Why is my sugar apple turning black?

It’s June, and you’re seeing the first baby fruits on your Sugar apple tree – suddenly, as you check your sugar apples – oh no! They have turned black.

You are frustrated and confused because how could one of your sweet sugar apples rot when you were doing everything right?

Look no further: Here are some reasons your sugar apples are turning black with solutions.

Why are my sugar apples turning black?

The sugar apple turns black because of the Annona seed borer, a sugar apple pest.

The Annona Seed Borer, also known as the ‘Chalcid Wasp,’ Is an Annonaceae pest in Florida that burrows its way into Sugar Apples.

Once they infest the sugar apple, they lay their eggs in the tiny seeds. 

This process creates a fungus in the sugar apple, turning it black & hard.

The process of the sugar apple turning black is known as mummification.

The Annona Seed Borer will crawl out of the black sugar apple and try to lay eggs in other non-affected sugar apples.

Taking care of this problem in your garden is essential to ensure the best sugar apple harvest.

In this video, I explain why the sugar apple (Annona squamosa) turns black on the tree before reaching full maturity (harvest).

Fungus attacks the sugar apple fruit when there is high humidity

The sugar apple fruit may turn black on the tree due to fungus attacking the fruit that causes it to turn black when the humidity is high.

This fungus thrives in humid climates, and if the sugar apple is planted in a location with high humidity, it could suffer from this fungus. 

If you notice your young sugar apple fruits develop black spots around the fruit, it could be the start of the fungus.

Once the fruit is infected, it will likely rot.

It is essential to perform pruning on the branches to allow airflow through to maximize airflow throughout the tree.

More airflow through the sugar apple tree will decrease the likelihood of a fungus attack.

The sugar apple turns black because of too many sugar apples on one tree.

If you perform hand pollination on your sugar apple flowers and the tree is too small to hold many fruits – it will naturally turn some black so it can focus on a few to ripen mature.

Annona trees, when hand-pollinated, can nearly guarantee a fruit – for more information on How to pollinate sugar apple flowers read this article here.

Because of this, sugar apple trees can overbear fruits, especially when young.

New sugar apple growers are often eager to fruit their tree (Trust me, I was this person many years ago hand pollinating every flower on my young sugar apple trees).

When sugar apple trees are forced to grow more fruits than nature intended, they naturally stop sending energy to the weakest fruits and abort them.

This will cause sugar apple fruits to turn black on your tree.

This occurs more often in sugar apple trees that are still young (3 or fewer years) and is over (artificially) pollinated.

Older sugar apple trees that set many fruits during the springtime may also develop black sugar apples.

Overproduction of sugar apples on a tree can cause the tree to thin itself naturally and remove sugar apples.

How can I prevent my sugar apples from turning black?

To prevent your sugar apples from turning black, you will need to follow the following steps.

  1. Remove all mummified black sugar apples from the tree and the base of the tree. Removing the black custard apple fruits is very important to stop the cycle of the wasp from reproducing.
  2. Cover your healthy green sugar apples with a protective fruit bag. We recommend these protective fruit bags.
  3. Prune your sugar apple tree to allow airflow through the tree. Trees with little airflow can be a breeding ground for the fungus that attacks the sugar apple fruits and turns them black.
  4. Spray your sugar apple trees with beneficial nutritional sprays to maximize the system of the tree to prevent diseases.
  5. Mulch and fertilize your sugar apple tree to ensure it can fight off future pests and diseases.

Are there any pesticides or sprays I should use to prevent my sugar apples from turning black?

Applying a nutritional foliar spray to your sugar apple tree is recommended to provide extra protection against the chalcid wasp and other Annonaceae pests like whiteflies and aphids.

Mixing an organic insecticide such as neem oil with a nutritional foliar spray can protect and boost your sugar apple health system to prevent it from losing more sugar apples.

To prepare a foliar spray for your sugar apple tree, add one tablespoon of neem oil with one tablespoon of an organic nutritional foliar spray and mix it with one gallon of water.

Spray the entire tree and behind the leaves to ensure your sugar apple tree gets maximum nutrition.

It is also highly recommended to bag your sugar apple fruits when young with protective outdoor fruit bags.

What does the Annona Seed Borer (Chalcid Wasp) Look Like?

Below is an image from Annona Breeding Projects Instagram of the chalcid wasp.

The wasp itself is tiny and has the potential to pierce through the skin of sugar apples, custard apples, atemoyas, cherimoyas, soursop, and many other Annonaceae fruits at an early stage. 

Chalcid_Wasp_Annona_Fruit_Pest_Sugar_Apple_Pest_Why_Is_My_Sugar_Apple_Turning_Black
Chalcid wasp captured by Annona Breeding Project

How can I protect my sugar apple fruits from turning black?

Fruit Protection Bags

Fruit protection bags such as organza bags or waterproof bags can provide overall protection against the chalcid wasp – a sugar apple pest that bores the sugar apple and lays eggs turning the fruit black.

It is recommended to bag the sugar apple fruits when the size of a marble to protect the fruits from the chalcid wasp.

The sugar apple skin, when young, is slightly weak and easy for the chalcid wasp to pierce.

Fruit bags will do a great deal of protection against this sugar apple pest.

Nutritional Foliar Sprays

Foliar sprays can boost the overall health of your sugar apple plants and give them a better chance at fighting off pests and diseases.

Applying a nutritional foliar feed during the early spring season will boost your sugar apple plants’ natural defenses against fungus and other sugar apple pests.

When spraying your plants, it is essential to spray when the temperatures are not too hot. An ideal time to spray is in the mornings or evenings when the intense weather has cooled.

Applying a nutritional foliar spray to the plant’s leaves, bark, and root system can increase its pest defenses and overall health.

Fertilizer

Fertilizing your sugar apple trees will better prepare them for a healthy fruiting season.

Applying organic or synthetic fertilizers can prevent the tree’s health from becoming unhealthy to the point where pests invade.

Pests will have a hard time invading a healthy fruit tree and often invade the weakest tree in the garden. It’s essential to have a fertilizer plan for your sugar apple trees to ensure a healthy and abundant harvest.

My favorite sugar apple tree fertilizer is Osmocote plus 15-9-12, which was recommended to me by a sugar apple farmer with some of the most beautiful and healthiest sugar apple trees I’ve ever seen. It works great for young and mature sugar apple trees and helps them get a boost. Its also used by many nurseries across Florida to grow several tropical fruit trees.

Mulch

Adding mulch around the base of your sugar apple tree can protect its roots from drying out and from weeds growing in.

It may not seem like it’s doing much, but by adding mulch and lots of it, you can better provide your tree with an organic material that will break down into organic nutrients that the roots can absorb and feed from.

Mulch also will protect your sugar apple tree from weeds growing around the base to compete with water and nutrients.

You will also have to water less as the soil will be protected from the sun. This will prevent the soil from drying out constantly. Like humans, it’s vital to keep fruit trees well-hydrated.

Questions

Why is my custard apple turning black?

Custard apples or sugar apples can turn black due to a fungus due to high humidity, a seed-boring sugar apple pest called the “Chalcid wasp,” or due to a natural response from the tree to self-thin its fruit from too much fruit set – a common issue when hand-pollinated too many flowers.

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