Have you ever come across an apple that has dark-colored skin and a rough texture? If the answer to this question is yes, then you’ve come across an apple infected with apple scab.
Apple Scab is a fungal disease that is caused by the fungus Venturia inaequalis. As evident from the name of the disease, it is one of the most widespread diseases in the different types of apples.
However, the disease is not limited to apples. It can spread across various ornamental trees, shrubs, and fruits like pear and crabapple. Ornamental plants are those fruits that are grown for their decorative look instead of their taste or nutritional value.
Apple Scab Treatment refers to the various natural ways and chemical methods through which you can control the spread of Apple Scab.
Before we move on to the treatment of apple scab, let us first talk about its causes, spread, and symptoms that would help you in identifying it in the future and take preventive steps.
Apple Scab: Causes And Spread
Apple Scab is a fungal disease that first appears on the dead leaves and fruits left on the ground. Young fruits, especially apple and crabapple, are more prone to apple scab during the petal fall and the rainy season.
This is because, during both of these seasons, the fruit would fall on the wet ground along with the dead leaves. The stillness of the dead leaves, along with the wet surface and sunlight, make it a perfect place for the fungus to grow.
The primary stage of disease includes attacking the dead, fallen leaves on the ground. Once it has infected the leaves, it would move on towards the fallen apples and infect them. It is aggravated in the spring and the summer season because the light waves of wind would carry the fungal spores towards the healthy trees.
Although fruits that have matured are not prone to it, the buds of still developing primary fruits can get infected easily. This is possible because the fungal spores from the leaves coincide with the lesions. The lesions or outer parts of the closed bud and flowers allow the fungus to make its way through the flowering period and damage the whole fruit.
Once a single fruit on a healthy tree is damaged in the spring, and early summer seasons, it won’t take a lot of time to spread across the majority of the tree. The secondary infections spread at a much faster pace, especially during the petal fall and rainy season when the temperature is more than 50⁰F.
Therefore, we can summarize the complete chain of Apple Scab infection in the following way:
Fallen Leaf –> Fallen Fruit –> Healthy Fruits on Tress –> Whole Tree
Since we are aware of the fact that the Apple Scab disease first infects the leaves and fruit in wet weather, let us have a look at its early symptoms.
Identification And Symptoms of Apple Scab
Knowing the early symptoms of the Apple Scab would help you in identifying the infection and would also give you time to take preventive measures.
The symptoms of apple scab start to show on the leaves or fruit on the ground in the spring season. The leaves on the healthy trees became pale and began showing very small, light-colored, water-soaked spots. The spots caused by apple scab don’t have any particular shape, but they are mostly circular in shape.
As the primary infections would increase, the spots would become darker in color. Ultimately, the leaves would turn into a brownish-black color. All of this would lead to the infected leaves getting distorted, curled up, and dropping off early.
After infecting the trees, the disease would spread towards the fruits. The initial symptoms of the fruits include the development of spots and scabs. The scabs would be visible in the form of a raised brown and black circular area.
With time, the scabs would break the protective layer of the fruits and expose their tissue. The exposed tissue would become a black or velvety brown color. Along with the tissue, the scabs would also start spreading and turn into a brown color with a rough texture.
If the Apple Scab infection has spread to a large extent, it will result in a large number of leaves dropping off. This is the primary cause of thin canopies during the summer and the weakening of the trees.
Apple Scab Treatment and Prevention Techniques
The prevention and treatment of Apple Scab fungus can be divided into two different methods: Natural treatment and Chemical treatment.
1. Natural Treatment
Removing and treating apple scab fungus naturally is considered to be the best way to treat them. This is because making use of natural products and techniques ensures that no chemical would come in contact with the fruit or cause any side-effects.
The following are some of the natural ways through which you can remove and prevent Apple Scab in your fruits and garden:
- Scab-resistant varieties of apples: Instead of growing any apple tree, you should try to grow the types of apples that don’t get infected with apple scabs easily. Some of the scab-resistant varieties of apples are Akane, Chehalis, Liberty, Prima, and Tydeman Red.
- Prune your trees: You should prune or trim the dead and overgrown branches regularly. Doing this would allow the trees to breathe. Additionally, it would result in fewer falling-off branches and healthier trees.
- Dispose of fallen leaves and fruits: Doing this would ensure that apple scab doesn’t grow them. Also, disposing of the infected twigs, leaves, and fruits would result in fewer fungal spores.
- Regularly water your trees: Water your trees either in the evening or early morning hours. This would allow the leaves to dry and not allow the scab to grow and infect the trees.
- Make a layer of compost: Spread multiple layers of compost near the base of the tree but away from the trunk. Doing this will reduce the dispersion of apple scab spores towards the trees.
These ways are considered to be effective but would require quite some work from your end. Apart from them, you can also make use of chemicals to prevent and treat apple scabs.
2. Chemical Treatment
You can use the following chemical methods to prevent apple scab from infecting your trees, leaves and, fruit.
- Fungicide: You can spray any fungicide to protect the fruits and trees from the apple scab infection. However, it should only be used on trees whose quality of food matters and the one which has a history of severe apple scab.
- Sanitation Control: You need to be extremely careful while using any fungicide. Make sure that you don’t apply it too much, or else it can cause adverse effects. At the same time, don’t use it on secondary and severely infected trees that are already infected by the scab fungus as it doesn’t control the disease.
- Application of nitrogen on the fallen leaves: You can apply nitrogen and sulfur to increase the overall speed of decomposition. It would also result in the quick creation of compost layers.
- Use Dolomitic Lime: Dolomitic Lime is basic in nature. You should spray it during the fall season when leaves have fallen. Spraying it would increase the pH level and reduce infections of fungal spores.
While using any chemical treatment or fungicide, it’s important to know that they can’t be used on every type of tree. Moreover, they affect the quality and freshness of the fruit in one way or another.
The disease is caused by the apple scab Venturia inaequalis fungus. It is quite common amongst apples, especially crabapple and is therefore known as Apple Scab. The infection occurs first during the spring and leaf fall season and infects the dead leaves and the fruit. Afterward, its spores make their way towards the healthy fruit. Therefore, the first step of apple scab control is to dispose of the fallen leaves immediately.
It’s also important to trim the trees regularly and make a compost layer near them. It would prevent the fungal spores from getting in contact with the tree and, at the same time, would give nutrition to the tree.
Apple scab infections can be prevented through both natural and chemical ways, especially with any fungicide spray. However, it’s suggested to use the natural ways as it wouldn’t have any effect on the quality of the fruit.
James Fields is the founder of Gardener to Farmer. His passion for gardening goes back to his childhood days when he would visit his grandfather during the holidays and help him with the plants in the backyard. This has now translated to creating a dependable resource for gardening.