Characterization of Ustilaginoidea virens causing rice false smut and its bio-control in north India

A survey was conducted during 2017–2018 and 2018–2019 to collect the rice false smut (RFS) infected samples from Punjab and Uttar Pradesh for the study . The RFS disease appeared in September and incidence was 2.0–50.0%. The 23 isolates of U. virens showed a morphological variation on Potato Sucrose Agar medium i.e., white-greenish grey to black colony (73.9%), white reddish yellow (26.0%), fluffy mycelium (60.8%), compact mycelium (39.1%), undulated colony (56.5%) without undulation (43.4%) wavy colony margin (65.2%), circular colony margin (34.7%). The colony diameter of U. virens was in the range of 74–77 mm, 24 days after inoculation. The scanning electron microscope (SEM) revealed that chlamydospore size was 3–5 µm and were globose to rounded and ornamented with prominent spines (200–500 nm). A set of 25 novel actinomycetes were evaluated for their antifungal activity against U. virens using dual culture technique under in vitro conditions. Streptomyces harbinensis was most effective in the inhibition (58.9%) of U. virens fungus.