Interplanting, Ancient Roots

November 26, 2009

INTERPLANTING IS ANCIENT. It predates agriculture. Interplanting even predates the dinosaur, going back to the first plants growing side-by-side on planet EARTH. Indeed, interplanting is a natural ecological phenomena, existing much like the stars in the night sky.

On farms and gardens, interplanting is sometimes called companion planting. Ancient farmers observed natural interplanting or companion planting in their fields, along with winds, rains, heat, cold, insects, solstices and lunar and planetary movements across the sky. Today, much of the natural interplants occurring in farm fields and gardens is derisively referred to as weed growth (though major crops like maize and wheat still contain the genes of weed ancestors). Indeed, it is a value judgment when native wildflowers like prairie sunflowers are labeled weeds and destroyed by cultivation or herbicides.

In the U.S. state of Tennessee in the 1930s, during America’s Great Depression, the insect factor in interplanting was first subjected to scientific experimentation by an entomologist named Marcovitch. Writing in a 1935 issue of the Journal of Economic Entomology, a still extant publication of the Entomological Society of America (ESA), Marcovitch traced his interest to experiment station reports by other entomologists. Much like the ancient farmers who based planting decisions on empirical and astronomical observations, an entomologist writing in 1906 “advocated for the control of the melon louse the planting of mustard or kale or rape around the melon field. The lady beetles would thus become plentiful after feeding on the cabbage aphids and be ready to attack the melon louse.”

Marcovitch’s penchant to begin the modern era of experimental companion planting was also inspired by a 1929 entomological report that woodlots fostered populations of aphid-eating syrphid flies that destroyed aphids in garden peas. In contrast, pea fields away from woodlots were devastated by aphids and sometimes yielded no crop. Figuring that aphid damage to vegetables was a consequence of an absence of biological control by aphid natural enemies, Marcovitch began a series of scientific interplanting experiments to boost natural biological control in crop fields.

Tennessee turnip strips planted in March yielded aphid natural enemies like lady beetles and small parasitic wasps that migrated later into adjacent strips of peas, beans, corn, okra, cotton, cucumbers and watermelons. Aphid populations declined in the main crops, thanks to the adjacent natural enemy-laden turnip rows. In contrast, “control” watermelon plots lacking adjacent turnip rows to provide natural enemies were destroyed by aphids early in the season.

Since Marcovitch’s pioneering 1935 report in the Journal of Economic Entomology, books have been written on interplanting experiments to increase natural biological control in crops.


Beneficial Bugs Challenge Theoretical Physics

November 8, 2009

INSECTS, MICROBES, PLANTS and other organisms form complex ecological systems with all sorts of synergisms, antagonisms and cooperative interactions, leading oftentimes to beneficial insects controlling what we consider pests. Whether it be forest, desert, farm field or garden, intricate and nuanced ecological communities can be nurtured to provide a measure of “natural” biological pest control.

The nuanced complexity of biological and ecological systems has at times intrigued theoretical physicists usually more attuned to quarks, neutrinos, chaos theory and quantum phenomena. Murray Gell-Mann, winner of the 1969 physics Nobel Prize as a Caltech (Pasadena, California) professor “for his contributions and discoveries concerning the classification of elementary particles and their interactions,” created the Santa Fe Institute (New Mexico) to better focus on “the theory of complex adaptive systems.”

Humans, plants and animals are individually and collectively at the ecosystem level examples of complex adaptive systems. Which is one reason creating sustainable agriculture is such a challenge, and companies such as Rincon-Vitova Insectaries end up with catalogs of 55 pages of beneficial insects, microbes, seeds, traps and other inputs for creating sustainable garden and farm systems. And even then, it is not always easy and can take longer than expected to force changes in even the smallest complex adaptive system that is a backyard garden.

“Unfortunately, it will be a long time before human knowledge, understanding, and ingenuity can match–if ever they do–the “cleverness” of several billion years of biological evolution,” wrote Gell-Mann in his book, The Quark and the Jaguar. “Not only have individual organisms evolved their own special, intricate patterns and ways of life, but the interactions of huge numbers of species in ecological communities have undergone delicate mutual adjustments over long periods of time.”


Beneficials Sweet on Alyssum

July 22, 2009

INTERPLANTING SWEET alyssum (Lobularia maritima) is an excellent way to promote natural biocontrol of a wide array of landscape, orchard, field and garden pests like aphids, stinkbugs, leaf and fruit worm caterpillars, etc. Companion planting has ancient roots, figuring in the writings of the Greek Theophrastus in 300 B.C. and the Roman Pliny (Plinius Secundus) in 1 A.D. Though popular in organic gardening and farming, floral interplants escaped serious scientific scrutiny until recent years.

Australia’s wine grape growers are among those who take their sweet alyssum companion plantings very seriously. At Australia’s EH Graham Centre for Agricultural Innovation ecological engineers and entomologists like Geoff Gurr of Charles Sturt University are fine-tuning companion planting. Firstly, you need to choose companion interplants that supply nectar, shelter and other resources to beneficial predators and parasites but not to pest species.

The Aussies focused their scientific studies on a Trichogramma species parasitizing and destroying the eggs of the lightbrown apple moth (Epiphyas postvittana), a key pest of Australian vineyards. In “clean” vineyards where weeds and ground covers are destroyed by herbicides or cultivation, biocontrol species like Trichogramma may survive as few as two days, versus three days with water only and up to 20 days with sweet alyssum (the best ground cover tested). Alyssum flowers doubled the number of moth eggs parasitized over a 10 day period. In contrast, when the alyssum plants were deflowered the Trichogramma perished and there was little biocontrol.

But there is more to the story. “Not only is plant species important, but the cultivar within the species is critical,” Gurr told an Entomological Society of America annual meeting. For example, Trichogramma survive far longer on white-flowered alyssum cultivars compared to purple and other colors. Alyssum also boosted predators without aiding the apple moths, which was not the case for every ground cover interplant tested.

Most landscape and cropping systems have not been subjected to the same level of ecological and laboratory investigation as Australian wine grapes. Thus, Rincon-Vitova and other insectaries selling beneficial insects generally recommend blends of flowering plants supplying floral nectar throughout the season.