Michigan Organic Hops Production: utilizing current IPM models to investigate biocontrol effectiveness on hops pests and diseases in an organic production system
Our initial plans for testing biological disease and insect control inputs and products on our organic test plot of hops changed over time due to our time availability and the weather patterns. Upon being granted the funds to expand the yard and purchase biological agents for the pest and disease pressures, we were faced in 2011 with a horribly rainy Spring which impacted the timing of the expansion project. We were however able to accomplish this goal. It was just delayed through heavy equipment getting stuck in the mud. We successfully tripled the square footage from 1/5 acre to 3/5 acres and added more plants to fill the space. Previously, there were 9 varieties on site. In 2011 we added 2 more varieties and in 2012 an additional 2 to make 13 total now. On site are Magnum, Centennial, Chinook, Nugget, Perle, Sterling, Fuggle, Hallertauer, Golding, Mt. Hood, Willamette, Saazer, and Teamaker.
It has become apparent that some varieties are fed on preferentially over others, i.e. Sterling. Though aphid pressure was non-existent to test beneficial insect and biological control products, such as beneficial fungi and neem-based products, there was enough spider mite pressure to test our hypothesis. The great thing about the lack of (live)aphids was that the biological diversity surrounding the organic test plot was very hospitable to natural populations of aphid parasites as was evidenced by the aphid mummies we found on the undersides of a few leaves. The challenge to adding the disease control products portion into our test rotation was twofold. First, there was no significant disease pressure to obtain both a test and control set of data. Second, we had no opportunity to install a small on-site well, so the methodology of delivering root zone biological protectants could not be effectively applied.
The remaining grant funds will be used to get a viable water source on site at the organic test plot and a suitable flow-based injector for root zone application products. We will be testing these biological disease control products after the grant expires in our new commercial yard where we have all the tools to accomplish this goal as well as the organic test plot, once we can install the well and purchase the injector system.
With the new commercial yard project begun in February of 2012 we had all the space and available material to test pest pressure again, but this time in the large yard sited in Hickory Corners. The new business and new opportunity provided us with the chance to test our biological insect control experiments on starter greenhouse material. With the re-birth of the hop industry in Michigan, a couple greenhouse operations have been in the process of propagating hops from cuttings. The greenhouse industry has traditionally had trouble with spider mites as a pest. Last year was no exception. Pesticide resistance can develop and appeared to be the case in our starter-plants last year. We tried very hard to convince our contract grower that he needed to implement a biological program in his operation, but to no avail. There were not even yellow sticky cards for monitoring the various pests. With the resistant mite population unable to be controlled in the closed greenhouse environment, we decided to treat the “plugs” (2 1/4″ x 4″ – 21 cell flats) first with a Neem-based “sprench” followed by an application with spider mite predators, before transplanting into the commercial field. With between 3 to 5 applications out in the planted field, based on area specific pressure, we were able to successfully control mite population below the economic threshold necessary for a marketable hop crop and overcome the pesticide resistance problem brought from the greenhouse. This growing season in the greenhouse is totally different- everything is much more clean, there is less pest pressure and an IPM program is in place, as Bonnie can attest to having planned to visit every two to three weeks and monitor their (the greenhouse propagator’s) pest and disease practices. See the link below to a picture.
Impacts and Contributions/Outcomes
I think seasonal weather patterns will continue to keep growers of all horticultural, specialty, and value-added crops on their toes. With unseasonably milder winter comes lower pest die-off; look at the example of fleas in the animal realm. Also with higher temperature extremes comes quicker and greater pest and disease flare-ups. So having all the tools in the IPM manager’s toolbox will become more and more important over time, including having biological disease and insect control options available. Earlier and preventative measures especially can help reduce reliance on traditional pest control products and could potentially assist in reducing the pest resistance cycle that periodically becomes a problem in different growing systems.