Reasons for Lychee Leaves Turning Brown
Whenever a plant’s foliage begins to turn brown or yellow, there are a few specific things we need to inspect.
First, are they brown or yellow spots or speckles, or an overall discoloration of the leaves? Spots and speckles on foliage often signifies disease or pests. Are the lychee leaves turning brown only at their tips? Foliage that turns brown only at its tips can indicate a watering problem, either too much water or too little. Tip burn can also indicate overfertilizing or a nutrient deficiency. Do the brown leaves on a lychee tree cover the whole tree or just certain spots? If only half of the lychee tree displays brown leaves, it could simply be a sign of windburn, which lychee trees can be very susceptible to.
When diagnosing brown or yellowing leaves on a lychee tree, you will also want to take note of when these symptoms first occurred. Was it a period of cooler, wet weather followed by heat and humidity? Environmental conditions like this are not only perfect for fungal growth and spread, but they can also shock a tree with too much water and moisture. Did brown lychee leaves appear after a hot, dry period? Drought stress can cause dried out leaves and defoliation of lychee trees. Lychee growers recommend growing lychee in a full sun site with protection from wind. Though they will require deep watering during periods of drought, they are otherwise infrequently watered to allow them to grow their own deep, vigorous roots. It can be common for lychee trees to display yellow or brown leaves as they adjust to environmental changes. Commercially they are fertilized specifically to induce abundant fruit set, but lychee trees in the home garden will do best with a general-purpose fertilizer for fruit trees. Using slow-release fertilizer helps avoid fertilizer burn.
Other Causes for Lychee with Brown Leaves
If you have ruled out environmental changes as a cause for brown lychee leaves, it could be disease related. Brown or yellow spots, speckling, or mottling are symptoms of a few diseases that lychee trees are susceptible to.
Phyllosticta leaf spot is a disease which causes tan to black lesions and curling on lychee leaves. The light brown spots of Gloeosporium leaf blight merge together, eventually making the whole leaf look scorched brown, before defoliation occurs. Lychee leaf necrosis is a fungal disease which causes yellow and brown lesions to form on lychee foliage.
