Introduction
The avocado tree is known as a tropical and subtropical evergreen tree native to Central America and Southern Mexico. For many years avocados have been a popular food, with the fruit being consumed for its health benefits like being a substantial source of vitamins and minerals. However, when an avid avocado consumer decides to grow an avocado tree themselves and finds the tree is not producing fruit, the question remains: why is my avocado tree not producing fruit?
Factors Involved in Fruit Production
The scientific answer to why an avocado tree is not producing is complex; not all avocado trees flower at the same time and avocado trees rely on a mixture of environmental and manual cues to produce fruit. Firstly, before understanding why an avocado tree is not producing, one must understand the factors involved when an avocado tree does produce fruit. Plant scientists have studied the stages of flowering and pollination required for an avocado tree to produce fruit, and understand that there are many steps necessary before avocados growing to maturity. Primarily, there needs to be sufficient crosses between two types of avocado tree, referred to as ‘A’ and ‘B’ flowers. Secondly, there needs to be an appropriate temperature, the right amount of sunlight,and the use of suitable pollinators such as bees and other insects.
Flowering and Fruit Production
Light and temperature both play a role in influencing avocado tree flowering, with high temperatures and varying amounts of light being associated with successful avocado tree flowering. The flowering of an avocado tree is dependant on a combination of weather and manual cues, such as pruning or fertilising the tree. Unlike other types of fruit trees, avocado trees are sometimes slow to flower, taking four to five years or longer to flower depending on the tree’s species. Once the avocado tree does flower, the flowers quickly bloom and typically only live for a day before wilting. Flowering of an avocado tree mainly takes place between the months of March to June and again between the months of August to December. For an avocado tree to produce fruit both flowers of the same tree need to be pollinated.
Different Types of Avocado Trees
Moreover, when it comes to avocado tree fruit production, not all types of avocado trees are the same. Firstly, there are two plant types when it comes to avocado trees; ‘B’ and ‘A’ flowered trees. ‘A’ flowered trees are more common and are the self-fertile type, meaning they flower and produce fruit without requiring cross-pollination with another avocado tree. On the other hand, ‘B’ flowered trees require cross-pollination from another avocado tree of the opposite type usually within a 400 meter radius. Moreover, of these two types, ‘B’ type trees are mostly found in Southern Mexico and Central America, whilst ’A’ type trees are mainly isolated to those grown in California, Israel and Northern South American countries.
Fruit Production and Pruning
Furthermore, for an avocado tree to successfully produce fruit, it is imperative that the tree is carefully pruned. Pruning involves cutting, removing and shape shaping of the branches of an avocado tree in order to encourage healthy, strong growth as well as fruit production. Additionally, an avocado tree should be fertilised in order to provide it with the essential nutrients necessary for it to produce fruit, this includes applying a fertilizer high in nitrogen and phosphorous such as compost or manure. Pruning and fertilising the tree should take place during the spring to early summer months due to the optimal conditions of high temperatures and sufficient sunlight.
Pests and Disease
Additionally, plant diseases and pests or insects can all pose a threat to an avocado tree’s fruit production. An avocado tree has many pests which can reduce fruit production or even destroy the tree entirely. Common pests that insects avocado trees are the avocado lace bug and the avocado thrips. To protect against pests, avocado trees should be sprayed or treated with an approved pest control methods such as crop dust or pesticides. Plant diseases are caused by a fungus, bacteria or virus and can cause an avocado tree to suffer from a lack of healthy growth or fruit production. Common diseases include the avocado root rot and the phytophthora root rot. A way to detect if an avocado tree has a disease is to inspect the tree and its leaves for any discolouration or wilt.
Environmental Factors.
It is possible that an essential environmental factor may be missing which is necessary for an avocado tree to produce fruit. Strong wind or cold weather may be preventing avocado tree flowering. High rainfall is known to reduce the chances of avocado flowering due to soil waterlogging. The distance between avocado trees can even stop flower pollination, as avocado trees need to be within a 400 meter radius to successfully cross-pollinate and produce fruit. As such,the climate and environmental factors of where an avocado tree is located (such as temperature variations, sun exposure, wind direction and intensity, soil fertility and water availability) need to be taken into consideration for fruit production to occur.
The Role of Bees
Bees are vital for successful avocado tree fruit production. Studies by plant scientists have shown that honey bees can increase the production of avocado fruit as they act as pollinators which help the avocado flowers to cross-pollenate and develop into avocados. Moreover, some bees are more suitable for avocado tree flowering than others, such as carpenter bees and bumblebees to mention a few; these bees have longer tongues than other types of bees which allows them to reach the nectar of the ‘B’ type flowers.
Male and Female Avocado Trees
Whenit comes to avocado trees, there is an important distinction between genders; male and female. Male trees produce the long thin flowers that carry the pollen, whilst female trees produce the bell-shaped flowers that will develop into avocados. Although as mentioned ‘A’ type trees are self-fertile, ‘B’ type trees require cross-pollination between a male and a female tree in order to produce avocados. As such, in the case of ‘B’ type avocado trees, having only one tree will stop avocado fruit production.
Identifying Fruiting and Non-Fruiting Trees
To identify if an avocado tree is fruiting or not, look to the flowering and winter dormancy of the tree. An avocado tree that flowers but does not produce fruit is indicating that the tree is not receiving the correct environmental and manual cues such as temperature and fertilising. Furthermore, an avocado tree that does not flower and appears to go into a long period of dormancy during the winter months, may not have received the time to develop and grow. To stimulate the growth of an avocado tree, pruning should take place during the early summer months, and fertilising should take place either in late winter or early spring.
Repotting
When it comes to repotting an avocado tree, it is important to do this during the warmer summer months when the tree is in a state of active growth. Repotting an avocado tree in the spring will prevent fruit production due to the tree becoming stressed and breaking its winter dormancy too early. Repotting an avocado tree should take place whenever the tree needs to be transplanted, due to it growing in size or because of growth slowing down. It is advisable to pot the tree into a slightly larger pot due to root overcrowding, as this can prevent fruit production by hindering the growth of the tree.
Fruit Thinning
Fruit thinning is a process where a portion or all of the avocados on the tree are removed, this ensures that the tree does not become overburdened with too much fruit which can overstress the tree, leading to a decrease in fruit production and growth. Once an avocado tree has been thinned and the remaining fruit has developed, it is important to note that the fruit should also be picked and stored properly in order to grow and mature. An age-old trick for storing unripened avocados, or avocados in which you wish to ripen, is to store them with an apple or banana, who produce ethylene gas that helps to ripen the avocados.
Pruning
Lastly, it is important to keep multiple branches on an avocado tree, as this allows the tree to receive sunlight in multiple directions and increases the chances of fruit production.
Pruning an avocado tree should be done carefully, as too much pruning can cause stress and decrease the avocado tree’s chances of pollination and ultimately fruit production. Pruning should be done in a systematic way, firstly, begin at the top and make sure to leave the thickest branches and move downwards to the thinnest branches. Pruning can also be used to shape the tree into a desired size, shape and structure, making sure to avoid letting any one branch of the avocado tree dominate the tree.
