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Crab apple tree problem

crab_appleWhat should I get for a crab apple tree that bloomed in the spring but then dropped all the leaves in the summer and did not make fruit for the first time? It is an old tree. Thank you, Cindy

Answers: You do not mention what part of the country your crab apple tree is located in and what the weather conditions have been. Diagnosis is going to be difficult but here are some things to watch and check. There are only a few diseases and pests that bother crab apples, but if you had an overly wet spring your tree might have gotten attacked by Apple Scab, a fungal disease. It attacks emerging leaves in the early spring and then moves to the fruit. You would have seen dark olive green spots on leaves in May or June, turning black as the leaves matured. This can cause premature defoliation. Control will come in the spring when you apply fungicides as the leaves begin to emerge. I suggest you search the web for images of apple scab to determine this for certain and then for suggested fungicides if you feel it may have been affected. Fruit may have been damaged early and fallen, or weather conditions may have been such that flowers were not actively pollinated, causing fruit to not develop or to be insignificant. 

The Midwest had some very dry spells, causing many of the trees, including crab apples, to drop a significant amount of leaves as a means of self-preservation. If you have been experiencing such dry spells this could be the reason for the leaf drop, and possibly the lack of fruit if the dry spell was early in the season.

Also consider any environmental conditions that may have happened in the previous winter or summer that might have weakened the tree. Trees are often slow to react to stressors, so whatever has affected it might have happened a season or two earlier. Also if you have sprayed any herbicide around it in a more concentrated amount, it might have caused some stress to the tree.

You can check the branches to make sure sap is still flowing to them by carefully scratching the bark with your fingernail or a small knife.  You should see green in the layer just below the bark. If the branches are still green then the tree is still actively transporting vital nutrients to its outer limits, but at a reduced rate. It is currently setting bud for next spring.

Fertilizer should not be applied to the tree in the fall but in the early spring as the tree starts to move the sap up the tree. This time will vary for each zone so check online for the best time for your region. You will want to apply a nitrogen-rich fertilizer at that time.  This is one where the first number in the sequence is highest, such as 25-10-10.

For the moment there is not a lot you can do except make sure all the leaves are cleared away.  If it was apple scab you don’t want the fungus wintering over and recurring even worse next season, and make sure it has sufficient water through the fall season. Then wait to see what happens next spring. Hopefully it was just an environmental condition and will be beautiful again.

Best of luck,

Karen

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