Archive for May 26, 2008

Beetle battle

Colorado potatoe beetle

   Gardeners and farmers market vendors I’ve spoken to this spring show consensus that everything is at least two weeks behind our typical Iowa growing season.

   For the most part, I agree. While it’s nice to enjoy the scent of lilacs at the end of May, I’m still waiting to pull my first radish.

   But one thing, I discovered, seems even earlier than usual.

   This weekend I was encouraged to see that all my potatoes had finally emerged at the garden I lease from the city.

   While things are slow, most plants are looking great.

   Upon closer inspection, I saw something striped and moving and NNNOOOOO!!!

   Already, it’s time for Iowa’s pest season to begin.

   The dreaded Colorado potato beetle — Leptinotarsa decemlineata — the bane of my tiny potato crop, was already at work decimating the foliage just as the plants emerged from the ground.

    I looked to the helpful New York Times “1,000 Gardening Questions & Answers” book, a gift from my friend Dru (thanks DruJ) to research what I might do this year to battle these beetles.

   What I found was somewhat discouraging.

   The organic methods I prefer aren’t very effective when a single female can produce 10,000 offspring by the end of summer.

   I’ve used the powder Garden Guard on the potatoes, but it only stays on as long as it’s not windy or rainy. That’s what — about two hours on any given day this spring?

   Knowing the damage they wreak, I’m much less squeamish about squishing the little buggers than I would have been in the past.

    The Times’ book recommends organic gardeners apply a dose of Bt (Bacillus thuringiensis) to kill the small larvae.

    Larger larvae and adults can be killed with rotenone, a strong but short-lived botanical poison favored by organic gardeners when they must take extreme measures.

   To add insult to infestation, the book notes, Colorado potato beetles can live a full two years. But they won’t stay if there’s nothing to eat, so the final – or first – line of defense is late planting. If they don’t find any potato, eggplant or nicotiana leaves when they emerge from the ground in spring, they’ll leave.

   So, I’m too late (or I was too early) to try that last idea.

   I do try to rotate where I plant the potatoes, but it doesn’t seem to matter where they go. The beetles will find them. Maybe next year, I’ll go for the late start. Any other suggestions?

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