Mandarin / Tangerine

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.

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.

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.

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.

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.

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.

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.