“Horsfall–Barratt (HB) Scale” is used for measuring –

Correct option is C

Correct option: (c) Disease severity
· HB scale is a logarithmic scale used to estimate disease severity based on percentage of infected plant area.
Other options:
· (a) Spore measurement – False.
· (b) Spore dispersal – Not related to HB scale.
· (d) Disease incidence – Measures % of plants affected; HB scale is not used for incidence.