by Marilyn Odneal, Horticulture Adviser
(Mountain Grove) – Many people have a problem thinning fruit from their apples, peaches, plums and pears. They think they will get less fruit in the long run and certainly don’t want to lessen their harvest. The fact is that less than 10 percent of the potential fruit is needed to develop to produce a full crop.
The practice of fruit thinning apples, pears and stone fruits is beneficial. First, the fruit that is removed will allow the remaining fruit to develop adequate size and quality. If too much fruit is on the tree, sugars produced in photosynthesis and other nutrients will be spread too thin over all. If there is less fruit on the tree, they will develop to be sweeter, contain more nutrients, and will grow to be bigger in size. An extra advantage of hand thinning is that you can select the best fruit and remove misshapen, small and/or diseased ones.
It is also important the trees are not overloaded with fruit because when they size up, the branches may break if they cannot hold up the weight. Last but not least, if thinning is done early enough, it will increase the plant’s ability to initiate flower buds for fruit production in the next year.
Thin excess fruit when the fruits are the size of the end of a dime–about 1/2 inch in diameter. If you have a lot of trees to thin, you can start earlier. A good procedure is to start at one end of a branch and systematically remove fruit, leaving about one fruit every 6 to 10 inches down the branch (you can thin plums a little closer – from four to six inches). Be sure to leave only one fruit at a given site; when fruit grows together in a pair and touches, this provides homes for both insects and diseases.
At the Missouri State Fruit Experiment Station, two people will thin the fruit on one tree. They start together on one side and thin each branch as they proceed around the tree and meet at the other side. That helps make sure that all parts of the tree are thinned.
Apples are produced in groups of five or so. Thin to one fruit at each site. Apples will naturally thin fruit that was poorly pollinated in late May or early June. You can see if this natural thinning is occurring by shaking a limb and noting the fruit that falls. You may want to wait until after this natural drop occurs before you hand thin your apple trees.
So, thin fruit trees when they are about the size of a dime and they will grow to be large sized and luscious. Remember that thinning is necessary for apples, peaches, nectarines, pears and plums, but not cherries. And don’t worry – you really won’t reduce your fruit crop by thinning. Instead you will get bigger and better tasting fruit for your effort.
Please direct comments or questions concerning this column to Marilyn Odneal via email at MarilynOdneal@missouristate.edu; write to Missouri State Fruit Experiment Station, 9740 Red Spring Road, Mountain Grove, Mo. 65711; or call (417) 547-7500. Visit our website at http://mtngrv.missouristate.edu.