Chestnut tree diseases: recognize them and fight them effectively

The chestnut tree is one of the most emblematic trees in the Italian landscape, highly valued for its fruit. It is a long-lived plant and can survive even at considerable heights. Despite this, as with all plants, it is good to pay attention to possible threats. In fact, the chestnut tree is also subject to various fungal diseases and pests, which can compromise its productivity.

In this article we will look at the most common diseases and pests and ways to combat them.

Ink Sickness

The best-known disease of the chestnut tree is undoubtedly ink blight, caused by the fungi Phytophthora cambivora and Phytophtora cinnamomi. It causes progressive desiccation of the plant and manifests itself through yellowing of the leaves and a general wilting. In addition, it can lead to browning of the collar, reddening of tissues under the bark, crown distress, and eventually plant death.

This pathogen has been increasing in recent years, and its main channels of spread are surface runoff and infected soils. Inoculation occurs from the root system to the bark. Therefore, the outcome of the disease is often lethal for the chestnut tree.

In this case, prevention is the most effective tool. It is important to avoid water stagnation and monitor soil drainage. In addition to this, rock powders (such as Kaolin or Zeolite) can be used to prevent fungal diseases by absorbing soil moisture.

In case the disease has already occurred, it is important to remove infected plants, use resistant rootstocks and avoid producing wounds in the collar area. In addition, potassium phosphite fertilizers should be used, and replacing plants that have died of the disease in the short term is not recommended.

Root rot

Root rot is another disease caused by polyphagous parasitic fungi: Armillaria mellea and Armillaria gallica. This disease attacks the subcortical tissues of the roots and collar, and the main symptoms are:

• Stunted vegetation.
• Withering and desiccation.
• Mycelial felt under bark.
• Appearance of the fruiting bodies of the fungus.
• Widespread rot in the root system of the plant.

To combat root rot, it is necessary to remove affected plants and remove all woody material present in the soil. Also, in reforestations it is best not to plant trees too close together and to diversify species to reduce the risk of spread.

Cortical cancer

Diseases that can affect the chestnut tree include cortical cancer, caused by the fungus Cryphonectria parasitica, which affects the trunk of the plant. This fungus was first identified in 1938 and posed a major threat to the chestnut tree until the mid-1980s. Subsequently, a biological control system was developed based on the spread of strains of this disease, called hypovirulents. Through contact between virulent and hypovirulent strains, it is possible to make the symptoms of the disease less severe.

The fungus responsible for the disease is of the ascomycete type and manages to survive all year round on diseased plants and spreads via wind and rainwater. In particular, during the autumn period it is very important to pay attention to fungi of this type, because they are able to hide in protected places.

Cortical cancer initially manifests itself on the bark by irregular red spots, which tend to enlarge. Subsequently, the bark tends to swell until it tears. The plant reacts by scarring the destroyed tissue, creating cortical necrosis called, indeed, cankers. The leaves take on the typical flag-like appearance and several epicormic twigs appear.

Two types of cancers can then be distinguished:

1. Normal cancers: typical symptoms that do not heal and lead to crown desiccation.
2. Abnormal cancers: reduced symptoms with limited pycnidia production and superficial spread of mycelium.

To combat and prevent cortical cancer in the chestnut tree, it is essential to follow certain guidelines:

• Cut off dead or dry branches to prevent the spread of infection.
• Always disinfect tools so as not to transmit the disease from one plant to another.
• Protect the graft wound with specific materials (such as healing mastics or antagonistic microorganisms), as this spot is very delicate and easily attacked by fungi.

Wood decay

Wood rot is a disease caused by the fungus Laetiporus sulphureus, which can cause a brown rot of the heartwood that can spread to the roots. This yellow-colored fungus can rapidly cause the plant to lose stability and is transmitted through parasitic lesions or wounds due to cutting at the aerial or root system.

To prevent wood decay, it is essential to adhere to ideal agronomic practices for chestnut tree care. In addition, it is recommended to protect large pruning wounds.

Fersa

Fersa, also called leaf rust, is another fungal disease, resulting from the fungus Miycosphaerella maculiformis. Symptoms of this disease occur on the leaf blade, with darkened, irregular speckles. Affected leaves, sometimes accompanied by yellowing and necrosis, fall early. The damage the disease can do to chestnut trees are:

• Early phylloptosis.
• Weakening of the plant.
• Reduced productivity.

