| Leaf damage |
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. |
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
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. |
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 . 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. |
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
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
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
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
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
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
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
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
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. |
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 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
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 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 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. |
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.
|
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 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 |
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. |
Diaprepes root weevil
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 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. |
