[Market-farming] Bean Leaf Beetles

Ken Bezilla kenbez at hotmail.com
Sun May 18 10:59:53 EDT 2014

Alex McGregor emailed this to me directly since he's having trouble posting to the list, so I'm passing it on to the list -- thanks Alex!


    We have had trouble with them in the past. They decimate the leaves
    on our pole beans, killing the plants and the larvae chew on the
    maturing bush beans making them unmarketable.


    What we did was look at all the ways of controlling pests
    organically: Repelling, barriers, approved pesticides.


    We eliminated repelling (garlic oil, etc.) because it's a lot of
    work to mix & spray regularly, especially with overhead
    irrigation washing it off. We don't even consider approved
    pesticides (rotenone, etc.) because they are nerve agents and just
    as dangerous to breathe or get on skin, though break down rapidly in
    the environment. Also, they're broad spectrum killers- kill
    pollinators and predators, too. These populations recover much
    slower than the pests. And some pests survive and breed anyway.


    So, we went to barriers. We dropped pole beans and trialed different
    bush beans for flavor and production- this to please customers who
    insist on pole beans. (It takes some free samples to convince them
    that our bush beans are as good as pole beans.)


    The barrier we use is lightweight row cover. We plant bush beans in
    beds, cover bed right after planting and remove cover when first
    blooms appear. This is to let the pollinators in. (Some legumes are
    considered- self pollinating, but research has shown they produce
    more if pollinated. This also feeds and encourages pollinators and
    predators.) The mature bean beetles move in also and eat a bit of
    leaf and lay eggs. 

    The adults do a bit of leaf damage, but Rodale Institute years ago
    experimented and found that up to 20% leaf area loss by pests
    increased the overall harvest.


    Since most bush beans only set one good set of beans, when they are
    ready we pull them out, load in carts and pick the beans off in the
    shade. About now the larvae have started hatching, so we shred the
    plants and put them in the middle of a hot compost pile.


    Hope this gives you some ideas.


    Alex McGregor

    Walden Farm

    Walden, TN

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