Each spring, fruit trees and berries produce all the blossoms they can muster. By late June and early July, the fruitlets are forming and it’s time to thin them out. If pollinated, each bloom can produce fruit and, more important to the plant, lots of seeds. I’m referring to fruit trees, not berries, which are never thinned.

Seed and fruit production requires lots of energy from new photosynthesis or from stored resources in the roots. Seeds are high in oils and carbohydrates. If we don’t thin out the fruit-set, the sun’s energy is being converted into a gazillion inedible seeds, and many small inferior fruits.

A better approach is fewer fruits/seeds reaching maturity and, therefore, larger and sweeter fruit of better quality.

Delaying gratification

Cherry trees in their productive years are never thinned, but there is an excellent argument for thinning sweet cherries when they are young and still getting established. Assuming good pollination, sweet cherries especially have a tendency to overbear before they are properly established.

A spindly, young tree producing a large crop is not a healthy outcome.

In their youth, fruit trees still are developing strong roots and building their upright, woody structure. Allowing a heavy crop on a young tree can dramatically stunt growth, or even kill the tree; never allow them to fruit the year they are planted.

After a few years, if they are growing well, save a few cherries for a fall snack and remove the rest. Delaying gratification means you’ll both be happier in the long run.

Apples — thin yearly

Apples are thinned every year in the early summer. Growing one apple to ripeness requires the photosynthetic action of 30 or more leaves, and each blossom cluster may produce a few or a dozen swelling fruitlets.

Thin out the fruitlet clusters, keeping one or two fat ones and carefully pinching off the rest. If the tree experienced excellent pollination, you may need to remove many fruit clusters, entirely. As you thin, don’t damage the fruiting spur where the fruitlets, and next year’s blooms will originate.

Waiting longer to thin the crop means the tree’s energy goes, needlessly, into fruit and seed that you will remove later. A mature, well-managed apple tree might require an hour or more to thin, ladder and all.

For apples, the requirement for annual thinning speaks volumes about the need for regular spring pruning so that the fruit is safely accessible for thinning and harvest.

In Haines, several remaining apples trees, planted by Anway, Vermiere and McRae and others, over 100 years ago, are enormous and still productive, but impossible to safely thin or fully harvest.

Apple scab and thinned/fallen fruit

Thinned fruitlets and fallen apples are a vector for the endemic apple scab fungus. Remove all entirely from the orchard area.

Orchardist-Educator Michael Phillips doesn’t want thinned or fallen fruit anywhere near productive trees. He suggests tossing them in the ditch far from the orchard, or giving them to the chickens.

If you mulch or compost fallen or thinned fruit, the final compost should not be applied in a fruit orchard.

Here in Haines, where very elderly apple trees have habitually been ignored for decades — and wet, fallen fruit abound — you will find apple scab, for sure. Selecting “scab-resistant” varieties is a smart approach.

Thinning biennial producers

Frequently trees are “biennial,” producing a large crop one year, followed by a weak crop the next. A boom followed by a bust. This habit can be genetic, or energetic.

The tree has thrown all its energy into one year’s productivity; resting in the next, it will produce fewer blooms and set much less fruit. To balance the biennial habit, be more aggressive in thinning on the “boom” year.

No pollination, no fruit

Crop-thinning relates directly to pollination. No pollination, no fruit. Apples, cherries or plums that bloom well year-after-year, but set little (or no) fruit need one or more friends with benefits. Cross-pollination from a different cultured variety is essential for many fruit trees.

Remember that only “early-ripening” fruit varieties should be considered for our latitude. Here at latitude 59 North, a Pink Lady, Fuji or Winter Banana apple will never, ever ripen or sweeten. Plant cross-pollinating, early-ripening varieties.

For no-cost advice and help in establishing an orchard contact the Chilkat Valley Orchard Project ([email protected]) or call 907-314-0331 — a program of the Chilkat Valley Historical Society.