A plug tray of young Heuchera plants arrived at the UMass Extension Plant Diagnostic Lab recently with distinct angular leaf lesions. Foliar nematodes were found in lesions examined microscopically.
Foliar nematodes (Aphelenchoides species) swim in films of water. They can be splashed up from the soil by rain or irrigation, or they may swim up stems and petioles of wet plants. They enter leaves through stomata and feed on internal tissues, causing leaf spots and sometimes the death of entire leaves.
The best way to prevent foliar nematodes is to ensure that above-ground plant parts remain dry. Avoid overhead irrigation if possible. Water early in the day. Encourage rapid drying of foliage by increasing air circulation and spacing plants properly.
- Angela Madeiras, Extension Educator and Diagnostician, UMass Extension Plant Diagnostic Lab