Citrus greening and backyard citrus — Sebastian, Florida

Citrus greening slowly starves an infected Sebastian citrus tree, leaving it unproductive and usually dead within a few years, because the bacterium has no treatment.

The disease that Sebastian growers call greening goes by its Chinese name. UF/IFAS Gardening Solutions explains that huanglongbing, or HLB, was named in the mid-1900s by researcher Lin Kung Hsiang and translates to yellow dragon disease, for the yellow shoots on infected trees (UF/IFAS Gardening Solutions). It says HLB infection eventually renders infected plants completely unproductive.

The federal description is blunter. USDA APHIS calls citrus greening one of the most serious citrus diseases in the world and states that, once infected, most trees die within a few years (USDA APHIS). An infected tree can remain without symptoms while serving as a source of bacteria for other trees, which is why one neglected orange in a Sebastian Highlands backyard matters to every citrus tree on the block.

The fruit tells the story at harvest. APHIS says infected trees produce fruit that is poorly colored, possibly lopsided and bitter, and that such fruit can only be sold for juicing. In an Indian River County yard, that usually means a tree that still flowers but gives small, sour oranges a few seasons after infection.

Agriculture runs deep here. UF/IFAS Extension Indian River County notes that the county has a history rich in agriculture, notably in cattle and citrus (UF/IFAS Extension Indian River County), and the backyard tree along Indian River Drive or in Roseland is the last trace of that grove landscape for many households.

Sebastian growers spot greening by blotchy, uneven yellowing across a leaf's midvein and fruit that stays green at the blossom end, and spot the psyllid by its tiny adults and waxy white nymph residue.

The insect is small but visible. USDA APHIS describes Asian citrus psyllid adults as gnat-sized, only about 1/8 inch long, with mottled brown wings, and says they jump or fly when approached (USDA APHIS). Eggs are yellow-orange and almond-shaped, tucked in leaf folds, and nymphs leave waxy white excretions, the sign most often noticed on new flush in a Sebastian yard.

Leaves carry the clearest clue. UF/IFAS calls blotchy mottle, a random pattern of yellowing that is not the same on the right and left sides of the leaf midvein, one of the best ways to identify infected trees (UF/IFAS Gardening Solutions). Vein corking and green islands on leaves follow as infection spreads, and symptoms are easier to see in shade or on overcast days, a useful tip under the bright Treasure Coast sun.

Fruit shows it inside and out. Infected fruit may turn orange near the stem while staying green at the blossom end, and inside may show aborted seeds, a curved central core or an off flavor, according to Gardening Solutions. Suspect leaves can go to the weekly Master Gardener plant clinic in Sebastian, which meets on Wednesday mornings, 10 a.m. to noon, inside the North Indian River County Library on CR 512 (UF/IFAS Extension).

For a Sebastian yard, the safest bets are HLB-tolerant or cold-hardy types such as the Sugar Belle mandarin, kumquat and calamondin, plus a spread of oranges and grapefruit chosen by ripening season.

Breeding has started to help. UF/IFAS Gardening Solutions says Sugar Belle is a hybrid mandarin developed by the University of Florida to be more tolerant of HLB infection, withstands temperatures as low as 18 degrees F, and ripens from November through December (UF/IFAS Gardening Solutions). Kumquats withstand 16 degrees F and calamondins 22 degrees F on the same page, comfortably beyond a typical Indian River County frost.

Seasons spread the harvest. UF/IFAS EDIS HS132 says one sweet orange from each of the early, midseason and late groups will supply fresh fruit continuously from early November to July (UF/IFAS EDIS). Gardening Solutions adds that citrus does not keep ripening after it is picked, but ripe fruit can be stored on the tree for a few months (UF/IFAS Gardening Solutions), so a Sebastian Valencia can be picked as needed through spring. Certified citrus and other fruit trees for Sebastian yards are among the fruit trees on Digital Towns Market. Digital Towns Market is our marketplace.

