Seeing unripe fruit or nuts on the ground, under your tree, can be normal or may indicate a problem.
Fruit drop, or June drop, is a natural process that allows a tree to get rid of more fruit than it can support. Fruit drop is common to citrus, apple, avocado, almond, tomatoes, and many other crops. Earlier in the growing season, some trees will rid themselves of unwanted blooms (blossom drop) for the same reason. Some trees, such as loquat, can be messy during this time. Manual fruit thinning works the same way, reducing the quantity of fruit but improving its quality.
Fruit drop can also indicate insect pests, disease, or adverse environmental conditions.
Fruit drop caused by insects
Black scale feeding weakens the tree, leading to wilting, twig dieback, stunting, and early fruit drop. Mealybug feeding can cause early fruit drop, chlorosis, and sooty mold. Feeding by mites can also reduce a tree’s ability to support a crop, causing fruit drop. Finally, while weevils are better known for burrowing into beans, cotton bolls, and cereal grains, they will also feed on roots, stems, buds, flowers, leaves, and fruit. Often, the first sign of a weevil infestation is leaf wilting, scalloped leaf edges, and early fruit drop.
Fruit drop caused by disease
Trees will frequently abort diseased or malformed fruit rather than invest water and nutrient resources in fruit that won’t reach maturity.
Fruit drop caused by environmental conditions
Sudden cold or extreme heat can cause fruit drop, especially in young trees. Strong winds can blow unripe fruit from trees. The most common environmental cause of excessive fruit drop is insufficient irrigation or unbalanced soil nutrients. Almonds and tomatoes are particularly sensitive to feeding and irrigation fluctuations.
Pollination and fruit drop
Fruit drop can be the result of insufficient pollination. Some trees need genetically compatible neighboring trees they can use for cross-pollination. It can also mean there are not enough pollinators in your area. You can attract more pollinators to your garden by avoiding the use of broad-spectrum pesticides and by installing a wide variety of flowering plants. Or, you can start raising honey bees. Honey bees take up surprisingly little space, boost pollination of nearly all your crops, plus you get honey!
Fruit drop and pruning
Heavy pruning can leave a tree unable to support the initial crop, resulting in fruit drop. Unless necessary, it is better to leave pruning and tree training for the dormant season.
Fruit drop and the soil
Low magnesium (Mg) levels in the soil can cause fruit drop, as can high potassium (K) or boron (B) levels. You can’t know what your soil’s nutrient levels are without a soil test from a local, reputable lab. While they look convenient and appealing, over-the-counter soil tests are not yet accurate enough to be useful. The type of soil can also have an impact on fruit drop. Sandy soils are far more prone to fruit drop than heavy clay soil.
Don’t panic if your orange tree drops dozens or hundreds of tiny green fruits in May or June. It is normal. Just pick them up and add them to your compost pile. If you notice heavy insect infestations, signs of disease, chlorosis, or wilting, track down the cause and correct it.
Remove fallen fruit and mummies to avoid creating a disease triangle or a hotel for pests.
You can grow a surprising amount of food in your own yard. Ask me how!
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