Even though this is the Year of the Bean, not all our bean experiences can be positive. In fact, I can tell you in all honesty that I am done with growing pole beans in my community garden plot. I’ve tried it for three years now, and failed to get much of a crop each time due to pests: first (doing only moderate damage) Japanese beetles, and then later in the season (devastatingly) Mexican bean beetles.
But surely I know how to deal with these pests, you say. Well, yes. I don’t want to spray organic insecticides, not because I’m opposed to them under these circumstances, but because getting sufficient coverage on the long vines of pole beans is such a pain. But I’ve had good luck with hand-picking pests and drowning them in soapy water, both in home gardens and in the demonstration garden. The problem is that no matter how vigilant I am drowning adult beetles and squishing the bright yellow MBB larvae and eggs, if the gardeners with nearby plots aren’t, I’ll return to find my plants re-infested.
In previous years I have indeed been vigilant, though last year I did let the very-late-arriving MBBs get a bit of a head start before discovering them. But then I was out there with the bucket and the yellow-tinged gloves. And when I gave up and decided to take my plants out, I dipped each branch I cut off into soapy water to destroy as many beetles as possible. This year, I’d just had enough – the plants went out to the compost pile as is.
Yes, there are still live beetles on there, and I don’t care.
I still have some bush beans in the ground, and I’m keeping a covered water bucket nearby to pop beetles into as I find them. Perhaps I will be able to harvest a few beans before those plants go. And next year, if I decide to grow bush beans, I’ll cover them with floating row cover. Beans are self-pollinating, so they can stay covered till harvest time. Covering pole beans is impractical, though. I may be able to fit in some vining plants in my too-shady garden at home, where I can deal with pests in the knowledge that more won’t fly in from someone else’s infested plants a few dozen feet away.
Not that I don’t love community gardening – it’s great to have interesting neighbors who grow all sorts of fascinating plants, and personally I feel the peer pressure enough to keep my garden plot neater than I ever did at home, particularly in the heat and humidity when my love of gardening struggles to win out over air conditioning. Unfortunately not everyone feels that way, and some gardens get neglected; pests are challenging to deal when you’re busy, and not always recognized before it’s too late. Grow It Eat It can help with information gaps, though! Here’s the GIEI page on Mexican bean beetles – where I discovered that it is possible, especially in community gardens, to buy and release a parasitic wasp that will help control MBB populations. Perhaps that’s an option for our garden.
Or perhaps we can hire some minions. Thanks to MG Darlene Nicholson for this photo-manipulated view of MBB larvae and pupae: