Well in advance of the hurricane season, an assessment of the location and size of the fruit trees in the home landscape should be made. Ideally, fruit trees with a potential to become large (e.g., avocado and mango) and not regularly pruned should be planted 25 ft or more away from the home, other structures (e.g., garages and toolsheds), power lines, and other trees. If, however, a large fruit tree is already in place, a certified arborist should be contacted to reduce tree height and properly prune the tree to open the canopy to wind movement.
The most effective cultural practice to reduce the potential for tree toppling and major damage is managing tree height and spread. Ideally, fruit trees in the home landscape should be pruned annually or biannually beginning soon after planting to develop a strong tree structure and later to remove dead wood, reduce tree height and spread (if needed occasionally), and open the tree to wind movement. Small fruit trees such as guava and sugar apple may be kept at 3 to 12 ft and 6 to 12 ft high, respectively. Potentially large trees like avocado may be kept at 10 to 15 ft, and mango at 6 to 15 ft high, with judicious but regular pruning.
Proper planting of fruit trees will reduce the potential for storm-related toppling and uprooting in the future. The deeper and more extensive the lateral root system the less likely the tree will topple, uproot, or lean after a windstorm. Root growth and establishment will be facilitated by loosening a large area of soil during the planting process. In sandy-type soils found throughout much of Florida, the planting hole should be 3 times the size of the container the tree came in. In Miami-Dade and Monroe Counties where the soil is often a rocky, limestone-based material, augering or excavating large holes or multiple holes is essential in establishing a root system with some ability to anchor trees in place.
Flooding potential before planting is an important factor to consider in south Florida. If there is a possibility of flooding, then consider bedding or mounding the soil, and choose flood-tolerant fruit species. Tools to have on hand include a lopper, a hand clipper and a hand saw, a pole saw, a shovel, a pick and a digging bar, and, if possible, a chainsaw with extra chains and fuel.
Before a storm, photographs of the landscape may be useful documentation, especially if the landscape is insured. Immediately covering the upper, sun-exposed surface of the tree trunk, major scaffold limbs and exposed roots with detached (fallen) limbs and/or other debris will shade them from sunlight. Alternatively, immediately painting the exposed areas with a 50/50 mixture of white latex paint and water will reflect sunlight and keep the exposed surfaces from overheating due to excessive sun exposure.
Fruit trees that have fallen over but still have some root system in the ground and have leaf canopy remaining can be saved but are in danger of drying out (drought stress). Pruning to remove some but not all the canopy (maybe 1/3 of what remains) will reduce the water demand of the tree by reducing the water loss from the tree. Resetting large (15 ft tall or greater) trees requires large equipment such as a tractor or backhoe and may not be feasible for most home owners to do themselves. Hiring a licensed arborist or landscape contractor may be appropriate.
Trees showing signs of drought stress that have fruit tend to decline and die at a greater rate than those with little or no fruit. Recommendations for small trees that have fallen over include covering the trunk and major limbs with debris, removing 1/3 to 1/2 of the canopy, and resetting the tree to an upright position as soon as possible. Small trees that have not fallen over and that have retained their leaves and/or fruit should be monitored closely for signs of drought stress, an indication of root and/or trunk damage.
The tolerance to flooding or saturated soil conditions of tropical and subtropical fruit trees varies. Some fruit trees such as avocado and papaya may not withstand more than a day or two of saturated or flooded soil conditions. In contrast, mango trees may withstand several weeks and guava trees a week of saturated or flooded soil conditions. Symptoms of flooding stress include dead roots, leaf and stem wilting, leaf yellowing and browning, leaf drop, stem and limb dieback, fruit shriveling and/or drop, and tree death. Fruit should be removed from trees with little to no tolerance to saturated soil conditions, and trees showing signs of flooding stress should have up to ½ the leafy tree canopy removed to reduce the stress imposed by soil conditions.
The hurricane and tropical storm season in Florida lasts from June through November. The minimum and optimum temperatures necessary for tree growth of tropical and subtropical fruit trees vary, but warm to hot weather with periodic rainfall after early and mid-season windstorms is generally conducive to new shoot and leaf growth and rapid recovery of the tree canopy, whereas cooler temperatures and less frequent rainfall after late-season windstorms, i.e., those in October through November, result in less canopy recovery and/or nutrient-deficient regrowth.
Trees that remained standing after the storm with most of their canopy intact should be watered regularly (e.g., 2 to 3 times per week) to keep an adequate soil moisture level, especially during prolonged dry periods. Only trees showing drought symptoms should have 1/3 to 1/2 of the canopy removed to reduce tree water loss. For trees that have few to no leaves or that toppled and were reset, reduce watering until new shoots and leaves begin to emerge, and then resume regular watering.
Trees that remain standing after a storm with 1/3 or more of the canopy remaining should be fertilized frequently with small amounts of complete (nitrogen, phosphate, potash, magnesium) fertilizers. Once leaves emerge and are about half-grown, foliar micronutrients (zinc, manganese), and soil drenches of chelated iron materials should be made every 2nd or 3rd month until the leaves are full-grown. Trees with few to no leaves or with some of the canopy cut off by pruning should be fertilized with a reduced amount of fertilizer (e.g., if half the leaves are gone, reduce the rate by 50%).
Weeds should be controlled manually or with approved herbicides to reduce the competition between the recovering tree and weeds for water and nutrients. Do not use residual herbicides because they may cause damage to the trees. Four to 6 inches of mulch applied several inches from the trunk outward to the previous drip-line will assist in suppressing weed growth and help maintain soil moisture.
Visit SouthFloridaTrees.com for more local tree care information and resources. By properly preparing your subtropical trees for hurricane season, you can help ensure their long-term health and resilience in the face of extreme weather.
