Tuesday, July 26, 2011

Phytoseiulus persimilis: Ace in the Hole

Mites and aphids. Those two words uttered in the presence of a hops farmer and you will likely see them shudder in fear of their crop. But for these two hops farmers, we get excited at the opportunity to try something cool to combat these pests. 

The first signs of spider mites arose during the last week in June. A few light-coloured leaves with a smattering of bleached spots on the upper side of the leaf and a light webbing on the underside near the petiole was a sure sign that the mites have arrived. 

We have never really witnessed the speed at which these pests can progress so it came as a surprise that in one week's time, a few localized outbreaks had impacted our plants significantly. Tim being the insect man, already had the answer. Unfortunately, he was the only one who could pronounce it: Phytoseiulus persimilis.

It turns out that the above scientific name is nothing but a mite with an appetite for other mites, especially the spider mite pest. What makes these mites so special is that they are small enough to penetrate the protective webbing of the spider mites to attack them on their own turf. Once consumed, the predatory mite can reproduce much faster than its prey. Soon enough, there are are more wolves than deer, so to speak and Voila! Problem solved. At least, that was the idea. 

The application procedure was simple yet time consuming: take one leaflet infested with the predatory mite and attach it to the hop leaf at the petiole. Over an over again to each affected plant. 

The method is proven to be effective in green houses but not fully tested on open-air hop farms. Consider this as trial one.  Time will tell whether this pest infestation will be curtailed by our last-minute bio-control application method. 

Stay tuned with how these organic hop farmers are dealing with the aphids...

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