What is happening to the fruit on my cherry trees?
I have three cherry trees. A North Star, Mesabi and Meteor. The last two are next to each other while the North Star is on the other side of the yard. Last year, the cherries on the Meteor began to display a brown area on the back side of the cherry before the cherry was completely ripe. The side facing the sun would look red but turning them over revealed the browning spot. Made most of the cherries on the Meteor unacceptable. This year, the Mesabi is doing it also. The North Star is untouched and produced a huge crop. With the birds getting a large portion (the trees are now too large to net), this leaves little usable cherries from these two trees. The trees were all planted in 2004 and started producing in 2008. Any ideas? I have not had to spray the cherries as until now they have had few problems (other than birds).
Scott County Minnesota
Thank you for the question. Perhaps the problem with your Mesabi and Meteor cherries is brown rot, a fungus that can attack all stone fruits and trees. The infection creates brown rotten spots in the fruit. Wet weather and temperatures in the 60's-70's are particularly conducive to the development of this fungal disease. Fruits are more susceptible as they ripen and the fungus is opportunistic, just waiting for the slightest injury to the fruit in order to give it entrance.
The key to managing this is through good sanitation practices. Promptly clean up all fallen fruit and remove mummies from the tree. Prune out twig and branch cankers in the winter and check for wild stone fruit trees nearby that might be neglected and serve as a reservoir for the disease.
Purdue University Extension has a good article on this disease and is where I got the information for your answer: https://www.extension.purdue.edu/extmedia/BP/BP-45-W.pdf
If you don't think this is the problem, submit your question again, this time with photos of the entire tree and close up of the fruit.
Thank you for contacting Extension.