The ideal time for the spread of this fungus is from late summer and is favored by particularly wet and rainy seasons.

Fruit rot

Fruit rots are caused by different species of fungi, and there are two types of the disease: black rot, also called black mold, or brown rot. Here are the main differences:

• Black rot: caused by Ciboria batschiana, lives in the tissues of buds and shoots and at flowering can spread into the urchins. The colonized fruit flesh turns grayish and then black in color. These symptoms occur mainly after fall and can spread during storage.
• Brown rot: caused by Gnomoniopsis castaneae, can cause cankers and necrosis in buds and shoots, and the infection develops as early as flowering after which it is also visible in the fruit flesh. Affected fruits become spongy and brownish-brown in color.

Chinese Wasp

The Chinese wasp, also known as the chestnut gall wasp, is a hymenoptera native to China that was introduced to Italy in 2002. In its adult form it lays its eggs on buds in formation. Then the larvae develop inside the buds, causing the formation of galls, which provide protection and nourishment to the larvae and interrupt the vegetative growth of the plant, sometimes causing it to decay.

One of the methods to combat this pest is the hymenopteran insect Torymus sinensis.

Tortrices of the fruit

Tortrixes are lepidopterans, the larvae of which can cause great production losses. There are three types of this pest:

• Early Tortrice – Pammene fasciana: The larva is whitish in color and flies from June to September. It penetrates hedgehogs and fruits, which turn brown and subsequently fall off. Larvae in the mature stage overwinter in the bark or soil.
• Tortrice intermedia – Cydia fagiglandana: the larva is reddish in color, flies from July to October and also penetrates the fruit, after which, at maturity, it escapes and overwinters in the soil.
• Late tortrix – Cydia splendana: This species flies from late August to September. The yellow-colored larva penetrates the hedgehogs and feeds on the seeds. At the maturity stage they emerge from the fruit and overwinter the soil.

Balanino

The balanine, also known as the chestnut weevil, is another dangerous pest of the chestnut tree. It is a whitish-colored beetle, present from August to October, that feeds on the fruit of the plant. It feeds on the seed of the fruit and at maturity escapes and overwinters in the soil. The extent of damage that the balaninus can cause to the chestnut tree varies depending on the thorniness of the hedgehog.

The physiopathologies of the chestnut tree

In addition to the threats listed in this article, the chestnut tree is vulnerable to some physiopathologies, which are disorders not caused by pathogens but by unfavorable environmental conditions. Here are the main ones:

• Prolonged drought: causes leaves to yellow and branches to dry out in the chestnut tree. To prevent this from happening, it is important to ensure proper irrigation during the driest periods.
• Excess water: excess water and poorly drained soils also cause root asphyxia in the plant. Symptoms of this physiopathy are evident in the leaves and general weakening of the chestnut tree, which becomes more vulnerable to fungal diseases. To prevent this, it is essential to drain the soil.
• Nutritional deficiencies: these can occur if the soil is exploited by intensive cultivation or lacks organic matter. This can cause a slowdown in growth and a decrease in fruit production. It is, therefore, important to enrich the soil with organic fertilizer.

Plantvoice

The chestnut tree is a very valuable plant in the Italian ecosystem, but, as we have seen, it can be vulnerable to various threats. Therefore, to keep the crops healthy, careful monitoring is essential so as to detect early signs of stress.

In this context, knowing the innovative technology proposed by Plantvoice can make all the difference. This system introduces a revolution in chestnut tree monitoring through real-time monitoring. Through a minimally invasive phyto-sensor, it analyzes the sap of the plant, identifying any deficiencies. So, investing in monitoring systems such as Plantvoice ‘s makes it possible to protect crops sustainably while optimizing resources.

Here’s how it works:

1. The first step is to scan the QR code on the control unit with your cell phone to get the data into the Plantvoice app.
2. Insert sensors to the “sentinel plant” and activate them from the app.
3. Through the dashboard, plantations can be visualized and managed.
4. With the app, real-time notifications on plant status and needs can be checked.
5. The probe sends a real-time analysis of the sap to the app.