Why are so many apples on my Cortland tree dropping before they fully ripen?
Why are so many apples on my Cortland tree dropping before they fully ripen? They are sour and the seeds are not brown yet.
There are numerous reasons why your Cortlands might be dropping underripe fruit. Dry conditions can exacerbate early fruit drop, so you may just be dealing with the fallout (no pun intended) of a droughty year–I have heard at least one grower report the same issue. In addition, apples release ethylene into the air around them as they ripen; if the fruits are crowded, that ethylene accumulates in local pockets and can increase the risk of individual fruits releasing too soon. The best way to prevent this is to thin the fruit earlier in the season–always bittersweet for the home gardener, but thinning generally produces a better crop in just about every food plant. One or both of these is most likely the culprit.
It is possible that you have an issue with your soil or a pathogen of some kind (though you didn’t mention any other damage to the fruit), so it’s always a good idea to get your soil tested by submitting a sample to the UMaine Analytic Lab, if you haven’t before or if it’s been a while. At the moment, our plant pathologist is on leave so it would be a little trickier to get a pathogen analysis–we can help you send a sample to the UMass Extension Laboratory, but unfortunately there is a fee involved (UMaine typically provides this service free to our residents). If the tree and fruit look otherwise healthy, I would advise holding off until next season. If you are concerned about infection because of visible damage, please send back some photos and our team will do its best to get an answer for you.
There is some great information on premature apple drop in this Michigan State Cooperative Extension article on the subject. You will see that Cortlands are listed as an intermediate risk for the condition.