Leaf drop on Plants

Symptoms

Leaf drop can look different depending on what is behind it. On many plants, it shows up as sudden wilting along with the leaves falling. Leaves often turn yellow before they drop too. A severe spider mite infestation can leave leaves dry before they fall.

Look for stippling, a gray or bronze cast, and fine webbing when mites are active. Thrips cause infested leaves to turn yellow and drop. Whiteflies bring on the same pattern of yellowing, lower vigor, and leaf drop. Mealybug feeding tends to stunt growth and push leaves to drop early.

Scale, mealybug, or aphid activity can also cause leaf drop or dieback in the branches. Check for a sticky residue, sooty mold, and small insect bodies on the leaves as a sign of these pests. Yellowing and dropping leaves can also trace back to poor root health from overwatering, dryness, or too much fertilizer. Excess salts in the soil or water, and a sudden change in light, temperature, or humidity, can cause the same symptoms.

Causes

Several different problems can lead to leaf drop, and most trace back to the roots, the soil, or a pest. Poor root health is a common cause of leaf drop. It can come from overwatering, letting the soil dry out too much, root disease, or too much fertilizer. Excess soluble salts in the soil or water can also cause leaves to drop.

Compacted soil or roots that have outgrown the pot are another cause. A sudden change in light, temperature, or humidity can trigger leaf drop as well. A toxic chemical poured into the soil is a less common but serious cause. Inadequate light, low temperatures, overwatering, or poor soil drainage can all play a part too.

Soil-borne insect or disease pests are another possible cause. Above the soil, a spider mite, thrips, whitefly, scale, mealybug, or aphid infestation can also bring on leaf drop. Good soil aeration and drainage, along with watering on a steady schedule, go a long way toward preventing root rot.

Diagnosis

A plant dropping its leaves can have more than one cause, so check it in stages. Look first at how the leaves are falling: sudden wilting with leaf drop is one common pattern. Yellowing before the leaves fall is another pattern to note.

Next, check the roots and the soil. Poor root health, compacted soil, pot-bound roots, and excess salts in the soil or water are common causes of leaf drop. A recent change in light, temperature, or humidity, or a toxic chemical poured into the soil, are also worth ruling out.

Stippling, a gray or bronze cast, and fine webbing point to spider mites, especially if the leaves are also dry and dropping. Yellowing leaves that drop can also mean thrips or whitefly are feeding on the plant. A sticky residue, sooty mold, and small insect bodies on the leaves suggest scale, mealybug, or aphids. On poinsettias, whiteflies are an especially common cause of yellowing leaves and leaf drop.

Treatments

Treatment depends on what is behind the leaf drop, so match the approach to the cause you find. If root rot is behind the leaf drop, good soil aeration and drainage help prevent it. Watering on an appropriate schedule, rather than too often or too little, also helps prevent root rot.

For spider mites, wash the leaf surfaces often with water and cut down on dust around the plant. Dispose of any plant parts that are heavily infested with mites, rather than leaving them on the plant. If a spider mite infestation keeps going or gets worse, discard the plant.

For thrips, wash them off the leaves with water and dispose of the infested parts. For whiteflies, wash the eggs and crawling young stages off the plant with water, and dispose of the infested parts. If a whitefly infestation grows large, discard the plant.

For scale insects, scrape them off the plant and wash the crawling juvenile stage off with water. When an infestation is heavy, prune out the affected plant parts or apply a contact spray. Insecticidal soap or horticultural oil are the active ingredients to look for in that kind of spray. Washing leaves, cutting dust, and removing infested parts are all cultural controls, while pruning and applying a spray with these ingredients counts as an organic treatment.

Prevention

Preventing leaf drop starts with avoiding the conditions that commonly trigger it. Keep the soil from staying too wet or too dry, since poor root health is a common cause of leaf drop. Avoid overfeeding and watch for excess soluble salts building up in the soil or water. Use a pot with enough room for the roots and soil that drains well, since compacted or pot-bound roots are also a cause.

Try to avoid sudden changes in light, temperature, or humidity where you can. Keep toxic chemicals away from the soil around the plant. Good soil aeration and drainage, paired with watering on an appropriate schedule, are the main defenses against root rot. Washing leaf surfaces with water and cutting down on dust also helps keep spider mites from building up.

Plants most often affected

Poinsettias are a documented host for this problem, since whiteflies commonly infest them. On poinsettias and other plants, a whitefly infestation causes leaves to yellow and drop. Whitefly feeding also tends to lower the plant's vigor along with causing leaf drop. This pairing of poinsettias and whiteflies is one of the more commonly documented causes of leaf drop on this list.

No plant page in this build records this problem yet.