Indian River County sits inside federal citrus quarantine territory, so Sebastian residents buy only certified citrus from state-registered nurseries and keep citrus plants, branches and green waste from leaving the area.

APHIS spells out four steps that apply to Sebastian residents: know the quarantines in the area, buy only USDA-certified citrus plants, do not move branches, green waste, dead trees or other regulated items out of a quarantined area, and do not mail or transport home-grown citrus fruit or plants out of one (USDA APHIS). Gardening Solutions adds that it is very important to purchase only certified nursery plants from nurseries registered with the state (UF/IFAS Gardening Solutions). Last verified: October 10, 2026, on the USDA APHIS website.

Canker is the second regulated disease. APHIS states that citrus canker, a bacterial disease that thrives with high rainfall and warm temperatures, is found throughout Florida and has no treatment (USDA APHIS). It spreads by wind and rain and by people moving contaminated equipment, infected fruit, plants and clippings, which is why a Sebastian yard crew's trimmings from a citrus tree count as regulated material.

The eradication fight is over. APHIS records that canker was rediscovered in Miami-Dade County in 1995, that storms in 2004 and 2005 spread it beyond eradication, and that the Secretary of Agriculture ended eradication efforts in 2006. For Indian River County, that history means canker is managed as a lasting condition of backyard citrus in Sebastian rather than a disease the state still tries to wipe out.

In Sebastian sand, a citrus tree is planted at its nursery soil line inside a water basin, fed about every six weeks the first year, and kept free of grass and mulch at the trunk to prevent foot rot.

The basin does the watering work on a new Sebastian planting. HS132 says to set container trees at the same soil line, build a basin holding five to ten gallons, and run a hose in it ten or fifteen minutes twice each week for the first month (UF/IFAS EDIS). Fertilizing begins when buds swell or three weeks after planting, then about every six weeks from February through October in the first year. Gardening Solutions says that after the third year citrus is fertilized four to five times per year (UF/IFAS Gardening Solutions).

Local law leaves room for that schedule. Indian River County's fertilizer ordinance blocks fertilizer from June 1 to September 30 for lawns and landscapes but exempts trees grown for their edible fruit (Indian River County). That county ordinance applies in the unincorporated areas; inside Sebastian, Section 50-5 of the city code sets the same June 1 through September 30 period and the same exemption for trees grown for their edible fruit (City of Sebastian), so Sebastian citrus can stay on its UF/IFAS schedule through summer.

The trunk needs bare ground. HS132 says weeds and sod should be removed from under the canopy because weeds near the trunk can promote foot rot, a soil-borne fungus that can kill the tree, and that mulch, if used, should stay at least a foot from the trunk. The optimum soil pH is 5.5 to 6.5, and Master Gardeners with UF/IFAS Extension Indian River County perform soil pH tests for residents, including those in Sebastian (UF/IFAS Extension).

Sebastian growers slow psyllids with the state's free Tamarixia wasp releases, ant control on the trunk and early removal of trees that stop producing, since sprays alone are costly and losing ground.

The wasp is the homeowner's ally. Gardening Solutions says Tamarixia radiata wasps have been released in commercial and research groves since 1999, attack only the Asian citrus psyllid, and are now available to home gardeners through a Florida Department of Agriculture and Consumer Services Division of Plant Industry program for dooryard citrus (UF/IFAS Gardening Solutions). Wasps must be released away from insecticide sprays and where psyllid nymphs are present, a fit for an unsprayed Sebastian tree.

Ants undo the work. The same page warns that ants can decrease the effectiveness of wasp biological control by 85 percent, and recommends a 2 cm sticky, non-insecticidal barrier around the trunk, a simple step for any Sebastian Highlands citrus tree.

Sprays have limits. APHIS says intensive chemical control is the primary management tool against the psyllid, but that this strategy is costly and increasingly ineffective (USDA APHIS). UF/IFAS advises that infected trees, once unproductive, are usually destroyed to minimize further spread, and that the county extension office in Vero Beach can explain safe disposal for Indian River County residents (UF/IFAS Gardening Solutions).