Insect & Disease ID And Diagnosis Guide: Patches
Diagnose pest and disease issues that manifest as patches.
January 19, 2009
Scouting tip: After determining the problem, discard plants with contagious diseases and take appropriate control measures.
Downy mildew on salvia causes brown vein-bounded spots.
Look on the underside of leaves like this for fuzzy patches of downy mildew. Foliar nematode injury can look similar.
Round white spots on snapdragon leaves indicate impatiens necrotic spot virus (INSV).