Citrus Tree Diseases & Pests

Written by erin maurer
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Citrus Tree Diseases & Pests
Learn about the pests and disease that affect citrus trees. (orange trees on the street image by Daria Miroshnikova from

Growing citrus trees at home can be a rewarding endeavour for many gardeners. Fruit trees like lemon, orange and lime not only lend a tropical feel to a gardener's yard, but produce wonderful fruits for a family to enjoy. While raising citrus trees is an excellent pastime, there are some diseases and pests for which gardeners should prepare. Pest problems include snail and aphid infestations. Some potential diseases include citrus canker and greasy spot.


A common pest found on citrus trees is the snail. The University of California, Davis, warns against the brown garden snail, which may chew holes in leaves and fruit. Typically, snails feed at night, so it may be difficult to track their activity at first. Keep an eye out for a slimy, shiny trail on citrus tress during the day, which indicates snail activity. Tree Help recommends pruning low-hanging branches as a way to ward off snail infestation. The website also recommends using a snail bait trap and placing a bug band on the tree trunk. Bug bands prevent snails from climbing the trunk to feed on leaves.


Like snails, aphids may also invade citrus trees, according to the University of Florida's website. Aphids typically appear as a colony during the spring because they are attracted to new growth on the trees. Aphids may cause stunted growth, leaf cupping and leaf twisting. These small bugs may be green, yellow, brown or black and typically only measure 2 millimetres long. According to the Tree Help website, aphid infestations may be prevented by spraying leaves with an insecticidal soap.

Citrus Canker

According to the Tree Help website, citrus canker is a contagious bacterial infection that can affect citrus trees. The infection spreads through air currents, animals, insects and people. Due to its contagious nature, it can be difficult to contain. The infection causes scabby lesions on leaves, fruit and twigs, according to the University of California, Davis. UC Davis also warns that any signs of a citrus canker infection should be reported to the state's agricultural department. Tree Help recommends using a liquid copper fungicide to help prevent a citrus canker infection. It is increasingly important treat your trees if a citrus canker infection is reported in the area. Infected trees are destroyed to prevent the spread of the bacteria.

Greasy Spot

Greasy spot is a fungal disease that may affect citrus trees. According to Tree Help, greasy spot may be identified by yellow-brown blisters on the underside of the leaves. University of Florida warns that greasy spot may cause the citrus trees to drop leaves before the autumn. The university recommends spraying trees to prevent greasy spot twice annually, in May and August. Tree Help suggests regularly removing fallen leaves, which may help prevent new greasy spot spores from developing.


Citrus trees may develop sunburn in which the sun damages leaves and fruit, according to UC Davis. The sun causes yellow or brown blotches on the fruit and leaves and blotches in the bark. Typically, sunburn damage can be found on the southern- and western-facing sides of a tree. Thin-skinned citrus fruits like murcott are more prone to sunburn, according to the University of Florida. Provide occasional shade for trees; plant trees in areas where they are not exposed to constant sun.

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