What is wrong with my Calamondin (Calamansi) plant?

Do the fruit have raised, light brown, corky areas on them?

Do the fruit have firm, light brown spots on the rind?

Do the leaves have oily brown spots on the undersides?

Does the fruit have small, brown, sunken spots that turn dark?

Does the trunk have brown patches that exude a thick, amber gum?

Have the leaves turned pale green or yellow?

Do the leaves have white, cottony masses on them?

Does the fruit's insides contain webbing?

Do the leaves have pale yellow stipples?

Have the leaves turned yellow and fallen off and the whole tree declined?

Citrus scab is a fungal disease that attacks calamondin trees. To control citrus scab, prune, and site trees so that foliage and fruit remain as dry as possible during spring growth.

Brown rot is a fungal disease that appears in humid weather as white mold on the rind of the low-hanging fruits. The simplest control is to mulch the soil around the tree and prune away low-hanging branches. Copper spray applied to the ground and low-hanging limbs also work.

Greasy spot is a fungal disease that causes oily brown spots on the undersides of the leaves. Since the disease overwinters on leaf litter, the simplest control is to collect and destroy fallen leaves. Keep leaves as dry as possible, especially during the early summer. For recurrent greasy spots, spray with superior oil or copper.

Melanose is a fungal disease that usually attacks calamondin trees older than 10 years. Leaves will have small, dark, circular depressions with yellow margins. Copper spray applied just once at the fruit set controls this disease, but since fruit damage is only cosmetic, spraying isn't really necessary. Keep melanose in check by pruning out dead wood, which may harbor the disease.

These patches are caused by a fungal disease Brown rot gummiosis. Eventually, brown patches form dark, sunken cankers. To control this disease, scrape away the canker into healthy bark, allow it to dry, and spray it with copper. To prevent the disease, keep surface water and sprinkler water away from the trunk.

Pale green or yellow leaves in calamondin trees usually mean nutrient deficiency. If old leaves turn yellow and drop off, suspect nitrogen deficiency and if young leaves turn yellow with green veins, suspect an iron deficiency. To correct nitrogen deficiency, apply an organic nitrogen source directly to the soil. To correct iron deficiency, adjust the soil pH to be more acidic.

White cottony masses on leaves are caused by mealybugs. Leaves may also be covered with a sticky honeydew excreted by the mealybugs or a black mold, which feeds on the honeydew. Natural enemies, such as lacewings, usually keep mealybugs in check but you can also introduce a predatory beetle called mealybug destroyer that does extraordinary work in controlling mealybugs.

Navel orange worms are reddish-orange, brown-headed larvae that bore into cracked fruit and spin their cocoons inside. Control pests by picking off damaged fruit. Clean up dropped fruit. Spray BTK to kill larvae before they enter.

Citrus mites are tiny spiderlike insects that attack calamondin leaves and fruits. Fruits may turn silver or brown and drop prematurely. The simplest mite remedy is to hose down the tree with plain water or insecticidal soap solution. For more serious infestations, spray superior oil. The introduction of predatory mites, such as Amblyseius species is a good control method.

Various types of scales cause calamondin leaves to turn yellow and fall off. The whole tree may decline and look sickly. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season. Attracting hoverflies will control scales.

If the new leaves are curled or twisted most likely culprit are aphids. These tiny insects can vary in color, green, pink, black, gray to completely white. They cluster under leaves and on growing tips where they feed on plant sap. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations. Ladybugs are their natural enemies.