Tagged: biodiversity

I refuse to use herbicides for weed control, and here is why.


Pacific Chorus Frog, aka Pacific Tree Frog (Pseudacris regilla) stuck to a window

Tree frog in my plastic greenhouse.

As a master gardener trainee, and as a student of horticulture at a local community college, I was consistently presented with the idea of Integrated Pest Management. The IPM approach does not eschew the use of pesticides and herbicides, but it encourages alternative approaches to their use. This implicitly acknowledges the dangers of improper use or overuse, and reading between the lines, may be some acknowledgement of the dangers of even proper use.

I admit to using pesticides in the case of treating buildings for termites and carpenter ants. But then, with proper maintenance, this would not be so much of an issue. In the garden, I may use Deadline for slugs although I am considering quitting this habit as well.

I’ve never felt the need to use herbicides because in my previous small urban garden plots, I never needed them.

Now, I face a weed control issue of magnanimous proportions. I’ve got everything here: reed canary grass,  English ivy, scotch broom, and various grasses and weeds that invade my new beds and exponentially increase my maintenance work.

My place is also a home for hundreds if not thousands of tree frogs. These tiny amphibians start out life in lake and surrounding wetlands, but during the summer, the explore the upland areas as well, and can be found hundreds of feet from water on the warmest days. Mowing and weed-whacking become a challenge as I attempt to dodge the little green hoppers that fly out of the grass before me.

Herbicides are often used in the PNW for reed canary grass control. This invasive grass is generally found in moist areas and can destroy entire wetlands by distributing its creeping rhizomes to form a nearly impermeable mat. I’ve seen the damage myself, and seen small water courses otherwise useful for fish completely filled by this introduced grass. Yet several studies have found that at least one common herbicide has the potential to kill tadpoles on contact and may affect other elements of aquatic ecosystems, including oxygen levels and even predator-prey interactions.

I would vote for patience over parsimony in most any case for which herbicide offers a quick solution. I mow and pull the reed canary grass on my land, and have considered deploying black plastic to kill back other populations long enough to use interplanting to shade it out. Agencies with short fiscal timelines will often advocate broad-use applications of herbicides to get more immediate results. Many will argue the long-term effects are minimal. Yet I would argue that there is plenty we don’t know about the comprehensive impacts of the chemicals that we use. Studies of biodiversity and chemical controls suggest that we may be altering our ecosystems in ways we don’t completely understand (e.g. http://www.moraybeedinosaurs.co.uk/neonicotinoid/Pesticides_and_the_loss_of_biodiversity.pdf). Instead, we are left wondering why our frog populations are disappearing. One species may not have an effect noticeable to us, but that is because we usually aren’t looking.

The Pacific tree frog is, in my years of observations, the most common frog out here. In fact, I don’t see any other frog species on the island and usually only tree frogs elsewhere around the Puget Sound. What will fill its place?

Casual use of herbicides by homeowners, or even as a primary tool for habitat restoration, may not be worth the cost. The stakes aren’t high enough if the goal is to save time and reduce labor.  I’d rather keep the frogs.


Why I don’t use herbicides



The drab moth had been on my bathroom wall for several days before I poked it to determine if it was really alive.  It was pressed flat to the tile, approximately 2 inches across, and marked with a distinct pattern of brown waves and scallops on its forewings with a thin white border of white on the edges.  The color and complexity of the pattern rendered it compatible with pine bark, but noticeably out of place on blue-and-white bathroom tile. Yet, I’d seen these kinds of moths many times before, and learned to call them ‘miller moths’ in accordance with my southern mother’s terminology.


I pulled out my thin paperback moth guide, Macromoths of Northwest Forests and Woodlands (Jeffrey Miller, Paul Hammond USDA Forest Service, FHTET-98-18, 2000) and flipped through the pages until I found something closely resembling the specimen at hand. It was, I concluded, a barberry looper moth (Coryphista meadii), with a caterpillar revealed on bugguide.net to look just like the gray and white loopers with red heads that I had observed on my Berberis thunbergii Crimson Pygmy planted in June shortly before it became a network of defoliated twigs.


It was an ah-ha moment. We had had no barberries on the property before this, and yet suddenly here was a moth that looked like one I’d seen all my life suddenly taking on a new aspect completely unbeknownst to me. I’d never even thought of what its caterpillars looked like, but now I knew its life cycle and suddenly, it affected me and my ambitions. Presumably there might be other plants in the family Beriberidaceae on the property that might have harbored them, or perhaps the eggs came in from the nursery supplier, for of the four plants that I bought, only this one was eaten by loopers.


I am reminded of the song about the hole in the bottom of the sea, where sat a frog on a log, with a bump and a wart and a hair and a flea and so on until the microscopic world had been achieved on that one frog. Then the kids singing the song gave up for lack of ideas beyond bacteria. How little did I realize when I was a child that I was singing a song that celebrated biodiversity.


The other day, while removing the plastic clips that hold electric fence tape from a series of fence posts, I noticed that nearly every clip harbored a tiny, pale brown spider.  The little beasts were flattened to where they could lie almost two-dimensional on any surface, and apparently liked the narrow space of the clip designed to hold the polytape because of the shelter it offered. As I worked to pull the clips off one set of posts to move them to another, I witnessed a tiny arachnid paratrooper dropping from nearly every clip. Every other clip seemed to hold a small white package of spider eggs. I had created habitat in spite of myself.


Of course, both moth and spider were probably here long before I was, and my surprise was merely that of my own unexpected discovery. Still, everyday that we open our eyes to the variety around us, we are richer for it. From mushrooms, to moths, to spiders, I am sure that this property has untold thousands of species I’ve yet to discover. But they don’t need my knowledge of them to validate their existence. They have every right to go on, even if they encroach on my world now and then.

Private lessons in biodiversity