Growing citrus trees in the backyard is one of the great pleasures of living in a warm climate. Sometimes, however, citrus trees can develop problems that perplex home gardeners. The sudden loss of leaves from the citrus tree can send citrus gardeners scurrying to their local nursery or agricultural extension agency. Citrus trees can generally handle the extreme conditions of hot climates, but there are a few pests and diseases that can cause leaves and fruit to drop.
Citrus trees are drought-resistant, but if there is too little moisture they will be stressed and respond by dropping their leaves. Overwatering can also cause leaf drop. Gardeners should pay particular attention to a uniform, adequate watering schedule, particularly during drier months. This can help prevent many diseases and problems such as leaf drop and fruit-splitting.
A variety of nutritional problems can cause leaves to fall from citrus trees. Nitrogen deficiency can cause mature leaves to bleach and fall from the tree. Deficiencies of micronutrients such as magnesium and iron can also cause leaves to fade and eventually drop. Making sure citrus trees have adequate fertilizer with micronutrients is the best way to prevent this.
Citrus psyllid can infest trees, causing leaf distortion, curling and dropping. Oil sprays are a good way to control the pest if applied frequently. Brown, soft scale is a common problem that causes leaf drop in citrus trees. It appears as crusty or waxy bumps on the tree that sucks the sap, causing the leaves to yellow and drop off. Horticultural oil spray is the best way to control these pests. Citrus red mites can also cause leaves to drop. They can be controlled with pyrethrum spray.
Greasy spot is a fungal disease that can cause leaf drop. Copper fungicide is used to treat this. Phytophthora, or root rot, is a soil-borne disease that can also cause leaves to drop from citrus trees. To prevent this problem, avoid wrapping or mulching trees. Alternaria Brown Spot can also cause leaf drops and should be treated with copper fungicide when new leaves are ¼ to ½ expanded and again when leaves are fully expanded.
Citrus trees that are exposed to rapidly fluctuating temperatures often respond to the stress with a leaf drop. Once the period of varying temperature passes, the tree will likely recover on its own.
- Photo Credit Orange tree image by Evgeny Berdjansky from Fotolia.com