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Sunday, July 3, 2011
Sunday musings about insects & hops
While sending an email to a colleague about insect & hops in North Carolina this morning, I started thinking about the context in which I get questions about insects, especially in new or speciality crops.
From my email, "I think folks focus somewhat on insects and diseases because these are things we have management tools, and answers, for. The harder question to answer is if a crop itself is ready to be grown where people want to grow it. We can recommend a pesticide or cultural strategy for insect management, but we don't know if there are any hops varieties (or other new crops) that will grow well (or well enough to be commercially profitable) in our state. I would rather see this question as the focus of the conversation rather than 'spray X' or 'release predator B'."
Japanese beetle feeding at the Lake Wheeler Hop Yard, 2010. Photo: HJB
The insect questions still arise, however, but I think these need to be pragmatically address in the context of a still unproven agricultural system. Japanese beetles are a common insect seen feeding our hop yard at Lake Wheeler, and I commonly get questions about them from beginning hops growers. I don't think Japanese beetles require treatment unless they are feeding extensively. If mature (second year or older) plants have so little foliage that JB feeding seriously threatens defoliation, the problem is not JB--it's plant vigor, and all the big guns thrown at the beetles are not going to produce a viable crop. Grapes are an excellent example of this--JB feed at the top of the plant, and as long as they don't go below the top trellis wire and are not in fruit, growers do not need to treat. That foliage will be removed anyway. For first year plantings, the scenario is different, but folks should distinguish between baby plants and mature plants in terms of JB management.
Browning on developing hops cones. Photo: HJB
Another insect I got a lot of questions about last year was thrips. We have extremely high thrips populations in the SE, but I have yet to see thrips in cones at Lake Wheeler. This means that the cone browning observed is unlikely to be thrips injury and is more likely to be due to uneven aging associated with our early and prolonged flowering period. I'd hate to see anyone treating for thrips in hops based on cone browning, especially if the browning is observed in the oldest cones.
My thought process around pest management in emerging and new crops is evolving, but sustainability, environmental & economic, remains the key driver of my pest management philosophy. Understanding pest biology is important, but more important is the feasibility of the whole agroecosystem. Although one factor can sink a farming system, everything must work in harmony for it to succeed.