Is this gummosis?

Asked June 12, 2018, 8:52 PM EDT

I have a five year old plum that is growing in a bit too much shade and in soils that are more clay-rich than ideal (although it is at the top of a small slope). During my June prune I noticed amber gum ooze. I'm assuming this is gummosis because there is no obvious frass. Can you confirm that? If it is gummosis should I try and cut out the infected area? It is about 7 feet up on the main trunk. The entire tree is maybe 13 feet tall. Any advice would be much appreciated.

Montgomery County Maryland

3 Responses

You did not mention if the tree is ornamental or a fruit tree. Usually stone fruits are pruned from petal fall through budswell in the spring as they can be susceptible to a canker disease.

The gummosis can be due to several reasons such as the lesser peach tree borer, stress, cankers, or possible root injury. Plums and cherries are sensitive to high moisture and this can result in possible root injury. You can try to carefully remove some of the gummosis and look for possible holes and monitor the area.
See common problems of stone fruits

All you can do is keep the tree as healthy as possible through proper pruning proper planting, watering, fertilization, pruning, and pest management. See our website on stone fruits for more information


Thank you, this was very helpful!

I actually made an error in my submission but I don't think it will change your response. The plant in question is a cherry tree for fruit production. If that changes your advice, please let me know.

I do have an issue with my plum for fruit production but it is a very different problem. The plum tree has dropped about 1200 (yes, twelve hundred) fruits this year. There are many left so I'm hoping it will work out this year. Last year the late snow killed all flowers and two years ago it dropped 500+ fruits and we got only one. Now that it is older I'm hoping it will drop fewer fruits. If you have any advice on that problem, I'm all ears.

Thanks again,

Plums can drop their fruit for several reasons. Poor pollination - bee activity can be low during cool wet weather. Plums - there are Japanese and European types. Some are self fertile and and some require a pollinizer tree for cross pollination. See our website for pollination requirements.
Be sure to thin the fruit. This increases overall production.
Stress, poor soil conditions, and a frost during bloom can affect the fruit. Check for insect and disease (brown rot) on the fruits. Open up the fruit and look inside for insects.

In general tree fruits can be a challenge to grow for the average homeowner. They may eventually require a spray schedule for control. Monitor the trees and you can send us photos if you notice additional symptoms. See our website on stone fruits and view the spray schedule from VA Tech