Stella Otto: The Backyard Fruit Gardener

Today's Tip: Mow vegetation short around the base of fruit trees and bushes to reduce winter habitat for rodents.

Thinning Fruit—How?

I’ve already dis­cussed why you should thin fruit from your tree. Yes, you really should!

I’ll men­tion one more rea­son now that I didn’t touch on in the last post: Many young, devel­op­ing, dwarf fruit trees tend to be pre­co­cious. That is, they often start bear­ing fruit in their sec­ond or third year of growth. Nat­u­rally, we are all excited to see that fruit! How­ever, allow­ing it to remain on the tree diverts energy from the tree’s abil­ity to grow a strong branch struc­ture or weights down the leader. As a result the tree often becomes a runt. If you weren’t con­vinced by my ear­lier post to thin your fruit, hope­fully you will reconsider.

Now on to the how…

  1. There are 3 ways to exert some con­trol over the amount of blos­soms pro­duced:
    Annual prun­ing removes excess branch growth and with it excess buds. When done prop­erly, it also allows light into the tree, which helps with fruit bud ini­ti­a­tion, as well as main­tain­ing the health of the tree in many ways.
  2. Excess fruit can be removed by hand.
  3. Apples can be thinned using plant hor­mones, as well as one insec­ti­cide that mim­ics a plant hor­mone and causes fruit thinning.

Most fruit buds pro­duce from 3 to 6 blos­soms in a clus­ter. The king bloom is the first and cen­tral one in the clus­ter. If you are grow­ing apples, ide­ally, the goal is to “keep the king.” It typ­i­cally opens, is pol­li­nated, starts growth first, and results in the largest fruit.

Properly thinned apple fruitlets

Achiev­ing the proper bal­ance between fruit and the leaves needed to mature them is the goal of fruit thinning.

The goal of proper fruit thin­ning is to bal­ance the num­ber of fruit on a tree with it’s capac­ity to sup­port them. This is depen­dent on the num­ber of pho­to­syn­the­sis fac­to­ries, bet­ter know as leaves, the tree has. Depend­ing on the type of fruit, the vigor of the vari­ety, and the health of the tree, it takes any­where from 30 to 75 leaves to sup­port a fruit that will develop to a diam­e­ter of 2 ½ inches or more. Gen­er­ally this means that you want one fruit for every 6 to 12 inches of branch growth or no more than a sin­gle fruit per spur on com­pact varieties.

You can start hand-thinning when June drop is done or roughly 4 to six weeks after bloom. Best results for cre­at­ing large fruit are achieved if thin­ning is com­pleted before the end of July.