Complete Citrus Reference Library

Round to slightly oval fruit; use peel, size, leaf and petiole together.

Usually larger and broader than an orange.

Often oblong with a noticeable nipple at one or both ends.

Often smaller than lemon and round to oval.

Blotchy, uneven mottling and overall decline are stronger clues than a perfectly mirrored nutrient pattern.

Look for raised corky lesions with a distinct yellow halo on leaves, twigs or fruit.

Look for a tiny mottled brown wedge-shaped adult feeding with its rear end raised at about a 45-degree angle; nymphs are yellow-orange on new flush.

Rootstock supplies the roots; scion is the desired fruiting top above the graft.

Start with the trifoliate leaf: three leaflets on one petiole, often with a noticeable winged petiole.

Look for relatively narrow mandarin-type leaves and small orange mandarin-like fruit on this rootstock type.

Look for unmistakable trifoliate leaves plus stout thorns; fruit is small, yellow and very seedy/bitter.

Look for a lemon-like rootstock fruit with a distinctly coarse, rough or pebbled rind.

Look for a noticeably flattened, orange-like fruit with a smoother rind than rough lemon.

Look for an orange-like fruit and a leaf with a broad, obvious winged petiole.

Start with trifoliate leaves, then look for the larger citrus-hybrid leaflets and strongly winged petiole.

Look for a lemon/rootstock fruit that is usually rounder and smoother than rough lemon, often yellow-orange when mature.

Look for a large yellow lemon with an elongated oval shape and a noticeable nipple at the blossom end.

Look for very small round orange fruit—much smaller than a typical mandarin.

First confirm the navel at the blossom end; when cut, the flesh is pink to red rather than standard orange.

Look for a small, smooth, deep-orange mandarin with an easy-peel appearance.

Recognize grapefruit size first; when cut, Duncan is white-fleshed and notably seedy.

Look for a large early-season mandarin with a deep orange-red rind and a broad, slightly flattened form.

Confirm grapefruit size, then use the interior: Flame is a red-fleshed grapefruit with very few seeds.

Look for a broad, relatively large citrus leaf with a conspicuously winged petiole.

Look for a round sweet-orange fruit with a smooth thin rind and no navel.

Look for a small, round-to-oval lime with a thin rind; ripe fruit can turn yellow and is commonly seedy.

Look for a very small orange citrus fruit, often oval, with a proportionally thick sweet peel.

Look for an elliptic leaf with little or no petiole wing and a slightly toothed margin; young growth may be reddish.

Confirm grapefruit size, then use the inside: pale/white flesh with very few or no seeds.

Look for the classic bell/pear shape with a pronounced neck at the stem end.

Look for a medium, deep-orange, slightly flattened tangerine with a tighter peel than Satsuma.

Look for a medium oval citrus leaf with a narrow wing on the petiole.

Look for a round to slightly flattened tangelo, generally without the dramatic neck of Minneola.

Look for a tangelo leaf with a citrus-hybrid appearance and a noticeable winged petiole.

Look for a larger oval lime, usually seedless, with a thicker rind than Key lime.

Look for a round midseason sweet orange with no navel; if cut, expect more seeds than many commercial sweet oranges.

Look for the largest citrus fruit in the set, often round-to-pear-shaped with a very thick rind.

Confirm grapefruit size and inspect the cut flesh for a deep red color.

Look for grapefruit size with pink-to-red flesh and a possible pink blush on the rind.

Look for a distinctly flattened mandarin with a loose, puffy, very easy-peel rind.

Look for a medium tangerine with a deep reddish-orange, smooth glossy rind and a somewhat flattened shape.

Look for a deep orange-red, round-to-slightly-flattened tangor with a somewhat pebbled rind.

Look for a medium broad citrus leaf with a visible but not grapefruit-sized petiole wing.

Look for a round-to-oval sweet orange with a thin smooth rind and no navel.

Look for the secondary 'navel' structure at the blossom end of a seedless sweet orange.

Look for leaf chlorosis and tip/marginal scorch associated with fertilizer-grade urea containing too much biuret.

Look for dieback, misshapen growth and coarse or gummy symptoms on shoots/fruit rather than a simple uniform yellow leaf.

Look for herbicide injury expressed as irregular chlorotic or necrotic leaf areas rather than a tidy nutrient pattern.

Look for distorted, narrow or strap-like new growth with chlorosis after herbicide contact.

Look at the newest leaves: the tissue turns yellow while the veins remain sharply green.

