Flower Power Helps Fight Pests
Lessandro Gontijo, a doctoral student in the entomology department, sweeps for bugs.
Washington State University researchers have found they can control one of fruit growers’ more severe pests — aphids — with a remarkably benign tool: flowers.
The researchers recently published their study in the journal Biological Control. They found that plantings of sweet alyssum, a popular annual with small, white, sweet-smelling flowers, attracted a host of spiders and predator bugs that, in turn, preyed on woolly apple aphids, a pest that growers often control with chemical sprays.
“The results were striking,” said lead researcher Lessando Gontijo, a doctoral student in the WSU Department of Entomology. “After one week aphid densities were significantly lower on trees adjacent to flowers than on control plots, and these differences were maintained for several weeks.”
To select an appropriate flower for the study, the researchers screened six candidates, including marigolds and zinnias. They chose sweet alyssum because it attracted the greatest number of hoverflies, or syrphids, which have larvae that often feed on aphids. Hoverflies and other insects are attracted to flowers because they can find food in the form of both pollen and nectar.
Alyssum attracts beneficial insects that eat and help control wooly aphids.
Researchers compared plots of apple trees with interplantings of sweet alyssum to tree plots without flowers. While the sweet alyssum attracted hoverflies as desired, Gontijo and colleagues found few hoverfly larvae, indicating that the hoverflies were not the primary biological agent of control for aphids in the test orchard.
The mystery of the disappearing aphids seemed solved when the researchers found a diverse community of spiders and predatory bugs in the plots with sweet alyssum. But was it really the flowers that attracted these aphid predators? The scientists sprayed protein markers on the sweet alyssum and later captured bugs at a distance from the flower plots. Many of the creepy-crawlies tested positive for the proteins, proving that they had visited the flowers.
Betsy Beers, WSU Research/Extension Entomologist, mentor of Gontijo and co-author on the paper, notes that “the woolly apple aphid is surprisingly damaging for an aphid, attacking tree shoots and roots. The aphids also secrete a sticky liquid called honeydew, which can coat the apples, causing much annoyance during harvest.”
The aphids were previously kept at bay when orchardists sprayed pesticides to control codling moths. Since the phase-out of organophosphate insecticides used for codling moth, the woolly apple aphid has been making a comeback in central Washington and elsewhere.
The researchers say that the use of sweet alyssum for biological control can be easily integrated with standard orchard-management practices, but should be even more appealing to organic growers who have fewer insecticide options.
The article, “Flowers Promote Aphid Suppression in Apple Orchards,” was published in the July 2013 issue of Biological Control, and is available online at http://bit.ly/165spKS. WSU entomologist William Snyder was also a co-author.
High-Residue Farming in the Columbia Basin Keeps Soil in its Place
|“No till,” a high-residue farming practice, reduces soil erosion. If you’ve ever eaten a Taco Time burrito, you’ve sampled no-till beans grown by Central Bean Company.|
A growing number of farmers in the Columbia Basin who grow crops under irrigation are adopting tillage practices like no till, minimum till or strip till that leave crop residues on the soil surface and leave soil undisturbed. These high-residue farming practices reduce soil erosion, build soil quality, and more. Increasingly, producers find high residue farming not only improves soil and keeps it in place, but it’s the neighborly thing to do (less dust) and it can improve their bottom line. A win-win-win.
For the last eight years, McGuire has been helping farmers in the irrigated Columbia Basin learn how to leave crop residues on the ground. In irrigated areas, crop yields are generally higher than in dryland farming, but, as McGuire points out, “More residues are produced, but because of our low humidity the residues above the soil don’t decompose quickly. Residues need to be carefully managed to get the soil benefits but not have residues get in the way of planting seeds and allowing seedlings to emerge.”
A significant benefit of high-residue farming is that it helps minimize erosion caused by the high winds that blow through the area. “Wind is a big factor in the Columbia Basin. Residues left on the soil surface keep soil particles from being carried away and protect emerging crop plants from wind damage,” McGuire says.
