Small, water-soaked, translucent spots on leaves that enlarge and turn brown-black with a yellow halo, sometimes oozing bacteria in humid conditions; can collapse whole leaves in severe cases.
Cause & development
Affects Philodendron, Monstera, and related aroid houseplants (originally described on Dieffenbachia, in the same family). EPPO code XANTDF.
Favorable conditions
•High humidity with wet foliage
•Overhead watering or misting that leaves water sitting on leaves
•Contaminated cutting tools or new, unquarantined plants
Management
1Avoid wetting foliage when watering
2Remove and discard infected leaves
3Sanitize cutting tools between plants
4Isolate new plants before adding them near others