The Bay Gardener by Dr. Frank Gouin

Herbicides and Pesticides

Why I sometimes recommend them — and always recommend care

Several readers have expressed concerns about my recommending herbicides such as Roundup for controlling weeds.

The herbicides and pesticides of today are very different from those of yesteryear.

I started conducting research with pesticides in 1958 when Agent Orange, lead and calcium arsenate, DDT and many other compounds were commonly used. These materials had long half-lives, and very little information on their effects on the environment was known.

The companies that manufacture today’s pesticides such as Roundup, Preen and 2,4-D spend millions of dollars studying their uses and effects on plants and animals. Before they can be registered for use, they undergo years of testing. Vast amounts of data, including toxicological affects, are accumulated. If finally approved, they go on the market with very specific instructions on how to use them and where not to use them.

As a researcher at the University of Maryland, I was involved in conducting research with many herbicides and submitting data for review. I also reviewed data from other researchers working with the same pesticides.

Farmers and commercial applicators must receive training and be certified to purchase and use pesticides that the general public does not have access to. This makes them liable should they not use them properly.

Those pesticides that are made available to the general public have a wide margin of safety. However, you must read labels and follow directions carefully. If the recommendations are for a teaspoon per gallon of water, do not put in two or sometimes a tablespoon for presumed better results. This practice is not only wasteful but also dangerous to both the applicator and the environment. Pesticides that are available to the general public should be used as carefully as prescription medication.

The Lesson of Weeds

Q I do not plan to use herbicides or pesticides in my garden. I have not learned how to read weeds, but it’s on my list of things to learn in my lifetime. Weeds can tell us what’s going on with the soil (where there are deficiencies or an overabundance of something), and that’s where we should probably direct our work. If I have pests and weeds, it means I’m not feeding the soil, or not feeding it properly; there’s an imbalance being exploited. If we approach weeds or insects with a battle mindset, we’re always going to end up the losers.

–Leigh Glenn, via email

A You have a lot to learn. Weeds are survivors, and no matter how well you prepare your soil or how well you balance your nutrients, they will take over if you are not out there and either pulling them out of the ground or smothering them with mulching materials. I have more than 40 years of research with improving soils with compost. Weeds have been and will always be pests that must be dealt with, and that is why those of us who work in plant nutrition have had to also study and use herbicides.

With regards to insects, they are survivors also, and that is why they are still around and we are still fighting them.