To the question of survival of the fungi Colletotrichum lupini var. lupini – the lupin anthracnose pathogen – in the conditions of the Bryansk region

Abstract

The results of studying the viability of the fungus Colletotrichum lupini var. lupini, which is the causative agent of a dangerous disease of lupine – anthracnose, are presented. The purpose of the study was to determine the viability of the fungus under different terms and conditions of storage of lupin seeds and plant residues in climatic conditions of the Bryansk region. The work was done in 2018–2021. The object of research were the seeds, seedlings and plant residues of the Michurinsky variety white lupine and the Vityaz variety narrow-leafed lupine stored under different conditions for four years. Seed anthracnose infestation before and after storage was determined by paper roll method. The fungus was identified by conidia type using a light microscope. The viability of the fungus on plant residues (bean leaflets, stems) was determined by isolation into pure cultures on nutrient medium. It was found that infected seeds were the main source of anthracnose infection. In the conditions of a granary with a natural regime of temperature and humidity for the first year of storage the infection of white lupine seeds with anthracnose decreased from 8.1 to 4.0%, and narrow-leafed lupine – from 4.8 to 1.7%. After three years of storage, the number of the seeds with viable infection of the fungus was 1.1 and 0.4%, respectively. Consequently, lupin seeds from previous years pose less risk as a source of infection. The viability of the fungus decreased on the infected crop residues under room conditions and under the roof of the granary from the first year of storage. By spring 2021, it was 12.0 and 19.0%, respectively. The viability of the fungus decreased faster on unplowed crop residues. It was 2.0% in the spring of 2020 and leveled off completely by the fall. Decomposition of plant residues in the soil is faster than on the surface, and after overwintering, the fungus on them completely loses its viability and cannot be the source of infection.