Common diseases of apple trees

Apples are subject to a variety of diseases that can cause minor cosmetic damage or more significant damage, such as reduced yields and even tree death. Fortunately, home growers can avoid most diseases by planting disease resistant varieties. Below are a few of the most common apple diseases:

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Apple scab is one of the most common and most serious diseases that afflict apple trees. It usually appears in early to mid-spring and is more prevalent during rainy weather. The disease is caused by the fungus Venturia inqequalis, which overwinters in infected leaves left on the ground. The fungus spores are released in the spring during wet weather and are blown by the wind onto vulnerable, newly emerging leaves.

Apple scab first appears as small, olive-colored lesions on the undersides of the leaves. As the fungus spreads, the top sides of the leaves develop lesions, as well, that may become black or mottled with defined edges. Severely infected trees may become defoliated by mid-summer, making the tree vulnerable to other diseases. The fruit develop black or brown scabs or soft areas. The scabs may appear hardened and cracked, but don’t usually affect the inside of the fruit.


Fire blight is a bacterial disease that runs rampant in many parts of the U.S. and is difficult to control. Trees infected with fire blight may have water stained, brown blossoms and brown leaves. The twigs and the branches of the tree may turn brown or black and have open cankers that ooze a thick, brown liquid. The twigs may also turn downward at the tips to resemble a shepherd’s crook. The disease overwinters in infected wood and is spread in the spring through rain and insects.

Plant resistant varieties, such as Jonafree, Liberty, Pristine and Williams Pride and avoid susceptible varieties, including Beacon, Granny Smith, Jonathan, Gala and Fuji. Fertilize the tree in early spring before growth starts and avoid applying excessive fertilizer, which will promote rapid, lush growth that is most susceptible to infections.


Cork spot may resemble hail or insect damage, but is caused by low soil pH and subsequent calcium deficiency. Cork spot appears as small dimples on the skin of developing apples. The dimples spread to ½-inch wide and may appear corky or soft. The fruit is edible, but the spots reduce its aesthetic appeal.

Add lime to the soil, according to the recommendations of a soil test analysis, if the pH of your soil falls below 6.0. Spray the trees with calcium chloride at a rate of 1.5 tablespoons calcium chloride per gallon of water per tree. Make four applications, beginning immediately after full bloom. Reapply the solution every ten days to help control cork spot.


Powdery mildew is caused by the fungus Podosphaera leucotricha and develops first as white, felt-like growths on the undersides of leaves. As the disease spreads, it causes wilted leaves, stunted growth and black pinpoint specks on the leaves and twigs.

Avoid susceptible varieties, including Granny Smith, Jonathan, Rome and Cortland. Plant the trees in full sun and allow plenty of space between them for good air circulation. Spray the trees in early spring with Myclobutanil, lime sulfur or sulfur.


Rust is an interesting disease because it requires a host plant, such as cedar, quince or hawthorn to develop. The fungus develop in large galls or growths found on the host plant. In spring, the galls dry, releasing the spores into the air where they are carried to apple trees. Rust causes yellow or orange spots on the leaves and distorted or mottled fruit.

To control rust, grow resistant apple varieties and remove any nearby host plants. The spores can travel up to two miles, though, so any neighboring plants may infect your trees. Spray apple trees with sulfur, Myclobutanil or lime sulfur.


Black rot and Frog Eye leaf spot refer to the same disease at different points in the disease cycle. The disease, caused by Botryosphaeria obtuse, first manifests as brown spots on the ends of the fruit. The spots enlarge in concentric circles and eventually turn black, rotting the fruit. Leaves may become covered with small brown spots or holes. Later, the disease spreads to the tree limbs, causing cankers which can eventually kill the tree.

To combat this disease, prune out all infected tree materials and burn or discard immediately. Trees infected with fire blight disease may become weakened making them more susceptible to Black Rot. Spray the trees with Captan or sulfur while the disease is in the early stages.

Key points in apple production

How important agro-measures are?

Without the application of agro-technical measures at the right time, good quality and yield can not be expected. However, fruit growers face one serious problem. Although there are key periods in the vegetative cycle of apples during which agro measures should be taken, this doesn't mean that they are carried out only then. 

The apple requires 16 micro and macro nutrients, and of course water and light should be added to this. Intensive production simply requires constant adjustment-optimization of production conditions. 

The fundamental problem for fruit growers is of organizational nature. The number of factors that affect the quality and fertility of fruits is huge, very often independent of man, and it is extremely difficult to regularly monitor and predict everything. 

The technology can make every day in orchard more efficient.



The technology can make it easier to calculate optimal consumption of basic elements that are necessary for proper fertilization. 

It is known how much nutrients the plants need, and on the basis of its size and vegetative mass, it can be calculated how much of nutrients should be spent in the season. Chemical soil analysis can give us initial information on what we are dealing with. But it is necessary to perform calculations so that the application of measurements give optimal results. If we run these calculations manually, we will just be wasting time. 

MapMyApple provides fertilization plan (recommended preparations and their quantities) based on previously calculated amounts of nitrogen, phosphorus, potassium, calcium and magnesium. 



When the water regime is concerned, digital technology can, based on the vegetative mass of trees, calculate in the short term how much water the plants need for optimum development. In addition, thanks to the internet, availability of data, satellite monitoring of weather conditions, irrigation can be fully adjusted to the amount of precipitation, sunshine and even wind, and the adjustment can be done on a daily basis.. 

According to expected precipitation and average daily temperatures, MapMyApple proposes daily irrigation plan.



Even the appearance and protection against pests can be improved by the use of digital technologies. The onset of disease and pests are significantly affected by climatic conditions. It is not a question of whether it will appear, but the probability that certain diseases and pests will occur, according to existing weather conditions. 

MapMyApple advises how to deal with pests and diseases. Plan includes the products and quantities to be applied, through the spraying plan.

Can agriculture become smart agriculture?

Perspective of smart fruit growing

Agriculture has seen many revolutions and we guess that it is undergoing a fourth revolution triggered by the exponentially increasing use of information and communication technology (ICT) in agriculture.

Robots are replacing human workers at a faster pace than any other point in history. Most of these robots are in factories, but a new kind of mechanized worker has hit apple orchards. Harvesting of apples autonomously based on colour and size is already possible. There are already tractors that are capable of mowing and spraying your entire orchard (and it will even send you a message to refill the vat or fuel tank as needed). Computer vision, where a computer is programmed or taught to identify objects based on size, colour, shape or any almost any other characteristic to provide measurements, already exists.

In recent years, there were many innovations in fruit growing, we also heard of various sensors, drones, satellite imagery and applications for smart devices, which together work to produce only the best, and with less risk.


These tools will help productivity, profitability, and sustainability for farms of all sizes. New technologies help farmers grow more efficiently, and they help provide the rest of us with tasty, nutritious, affordable food.

Based on location, and thanks to satellites, digital technology can monitor the weather, rainfall, sun hours, as well as the vegetative mass of your orchard. There are already applications that perform their calculations on the basis of these data. MapMyApple, a mobile phone application, is specially designed for apple growers. It gives daily recommendations for agro-measures on the basis of these data and the knowledge and experience of the world's most eminent apple growing experts. Through this application you can control the most important stages of production of apples and align them with environmental factors and meteorological-climatic conditions effortlessly. We can say that it covers all the key points in apple production!


In the end we have to agree about one thing - no technology can do the job instead of fruit growers, but it can help him significantly to be faster, more accurate and more productive. Investments in agricultural machines, infrastructure and know how contribute to better conditions of work, better efficiency and profitability. That’s why we’re working with technology experts worldwide to develop, test, and roll out new ways to take farms digital.