Use a garden hose to water the soil around the tree once a week, applying just enough water to create visible moisture on the surface of the soil.  During rainy seasons, additional waterings may not be needed. On the other hand, during abnormal droughts, you may need to increase your watering schedule from once to twice a week. Regardless of how the weather is, the idea is simply to keep the soil regularly moist. Consistent sources of water are especially important while mahogany trees are young and have not yet established themselves. Fully mature trees can tolerate some drought without dying, but dry spells may cause the tree to drop its leaves early for the season. Feed the tree with a dose of fertilizer in the spring, summer, and fall. Use a balanced granular fertilizer for best results.  The same type of fertilizer used at the time of planting can be used for yearly maintenance. The fertilizer should contain equal parts nitrogen, phosphorus, and potassium. Follow the dosage instructions provided on the label of the fertilizer used. For best results, mix the fertilizer into the soil around the tree instead of spreading it over the surface of the soil. During the first two to eight years of the tree's life, yearly pruning can help control the height and spread of the tree.  Check the arrangement and space between limbs. The healthiest mahogany trees will have several evenly spaced major limbs that spread out along one central trunk or central leader. As the tree grows, these limbs will be at least 2 feet (61 cm) apart from one another, if not further. Prune away any upright leaders aside from the central trunk. These upward growing branches can make it more difficult for the tree to tolerate strong winds and storms, thereby weakening it. Cut away any branches that grow larger than two-thirds of the diameter of the central trunk. Such limbs can put stress on the tree and shorten its lifespan. There are a few common pests that may present a problem to the health and longevity of your tree. When you spot such pests, apply an appropriate pesticide to the area.  Some of the biggest problems come from shoot borers, longhorn beetles, powder post beetles, tent caterpillars, tip moths, scale, leaf notchers, leaf miners, Cuban leaf beetles, mahogany webworms, and Sri Lanka weevils. Among these insect pests, borers present the greatest threat to the health and longevity of the tree. When borers are present, pesticides should be applied. The other pests mostly cause aesthetic damage to the tree and don't often cause structural damage. As a result, pesticide application is not as crucial when these pests are spotted. You can treat the tree or choose not to do so. When selecting a pesticide, look for one specifically labeled to work against the type of pest you are trying to kill. Do not assume that all pesticides will work on all pests. While diseases rarely strike mahogany trees, nectria infection can develop when the tree becomes stressed or injured.  Look for discolored bark along the branches of the tree, particularly where the branch meets the trunk. As the fungal disease progresses, the discoloration can turn into small cream-colored to reddish cankers that develop on the surface of the bark. These bumps will continue to grow and can eventually kill entire branches or trees. The best way to save a mahogany tree facing nectria infection is to remove the infected wood. You may also apply a fungicide to the tree, but fungicides do not always work on this particular type of infection.

Summary:
Water regularly. Fertilize three times each year. Prune young mahogany trees. Watch out for pests. Monitor the tree for signs of infection.