In the field, the right flower arrangement can improve organic pest control

Jan 17, 2014 by Ann Perry
ARS horticulturist Eric Brennan has found that randomly interspersing alyssum plants throughout rows of organic lettuce helps maximize visits by hoverflies that prey on lettuce pests. Credit: Stephen Ausmus

Studies conducted in an organic lettuce field managed by the U.S. Department of Agriculture (USDA) indicate that there's more to sweet alyssum than just good looks. Agricultural Research Service (ARS) horticulturist Eric Brennan has identified ways to improve how the pretty white flowers control aphid pests that prey on lettuce leaves. ARS is USDA's chief intramural scientific research agency.

Lettuce growers in California's central coast plant alyssum to attract adult hoverflies that feed on the flower's pollen and nectar. After eggs laid by the well-fed females hatch, the voracious larvae prey on currant lettuce aphids—an important primary insect pest of lettuce in the region. The aphids are particularly difficult to control because they colonize the interior leaves of the lettuce plant.

Brennan, who works at the ARS U.S. Agricultural Research Station in Salinas, Calif., wanted to figure out the most cost-effective alyssum planting patterns in lettuce fields to help organic producers maximize their profits. At a working research farm in Salinas that is certified for commercial organic production, he established experimental beds with eight different planting combinations of alyssum and romaine lettuce.

For two growing seasons, Brennan evaluated how alyssum biomass and flower production varied with alyssum planting density and how competition between lettuce and alyssum affected the biomass of both plants. In beds where alyssum had been planted in addition to a full complement of lettuce, the alyssum produced more blossoms per gram of alyssum dry matter.

This response indicated that the alyssum and lettuce planted in this pattern may have been in stronger competition for nutrients needed to support biomass production. But the resulting boost in blossoms increased alyssum's value as an insectary plant, which is a flowering plant cultivated in crop fields because it attracts insect predators to feed on pests.

Brennan has also concluded that randomly interspersing alyssum plants throughout all the lettuce rows could minimize competition between lettuce and alyssum and encourage adult hoverflies to forage for pollen and nectar more evenly throughout the field.

Results from this study were published in Biological Control in 2013.

Explore further: Ivory in Uganda seizure likely stolen from impound vault

More information: Read more about this work in the January 2014 issue of Agricultural Research magazine.

add to favorites email to friend print save as pdf

Related Stories

Flower power fights orchard pests

May 14, 2013

Washington State University researchers have found they can control one of fruit growers' more severe pests, aphids, with a remarkably benign tool: flowers. The discovery is a boon for organic as well as ...

Researchers test effects of LEDs on leaf lettuce

Nov 19, 2013

In the life cycle of plants, most developmental processes are dependent on light. Significant biological processes such as germination, shade avoidance, circadian rhythms, and flower induction are all affected by light. Recent ...

New romaine lettuce lines launched

Jan 18, 2011

California and Arizona, the two largest lettuce-producing states, account for more than 95% of the lettuce grown in the United States. Since the early 1990s, the states' lettuce crops have been subject to ...

Recommended for you

Fish catch break on world stage at global conference

3 hours ago

Inland fishing - the powerful yet quieter sister to the large, salty marine aquaculture powerhouse - has gained what experts say is a much-needed visibility boost this as the first partnership between Michigan ...

Monarch butterflies rebound in Mexico, numbers still low

4 hours ago

The number of Monarch butterflies that reached wintering grounds in Mexico has rebounded 69 percent from last year's lowest-on-record levels, but their numbers remain very low, according to the World Wildlife ...

Satellites, mathematics and drones take down poachers in Africa

6 hours ago

In 2014, 1,215 rhinos were killed in South Africa for their horns, which end up in Asia as supposed cures for a variety of ailments. An estimated 30,000 African elephants were slaughtered last year for their tusks to be turned into trinkets. The world loses three rhinos a day and an elepha ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.