You have certainly seen this type of damage many times: Thick growths are found primarily on apple trees, but also on other fruit and deciduous trees. Over time, these even increase in size and cause branches and twigs above them to die off due to the lack of supply. However, there are preventive measures that can be taken to avoid an infestation.
The quicker the fruit tree canker is treated, the better
cause and damage
The cause of fruit tree cancer is not uncontrolled growing cells like in humans, but a fungus. As a result, the fruit tree disease has nothing to do with the human disease, despite the same name. If this disease occurs, growths develop on the trunk or branches, which continue to expand. Above the canker sites themselves, the branch or twig dies because the water and nutrient supply is interrupted. In winter, spherical red mushroom fruits develop, which contain the spores of the fungal pathogen. They enter the tree through wounds; these can be cuts, but also wounds caused by hail, frost or game.
prevention
For this reason, larger cuts, such as those caused when pruning fruit trees, should be covered with a wound sealant such as Malusan or similar. As a preventative measure, fruit trees should only be planted in locations that suit them, with cold locations and damp, heavy soil favoring the occurrence. One-sided or very nitrogenous fertilization also has a cancer-promoting effect, which is why fruit tree cancer is often found in cottage gardens fertilized with liquid manure. Certain apple varieties are considered to be very susceptible, this applies in particular to 'Berlepsch', 'Cox Orange', 'Gloster', 'James Grieve', 'Klarapfel' and 'Oldenburg'.
combat
Cut off twigs and branches infected with fruit tree canker a hand's breadth below the cancerous spot. On the other hand, cancerous areas on the trunk and on stronger branches are cut out with a knife or, if necessary, with a saw, right down to the healthy wood. The final treatment with a wound sealant is absolutely necessary to prevent the pathogen from re-entering the area. In commercial orchards, agents containing copper are used to combat the disease, but these are not approved for use in home gardens. As a heavy metal, copper accumulates in the soil and affects the organisms living there.
Proper wound care in fruit trees
Damage to fruit trees caused by tree canker (as well as by frost, pest and wildlife damage, twig monilia or fruit tree pruning) should be treated to ensure that they heal quickly and prevent the entry of fungi and other pathogens. For larger cancer areas, proceed as described:
- First, cut out the cancerous areas deeply with a saw.
- Very deep infested areas are then reworked with a chisel.
- At least one third of the circumference of the branch must be left over for care.
- To ensure rapid healing, the edges of the wound are smoothed out with a sharp knife.
- Apply a wound sealant to large wounds.
tips
Winter frost damage can be avoided if you coat the fruit tree with lime.