Fruit Tree Dropping Fruit Early? June Drop and Other Causes

What June Drop Is

June drop is a fruit tree shedding part of its young crop on its own, and in most cases it is normal. Iowa State University Extension describes two waves. The first drop begins shortly after petal fall and may continue for 2 to 3 weeks, and the fruit that falls is pea-sized. The second drop usually comes in early June, which is where the name comes from, and those apples are about 1/2 to 1 inch in diameter. Apples, pears, plums and cherries all do it.

The reason is supply and demand. Purdue University calls it physiological fruit drop, caused by a shortfall of carbohydrates: a tree has limited leaf area to make sugars and a large number of young fruits all drawing on them, so the weaker fruits lose out and fall. A tree can afford the loss. Only one bloom in 20 is needed for a good crop on a full-blossoming apple tree, a figure both Purdue and the Royal Horticultural Society give.

Timing shifts with climate. In the cooler British season the RHS puts the peak about eight weeks after flowering, in early July, with losses continuing to mid-July.

How to Tell June Drop From a Problem

Collect a dozen fallen fruits and look at their size, their skin and the date.

Normal June drop fruit is 1/2 to 1 inch across, green and unmarked, and it falls over a short period in early June while plenty of fruit stays on the tree. Four other patterns point elsewhere:

• Pea-sized fruit in the 2 to 3 weeks after petal fall. This is the first drop, usually caused by lack of pollination or incomplete pollination.
• A crescent-shaped scar on the skin. Plum curculio laid an egg there.
• An entry hole with sawdust-like frass. A codling moth larva has tunneled toward the seeds.
• Fruit dropping in the heat of mid to late summer, often with a bleached or browned patch on the sunny side. This is heat and water stress, or early ripening.

A much heavier June drop than usual has a weather explanation too. Purdue expects more drop after cool, cloudy weather soon after bloom, because photosynthesis slows. University of Delaware puts numbers on it: a continuous 4-day run of cloudy days during the period 5 to 7 weeks after bloom will cause fruit to drop. In stone fruit, unfertilized fruit can hang on for 25 to 50 days after bloom and then fall before the pit hardens, so a peach tree may shed later than you expect.

Poor Pollination and Frost at Bloom

Fruit that was never fertilized makes up the first drop. Apples, sweet cherries, pears and Japanese plums are cross-pollinated, and Colorado State University Extension advises planting two compatible cultivars within 100 feet of each other. Apricots, sour cherries, peaches, nectarines and European plums are generally self-pollinated. Even with the right partner, cool, rainy weather during bloom cuts bee activity and leads to poor pollination. Our guide to self-pollinating and cross-pollinating fruit trees covers pairing.

Frost acts at the same stage. Washington State University’s critical temperature tables give the air temperature at which open blossoms are killed. Once the first blossoms open, 10 percent of apple and cherry blossoms are killed at 28°F and 90 percent at 25°F. At full bloom, pears lose 10 percent at 28°F and 90 percent at 24°F, and peaches lose 10 percent at 27°F and 90 percent at 24°F. A single cold night in that range can remove most of a crop, and the damaged fruitlets fall in the weeks afterward. Nothing on the tree needs fixing in that case. For next year, see protecting fruit trees from late spring frost.

Can Heat Stress Cause Early Drop or Premature Ripening?

Heat does more damage to fruit size and skin than it does to the ripening date. Oregon State University Extension notes that most plants grow best between 59 and 86°F, and that sustained temperatures above 90°F slow growth and bring on signs of stress. Washington State University explains the mechanism in fruit trees: they transpire heavily to cool themselves, lose moisture, and may shut down photosynthesis, which results in lower yields of smaller, poor-quality fruit. Trees stressed by heat during bloom set less fruit to begin with.

Sunburn is the visible part. Sunburn browning appears on apples when the fruit surface reaches 113 to 120°F, depending on the cultivar, and the skin dies outright above 126°F. Scalded fruit shows a discolored, blistered or sunken patch on the side facing the sun.

Ripening can be pushed forward close to harvest. Rutgers’ harvest guidance for apples explains that maturing apples produce ethylene, which loosens the stem and causes pre-harvest drop, and in its advice on timing stop-drop sprays it cautions that ripening can be accelerated when temperatures are too hot. A hot spell in the last weeks before harvest can therefore bring fruit down sooner than expected. A hot spell in June or July mostly means smaller fruit, sunburn and a heavier drop.

The response is the same in both cases: water deeply instead of little and often, mulch to slow evaporation and steady the soil temperature, and shade young trees where you can. The summer watering schedule has the routine.

Insects That Make Fruit Fall

Cut open any fallen fruit with a mark on it.

Plum curculio is a weevil about 1/4 inch long, brown to black with light gray and brown markings. University of Illinois Extension notes that it feeds on almost all stone and pome fruits, including apples, peaches and plums. The female cuts a crescent-shaped slit in the skin to lay each egg. Utah State University Extension puts the start of egg-laying at about petal fall, continuing for roughly 30 days, and the larvae need 8 to 22 days inside the fruit. Infested fruit drops in early summer, which is why curculio damage is easy to mistake for June drop.

Codling moth larvae tunnel into apples and pears and feed on the seeds. Look for an entry hole plugged with sawdust-like frass. In Maine this damage shows up later in July and into the fall. Apple maggot flies emerge in late June and July, and their larvae leave brown trails through the flesh.

Sanitation is the home gardener’s main tool. Utah State University Extension advises removing fallen fruit through the summer and putting it in the trash, so the larvae inside cannot finish developing. Fruit that rots on the branch instead of falling clean is a different problem, covered in brown rot on fruit trees.

What to Do After the Drop

Wait until the natural drop has finished, then thin by hand what the tree kept. The RHS warns against thinning earlier, because you may remove fruit the tree was about to shed and end up with too little. Iowa State sets the other limit: hand thinning of apples should be done within 6 weeks of full bloom.

Fruit	Space left between fruits
Apples	6 to 8 inches (Purdue); 8 to 10 inches (Iowa State)
Pears	6 to 8 inches (Purdue)
Peaches, nectarines, plums	4 to 5 inches (Purdue)
Apricots	2 to 4 inches (Purdue)
Cherries	Rarely need thinning

Spacing figures differ between extension services, and several give peaches more room than Purdue does. The fruit thinning guide sets the recommendations side by side.

Thinning matters beyond this year’s fruit size. Trees that carry a large crop tend to follow it with a small one, a two-year cycle called alternate or biennial bearing, and removing surplus fruit early evens it out. The method is covered step by step in thinning apple and peach trees.

No spray prevents June drop. The RHS’s advice is good cultivation: prune so light reaches the inside of the canopy, water and mulch during dry springs, and avoid over-feeding with nitrogen. Keep a note of the bloom date, the lowest temperature that week and what the fallen fruit looked like. Next spring those notes will tell you whether the tree needs a pollination partner, frost cover or a pest plan.

Quick recap

• First drop: pea-sized fruit in the 2 to 3 weeks after petal fall, usually from poor pollination.
• June drop: 1/2 to 1 inch fruit in early June, caused by competition for carbohydrates. It is normal.
• One apple blossom in 20 is enough for a full crop.
• Open apple blossoms take 10 percent kill at 28°F and 90 percent at 25°F.
• A crescent scar means plum curculio. A hole with frass means codling moth. Pick up fallen fruit.
• Thin after the drop ends and within 6 weeks of full bloom: apples 6 to 8 inches apart, peaches and plums 4 to 5 inches by Purdue’s figures.