UC Master Gardeners

Thin your trees for a bumper crop of bigger fruit

UC Master GardenerApril 23, 2014 

These young apricots are at the perfect stage for thinning.

COURTESY PHOTO

Q: I had a lot of small fruit last year and much of the fruit dropped prematurely. How can I prevent this from happening again? — Robert, San Miguel

A: This premature fruit drop is referred to as “June drop,” which occurs in our area around May. It is a natural process that thins fruit in an attempt to prevent overbearing — or a crop load that the tree cannot successfully support.

However, this natural thinning is sometimes not enough. Signs that too much fruit is produced by the tree include broken branches laden with fruit, small fruit or alternate bearing of crop.

In this extreme drought year, thinning your fruit is particularly important. Manually thinning will help your tree to get through this season with less stress, minimizing susceptibility to diseases and even sunburn.

Some examples of trees that benefit from thinning include apples, Asian pears and certain European pears. These trees produce flower clusters from each bud and each flower can become a fruit. Thin these pome fruits to one or two fruit per cluster and at least 6 to 8 inches apart. The size of the fruit should be a half inch to 1 inch in size at the time of thinning.

Stone fruits such as apricots, plums, peaches and pluots produce one fruit per bud, and often — for example with apricots — on the entire length of the branch. Thin all the fruit clusters to just one fruit and leave 2 to 4 inches between each fruit. Thin when the fruit is three-quarters to 1 inch in diameter.

If you have small trees or believe in keeping your trees small with summer pruning, hand thinning is the easiest and also produces the most accurate results. If you have a large tree and ladder climbing is no longer your hobby, attach a short rubber hose or cloth to a long pole. Strike individual fruit or clusters once or twice to break the fruit up and it will drop. Remember to clean the dropped fruit off the ground to reduce the spread of diseases. If you want to see a demonstration on “How to thin fruit,” join the Master Gardeners at 1:30 p.m. today for a one-hour seminar in the Demonstration Garden, 2156 Sierra Way, San Luis Obispo.

GOT A GARDENING QUESTION?

Contact the University of California Cooperative Extension Master Gardeners at 781-5939 on Mondays and Thursdays from 1 to 5 p.m. in San Luis Obispo; at 473-7190 from 10 a.m. to noon in Arroyo Grande; or at 434-4105 on Wednesdays from 9 a.m. to noon in Templeton. Visit the UCCE Master Gardeners website at http://ucanr.org/sites/mgslo or email mgsanluisobispo@ucdavis.edu  .

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