A new study by horticulturist Eric Brennan, from the Agricultural Research Service, shows that organic lettuce growers in California are using Alyssum (Lobularia maritime) as a companion plant, to help naturally protect their crops from destructive aphids.
Alyssum, an easy-to-grow annual, produces small, elegant flowers that attract hoverflies. The hoverflies feed on Alyssum’s nectar and eventually lay eggs. Once the eggs hatch, the larvae feed on aphids common to lettuce crops. Aphids can be particularly difficult to control on lettuce crops because they tend to live in the inner leaves of the plant.
The study shows that Alyssum is so effective in protecting lettuce crops from aphids, that California farmers are using the wildflower on as much as 10 percent of their land.
Brennan shows that best practice for the companion planting is to randomly intersperse Alyssum throughout the rows of lettuce, which helps to encourage hoverflies to feed and lay eggs more evenly throughout the crop.