Monday, July 12, 2021

I Choose Hand to Hand Garden Warfare

Long ago, for a lower school essay assignment, I took on the topic of chemical warfare as my subject matter. It was so long ago, in fact, that Agent Orange never arose in my research. While I do not think that research paper long ago had a direct impact on my garden philosophy, it lingers in the back of my mind each time I go out to the garden to defend my food supply from those usually smaller creatures that also wish to devour it.

My gardening roots entangle with those of my maternal grandfather, who had a large garden in Iowa and with whom we spent a month or more each summer of my youth. While my cousins were off doing other things, I spent most of my time in that garden, helping pick and weed, or sitting in a comfy perch in a nearby apple tree, reading, looking out at the garden and listening to the birds and insects who shared their space with me. I never once saw Grandpa spray and I was never once told to stay out of the garden, as I know Mom would have insisted had anything been amiss. Even if something "safe" had been applied, Mom was super over-protective.

So now, as I work to defend my turf and my food, my go-to is essentially hand to hand combat. I literally lay a hand -- or at least a finger or two -- on any "pest" that I find.

These days, the marauding horde is mostly Colorado Potato Beetles (Leptinotarsa decemlineata). They are about 10 mm (38 in) long, with a bright yellow/orange body and five bold brown stripes along the length of each of its elytra (the hardened wing sheaths that you see on their backs.)

I have, over the years, become quite familiar with these creatures, and have become pretty adept at finding the yellow egg clusters, laid on the underside of leaves, as well as the adults and the larvae in their various sizes and guises. I am pretty happy with my hand to hand combat approach, as they will not likely develop a resistance to this technique, as they have to many pesticides.

The "babies" start out as very tiny, brick red spots with black heads, much smaller than the proverbial head of a pin to which small things are often compared. In my experience, they tend to hide in the tightly folded new leaves at the top of a potato shoot or tucked into the node where the leaf stem meets the plant. In good light situations (don't try to hunt them near dusk!) I find the tiny things, as well as their larger kin, easy to spot, even several feet away if I am looking from the correct angle. Moving the plants around helps bring more bugs into view.

As the larvae grow, they change color and eventually end up a very light, large hungry beast. These are what do the most of the damage. BUT I have found egg masses (turning the plants to one side then the other to reveal the underside of leaves, with a eye peeled for the flash of bright yellow which indicates an egg mass), larvae of various sizes and adult beetles in the garden at the same time and even on the same plant!

De-bugging is a daily event for me, and takes about an hour for my 4, 75' long rows of potatoes. I either plan to squish every stage of bug development that I find, or I am prepared with a small container of water with a wee bit of detergent (to cut surface tension) into which I knock the adults, drop the larger larvae and the sections of leaf with egg masses. the smaller larvae get squished. 

It is coming on mid-July now, and I am seeing Japanese Beetles (Popillia japonica) beginning to appear on the potatoes also. If I am quick, I can knock them into the soapy water, too. I am learning to come at the beetles lounging on the plant's leaves with my hand from above with the water just below, as if one attempts to fly away, it will likely hit my hand and fall into the water.

If you should get tired of the daily debugging session, keep in mind that:

  • Potatoes can usually tolerate up to 30 percent defoliation when they are in the vegetative stage.
  • They are much more sensitive when tubers are beginning to bulk and can only tolerate about 10 percent defoliation.
  • Tuber bulking begins soon after flowering, making this time critical for beetle management.

And if they do get away from you, you can always resort to chemical warfare. I had to do so a couple of time when I was working full time and had to miss a de-bugging session or two in a row due to weather and my work schedule. As the University of Minnesota extension office says, the main drawback to chemical control is the bugs developing resistance, I found that using Bonide's Captain Jack's Deadbug Brew (approved for organic gardening) worked well.

[all photos courtesy of University of Minnesota Extension web site]