July 8, 2015
Research generated by the USDA’s Agricultural Research Service in the heart of America’s Salad Bowl is showing how lettuce growers can control pests without the use of insecticides, by allowing a few flowering plants to grow among the salad greens. Organic farmers have long known that planting sweet alyssum throughout a lettuce field effectively controls aphids, a major pest of salad crops. Sweet alyssum attracts beneficial insects including hoverflies, whose larvae each chomp down as many as 150 aphids per day.
Read more about the research project in a short summary on the Organic Farming Research Foundation website.
Or watch the video where researcher, Dr. Eric Brennan explains this fascinating nine year research project using sweet alyssum as an insectary plant.
“Additive intercropping” inserts one or two alyssum plants per every 50 lettuce plants. Brennan says. “Farmers can provide the beneficial insects with the resources they need to control aphids, without giving up any valuable lettuce-growing area.”
This past winter, I planted a container of alyssum and placed it next to my stand of kale. I couldn’t resist the magenta mix, though the research found Sweet Alyssum performed better than ornamental alyssum. Purchase organic seed at Seeds of Change.
This spring I had no aphids on my kale. Usually the aphids swarm my brassicas as the weather warms. I confined my alyssum to a container since it self-sows freely–like a weed in my area.
I might try interplanting with a newer alyssum, ‘Snow Princess’ from Proven Winners–a hybrid that doesn’t self-sow. I’ll wait until it becomes available in 6-packs and I’ll see if the hoverflies like it.
Photo credit, first photo: Papio Valley Nursery