Mango leaves turn yellow for five main reasons. Overwatering, nutrient shortage, cold damage, pests, and natural leaf drop all cause this problem. Finding the right cause takes some detective work. You need to check several things about your tree before you can fix the issue.
Start your diagnosis with watering habits since this causes most mango leaf problems in home gardens. Stick your finger two inches into the soil. Wet or soggy soil points to overwatering. Mango roots rot fast in constant moisture and yellow leaves often appear first. Let the soil dry out between waterings and check for soft brown roots if you suspect root rot already took hold.
I panicked the first time my young mango dropped yellow leaves all over my patio. The soil felt wet even though I had not watered in days. I repotted into fresh dry mix and cut back any mushy roots. The tree bounced back within a month and pushed out healthy new growth. Now I always check soil moisture before I water.
Nutrient problems show up in specific patterns on the leaves. Nitrogen shortage causes older leaves to yellow from the bottom of the tree upward. Iron shortage looks different from nitrogen problems. You see yellow between the leaf veins while the veins stay green. This pattern is called chlorosis. Feed your tree a balanced fertilizer to fix nitrogen issues. Iron problems need chelated iron sprays to correct.
Cold exposure damages mango leaves at temps you might not expect. Seedlings show stress below 59°F (15°C) and yellowing often follows cold nights. Mature trees handle cooler temps better but still suffer below 40°F (4.4°C). Move container trees indoors before cold snaps hit. Watch for yellow leaves a few days after any cold weather arrives in your area.
Check the undersides of leaves and stems for pests when other causes seem ruled out. Spider mites, scale, and mealybugs all drain sap and cause yellow spots or overall yellowing. You may see tiny webs, bumps, or white cotton on affected leaves. Neem oil or insecticidal soap treats most of these pests within a few weeks of regular spraying.
Sometimes a yellowing mango tree just needs to drop old leaves. Mango trees shed older leaves as new growth pushes out. This natural drop happens most in spring when the tree gets ready to flower and fruit. A few yellow leaves at the bottom of the canopy during growing season is normal. Worry only when many leaves yellow at once or when new growth turns yellow too. Healthy trees replace dropped leaves fast and keep a full green canopy.
Read the full article: Growing a Mango Tree From Seed in 5 Steps
