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Citrus

Young Tree Pests and Their Damage

On this page
Diseases and disorders
  • Frost
  • Nutrient disorders
  • Phytophthora gummosis
  • Sunburn

Vertebrates

  • Ground squirrel
  • Pocket gopher
  • Rabbits

Invertebrates

  • Aphids
  • Brown garden snail
  • Citrus leafminer
  • European earwig
  • Fuller rose beetle
  • Glassy-winged sharpshooter
  • Grasshoppers
  • Honeydew-producers
  • Southern fire ant

Exotic pests

  • Asian citrus psyllid
  • Citrus canker (Bacterial canker)
  • Citrus greening (Huanglongbing)
  • Diaprepes root weevil
  • Light brown apple moth

Leaf damage
Trunk and limb damage
Root damage

Names link to more information on identification and biology or management.

Click on photos to enlarge
Leaf damage
Brown garden snail
Brown garden snail chewing
Identification tip: Snails chew irregular holes in leaves and fruit. Snails feed mostly at night, but they leave behind shiny, dry or wet, slimy trails on plants and the ground. If snails are the suspected cause of chewing, look for them where they rest during the day beneath trunk wraps, in leaf litter, around irrigation emitters, or attached to leaves or bark.
Grasshoppwer chewing
Grasshopper chewing
Identification tip: Grasshoppers chew foliage, usually from the leaf edges. Some leaves can be so extensively chewed that only the main vein remains. When abundant, grasshoppers can eat most all of the foliage on entire small trees. Damage is most likely on trees growing near unmanaged vegetation, from which grasshoppers migrate to citrus.
European earwig chewing
European earwig chewing
Identification tip: Earwigs chew buds, leaves, or small fruit. Chewing damage can be common on trees with trunk wrappers, on lower canopy foliage where trees are not skirt-pruned, and where abundant leaf litter or other harborage provide earwigs places to hide during the day.
Weevil chewing
Fuller rose beetle chewing
Identification tip: Ragged, notched, or serrated leaf margins, usually on lower foliage, can be from Fuller rose beetle or the exotic Diaprepes root weevil (1.3 MB, PDF). In comparison with the Fuller rose beetle, Diaprepes chews notches that are larger and tend to occur more widely throughout the tree. Unlike Fuller rose beetle, Diaprepes rolls or glues leaves together where it lays its eggs. Report to agricultural officials any findings of the exotic Diaprepes root weevil.
Caterpillar leaf shelter
Light brown apple moth leaf shelter
Identification tip: Young citrus leaves and shoots are chewed, rolled, and webbed by many different species of caterpillars including amorbia, fruittree leafroller, and orange tortrix. Light brown apple moth, an exotic leafroller (Tortricidae), also causes this damage.
Citrus leafminer distortion
Citrus leafminer distortion
Identification tip: Citrus leafminer bores pale or dark (excrement-filled) winding tunnels just under the leaf surface. Infested succulent shoots and young leaves may be distorted, galled, or rolled.
Frost dieback
Frost dieback
Identification tip: Brown dead leaves remain attached to trees damaged by cold weather, giving plants a scorched appearance. Certain other leaf and twig diseases and disorders cause similar damage. With cold injury, damage is most prevalent on outer, exposed branches. Young trees are especially susceptible to cold.
Asian citrus psyllid waxiness
Asian citrus psyllid waxiness (868 KB, PDF)
Identification tip: This exotic, aphidlike insect sucks phloem, distorting leaves and shoots. The yellowish orange nymphs produce abundant white wax. The brownish adults spread citrus greening disease (Huanglongbing). Report to agricultural officials any findings of this pest.
Aphid leaf distortion
Aphid leaf distortion
Identification tip: When leaves and shoots are curled, look closely for insects or other symptoms to help you identify the cause. Foliage can be distorted by aphids or other Homoptera, caterpillars that web foliage, citrus thrips, citrus leafminer, citrus bud mite (in coastal lemon), and certain diseases and disorders.
Sunburn discoloring
Sunburn discoloring
Identification tip: Exposure to hot sun can kill parts of leaves and fruit, resulting in yellow-to-brown blotches. Sunburn also causes bark cankers (not shown). Injury is most prevalent on the south and west sides of the tree if sun exposure is the cause of damage.
Honeydew-producer damage
Honeydew-producer damage
Identification tip: Where dark sooty mold or sticky honeydew is evident, look for phloem-sucking Homoptera, including aphids, cottony cushion scale, citricola scale, black scale, brown soft scale, mealybugs (shown here), and whiteflies. Also look for ants that tend these pests.
Glassy-winged sharpshooter excrement
Glassy-winged sharpshooter excrement
Identification tip: This whitish coating is sharpshooter excrement. Infested leaves may also have elongate yellowish blisters or brown scars where females inserted their eggs.
Citrus greening
Citrus greening (636 KB, PDF)
Identification tip: Mottling and yellowing that cross leaf veins help to distinguish citrus greening (Huanglongbing), an exotic tree-killing bacterium. When zinc deficiency is the cause, discoloring occurs between distinctly greener veins. Report to agricultural officials any finding citrus greening disease.
Iron deficiency on young citrus leaves
Nutrient disorders
Identification tip: Leaf discoloring occurs between distinctly greener veins when nutrient disorders such as a deficiency of iron (shown here), potassium, or zinc are the cause.
Citrus canker
Citrus canker (636 KB, PDF) lesions
Identification tip: Circular, scabby lesions develop on both sides of leaves and also on fruit and twigs. Lesions on fruit and leaves are surrounded by a dark or water-soaked margin and yellowish halo. Report to agricultural officials any finding of this exotic disease. Photo by University of Florida.
Trunk and limb damage—Top of page
Phytophthora gummosis
Phytophthora gummosis
Identification tip: Phytophthora gummosis is the most common cause of profuse dark exudate from bark. Several other limb, trunk, and root diseases cause oozing bark and can stunt and sometimes kill trees.
Sunburn
Sunburn discoloring
Identification tip: Sunburn causes bark cankers on exposed wood, usually on the south and west sides of trunks that are not whitewashed and that lack trunk wraps.
Citrus canker
Citrus canker (636 KB, PDF) lesions
Identification tip: Citrus canker forms circular, scabby scars on twigs and also on leaves and fruit. Citrus canker lesions are raised, unlike the sunken twig scars from hail impact and mechanical injuries. Photo by University of Florida.

