Diagnostics of carrot diseases caused by the FUNFI botryotinia fuckeliana (de bary) whetzel. And sclerotinia sclerotiorum (lib.) De bary

Abstract

The gray and white mold of carrot, which are caused by fungi respectively Botryotinia fuckeliana (de Bary) Whetzel. (Botrytis cinerea Pers.) and Sclerotinia sclerotiorum (Lib.) de Bary is a common and dangerous diseases in different regions of the world. However, the first step to control of harmfulness diseases is significant their diagnosis. As in most literature are typical signs of disease, there is a need knowledge of symptoms at different stages of the pathological process.

The study of the symptoms of gray and white mold conducted on selected carrot roots during storage. Laboratory diagnosis was performed in problematic research laboratory "Mycology and Phytopathology" National University of Life and Environmental Sciences of Ukraine.

The study of botrytis symptomatology allowed establish that symptoms are characterized by variability diagnostic features. In particular, the pathological process in the root crop appears as a tint of brown spots, which is soft and wet. Thereafter, on the surface of the affected area is formed mycelium of the fungus, which is initially light shade, and if conidial sporification becomes gray color. Internal tissue affected of root and become brown color. We also detected atypical symptoms. They are characterized by the formation of the affected part of root necrosis, wrinkly, liquid sporification pathogen and slightly visible sclerotia. This phenomenon occurs at low relative humidity. In cases of parasites on the roots of carrots mycelium strains of B. cinerea mycelium is formed of light, which eventually colonizing the entire root.

B. cinerea fungus on infected root forms sclerotia. Latest first single, and later their number increased. They take the form of black humps with a rough surface. Such strains of root surface to form a solid crust of sclerotia. The size of sclerotia ranged in diameter from 1 to 5 mm. Increasing their size is due to the growth of each other. Sclerotia densely attached to the substrate.

The initial symptoms of white mold during storage occur in any place in the form of root wet spots that lead to discoloration of tissue. The latter becomes soft and watery. Thereafter the affected area increases in size and covered extensively developed, fluffy, white mycelium cotton-like. At the conditions low relative humidity  it is liquefied, less developed, saturation of the affected area moisture is not visible. Later in conditions conducive to disease development the whole root is covered with white mycelium, softens and rots, thus retains its shape. In some cases, the possible formation of root crops constrictions of dead tissue. Internal infected tissues of root darker and become saturated with water. This mold odor is not felt.

Characteristic signs of root crops S. sclerotiorum fungus is forming on the surface of a large number of sclerotia. At a young age they are white, soft, shiny on the surface of the droplets of liquid. Later during ripening sclerotia are black and hard. At the final stage of the disease the most part covered sclerotium of root mass. In case after the beginning of disease manifestation unfavorable conditions for air mycelium pathogen, the latter suspends colonization of neighboring tissue and enters sclerotium form. This visible white mycelium absent. In our studies, sclerotia formed roots were affected in various shapes, convex, from 0.3 to 3.5 cm long and 1.5 cm in length. They are easily separated from the substrate.

During diagnosis mold of carrots we also detected affection compatible root fungi B. cinerea and S. sclerotiorum, B. cinerea, S. sclerotiorum and Alternaria radicina Meier, Drechsler & E.D. Eddy, and S. sclerotiorum and Fusarium spp., Which complicates the visual definition of the type mold. For this purpose, conducted microscopic analysis of pathogens and is specified their morphology. In particular, sporification B. cinerea presented conidiophore and conidia. S. sclerotiorum mycelium forms characteristic septate.