How to identify pine resin canker or gray mould?

Pine resin canker is a fungal disease that affects the trunks and branches of pine trees, causing wounds that leak resin. This disease can lead to weakening, deformation and death of the tree. In this article, we will describe the first symptoms of pine resin canker and how to spot it.

What is pine resin canker and how does it occur?

Pine resin canker is a disease caused by various species of fungi in the Cronartiaceae family, such as Cronartium flaccidum, Peridermium pini, Endocronartium pini and others. These fungi are dioecious, meaning that they have two or more plant species on which they develop and reproduce. One of the hosts is pine, and the other is various types of herbaceous plants, such as willow, mint, chamomile, dandelion, nettle and others.

The disease appears as wounds covering the tree trunk. These wounds are of different lengths, elongated, and the size of the wound is constantly increasing. On the surface of the tree, where the disease develops, the bark begins to peel off, and then falls off.

If the pine tree is affected by resinous cancer or greying, the crown begins to shrink, and insect pests settle in the trunk.  It is important to take timely rescue measures, because the tree will weaken and may die.

Fungi get on the pine tree from the air, from fallen needles, from damaged parts of the tree or from other sources. Fungi penetrate the wood through wounds, pores, cracks or stomata (gas exchange holes). Fungi develop in the wood, producing mycelium (branching structure) and spores (reproductive elements). Fungi suck water and nutrients from the wood, which causes it to dry out, delaminate and rot. Fungi also produce toxins that poison the tree and disrupt its physiological processes. Fungi spread to other parts of the tree or to other trees through spores that are carried by wind, water, animals or people.

What are the first symptoms of pine resin canker and how can they be detected?

The first symptoms of pine resin canker can appear at any time of the year, but they are most often noticeable in spring or summer. Here are some of them:

 – Ulcers on the bark. This is the most characteristic and early symptom of pine resinous cancer. Cracks appear on the bark of the trunk or branches, from which resin leaks out. The resin dries up and forms resinous cones or streams, which can be variously coloured from yellow to black. Ulcers can be of various sizes and shapes, from round to irregular. The ulcers can be located at any height of the trunk or branches, but more often it is in the lower part of the crown or at the base of the trunk

– Deformation of the trunk or branches. This is a symptom that occurs as a result of blocking the movement of nutrients in the wood. In the areas affected by the fungus, the wood becomes dry and brittle, while in the undamaged areas, intensive growth occurs. This causes the trunk or branches to become crooked, twisted, split or cracked. The deformation may be visible from a distance or on close inspection.

– Drying and falling of needles. This is a symptom caused by fungal toxins in the tree. The needles turn yellow, brown or red, dry and brittle. The needles can fall off the tree or remain on it, but without any vital signs. Drying and falling of needles can start from the top of the crown or from individual branches and spread over the entire surface of the tree.

 Do not neglect the first symptoms of resinous cancer, if you notice them on the surface of a pine tree, please contact us at +380632851405

 The team of the Green Clinic Centre for Ecosystem Phytopathology will offer the most effective prevention and treatment methods to preserve your green spaces.