The massive sale of land in the late 90s led to a boom in suburban housing construction and a peak demand for planting material. One of the most popular and accessible trees in those years, and even now, were pines and spruces, which were in forest nurseries or grew en masse on overgrown abandoned fields of former state and collective farms. The age of the planting material corresponded to the norms for transplantation. All this was dug up uncontrollably and sold out. There was no question of any sanitary control, and even now, little has changed with sales at mini-markets and along roads.
The most popular coniferous species is pine. It grows quickly, unpretentious to soil, but relatively light-loving breed. The greatest demand was for trees from 2 to 5 meters. Good survival rate, if the protection against bark beetles was carried out correctly for the first three years after transplantation, made pine one of the most demanded crops for landscaping. There are plantings of this culture on almost any site of a large enough area.
Landings can be single, tapeworm and ordinary along the fences. Plants for planting, as a rule, are brought with a tightly bound crown. Most often, the planting of the material is carried out in early spring or late autumn. In the first and second post-planting years, the main problem is the protection of pines from bark beetles and simply the survival of trees in new conditions.
When conducting phytopathological examinations of plantations in areas with transplanted pine trees, I quite often noted such a fungal disease as rust of pine shoots, or pine wither... The causative agent of this disease (Melampsorapinitorqua) belongs to dioecious rust fungi. Visually, the disease is diagnosed by the S-shaped deformation of the terminal shoots of pine. By deformed, zigzag shoots of previous years, it is possible to identify the beginning of the development of a fungal infection and the period of the disease.
In young pine stands adjacent to aspen or poplar plantations, the pine whirligig is quite common. This is due to the fact that the main host of this type of fungus is pine, on the shoots and needles of which it develops in early summer, and the intermediate host is aspen or poplar, on the leaves of which the second stage of the fungus develops in the second half of summer and hibernates. In spring, pine leaves are re-colonized from leaf litter. The main problem of transplanted plants is not that poplar and aspen grow almost everywhere and infection with the pathogen can occur repeatedly, but that pines already infected with pine vertun are taken for transplantation quite often.
The most common disease occurs in the age category from one to ten years. Pine trees growing in unfavorable conditions, with high humidity, as well as plants with reduced immunity, can be carriers of an infection that proceeds practically without manifesting clinical signs. Subsequently, when the tree is dug up, 30-50% of the roots are lost. After transplanting a tree (it is good if the planting material did not stand on the site for a long time before planting) the plant experiences a strong weakening.
The restoration of the root system, depending on the height of the tree, takes from three to five years. This process is clearly visible from the change in the length of the needles and shoots over the course of several years after planting the tree in new conditions. Often, pines are brought from plantations with a high infectious background of the pathogen, and the weakening of the tree in the post-transplant period leads to a significant activation of the pine tree. And this can be observed for several years. The humid and warm weather in the spring promotes the intensification of the disease.
Pine vertchun hibernates on the shoots of trees weakened by transplantation for a number of years, and this period directly depends on the possibility of recovery and treatment of this disease. In spring, with the growth of infected shoots, their deformation occurs to varying degrees in accordance with the activity of the pathogen. Sometimes their dying off can occur, provided that the tissues die off in a circle. On the cut of such a shoot, one can see necrotic areas of growing tissues at internodes, due to which their S-shaped curvature occurs.
In the nodes of the shoots, numerous buds of renewal are laid. From them underdeveloped shoots are formed, which hang down, forming whorled "weeping" branches. If pine trees are damaged at a young age, the vertchun can lead to the formation of bush forms.
The formation of the future crown of pine infected with vertun consists in thinning pruning of excess shoots with simultaneous treatment of trees with systemic fungicides.
Treatment of this disease is difficult and time-consuming and depends on how quickly the tree's immune status will recover after transplantation. For treatments, such systemic fungicides as Skor, Horus, Thanos and some others can be used. The first treatment with fungicides is carried out at the beginning of May in the first phase of development of the shoot from the bud. Usually it is 2-3 treatments with an interval of 2 weeks and in compliance with the rules for the rotation of drugs. In practice, within 3-4 years, the disease can be reduced to nothing.
Pine whirligig affects not only Scots pine, but also Weymouth pine and cedar pine. Black pine and Banks pine are more resistant to the disease.
From all that has been said, the following can be distinguished:
- Carefully examine the planting material for diseases;
- If fungal infections are suspected, together with treatments for stem pests, include fungicidal preparations compatible with the insecticides used;
- To reduce the risk of pathogen resistance to fungicides, it is necessary to follow the rules for alternating drugs;
- As thickened shoots form, carry out thinning pruning.
- Top dressing with potassium-phosphorus fertilizers reduces the risk of infection and the development of fungal infections.