Tom Grebb agrees. “The main thing for me is tying down the soil as quickly and as long as you can. Soil with no residues blows out.” After leaving residues in place, he has noticed changes in soil organisms as well. “No till is also better for beneficials in the soil. I had never seen the number of earthworms until we started using minimum till. We also see more evidence of mycorrhizal activity,” Grebb said. Mycorrizal fungi live in the soil among plant roots, helping plants take up water and nutrients.
Grebb also finds that, because he needs to make only one or two passes across his fields with no-till equipment, not only does more soil stay in place, but he uses less fuel. However, because of the investment in the equipment, which is often more expensive than convention tillers, he isn’t prepared to say he saves money overall. In some cases, though, Grebb has enjoyed higher yields with no till.
McGuire notes some additional motivations for adopting high-residue farming practices. “Besides being a good neighbor by controlling dust, some farmers find they can double crop: grow one crop and then another short-season crop. And in deep-well areas, farmers who have to pay for water are interested in the water savings.”
Plenty to Learn
McGuire’s goal is to help farmers increase their profits while addressing environmental concerns. His research has resulted in a number of resources to help growers with high residue farming, but he finds there’s always more to learn, especially when it comes to adapting practices to conditions in the Pacific Northwest.
How much benefit does high residue farming provide for soil? Does growing crops like potatoes undo the benefits of leaving soil undisturbed? How well will high residue farming work with crops like alfalfa, timothy hay, or buckwheat? What about specialty crops? In California, McGuire pointed out, it took ten years to figure out how to successfully adapt high residue farming for tomatoes and cotton. Can it work for crops like carrots in the Pacific Northwest?
For more information about growing crops sustainably in Washington, check out the Perspectives on Sustainability blog at: http://bit.ly/uDDtUu.
Learn Mushroom Cultivation and Grow Your Own
During a recent mushroom cultivation workshop, Jim Freed of WSU’s Forestry program demonstrated ways to inoculate small logs with edible mushroom spawn. Photo by Kate Halstead.
Whether you have a tiny backyard or hundreds of acres, growing gourmet mushrooms can be a satisfying and tasty venture. In the Pacific Northwest, there are about a dozen species including oyster, shiitake, and maiitake, which can be grown using many of our native tree species. However, ensuring success with this type of backyard farming involves developing a good understanding of the process and knowledge of the techniques involved.
Join us Saturday, June 1, 2013, from 10am to 2:30pm at Ed’s Apples to learn about the different types of edible mushrooms that can be grown in our area and how you can start your own ‘fungi farm’. Ed’s Apples is at 13420 339th Ave SE in Sultan, just off SR 2.
Topics covered will include the different species that grow well in our climate and forests, plus various growing media such as log, stump, and sawdust culture. Demonstrations will include how to prepare and inoculate logs; care and harvest procedures to encourage optimum production; and low-tech processing and cultivation of oyster mushrooms using pasteurized wheat straw for indoor production. This cultivation method will appeal to people wanting to produce mushrooms in a very short time with minimal equipment. All participants will receive a packet of shiitake plug spawn with complete instructions for cultivating your own outdoor mushroom logs.
Instructor Jim Gouin is a staff mycologist and consultant with Fungi Perfecti, an Olympia-based company that specializes in home and commercial mushroom growing supplies. Jim has a forestry background and teaches forest fungi cultivation workshops throughout North America.
The cost is $65 per person, which includes the workshop, handouts, a catered box lunch, and 100 shiitake plugs to take home. Space is limited and your paid registration must be received by May 30 to ensure a spot. Register online at http://bit.ly/12srGg8. You can also download the form at http://bit.ly/11Yrntq and mail with your check. For registration information, contact Karie Christensen at (425) 357-6039 or e-mail firstname.lastname@example.org.
For more information on the course, contact Andrew Corbin, email@example.com, (425) 357-6012.
New Resources for Small Farms: English, Spanish, and Hmong
The Extension WSU Small Farms Team has put together four narrated slide shows, now available online, for small farmers in English, Spanish, and Hmong. These resources provide insights and information on market and consumer analysis, soil quality and fertility, getting started in Cooperative CSAs, and doing business professionally in agriculture. These resources are free to share with farmers and co-workers at http://bit.ly/14tneAc.