I live next to highway twenty, and perhaps because no one wants to pick on the side of a busy road, but that's where I find the biggest blackberries in town. However, I think the Department of Transportation may spray herbicides along roads to prevent overgrowth. How is this application done? Is it just right next to the road or as far as 5/6 feet away? The bushes I'm picking from are at about that distance, and growing on a fence. I guess if the bushes were sprayed with herbicide themselves, they wouldn't be as fruitful, but are blackberries perhaps resistant to herbicides? Or is there not enough product to cause damage to the plant, and by default, damage to my health?
You are right about roadsides - They are often sprayed by the Oregon Department of Transportation to keep the shoulders clear. The weed killers are not intended to be sprayed on (or near) food crops. That means it is hard to guess about the level of risk. We don't have the studies to show how long it takes for the product(s) to break down on foliage, or in soil.
You will make the decision based on your own risk-tolerance. Some questions to ask yourself:
- Do you see any signs of plant damage on the blackberry bushes? Or close-by? It would look as though parts of the plant have died, or dried up. Early in the process, you may see yellowing leaves, or curling leaves.
- Was the area sprayed before fruit developed? If so, there may still be small residues inside the plant, but the surfaces would be free of residue.
- Are you able to wash the fruit well?
- How many berries will you eat?
You can call our local ODOT office, located in Corvallis, and ask about any recent applications on Highway 20. Here's the number: 541-757-4211
If you're able to learn about a specific weed killer that was sprayed, we can dig into the literature and find out more. Please call the National Pesticide Information Center (NPIC) at 1-800-858-7378, which is located here at OSU. We are open from 8:00 am - Noon, every weekday.