The Giant knotweed plant, commonly called Goliath (the scientific name is Reynoutria sachalinensis), can be unsightly in roadside landscapes, a noxious weed in the home landscape, but is always a favorite forage plant for honey bees. It grows primarily in the eastern U.S. and when in plentiful supply produces a mild, medium amber honey that is favored by many, especially beekeepers who get to harvest the surplus.
The plant is an aggressive invasive weed that was introduced into the U.S. several years ago as an ornamental. It is native to Japan and Korea, grows to about 12 feet tall and can grow as much as 6 inches overnight. Its huge leaves actually offer shade in the summer and are often used around homes as a screen or shade producer. Of course that shade can be problematic for other plants, and left alone, Giant Knotweed soon commands large areas of land, shading out any competitors and out competing almost any other plant for water and nutrients. It doesnt like company.
However, Pam G.Marrone, Ph.D reports on the development of a new "green" pesticide obtained from an extract of this giant knotweed plant, at the recent American Chemical Society meeting in Philadelphia. "The product is safe to humans, animals, and the environment," says Marrone, founder and CEO of Marrone Organic Innovations, Inc., in Davis, California.
The new biopesticide has active compounds that alert plant defenses to combat a range of diseases, including powdery mildew, gray mold and bacterial blight that affect fruits, vegetables, and ornamentals. The product will be available this October for conventional growers, according to Marja Koivunen, Ph.D., the director of R&D for Marrone. A new formulation has also been developed for organic farmers and will be available in 2009.
Biopesticides are derived from plants, microbes, or other natural materials and are proven to be safer for humans and the environment. The active ingredient of the companys first product came from lemongrass oil.
Synthetic pesticides dominate the $30 billion pesticide market, but biopesticdes should reach $1 billion by 2010, about 4.25% of the global pesticide business.
One biopesticide commentator acknowledged that knotweed extract "induces phytoalexins which infer a plants resistance to powdery mildew and other diseases such as Botrytis". In other words, the extract helps the crop or ornamental plant fight the mold rather than attacking the mold directly. When the extract is made with organic alcohol, the fungicide should be considered organic, a boon for organic growers everywhere.
Why is this important?
One problem honey bees have had in recent years is that growers are legally allowed to apply fungicides to crops in bloom because the sprays have not been shown to be harmful to adult, foraging bees. However, recent long term studies by USDA scientists in almonds have shown that these fungicides are collected and returned to the hive and stored in the pollen collected by the bees while foraging. These compounds then sit and wait to be fed to the larvae or even adults later in the season, causing problems down the line.
Another issue is that when certain fungicides are coupled in a tank mix with certain insecticides, the toxicity of the insecticide increases exponentially, rendering a relatively safe insecticide deadly to bees, and apparently humans.
The addition of a safe biopesticide to the market place should be welcomed by not only farmers, but beekeepers, and anyone who is responsible for the health of their crops, and the people who eat them.
Of course pesticides have not been shown to directly cause Colony Collapse Disorder. Generally, however, pesticides are bothersome, and in many cases downright deadly to honey bees and other pollinators and reducing their use for any purpose will only help. And, though not indicted directly, pesticides are suspected to be one of the elements in the environment that are stressing honey bees' immune systems, leading to a more available path for whatever the suspect pathogens are that are directly responsible for CCD. Stay tuned.
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