Why are half-grown nuts falling off my tree?

Asked July 31, 2014, 1:12 PM EDT

My tree was full of nuts last year but nearly all of them fell off when they were about half grown. The same thing is happening again this year. The nuts are half way to maturity and the ground is littered with them, what can I do to remedy this?

Mobile County Alabama

1 Response

Good Afternoon,

Fruit drop (or nut drop) is often a natural occurrence. Trees may set large amounts of nuts in a season and some/most drop off naturally.

Pecan nut drop (I'm assuming you are talking about pecans as you are in Mobile, Alabama) is also caused by weather. Very wet seasons in the late spring and early summer can cause part of a pecan tree's crop to fall. The same happens if the trees experience hot extremely dry weather, particularly in sandy soils which dry out quickly.

Other causes are disease. The wet weather can also allow fungal infections to take place. Once infected, nuts are dropped by the tree in response.

Lack of pollination is another cause. If the pecans weren't adequately pollinated in May; usually due to weather there will be no embryo tree inside the nut causing the tree to drop it. Male flowers mature quickly in the spring and can be shedding pollen before the female flowers are ready. Also, if there is excess rain, pollination is interfered with. Poor pollination doesn't stop some nuts from forming, but, as the nuts don't have an embryo, they drop off.

Insect damage: Pecan weevils, pecan casebearer, and green stinkbug are all culprits causing lots of nut drop. Maintaining tree health and treating when needed will help. Please see the free publication for some tips:
http://www.aces.edu/pubs/docs/I/IPM-0027/IPM-0027.pdf
This document is directed at commercial growers but can be used to help determine pest problems.

Tree health; your tree, of any kind of nut, will require fertilization and adequate watering during dry periods to carry a good crop of nuts. If the tree is being defoliated by insects, infected by foliage diseases, or is pale due to inadequate soil fertility, the nut crop will be affected.

Some good additional reading:
http://www.aces.edu/dept/extcomm/specialty/pecans2.html
http://extension.uga.edu/publications/detail.cfm?number=B1348