Mandarin / Tangerine

Feed from March to early August, then stopMar – Aug

Apply a balanced 10-10-10 with micronutrients roughly every six weeks starting in March and ending in early August. Spread it evenly over a circle about 1.5 times the width of the canopy, not against the trunk. Do not feed from September through mid-February. Nitrogen after late summer pushes a soft autumn flush that has no time to harden before the first freeze, and that tender growth is exactly what a cold night kills. Bearing trees need the nitrogen already in place before flowering and fruit set.

⚠ Where citrus leafminer is established, late-summer nitrogen is doubly bad - it feeds the flush right when leafminer numbers peak. Keep fertilizer off the trunk and out of the graft union.

Light pruning in late winter, just before bloom

Wait until hard freeze danger has passed, then prune just before bloom or just after fruit set. Mandarins need very little: take out crossing and dead branches, and cut any sucker arising below the graft union right back to the trunk. Leave the tree full-skirted rather than limbing it up. Paint any newly exposed bark with a 50:50 mix of white interior latex paint and water. Pruning late in the season pushes tender growth that frost will kill, and shoots below the bud union come from the rootstock, so they never bear the fruit you planted. Bark that spent years shaded burns in full sun once you open the canopy.

⚠ Avoid pruning live branches more than once a year - each cut triggers a new flush, and staggered flushes are what keep citrus leafminer breeding all season.

Citrus leafminer: look, but on a mature tree do not spray

Check the summer and fall flush for silvery serpentine mines with a thin dark frass line inside, and curled leaves. On an established tree, leave it alone - do not spray, and do not pick off mined leaves, because the undamaged part of the leaf still feeds the tree. Do remove water sprouts, which flush for months and give the moth a nursery. Leafminer infestations on mature trees rarely if ever require insecticide treatment; parasitic wasps do the work, and a broad-spectrum spray kills them and makes the problem worse.

⚠ If a young tree is being repeatedly defoliated, azadirachtin or spinosad are the options that spare natural enemies, reapplied every 7-14 days. Imidacloprid holds longer but is a bee killer: never apply it during bloom or within one month before bloom, and strip the blossoms off young trees you treat.

Alternaria brown spot: first copper as the spring flush expands

On susceptible varieties only - Dancy, Murcott, Minneola tangelo, and less frequently Sunburst, Orlando, Nova and Lee - spray copper when the new spring flush is about a quarter to half expanded, before any spots appear. If infection is heavy, repeat as the flush nears full expansion. Satsuma is not among the susceptible varieties listed for this disease and generally does not need this program; if you grow one of the susceptible types above, do not skip it. The tangerine pathotype of Alternaria alternata infects young expanding leaves; heavy infection on the spring flush builds the spore load that later ruins the fruit, and once that happens brown spot is very hard to control.

⚠ Copper is protective only - it must be on the tissue before infection, not after. If you use a strobilurin (FRAC 11) instead, resistance is already documented in Florida tangerine blocks: limit strobilurin (FRAC 11), DMI (FRAC 3) and SDHI (FRAC 7) products to four applications a season and never more than two consecutive applications of the same mode of action. Follow the product label rate and pre-harvest interval, which vary by copper formulation.

Alternaria brown spot: second copper shortly after petal fall

On susceptible varieties, spray copper again shortly after the petals drop, then keep a protective film on the young fruit through the wet months - every two to four weeks depending on how often it rains. About 2 lb metallic copper per acre covers a three-week interval, or 1 lb if you spray more often. Young fruit is susceptible from set onward, and each rain both spreads spores and washes off residue, so protection has to be renewed rather than applied once.

⚠ This is a fungicide, not an insecticide - do not substitute an insecticide here, since bees are still working the tree at petal fall. Copper accumulates in soil and can burn fruit in hot weather; UF/IFAS bars Amistar Top, Gem, Headline, Pristine and Quadris from nurseries entirely.

Winter freeze protection: bank soil over the graft unionJan – Dec

In early December mound soil around the trunk to a height of about two feet, covering the region above the graft union, and remove the mound by mid-March. In-tree micro-sprinklers protect to a height of roughly five feet; commercial trunk wraps add some further protection. A mature dormant satsuma has come through 14-18F without serious injury, but the graft union is the part you cannot replace - if it survives, the tree regrows as your variety rather than as rootstock.

⚠ Take the soil mound off by mid-March - left in place through warm wet weather it invites foot rot at the trunk. Leaving mulch or wraps piled against the trunk year-round does the same thing.

Taste one before you pick, and pick satsumas promptly

Do not go by rind color - taste a fruit first. In humid climates satsumas often sweeten inside while the peel is still green. Once they are good, pick steadily: UF/IFAS reports satsumas hold poorly on the tree after maturity and must be picked promptly, or they go puffy and dry. Clip or snap the fruit off, then refrigerate at 32-36F, where they store well. Citrus does not ripen after picking - the fruit only slowly dries out - so the tree is the only place it can get sweeter, and a taste test is the only honest maturity test. Rind color develops well before eating quality in warm autumns, and long after it in cool ones.