by Marla Koss
Persimmon trees often fluster their owners by dropping so much immature fruit.
June is here, and for certain fruit trees with overly abundant crops of fruit forming, so is ‘June Drop’. During this month apple, peach, nectarine, plum, apricot, persimmon and plum-apricot hybrids tend to drop excess fruit on the ground to relieve themselves of too much of a good thing. The problem is, ‘June Drop’ doesn’t usually rid the tree of enough excess fruit to make a critical difference. One exception is the persimmon tree that does not get pollinated because there are no other varieties nearby. Unpollinated persimmon fruit is parthenocarpic, hence much more likely to fall off just as it begins to form.
Enough of the excess fruit has to drop off the tree – or be taken off by human intervention – to give remaining fruit the amount of carbohydrates it will need for sugar content, the space to grow to mature size without being crowded on the branch, and for the branch to not buckle under the weight of too heavy a load. Which puts the responsibility on a fruit tree owner to cull excess fruit in order to end the season with a healthy tree and high-quality fruit. Exceptions to this rule include cherry trees (hey, the blue jays will oblige if they get a chance!) and figs.
Pluot branch buckling under the weight of too heavy a load.
A tree only has so much in the way of resources to spend on its own health vs. reproduction (fruiting). Its leaves convert sunlight into carbohydrates via photosynthesis, which feeds itself as well as the developing fruit. Depending on the type of tree, the number of leaves each fruit needs in order to mature with decent sugar content varies; the typical ratio is about 45 leaves to each piece of fruit. While the tree has an internal method to take stock of the existing crop load and induce excess fruit to drop, if after ‘June Drop’ the crop load is still too heavy, a tree can begin shutting off next year’s latent fruit buds. Result: broken branches and too much fruit of poor quality this year, no fruit next year (alternate bearing). So instead of avoiding the garden in hopes ‘June Drop’ will take care of the situation by itself, we fruit tree owners need to march out there and train ourselves to be stoic about culling that excess fruit, even if it’s all so cute and perfect (hint: there is nothing you can do with immature fruit like this in your kitchen, so don’t even go there; at Farm2Market we take some of it to the pigs and goats at MakerFarm next door, but aside from tossing it in the compost, it’s worthless).
There are 6 clusters of apples on this short section of branch; thinning to one apple per cluster leaves only 6 apples in the same space, saving the branch from possible breakage.
Farm2Market’s 20 apple trees are so vigorous and put out such heavy crops that our rule of thumb is to thin the crop down to one apple per cluster (an apple tree that puts out a modest crop can be thinned to two apples per cluster.) We wear gloves because we use wickedly-sharp garden snips that can fit neatly into those tight clusters, even if it is hard to see what we’re doing (don’t try this with hand pruners; their blades are too wide and clumsy to snip with any accuracy). Pulling apples off by the fingers is not an option, since you risk pulling off or weakening every other stem in the cluster.
The sharp, narrow tips of garden snip blades fit easily into an apple cluster.
Peaches, nectarines and other stone fruit may be thinned using bare fingers, as long as you can reach the fruit. A padded broomstick knocked against fruit clusters high in the tree is a nice low-tech way to remove excess crop (sorry to say, this does not work as well for peaches or apples as it does for plums and apricots, but is worth a try if there’s no ladder around). A sort of D.I.Y. ‘June Drop’ can be attempted by shaking branches individually while the fruit is still quite small; this will at least relieve a tree of fruit that was destined to fall. After culling a crop, check back at least once a week to see if more fruit clusters have appeared (or if you missed some the first time around).
Maybe after a morning of culling fruit in your own yard, the tedium makes a huge impression and you wonder what commercial orchards do in order to control the size of their crops. Farmer Google informs me that for large operations, chemical sprays and mechanical means are both popular, in addition to later-stage hand-thinning. While small orchard owners may walk through during bloom time and pinch out random blossoms to ensure that fewer fruits will form, the bigger orchards can spray caustic on blossoms; this sort of chemical thinning works best on apples and pears. Stone fruit like peaches and apricots can be thinned with a mechanical string-thinner that looks like a big, round hairbrush mounted vertically on a tractor rotor. It goes spinning up and down orchard rows zapping blossoms and/or immature fruit (search for “Darwin String Thinner” to get a good look at this device.)