This year, fruit load is heavy on nearly every healthy fruit tree in the state. When these trees are not adequately thinned, they become subject too breaking down under the load, not to mention the production of small fruit. Most fruit growers understand the concept that the more fruit there is on the tree, the smaller the size of the fruit.
Fruit thinning for homeowners is one of the most difficult jobs to do when producing tree fruit. With all the expense and hard work that has gone into producing a healthy productive tree, the last thing homeowners want to hear is that they should knock the majority of the young fruit on the ground.
There are a couple of important reasons why fruit crops should be thinned. The most important reason to thin fruit is to increase fruit size. Another significant reason to thin fruit is to reduce fruit over bearing that often leads to a heavy crop in one year and almost no crop in the second year. A third reason to thin fruit is to reduce limb breakage that occurs when too much fruit is left and the fruit begins to grow in size.
Most deciduous fruit trees benefit from fruit thinning. Apples, pears, Asian pears, apricots, plums, peaches, kiwi, and persimmons all respond positively to fruit thinning. Cherries and nut trees are usually not thinned.
Learning how much fruit to thin off your tree will take some practice. Each fruit type will require a little different method. When working with apples, Asian pears, and European pears, thin fruit to one per spur. The spur is the short woody structure where flowers arise. It is best to leave only one fruit for about every six inches of branch. If the tree is healthy and vigorous it will have more than one spur every six inches along a branch. So, leave some spurs with no fruit on them. This helps to balance your crop for next year.
When choosing which fruit to leave look for the largest fruit. Fruit that is small or damaged should be removed first. Thin before each apple reaches the size of a dime in diameter. This usually occurs within the first 20 days after petal fall. Removing these small fruits early will keep energy available for the fruit that remain and fruit buds for next year. Thinning by homeowners is typically done by hand. Be careful not to break off the spurs while thinning. Spurs will produce flowers and fruit for many years if not broken during thinning and harvesting.
When working with apricots, peaches, nectarines, and plums, notice fruit is borne mostly on one-year wood and does not come off a spur. Plums will be borne on both one-year wood and small spur like structures. When thinning these trees try to space young fruit along the branches as singles with about six to eight inches between fruit. Young fruit should be thinned off trees within 30 days of the end of bloom.
Peaches, nectarines, cherries and plums will have a natural drop that occurs near early June. This is referred to as June drop. This is the trees way of lightening the crop load. The homeowner may want to leave a little heavier crop than the final crop to see which fruit the tree intends to drop. And, with time the homeowner will learn how to adjust for the June drop.
Remember when raising dwarf fruit trees to thin a little extra fruit off after bloom because the tree is not as strong structurally as a semi dwarf or standard tree. Dwarf fruit trees are developed and tend to bloom and set heavier fruit crops at an early age. Protect their young branches from being overloaded in the first few years.