Many of the lettuces beds I have worked with over the summer have been affected by “Powdery Mildew.” You can avoid this fungus by selecting varieties that are less susceptible or those that are resistant. Some non-chemical way to control…
- Remove infected leaves promptly to prevent spore release and contamination of the soil.
- Rotate lettuce crops to minimise the risk of infection from resting spores
- Do not overcrowd plants… high humidity increases the risk of infection
The mildew can be identified by yellow patches on the upper leaf surfaces, and are generally angular because they are limited by the veins.
A fuzzy growth of whitish mould on the underside.