more than 70 species. of woody shrubs and trees. These fungi have been present on fruit trees within the United States since a minimum of 1892 when Cytospora canker was first discovered on peach, plum, and almond trees in Pennsylvania and New Jersey. Cytospora canker was previously described only as a disease of stressed trees, but is now recognized as a devastating disease of fruit trees throughout the United States.
Growers hope the peach trees will live for 20 years. The first five of those years are early growth. The next 10 years are full production. Then, the tree’s productivity declines within the last five years of its life. This disease has reduced the lifetime of an orchard in Colorado from 20 years to 10 years or less. Trees infected throughout the first or second yr often die 4 or five years before peak production is reached.
Cytospora canker often enters through wounds and woody branches or twigs. Injury occurs when branches are pruned to take care of tree vigor or from severe freezing or hail. Freeze events are common in Colorado. and are particularly damaging in the autumn if temperatures drop suddenly without giving the trees enough time to acclimate to the temperature change.
Ice formation inside plants causes swelling and cracking of woody tissue, in addition to the formation of ice crystals inside plant cells that may puncture the cells, exposing them to oxidative damage and infection. Small cracks enable cytospora spores, like plant spores, to enter and cause infection.
Cytospora canker and freeze
In 2020, a serious freeze event damaged many trees in Colorado.
Temperatures after a warm October Dropped from 65 degrees Fahrenheit (18 degrees Celsius) to 10 degrees F (-23 degrees C) in a 48-hour period. In the fruit region across the town of Hotchkiss. Since recent temperatures were within the 70s, the trees didn’t have the right amount of adaptation to organize for this massive drop in temperature. The leaves were still green, and the sap was still flowing through the tissues of the wood.
This single freeze damage was directly caused Death of thousands of peach trees Across the western slope of the Colorado.
The sudden freeze also allowed the spread of latest cytospora canker infections on peach trees that weren’t killed by the freeze in any respect. Surviving trees were often more vulnerable since the cracked skin and bark of the peach branches were now vulnerable to fungal infection. This relationship between Cytospora infection and cold damage is considered a serious reason why Cytospora canker is a very necessary disease in Colorado.
To manage the pathogen, growers can remove infected trees, protect wounds with chemicals to stop latest infections and ensure trees are stress-free. However, management strategies have limited utility as a consequence of growing conditions. While Palisade is essentially the most ideal microclimate for growing peaches in Colorado, the weather is cold. Close to the limit that peaches can tolerate..
There were several nights in April 2026 when temperatures reached the low 20s F (-7 degrees C) at various orchards in Delta County, Colorado. The fruits had already began growing and were very sensitive to cold temperatures. As a result, around farmers Hotchkiss and Paonia lost their peach crop..
Palisade orchards avoided this level of injury because temperatures only dropped to the upper 20s F (-2 degrees C) on the identical nights, damaging some fruit but normally holding back enough for the complete crop. Such spring frosts reduce fruit production but generally don’t increase the spread of Cytospora canker.
David Stirl
Solutions are in progress.
Colorado State University researchers are working toward developing strategies to combat the disease. Our team has. Chemical options have been developed. For conventional and organic farmers who’ve helped reduce the spread. We are determining whether certain peach cultivars are tolerant to the pathogen, and we proceed to know the population biology of Cytospora to assist us develop latest management strategies.
The pathogen is airborne, on insects, during irrigation and potentially Movement of new peach trees in orchards. Many fungi cause canker in trees. Seeds are only transported short distances by rain splash.. But spores of the fungus have been present in collection nets about 250 feet (76 m) from a tree that’s producing spores.
We have established the Cytospora Working Group as a collaborative research, extension and cultivation group to collectively develop solutions to Cytospora canker. We proceed to higher understand the aspects involved in disease development and establish best management practices to assist growers combat the disease and keep the Colorado peach industry vibrant.