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10/17/2009: "Fall Spraying"

As I've mentioned in a previous post, I've recently realized how serious the weed problem was in the weed, er, wheat field. Bindweed is a non-native noxious weed, and it is a fierce competitor: roots that go thirty feet deep, seeds that remain viable for decades, ability to regrow from root fragments cut by rototilling, etc. So, after researching on-line a bit I came to the inescapable conclusion that spraying herbicide was going to have to be at least part of the strategy for getting it under control.

Fortunately, fall is the season that is best for spraying. The plants are sending energy down to the roots to store it for winter, and this makes the herbicide effective. I had previously purchased a backpack sprayer; it was originally intended for use in the orchard, but the man at Wilco thought that my approximate acre could be done with just a backpack sprayer. "Just walk forward at a steady pace, pumping about once every five seconds," he said. It sounded simple, and certainly cheaper than purchasing a tow-behind sprayer at a cost of $520.

I assembled my tools of destruction down at the field. These included a couple of six gallon water containers, since I didn't have a good way to refill the backpack sprayer via a hose.



Here's how the field looked on the day I sprayed. I used fiberglass flags to mark the field off in 20' x 20' sections so that I could keep track of where I had applied the chemicals.



The spraying process itself was pretty arduous. I got started about 7am, and wouldn't you know it this was a morning when the air was not still - there was a definite breeze out of the northwest right at dawn. There was no other day to do it, so I just gritted my teeth, suited up in my PVC suit, and got to work. It was a long, long day; it took 48 gallons of chemicals to cover the whole field, necessitating three trips all the way back up the hill to the orchard to refill my two 6 gallon water carriers. My left arm was pretty sore from the pumping, too, by the end of the day. But I got it done.

The biggest surprise while spraying was how much Canada thistle was also in the field. I made sure that each thistle patch got sprayed a little extra, not knowing if the 2,4-d/dicamba solution I was using was going to have any effect. I subsequently looked up canada thistle and found out that it, too, is a fierce competitor noxious weed, almost the equal of bindweed. It grows from a large underground network of roots in much the same way that bindweed does. The chemicals that I was using for bindweed control are also recommended for canada thistle, so I was fortunate there; there was one cryptic note about not wetting the thistle with the herbicide too much, which was puzzling (and perhaps unfortunate, as I was pretty generous when spraying the thistle).

A week later, I checked on the bindweed. Here is how it looked at that point.



I was a little worried looking at these results; when I've used RoundUp in the past there were usually visible results within a week.

However, after three weeks things were looking pretty good (good, as in good and dead).





Some other observations... the canada thistle was not hit as a hard as I had hoped. Some of the little buggers are still maddeningly green. A few are yellowed. But certainly not anything like a knock-out punch. I will need to do more research on how to deal with the thistle, I'm afraid.



One last note: I finally tracked down the article that appeared in New Farm magazine, regarding control of bindweed with pumpkins(!) ["This Feed Kills Weeds," John C. Mattingly, New Farm, September-October 1985, page 35]. I had to purchase a back copy of the magazine, as it was not available through interlibrary loan here in Oregon. You can download a scanned copy of the article through this link: This Feed Kills Weeds (494k file).

What is interesting is this: I didn't spray the garden patch where I grew beans, squash, and corn; the squash wasn't ready for harvest, so I actually put a tarp over the plants to protect them while spraying. When I went back after three weeks the squash vines had experienced a few frosts, and had died back. What I observed was that while the bindweed was still growing rampantly in the bean and corn areas of the garden, the bindweed under the dead squash vines was thin and sickly, almost dead! So perhaps there is something to the theory that cucurbits have a beneficial effect in killing off bindweed. We'll see next year, I guess; I'm going to do at least a trial planting of pumpkins according to the Mattingly artcile.