The two basic options for starting the plot that I deduced from our early discussions were 1) covering the area with plastic and 2) using herbicide. It seems the plastic would be very effective, smothering everything there and creating high temperature and humidity to destroy seeds near the soil surface. But the expense of the covering for an acre ($2,600!), and the labor to place the covering were too much for us. We opted to use glyphosate:
- broad spectrum, covers broadleafs and grasses
- limited persistence in the soil (weeks to months) when applied properly
- low toxicity to wildlife (and us!)
- low cost
On July 1, son Karl generously got us going with the sprayer rig he has on his work ATV. We used about 5 quarts of 41% glyphosate appropriately diluted in water to treat the acre, and we used a vegetable dye to see what we sprayed, plus some dish detergent for improved wetting. The sprayer had a very nice pattern, with tiny droplets landing in a uniform pattern with an average 1/4″ spacing. Coarse droplets minimized drift, though the wind was ideally low that day. After a couple weeks, here is the result:
Thistle and mullein were fully controlled if they had sprouted, though more came up from seeds later. The cinquefoil, clover and good old dandelion survived this round. Grass was significantly thinned, but as expected, was not fully cleared by this treatment. In the picture, below, you can see that the area in the plot, to the right of the stakes, is quite suppressed.
Next: Second Treatment