orange rust

noun

1

: either of two diseases of raspberries and blackberries caused by two rusts (Gymnoconia peckiana and Kunkelia niteus) and characterized by retarded growth and curled and distorted usually small leaves lacking in green color and with bright red or orange powder on the under surfaces

also : the fungus causing either disease

2

: a strong yellowish brown that is redder, stronger, and slightly darker than buckthorn brown and redder and deeper than centennial brown

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