A COMPENDIUM OF TROPICAL PLANT DISEASES AND DISORDERS
RUST DISEASES
SYMPTOMS
Yellow or reddish leaf spots that appear blotchy or angular on the upper leaf surface Rust pustules on the underside of leaves (and sometimes stems) occur when mature Rust pustules in concentric rings are common on some hosts like geranium and snapdragon
Rust diseases have been on the rise with a few new and economically important rusts entering the US. gladiolus rust, guava (eucalyptus) rust, white rust on chrysanthemum and most recently rust on Monstera. Very few of the rusts we see in ornamentals have the classic alternate host situation (common in wheat and other agronomic crops) as we are well able to maintain them in a single life stage by propagating them on our plant material year-round. Watch for rust diseases this fall and one some crops throughout the winter and spring.
Spores in pustules (whitish, yellow, orange, and brown, which is the most common color)
Sometimes leaves drop when the disease is severe
FAVORABLE CONDITIONS
High humidity and more than 6 hours of leaf wetness
Temperatures ranging from 60-85 and poor air circulation leading to prolonged leaf wetness
Using infected seedlings or cuttings and liners
PROSPODIUM RUST ON TECOMA
ROSE RUST
RUST ON FIG
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RUST ON SNAPDRAGON RUST ON SYZIGIUM
RUST ON MONSTERA
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