Possible Clues:

• Rust fungus
• Rust in plants
• Assured of keeping rust in plants
• Primitive ode compiled to nettle-rash
• Urticaria, rust in plants
• River party finds plant blight
• Hives will be significant in apiculture, doubtless
• Less common name for urticaria
• Hives
• Rude sort of circle - it's rust, in the garden