Photo_caption.
Ground squirrel girdling and burrows
Identification tip: California ground squirrels can chew bark and cambium virtually anywhere on trunks and limbs. Their burrow entrances (shown here) are open and about 4 inches in diameter, but openings vary considerably. Pocket gophers and moles also burrow in soil, but moles rarely if ever damage citrus.

Chewing damage
Rabbit chewing
Identification tip: Rabbits girdled this trunk and can chew bark anywhere within 2 feet of the ground. Voles (meadow mice) cause similar damage, but vole gnawing occurs no higher than about 2 inches above ground.
Southern fire ant
Southern fire ant mounds
Identification tip: Mounds of disturbed soil indicate ants are present, such as the native southern fire ant that made these shallow mounds. The red imported fire ant commonly makes larger, irregular domed mounds in irrigated or moist locations. Report to agricultural officials suspected infestations of the exotic, highly aggressive red imported fire ant.
Root damage
Chewing by vertebrates
Pocket gopher chewing
Identification tip: Ground squirrels, pocket gophers, and voles (meadow mice) chew roots. Pocket gopher chewing damage usually occurs entirely underground (shown here after soil was excavated). Note the underground tunnel opening next to the trunk.
Sparse roots
Diaprepes root weevil (1.3 MB, PDF)
Identification tip: Larvae (large grubs) of the exotic Diaprepes root weevil chewed off most roots from the young citrus at right. Report to agricultural officials any grubs feeding on citrus roots. In California, Phytophthora root rot and root asphyxiation (insufficient oxygen in soil, often from water logging) are common diseases and disorders that damage citrus roots.
Bark chewed by ants
Bark chewed by southern fire ants
Identification tip:  Several species of ants in citrus strip bark and chew trunks and  roots, sometimes seriously girdling young trees. When ants are the cause of chewing, trails of workers and mounds of disturbed soil are usually obvious nearby.

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