Edamame Harvest Disaster

Usually the soy bean harvest is a time of contentment and of rewarding, hard work. This year it is devastating.

The harvest process goes like this: Click here for a look at last year’s harvest.

• Lop off the bushy plants at their base.
• Snip off the lush, green foliage to reveal the branching stems crowded with pods. Return the foliage to the garden as mulch.
• Pull off the pods, each bulging with 2-3 full-sized beans.
• Fill a couple of plastic grocery bags with pods for the bicycle trip home from the community garden.
• Steam the pods for 6-7 minutes, then cool quickly in cold water, then shell.
• Repeat for 4 days, until the harvest is finished.

The family shelling party is a chance to chat, as we fill bowls with the perfect,bright green edamame beans.

The story is very different this year. (Click on any picture to enlarge.)

There is no lush green foliage. Most of the leaves are completely skeletonized by Mexican bean beetles. The few remaining green leaves have several bean beetle larvae feeding or metamorphosing on the their undersides.

Mexican bean beetle larvae on edamame soy. The larvae with white noses are the older ones, metamorphosing into adults.

Mexican bean beetles prefer common green beans and their close relatives (Phaseolus vulgaris) but if they can’t get green beans they will switch to soy (Glycine max). After killing all the green bean plants in the area the beetles attacked my soy at mid-summer when the plants were big and bushy.

Soy plants with whole branches of flat pods and leaves skeletonized & killed by Mexican bean beetles.

As usual, pods crowd the edamame stems. But this year about a third of them are flat, with only the merest hint of a bean inside. Another third contain small, very underdeveloped beans. And a third have full-sized beans. I attribute the flat pods and tiny beans to defoliation – it is difficult to grow full-sized fruit with almost no leaves. I’ve been growing edamame soy at the Vassar Farm community gardens since 2005 and this is first time I’ve lost a crop to bean beetles.

So I filled a single bag with full and undersized pods. It was very light-weight.

2012 Soy harvest

Last night I steamed the pods then we shelled out the beans. Instead of perfect green beans, they have brown spots and sunken areas. About half of the full-sized beans are damaged along with 90% of the underdeveloped beans.  And some of the beans in the OK pile have suspicious tan areas I don’t recall ever seeing before. The pods themselves look fine, with no hint of the damage waiting inside.

Stink bug feeding damage on edamame soy beans.

I’m attributing this damage to stink bugs. They seem to have these micro-fine stiletto mouth parts they can insert into fruits and vegetables (apples, tomatoes, peppers) without visible damage to the skin. During harvest I’ve found  both green stink bugs and brown marmorated stink-bugs, both nymphs and adults. I’ve squashed more than a dozen. (It took 5 minutes to collect the bugs in this picture from an asparagus planting in a local public garden. Photography took considerably longer, the things won’t stand still.)

Green stink bugs and brown marmorated stink bugs, both nymphs and adults.

I read some research from Ohio State University. Stink bugs feed by injecting saliva into the fruit, then sucking out the pre-digested contents. The digestive enzymes stop development of the fruit, leaving corky areas. So it is possible the stink-bugs have caused a lot of the under-developed beans. Although it is possible to cut stink bug damage out of a tomato, the damage fills most of a soybean so I’m discarding damaged beans.

Now, after harvesting three-quarters of the soy bean patch, yield is about 20% of normal.

Our conversation while shelling the beans got rather dismal. The brown marmorated stink bugs are invasive. In the last few years they’ve spread rapidly up the east coast. And according to Rutgers there are no good controls. On our trip across NYS last week we passed hundreds of acres of soy beans and apples, two crops by brown marmorated stink bugs. And there is drought through-out the grain belt. Is the time coming when the US will be unable to feed itself, never mind feeding Africa?