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Partnering with Nature

April 2, 2010

Some of our most exciting news for the new year is in the tiniest of packages. So small in fact we hope you never see it. We have undertaken to drastically reduce the amount of chemical that we use in our greenhouses. We have been practicing Integrated Pest Management (IPM) for many years by using scouting techniques to determine infestations and pest thresholds before spray applications. This step of using beneficial insects and predators is going a step further.

Over the past decade some pests have become too hard to control, and some like the Western Flower Thrip, arrived already resistant to all chemicals approved to counter them. Due to the increasing failure of chemicals to work and our desire to use less for cost and environmental reasons, we were excited to finally take the leap into biological controls.

This has resulted in our using a multi-faceted approach to control which includes prevention, predation, parasitism and perhaps most alarming, self-infestation. We have made a real leap of faith on this, hoping and trusting that it works. We have been working very closely with the BioBest corporation of Belgium and Canada, the providers or our predators and parasites and our regular IPM scout to manage the system.

It is difficult to explain the system in any summarized form, but what we are doing for the most part is introducing predatory insects and organisms to the greenhouses that are proven to be natural enemies of the pests that plague our flowering plants. The insects which cause us the most problems are the aforementioned Western Flower Thrips which are a major vector for disease and Green Peach Aphids, whose colonies can quickly destroy a crop by overfeeding. Greenhouses are generally plagued by fungus gnats and shore flies as well, both causes of disease transmission amid crops, and while we haven’t realized this as a problem for us in the past we are watching it.

Dipping trays of plant plugs in a trichaderma and nematode solution. Fighting thrips and fungal disease with a quick preventive bath.

We seed the majority of our plants in our own greenhouses, but due to timing, quantity and sometimes patent protection we buy in small seedlings and cuttings from a variety of other growers. Though we deal with premium and quality growers throughout the region, we have no control over the growing practices in these locations. Sometimes these transplants can arrive infested with disease or insects. To combat this we have begun “dipping” all transplants that enter the farm from non-sterile locations. The solution we dip them in is a suspension of Plantshield– a fungus that fights off more dangerous varieties of fungal disease–and a type of Nematode–a microscopic worm-like organism–that when applied kills off thrip larvae on the foliage and survives in the soil to do the same there.

Applying breeding colonies of mites to all of our plants, including seed trays, ensures protection against thrips from the get-go.

After transplanting these or any of our own home-grown crops we are battling the thrips by establishing breeding colonies on every tray and hanging basket of Ambylseius-cucumeris. This is a mite,in the arachnid family, that feeds on a few stages of the thrip life-cycle. The application appears as a tiny pile of bran meal on top of the soil of a plant. This is the most likely sight the customer will see of our actions. Inside the teaspoon sized pile are two active mite species.

Bran mites and thrip eaters breed to abandon in this musty pile of cereal.

One is a bran mite that feeds on the fungus that grows on the pile of cereal. The other is the real beast of burden, Cucumeris, which uses the other mite as a food source while it breeds in the little warm dry pile. Many of these predatory mites then leave their “nest” in search of more food, in this case the thrips which are attempting to prevent your geranium and dahlia from reaching its full potential. By feeding and nurturing this little colony we hope to create a self-sustaining pest free plant by mid spring.

In addition to the mites that attack the thrips, we are also releasing another mite to go after  the fungus gnat and shore fly larvae. These atheta coriaria mites are travelers and will seek out the best eating locales in the green house. Likewise the hypoapsis miles rove beetles that we have released are heavy feeders of all three pests. They are our strongest night feeders leaving their soil caves and roaming the greenhouses for tasty treats.

One of the hardest parts of this process to accept was the arrival of our banker plants. These grass like barley plants showed up in a styrofoam box, that when opened simply teemed with aphids. Thats right aphids. the scourge of every gardener. What took some time to accept is that these were in fact that a grass or cereal aphid, unlikely to attack the vast variety of plants grown on our greenhouses, but certainly a pest. These little guys are actually just hanging out in a grocery store of sorts for the real threat: Aphidius colemani.

Fresh barley plants, full of fresh cereal aphids, awaiting mummification. Sort of like lambs to the slaughter.

This tiny, smaller than an ant, parasitic wasp seeks out many types of aphids and injects its egg into them. the aphid body then forms a mummy of sorts turning from its vibrant green to a dull brown, while the wasp hatches inside and feeds off the host body, only to hatch and lay up to 500 eggs of its own in other aphids. The real appetite of this parasite to reproduce requires such an abundance of hosts that we need to actually provide them to keep the beneficial insect from moving on to greener buggier pastures. We introduce these banker plants, chock full of aphid hosts to each of our greenhouses every couple of weeks.

We don’t plan on stopping with just these measures, but we definitely want to proceed with caution as we track how successful the program is. To learn more about what we are doing and to see some of the beneficials in action make sure to come by our Saturday open house at 10 am when we have a special presentation and workshop going over our exciting new biological control program.

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