Look at older leaves for yellowing on both sides of the midrib that leaves a green inverted-V or arrowhead area near the base.

Look for a light-green/yellow leaf with a network of greener veins, usually less sharply contrasted than iron deficiency.

Look for broadly uniform pale green-to-yellow foliage, commonly beginning on older leaves.

Look for brown necrotic tips and leaf margins, often with a sharp boundary between healthy and burned tissue.

Look for small, narrow leaves with interveinal yellow mottling and shortened internodes/rosetting.

Look for dark brown necrotic lesions with yellow halos on young leaves and fruit, often with irregular expansion along veins.

Look for dark leaf spots that may enlarge or merge and are often surrounded by yellow tissue.

Look for firm brown leathery fruit decay, often beginning on fruit low in the canopy after wet conditions.

Look for chronic decline with bark symptoms such as gum impregnation, pitting or discoloration in susceptible mandarin/tangelo tissues.

Look for dark fruit lesions that can appear as hard spots, freckles or larger necrotic areas, often with contrasting orange/yellow tissue.

Look for an established tree with thinning canopy, wilt, twig dieback and chronic decline despite apparently adequate soil moisture.

Look for asymmetrical blotchy mottling that does not mirror across the leaf midrib; fruit may be lopsided or unevenly colored.

Look for raised corky, wart-like lesions that distort young leaves and fruit.

Look for scaling, shelling or cracking bark on susceptible rootstock tissue below the bud union, often with dwarfing.

Look at the trunk base for dark water-soaked bark, gum exudation, cracking and decay near the soil line.

Look for yellowish leaf spots above and dark, greasy-looking raised lesions on the underside of mature leaves.

Look on grapefruit rind for numerous small dark specks or pits that can create a pink-pitted or rind-blotch appearance.

Look for postharvest fruit decay that starts soft/watery and quickly develops white mold followed by blue-green spores.

Look for many tiny raised dark specks that feel like sandpaper; on fruit they may run in tear-stain streaks.

Look for sharply defined translucent or water-soaked-looking patches between veins that later turn tan or necrotic.

Look for orange-brown lesions on flower petals followed by dropped young fruit and persistent enlarged green calyx 'buttons.'

Look for scaling/flaking bark on trunk or scaffold limbs; young leaves may show temporary flecking patterns.

Look for brown decayed feeder roots together with a thinning, yellowing canopy and poor vigor.

Look for a black soot-like coating on leaves or fruit that sits on the surface over insect honeydew.

Look for very soft, watery postharvest fruit decay with a sour odor and pale fungal growth.

Look for decay beginning at the stem/button end and spreading downward through the fruit.

Look for decline or quick decline on susceptible rootstocks; stem pitting and vein symptoms may occur in some hosts.

Look for superficial corky/russet scarring on fruit where leaves or twigs rubbed the rind during growth.

Look for bright red-orange or yellow cushion-like fungal growth on whitefly scale stages; it is a beneficial fungus.

Look for a dark brown-to-black domed oval scale with a characteristic raised H-like ridge on the back.

Look for a broad-snouted adult weevil covered with blue-green scales.

Look for colonies of dark brown to nearly black soft-bodied aphids crowded on tender new flush.

Look for a yellow-brown fruit fly with patterned wings and a relatively long body/ovipositor in females.

Look for dark slate-black nymphal scales on leaf undersides, often ringed with waxy fringe; adults are small dark whitefly-like insects.

Look for winding silvery serpentine mines in tender leaves, often causing curled or distorted new growth.

Look for soft-bodied insects covered in white cottony wax, often clustered in fruit/stem crevices.

Look for a tiny mottled brown wedge-shaped adult feeding with its rear end raised at about a 45-degree angle; nymphs are yellow-orange on new flush.

Look for very small bright red mites/eggs on leaves and fruit together with fine stippling or bronzing.

The mite itself is nearly microscopic; identify the bronze/russet rind or leaf surface damage it produces.

Look for bark that appears dusted with snow from masses of elongated white male scales; darker females may be mixed in.

Look for a brown-orange female attached to a large white ribbed/fluted cottony egg sac.

Look for a large snout weevil with bold black-and-cream/yellow/orange striping or scale patterns.

Look for small round flattened reddish-brown scale covers on fruit, leaves or twigs, often with a central nipple.

Look for a gray-brown broad-snouted weevil with a rough/scaly body; leaf edges may show scalloped feeding.

Look for a long, very narrow brown mussel-shaped scale cover aligned along twigs/leaves.

Look for the large jumping hind legs, chewing mouthparts and stout body of a grasshopper.

