Here in Marin, we’re fortunate to have ready access to wonderful, healthy produce. And it’s even better if you can step into the garden and pick your own! Before harvesting, check out those leafy greens, or your apple, pear, lemon or lime trees, and look for the telltale signs of leafminers, the twisting trails (or mines) the larvae leave as they feed beneath the leaf surface. The mine becomes longer and wider as the larva grows.
In addition to citrus and pome fruit trees, these leafminers attack many different vegetable and flower hosts, including cole crops, cucurbits, tomatoes, peas, beans, aster, begonia, dahlia, impatiens, lily, marigold, petunia, and verbena. Adult female leafminers puncture leaves and sometimes petals to feed on exuding sap. These punctures eventually turn white, giving foliage a stippled or speckled appearance. Mining usually has little impact on plant growth and rarely kills plants. Unusually heavy damage can slow plant growth and may cause infested leaves to drop. Damage will not be serious on most plants older than seedlings, although it may make spinach or chard unsightly.
To manage these pests:
- Remove old plants at the end of the growing season.
- Inspect new seedlings before planting.
- Provide proper care, especially irrigation to keep plants vigorous.
- Clip off and remove older infested leaves.
- Plant resistant species or varieties.
- Small seedlings can be protected by protective cloth.
- Attract the predators of leafminers to your garden by planting attractant plants.