Frequent questions about pests, diseases and problems of mangoes

Why are the flowers on my mango tree turning black?

The fungal disease anthracnose is the most common cause of flowers turning black. The symptoms are small black spots developing on the flowers, stalks and small fruit. Preventative sprays can reduce the risk of infection. Fruitspotting bugs and bacterial flower disease also cause black spots on the inflorescence.

How do I control bacterial black spot?

Bacterial black spot invades young leaves and fruit mainly through surface damage caused by wind. Windbreaks reduce wind damage to trees and thus help to control infection. A sustained regular spray program using a registered fungicide will manage the disease.

Why are the leaves on my mango tree going brown?

Leaves turn brown for many reasons but the main cause is the disease anthracnose. Young leaves are particularly susceptible to infection, which is worse in wet conditions. If mainly the tips of the leaves are turning brown, it is probably fertiliser burn or saline irrigation water. Leafminers tunnelling through leaves can also cause leaves to turn brown.

Why is my new growth wilting?

Growth wilting is generally caused by two main insects:

  • the fruitspotting bug, which sucks sap from new growth, causing grooves along the length of the new stems and causing them to wilt
  • the mango tipborer, which hollows out the inside of new stems, causing more severe wilting than the fruitspotting bug. If you cut the stem lengthwise, you will find that it is hollowed out, often with a small caterpillar inside.

Why does some fruit never grow larger than an egg?

Egg-sized fruit is the result of poor pollination caused by cool night temperatures during flowering. Some of the fruit falls off and others develop to an egg size. This fruit is commonly called nubbins. If you cut them open, you find there is no seed.

Why is my fruit splitting?

The main reason for fruit splitting is infection by bacterial black spot.

What is the hollow in my fruit?

A hollow in the fruit is an occasional problem in Kensington Pride and some other varieties. The hollow develops at the top of the fruit where it is connected to the stem, known as stem-end cavity. It is related to a nutritional imbalance in the tree and fruit hanging on the tree for too long.

Why do my mangoes stay green?

Incorrect ripening practices and high nitrogen levels in the tree are the most common causes of mangoes staying green when ripe. Other causes include water stress, shade and harvesting immature. For more information, see What causes green ripe mangoes?

How do I avoid skin browning?

Incorrect harvesting and post-harvest handling practices cause skin browning. You need to manage your system to minimise skin damage from sap contamination, bumping, dirt, wetness and heat.

Why don´t my trees flower?

Mango trees are sensitive to climatic conditions at flower initiation. They need a dormant period in winter to initiate flowering. Poor flowering can also result from reduced carbohydrate reserves in the tree from a very heavy crop the previous season or late pruning.

Why do my trees flower but not set fruit?

Poor fruit set can be caused by poor pollination due to cold weather at flowering or fungal diseases, such as anthracnose in the flowers. There are also several insects that eat the flowers.

My trees are flowering early when the nights are cold. What should I do?

Early flowering at this time is difficult to manage. Flowers can be cut off as long as the weather stays cool. Healthy trees will produce new flowers in about six weeks. Remember to cut off just the flower panicle. There is a risk that late flower removal can result in the production of a leaf flush rather than flowers as the weather gets warmer.

Why is my fruit dropping off?

Mango flowers will set much more fruit than the tree can hold and have significant fruit drop. Other reasons for fruit falling off include water stress, poor pollination, disease and insect attack.

Last updated 07 October 2010