DIPLODIA SHOOT BLIGHT OUTBREAK IN YOUNG SCOTS PINE STANDS IN MOSCOW OBLAST
Anna A. Shishkina1,2, N. N. Karpun1
1Federal State Budgetary Educational Institution of Higher Education «Saint-Petersburg State Forest Technical University», St. Petersburg, Russian Federation
2Russian Forest Protection Center, Pushkino, Russian Federation
Keywords: Sphaeropsis sapinea, Pinus sylvestris, forest crops, diseases of young forest stands, shoot blight of Scots pine, necrosis, twist of shoots, deformation, multi-topped (bushy) plants, decreased increment
Abstract
The article presents the results of a 7-year study of the outbreak of Diplodia shoot blight, discovered in 2017 in young forest stands of Scots pine ( Pinus sylvestris L.) in the Moscow Oblast. The area covered by the disease at the peak of the epidemic was more than 2 thousand hectares. Previously, such a huge spread of Diplodia shoot blight with a high degree of damaged trees in forest stands of the Moscow Oblast had not been recorded. For the first time in the region, the symptoms of the disease and the periods of their development on pine in forest stands of different ages and origins have been described. New for the Moscow Oblast data on the complex development of the causative agent of Diplodia shoot blight ( Sphaeropsis sapinea (Fr.) Dyko & B. Sutton) and other pathogenic fungi that cause necrosis and cancer diseases of pine: Sclerophoma shoot blight ( Sclerophoma spp .) and Pine twisting rust ( Melampsora populnea (Pers.) P. Karst.) has been obtained. It was found that the highest level of the disease is usually observed in plantings aged from 3 to 6 years, afterwards a gradual weakening of the disease begins. The highest occurrence of disease and degree of crown damage were observed in forest plantations of different ages, pure in composition, in B2 type of growing conditions, as well as with a high level of anthropogenic impact. The density of forest plantations did not affect the degree of the disease development. The damage caused by Diplodia shoot blight included both the weakening of plants (up to complete death in isolated cases) as a result of the death of shoots immediately during the outbreak of the disease, and the subsequent deformation of trunks, formation of multi-topped (bushiness) crowns and the cankers, which reduced the resistance of young trees to snow and wind injury and can deteriorate the commercial qualities of the developing forest stands. Based on the results of measuring the growth of apical shoots, inhibition of plant growth due to damage by Diplodia shoot blight was revealed. The results of the study can be used for monitoring diseases in young pine stands and in projecting of a system of plant protection measures.
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