Mango

Water a young tree, mostly leave a mature one alone

Water at planting and every other day for the first week, then once or twice a week for the first couple of months, and about weekly in dry spells until the tree is three. From year four, irrigate only during a very prolonged spring or summer drought. Keep water off the flowers and fruit - run a low sprinkler or drip, not an overhead. Mature mango trees do not need frequent watering and overwatering produces poor-quality, watery fruit. Wetting the panicles is worse than useless - anthracnose needs free water on the flowers to infect, so an overhead sprinkler manufactures the disease you are otherwise spraying against.

Feed young trees six times a year, then cut the nitrogen once it bears

For the first three years, make about six applications a year, starting at a quarter to a half pound per tree and working up toward 1 to 1.5 lb, using a 6-6-6-2 or 8-3-9-2 type mix. From year four on, drop to four applications a year at 1.5 to 4 lb each, drastically reduce or eliminate the nitrogen, and raise the potash to 9-15 percent - 6-3-16 and 0-0-22 are the mixes UF/IFAS names. Nitrogen buys leaves, not mangos. A bearing tree fed heavy nitrogen puts its energy into vegetative flushes instead of flower panicles, and the fruit it does set eats poorer.

⚠ If you use a boron-containing micronutrient product, apply it at roughly 1/300th of the nitrogen rate - UF/IFAS warns boron is toxic to plants at moderate to high rates.

Iron and micronutrients if your soil is alkaline

On high-pH or calcareous soil, drench the root zone with chelated iron in the FeEDDHA form two or three times through the growing season, and add an annual foliar spray of copper, zinc, manganese and boron. On neutral or acidic soil, iron sulfate watered in two or three times a year is enough and costs far less. Above about pH 7 the ordinary iron chelates fall apart and the iron locks up as an oxide the roots cannot take, so leaves go yellow between green veins while the soil is technically full of iron. FeEDDHA is the one chelate that holds on at high pH.

Prune soon after you pick the last fruit

Once the last fruit is off the tree, take out a few upper limbs back to their crotches to hold the height down and open the canopy. UF/IFAS says pruning should be done soon after harvest; get it done early enough that any regrowth hardens off before the tree sets panicles. Severe pruning does not injure a mango, but it reduces production for one to several seasons. A mango sets its flower panicles on shoots that hardened off after the summer flush. Cut late and you are removing the wood that was going to bloom, or forcing a soft flush that will not be mature enough to flower.

⚠ Once a mango is 25 to 30 ft or taller, UF/IFAS says climbing the tree to prune it is dangerous and not recommended - hire a professional arborist who is licensed and insured.

Look for pests, but do not spray on principle

Walk the tree through the growing season and look for bud mites, red-banded thrips, scale insects such as false oleander and Florida red, spider mites, and ambrosia beetle entry holes in the trunk and limbs. Treat only when you find a large infestation, and ask your local extension office what is currently labeled before you buy anything. UF/IFAS is explicit that mango insect infestations are not predictable and control measures are justified only when large infestations occur. A calendar insecticide on a home mango mostly kills the thrips and flies that pollinate the panicles.

⚠ Never apply an insecticide while the tree is in bloom - thrips, flies and bees are what set your crop.

Anthracnose: copper on the flower panicles, then stop

Spray copper when the panicle is about a quarter of full size and again 10-21 days later. Sprays should continue at the recommended interval only until the fruit is about 1.5-2 inches long - then stop. Anthracnose infects the flowers and small fruit; the black spots that appear on a ripening mango are an infection that happened at bloom, months earlier.

⚠ Copper hydroxide's PHI on mango is 0 days, but the PHI is NOT the operative limit here: the extension spray window CLOSES months before harvest, so a summer copper spray is legal and still later than it should be. UF/IFAS says disease control on a home mango is usually not warranted or should not be intensive - cultivar choice and a hot, dry site are the primary controls. Wash fruit before eating. Copper can burn foliage if the spray pH is below 6.5.

Powdery mildew: sulfur preventively as the panicle expands

Time this to the panicle, not the calendar. UF/IFAS calls for one to two applications of sulfur and copper beginning when the panicle is about 1/4 full size, with a second 10 to 21 days later. Do not wait for the white powdery growth to appear: infection happens days to months before symptoms show, and sprays applied after infection have no effect on disease already established. If mildew does appear on flowers, young fruit, or leaf midribs, sulfur will still limit spread into new growth, but the crop-saving application is the early one. Unlike anthracnose, this fungus works in dry, mild spring weather rather than rain. A severe infection destroys the flowering panicles outright, so you lose the whole crop at set rather than losing fruit quality later - which is why UF/IFAS times the spray ahead of symptoms.

⚠ Follow the product label rate and pre-harvest interval for mango; the label is the law and MG216 does not substitute for it. Do not assume sulfur is pollinator-safe - it is a fungicide, not an insecticide, but it can harm some pollinators and beneficial mites, so spray early or late in the day when thrips, flies and bees are least active on the panicles. Do not apply sulfur above about 90F or within two weeks of an oil spray - it burns foliage.

Cover for cold - the flowers give up long before the tree does

Watch the forecast through bloom. A mature tree takes 25F for a few hours with damage limited to leaves and small branches, but open flowers and small fruit can be lost below 40F. Cover or heat trees under three years old whenever 29F to 30F is possible. Mango blooms in winter, so its most cold-sensitive tissue is out in the coldest part of the year. The threshold that kills the crop is nearly fifteen degrees warmer than the threshold that hurts the tree, which is why a grower can lose an entire year to a night that left no visible mark.

⚠ A young mango can be killed outright at 29F to 30F - protect the trunk of a tree under three years old, not just the canopy.

Pick mature-green, ripen on the counter at 70-75F

The fruit is mature when the shoulders and nose broaden and fill out. If you are unsure, cut one - mature flesh next to the seed has turned from white to yellow, and that happens before any color break in the peel. Pick firm and hold at 70F to 75F; mature fruit ripens in three to eight days. Mango ripens off the tree, and the internal color change at the seed is a truer maturity signal than skin color, which varies by variety and by how much sun the fruit saw.

⚠ Do not refrigerate a mango before it ripens. Chilling an unripe fruit causes brown or gray skin discoloration, surface pitting, uneven ripening and off flavors, and it is not reversible.