rubiginose

ru·big·i·nous

 (ro͞o-bĭj′ə-nəs) also ru·big·i·nose (-nōs′)
adj.
Rust-colored; reddish-brown.

[Latin rūbīginōsus, from rūbīgō, rūbīgin-, rust, from rōbus, red; see reudh- in Indo-European roots.]

rubiginose

(ruːˈbɪdʒɪˌnəʊs)
adj
rust-coloured or rusty