Look for clusters of bright green soft-bodied pear-shaped aphids on tender shoots.

Look for evidence of the beneficial fungus on rust mites—infected tiny mites may appear coated or anchored by whitish fungal growth.

Look for a green leaf-like insect with extremely long threadlike antennae and strong jumping hind legs.

Look for an alligator-shaped predator larva often carrying bits of debris/prey remains on its back.

Look for a small dome-shaped beetle, often red/orange/yellow with contrasting spots or markings; larvae are elongated predators.

Look for an elongated brown true bug with widened leaf-like expansions on the hind tibiae.

Look for a small yellow-brown fruit fly with bold patterned wings and contrasting body markings.

Look for a microscopic threadlike roundworm or for feeder-root damage associated with citrus slow decline.

Look for the giant swallowtail caterpillar that mimics bird droppings with mottled brown, white and orange markings.

Look for a tiny narrow-waisted wasp associated with parasitized scales/aphids/whiteflies; many are only a few millimeters long.

Look for a curved elongated mussel-shell scale cover that is dark purple-brown.

Look for reddish-brown ants of mixed worker sizes and characteristic mound colonies.

Look for a wedge-shaped leafhopper with strong jumping hind legs and wings held roof-like over the body.

Look on leaf undersides for tiny pale mites marked by multiple dark body spots; feeding can cause stippling.

Look for a broad bright-green shield-shaped true bug.

Look for tiny brownish-purple mites on upper leaf surfaces with stippled/gray foliage injury.

Look for tiny white moth-like adults and pale oval scale-like nymphs on leaf undersides.

Look for a small gray-brown snout weevil and repeated notches chewed from leaf margins.

Look for tiny slender yellow/tan insects and silvery or ring-like scarring on tender flowers/young fruit.

Look for tiny pale yellow-green mites with two dark dorsal spots, often with fine webbing.

Look for the distinctive seedhead with two (sometimes three) racemes forming a V or Y shape.

Look for a tendril-climbing vine with deeply lobed leaves and warty orange fruit that splits open to show bright red seed coverings.

Look for a fine-textured creeping grass with stolons/rhizomes and several finger-like seed spikes radiating from one point.

Look for alternate oval leaves, small white star-shaped flowers and clusters of shiny black berries when mature.

Look for opposite toothed leaves and small daisy heads with yellow centers; mature seeds are narrow black needles with barbed tips.

Look for deeply divided fern-like leaves and upright green flower spikes with no showy petals.

Look for a twining vine with extremely finely divided feathery leaves and small red star/trumpet flowers.

Look for tall upright growth covered in very fine threadlike, feathery foliage.

Look for an upright branching weed with small narrow serrated leaves and tiny pale flowers.

Look for a tall coarse bunchgrass with broad blades and a large open branched seed panicle.

Look for irregularly lobed aromatic leaves and clusters of tiny green flowers on an upright branching plant.

Look for a tall rhizomatous grass with broad leaves, a conspicuous pale/white midrib and a large open often purplish panicle.

Look for triangular/goosefoot-shaped leaves with irregular teeth and a whitish mealy coating on young leaves.

Look for opposite rough serrated leaves, square-ish stems and tight clusters of small multi-colored tubular flowers.

Look for a twining vine with opposite heart-shaped leaves and milky sap when damaged.

Look for a twining vine with heart- or arrow-shaped leaves and large funnel/trumpet flowers.

Roll the stem: sedges have solid triangular stems with glossy leaves arranged in three ranks and an umbrella-like seedhead.

Look for a woody vine with compound leaves made of toothed leaflets and clusters of berries that mature blue-black.

Look for an upright Amaranthus with alternate simple leaves and dense green flower/seed spikes.

Look for a large coarse plant with thick reddish-purple stems and long drooping clusters of purple-black berries.

Look for a low spreading mat with opposite rough/hairy leaves and tiny white star-like flowers.

Look for a grass bearing hard spiny burs that readily stick to clothing, fur or skin.

Look for a broad-leaved creeping/decumbent grass with several seedhead branches carrying rows of spikelets along one side.

Look for an upright tough-stemmed weed with narrow toothed leaves and small yellow hibiscus-like flowers.

Look for a stiff creeping perennial grass spreading by pointed rhizomes, with narrow leaves and a sparse open panicle.

Look for a woody climbing vine with five leaflets radiating from one point and tendrils for climbing.

Look for a basal rosette that bolts into branched stems bearing many tiny white flowers and flat round/oval seedpods.