Why Does My Fruit Taste Sour?

24 December 2022

Harvesting fruits is a great experience.

After years of hard work, pruning, and nursing the young plant till it matures, your plants finally have those fruits you have been expecting after several seasons.

The sad thing is that some of these fruits don’t taste as we expect. Sometimes the harvested fruit can end up tasting sour.

There are myriad reasons why fruits taste sour.

In this article, we shall discuss several reasons why your fruit tastes sour, and we shall recommend solutions on how to deal with it.

Why Does Fruit Become Sour?

Sour is one of the major basic tastes in fruits that is almost unavoidable and it merely indicates that there is a large amount of acid in your fruit.

Generally, a fruit that hasn’t ripened will have more acid and minimal fructose. A different phase of chemical changes happens when the fruit starts to ripen.

As the fruit ripens, the acid in the fruit will begin to decrease and the amount of fructose will increase, this will make the fruit sweeter.

However, fruits like lime which have too much acid can’t be sweet even after it ripens.

Causes of Sour Fruits

Sour fruits are mostly caused by irregular irrigation and excessive rain or water during the development of the fruit.

The common factors responsible for sour fruits are as follows:

  1. Soil-borne yeasts
  2. Rootstock
  3. Fruit maturity
  4. Citrus greening

1. Root Stock

Most trees are grafted to a rootstock. Grafting simply means joining two plants together.

In practice, a gardener can combine a desirable fruit plant (scion) with another plant that has impressive growth characteristics, stress tolerance, and disease resistance.

For instance, the majority of citrus trees are grafted completely to other citrus species at nurseries.

In most cases, rootstock produces fruit with a sour taste, thus it may not end well for citrus plants.

A reason for the sour fruits is that the rootstock will sometimes produce branches or shoots on its own, and if not removed, it will eventually compete with the scion to produce its fruit.

Another reason for this is common in young trees, where the scion is destroyed by cold, and the rootstock which is resistant to cold continues to grow and produce fruits that will eventually become sour.


Check the tree to see if the branch that is producing the sour fruit is above or below the bud union of the shoot.

The bud union is about 6 to 12 inches above the surface of the soil. The change in texture between the scion and rootstocks marks this area.

You should cut off anything that is growing below the bud union, as it can produce unwanted fruits with an undesirable taste.

2. Fruit Maturity

Fruit maturity is another factor responsible for sour fruits. This problem is common for citrus fruits.

Naturally, a fruit that is still unripe or not fully mature will taste sour because the starch in the fruit is yet to convert to sugar and the other nutrition compounds are still not found and in the developing phase.

Also, if you grow a plant outside its normal season, it is likely you won’t get the best out of the fruits.

The fruit will not mature properly and will have a sour taste flavor.


You must know more about the season and the best time to plant them.

For example, the citrus plant normally matures between October and May, however, it depends on the species.

Satsumas also mature in October and produce sweet fruits once temperatures drop to 50 degrees.

Tangerines mature between November and December, while oranges and grapefruits mature from December to April.

Thus, you must plant your citrus fruit within these periods and harvest them at the specified temperatures.

The good thing about citrus fruit is that they can still be stored on the tree even after it ripens. Therefore, the important thing is to understand the season of each plant you want to grow.

When you are also in doubt, harvest just a few fruits first to ascertain the maturity window of that particular plant.

3. Citrus Greening

Your fruits can have a sour taste as a result of citrus greening.

Citrus greening is a disease common in plants and it is caused by a bacterium called Candidatus Liberibacter asiaticus. The disease discolors the fruit and makes it misshapen. The disease infects the tree and this will stop the fruits from ripening properly.

Citrus greening mostly affects citrus fruits like limes, lemons, oranges, lime berries, and tangerines.


A tree infected with citrus greening can’t be cured, this is why early detection of citrus greening symptoms is really important.

Timely removal of infected trees is the only way to prevent the spread of the bacteria that causes the infection.

Infected trees only act as a reservoir for this economically harmful disease, as the trees can never produce useful fruit again.

4. Soil-Borne Yeasts

Fruits can taste sour when soil-borne yeasts enter the skin of the fruit. Soil-borne yeasts affect plants with clustered fruits.

These yeasts feed on the fruit and this will make the fruit ferment.

The small holes on the fruit caused by soil-borne yeasts, though not visible to the naked eye will be soaked with water and this will spread across the surface of the infected fruit.

Insects like wasps, vinegar flies, and pest insects can quickly spread the infection on tightly clustered fruits as they may carry spores with them and rub them on fresh fruits as they move around.

As the yeasts spread across the fruit, they will break down the tissues and this will make it slimy.

In some cases, gas bubbles may come out from those tiny pores on the surface of the fruit and a layer of mycelium may appear.

Sometimes, the color of the affected fruit may change, however, this depends on the species of the fruit.


It is impossible to save all fruits that are infected with soil-borne yeasts. However, you can prevent other fruits from getting affected.

You must first separate the fruits that seem to be infested with yeast. This method may be difficult on grapes, so you will have to remove the whole bunch.

A lasting solution to this is to first trap the flies. You can also install a screen house around the plant. This will protect it from future infection.

Another solution is to install a canopy over the plant so the fruits can receive fresh air. Yeast can’t survive in a dry environment.

Generally, there are no chemicals designed to control soil-borne yeasts, but if you apply kaolin clay at an early stage of plant development, it can deter vinegar flies from getting close to the plants.

Wrapping Up

A fruit that tastes sour can lead to an unpleasant condition where the fruit will leave a bad taste in your mouth.

This can be frustrating after years of waiting to harvest the fruits. You must do all you can to avoid this situation so that your effort won’t be futile.

The only way you can achieve this is to read and follow the preventive measures in this article so you can grow and harvest fresh fruits that are free of sour rot and bug infections.

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