PHYSIOLOGICAL CHARACTERIZATION OF Rosellinia bunodes AND SYMPTOMATOLOGY OF Rosellinia ROOT ROT IN POPLAR SEEDLINGS

Abstract

Poplar (Populus deltoides) is a forest species that has several phytosanitary problems, such as leaf spots, rusts and root rots. Since 2010, the death of poplar trees has been observed in commercial plantations in the state of Paraná, Brazil, caused by the fungus Rosellinia bunodes. Due to the lack of information about this pathosystem, the aim of this work was to carry out the physiological characterization of R. bunodes isolates collected from P. deltoides and the symptomatological characterization of Rosellinia root rot in the same host. Experiments were conducted at Embrapa Florestas, located in Colombo (PR), Brazil. The mycelial growth of nine R. bunodes isolates was evaluated in four culture media (potato-dextrose-agar, V8-agar, carrot-agar and water-agar) and seven different incubation temperatures (8, 12, 16, 20 24, 28 and 32 °C). The symptomatological characterization of Rosellinia root rot was performed on six-month-old poplar seedlings. The most favorable conditions for mycelial growth of R. bunodes were observed in potato dextrose agar (PDA) at 24 °C. The symptoms and signs of the disease internally in the stem showed up at 7 days after inoculation (DAI); however, chlorosis and wilting were observed only at 14 DAI. Sexual and asexual reproductive structures of R. bunodes were not observed on inoculated plants.

Comparative study on the monocyclic components of plum rust with isolates from three growing regions in Brazil

“…Temperature and wetness period (WP) stand out among the various environmental factors, with great influence on the early stages of a disease (Helfer, 2013; Kable et al., 1986). The determination of ideal conditions for fungal growth is essential in the development of methodologies, which can be applied in different types of phytopathological researches, such as the evaluation of the efficiency of phytosanitary products, the resistance of fungi to fungicides and prospecting for biological control agents (Kleina et al, 2018). The fungal development starts from a minimum temperature supported by the microorganism, shows its full expression at an optimal temperature and stops growing when the temperature reaches its maximum limit.…”

“…The fungal development starts from a minimum temperature supported by the microorganism, shows its full expression at an optimal temperature and stops growing when the temperature reaches its maximum limit. Within the same species and even among the isolates of the same species can occur changes in growth behaviour, with variation in the optimal temperature required by each organism (Kleina et al, 2018).…”