Q: My mango is not fruiting / my mango drops all the fruit before it ripens.
A: Any fruit tree may skip a fruiting season. This is natural, and especially common the year following a large crop. It is also normal for a young tree to abort fruit until the tree is large enough. See the pruning videos on how to encourage a mango to be bushy which allows a younger tree to bear fruit.
• It could be Fertilizer issues.
• Fungus There are two main fungal diseases that can inhibit fruiting in mangoes–anthracnose and powdery mildew.
Take care when spraying fungicides: avoid getting on your skin or eyes.
If fungus is problematic in your area, plant disease resistant varieties.
This is another good reason to keep mango trees pruned small, so they are easily sprayed, and also thinned out so air can circulate.
Mangos are especially susceptible to anthracnose, a fungus which grows best in warm wet weather. Oval black spots on the fruit skin is another symptom besides attacking flowers. Some varieties are more disease resistant. Cut off old fruiting spurs when picking the fruit since they harbor the spores. Spray with fungicide when flowers first appear but before they open and maybe again when the fruit just forms. You may need to spray more often when conditions are ideal for fungus.
The other disease that can cause sparse fruiting is powdery mildew which can attack mango flowers in cool dry weather. Treat when the bloom spikes first begin to emerge, again as they develop, and finally just before the buds open.
Controlling diseases of Mango Blooms (Dr. Crane YouTube video)
Use homemade fungicide. (also insecticidal soap & oil)
Or copper spray is an effective fungicide for anthracnose. Copper is available as a concentrated liquid in garden or home centers. One caution: copper is fatal to bromeliads. That includes pineapple plants.
Sulfur spray made from wettable sulfur and water is used for powdery mildew. Spray before 50% bloom, just before the flowers open, and again weekly until fruit set.
• Tree is too vigorous (too many leaves, not enough flowers or fruit). See the video section in the main menu.
Tree too large–can’t reach the mangoes. See the pruning videos to keep mango trees more manageable (8-15 feet maximum).
If you have a tree that is already too large, it can still be reduced in size. If it is a really vigorous variety, like a Valencia Pride or Hayden, that pushes out 3 or 4 flushes of growth per year, this will be a difficult battle. It is easier to manage a slower growing tree, like a Pickering, that puts out 1 or 2 flushes.
The safest way is to hire a professional tree trimmer, and have them remove no more than the upper 1/3 of the tree. This can be done each year over a few years until the tree is a reasonable size. Removing that much from a really large tree, or if it is near overhead wires, is definitely a job for a licensed and insured professional. It really is not worth taking a chance on getting injured, or tree limbs causing property damage.
The best time for maintenance pruning (video of Dr. Crane of TREC) is during or immediately after harvesting. Drastic pruning should be done in March to give the tree plenty of time to recover before the next winter. The lower part of the tree might continue to fruit, but accept the possibility of the loss of that year’s crop. Mangoes are very vigorous, and will create new branches quickly. After a few years, the whole tree will be a smaller size.
A second method is to remove just one or two main vertical branches each year. It is more likely you will continue to get fruit this way on the rest of the tree.
Once your large mango tree is smaller, follow the pruning techniques from the videos.
If your mango is too big, not fruiting, and you have decided to get rid of it anyway, there is a third really drastic way to force it to be small quickly. An arborist might be horrified, but have it cut down, leaving about a 3-4 foot clean stump. (be sure to watch the videos below–this is not for the faint of heart!) The tree service can advise how to protect the stump from sun exposure, disease and insects. Unless the tree has other health issues or rot in the trunk, it should re-sprout. After about 3-6 months there will be a lot of new sprouts. Remove all but the strongest to create a new symmetrical shape. Because it has a full size root system, it can recover quickly and form a bushy tree much faster than planting a new tree. Be sure to thin the new growth and maintain size.
This is also done with both avocado and mango to top work (graft on a new or more popular cultivar) onto an existing tree. Do not top work unless you can successfully graft on a seedling, or you know a grafting expert who is willing to help.