Tuesday, August 23, 2011

Tomato Patch: Coping with Stink Bugs

What's that on the window?
“Where are the stink bugs this year?” friends asked in May and June.

“Outside breeding so we’ll have a generous supply trying to figure out how to get into our homes in September and October,” I usually replied. It’s late August now, and the brown marmorated stink bugs have started to show up on our windows and sunning themselves on the western sides of our homes in late afternoon.

I’ve seen them all summer, of course, in our gardens. Their favorite foods at Meadow Glenn include tomatoes, raspberries, blackberries, green beans, cucumbers, and squash.

Stink bugs dining on Virginia Sweets tomato
In the Tomato Patch, the stink bugs seemed especially attracted to two large-fruited varieties, Virginia Sweets and Brandywine Red. Virginia Sweets is a large yellow tomato with reddish blush. Perhaps I shouldn’t be surprised that the stink bugs like the big yellow because researchers have found the bugs have some preference for that color. I haven’t figured out why the bugs preferred the Brandywine Red to the nearby Brandywine (Sudduth’s Strain) fruit.

The small Sungolds seem untouched, though I haven’t used a magnifying glass to verify that fact. The larger red Juliets showed minimal damage, though I think my picking at “breaker stage” this year helped minimize the bug attacks.

Brandywine with stink-bug "pinpricks"
In mid-June, when I saw the carnage the stink bugs were starting on our berries and tomatoes and realized my daily attempts to control the bugs by drowning them into soapy water was not going to be effective, I balanced the risks and began periodic spraying with a commonly available garden spray, Ortho Max Lawn & Garden Insect Killer (bifenthrin), which lists stink bugs among the insects it kills. I strictly followed directions and the more stringent California “days to harvest” after each spray. My decision to use a pesticide was difficult because I have had an essentially organic garden for at least 10 years.

Within 10 days the number of stink bugs went from “impossibly high” to “seldom seen.” Last year we harvested few raspberries, and those we did were usually stink-bug damaged. This year we harvested many quarts of beautiful berries. Last year we threw away many of our large tomatoes because of stink-bug damage. This year we have eaten most.

I've turned off the night light
Before dawn Sunday morning I found evidence of the stink bug hordes that soon will be seeking ways into our homes for protection from cold weather. As I stepped out of the garage to walk to our mailbox to get the Sunday Post, something caused me to glance up at the overhead night light. Scores of stink bugs swarmed around the light. Sunday night for the first time in 15 years I turned off the light.

Scientists from multiple disciplines are studying brown marmorated stink bugs and how they may be managed. I posted earlier about the EPA’s approval of pesticides for stone and pome fruits and for organic growers and about USDA experiments with tiny, parasitic wasps. An excellent overview of what’s happening is the University of Maryland Extension’s Entomology Bulletin, which details symptoms of the insect’s damage on crops and ornamentals and includes outstanding photographs. To link to the bulletin, CLICK HERE.

1 comment:

  1. Hi Bob,
    Thanks for the link to the entomology bulletin.
    I have been thinking about trying to use something to kill the stinkbugs on my raspberries. I have gardened organically for 30 years, but I am very discouraged at the destruction of my raspberries. What information do you have about bifenthrin? Is there a way to find out its half life? I assume that it will kill beneficials as well as pests.