The Big Picture

Most of us in North Idaho have a special place in our hearts for wildlife, wildflowers, and wild places. In addition, our economy is heavily dependent upon forage for livestock, healthy forests and quality outdoor recreation. However, there is a quiet, widespread infection threatening our landscapes that could prove as devastating to them as if a serious disease were left untreated in our own bodies. The disease is the systemic spread of noxious weeds. If not properly treated, the results could be permanent and devastating to both our resources and economy.

The host of aggressive foreign noxious weeds gradually dominating our wild lands is fully capable of devastating both native and desirable agricultural plant communities. This infection can be compared to foreign strains of flu, Lyme Disease or West Nile Virus, but unlike our bodies, native plant systems don't have enough time to develop an immunity to fight the onslaught. Human mobility is the source of the infection; it is therefore up to us to isolate and fight the disease.

As with human disease, weed treatments come in a variety of prescriptions that have a range of applications and effectiveness. Examples would be hand pulling of weeds (surgery), planting competing vegetation (increasing immunity), introducing weed eating insects (inoculation) and spraying with herbicides (drugs). Like a doctor prescribing antibiotics and bed-rest for us, using a combination of the weed control options is usually the most effective measure against a weed infection.

Comparison of herbicides to human drugs isn't as much of a stretch as it might seem. Both fit under the general definition of pesticides. As with antibiotics, herbicides aren’t always the best prescription, and can have very serious side effects if used improperly.

However, they are often necessary with the most resilient and virulent weeds.

Everything humans do has some risk of undesirable side-effects, especially when tackling serious problems. However, if we don’t use all the remedies at our disposal, the risks are very high that a lot of our wildlife, recreation areas, and family farms and ranches will be seriously, if not terminally ill. Herbicide use can be controversial. However, just as with antibiotics, they are effective and safe when used appropriately.

An then there was Silent Spring

Since the publishing of Rachel Carson's groundbreaking book "Silent Spring" in 1962 much has changed. First, nearly all of the pesticides (most were insecticides) identified in the book have been eliminated from use, second, the EPA review process has been established and, finally, also unfortunately, many new noxious weed species have come to our shores. In my re-reading of the book after about 40 years, I found a couple of quotes that are appropriate to highlight here. (1) Near the end of chapter 2, "The Obligation to Endure" she states: "It is not my contention that chemical insecticides [read: pesticides] must never be used. I do contend that we have put poisonous and biologically potent chemicals indiscriminately into the hands of persons largely…..ignorant of their potential for harm." And then in chapter 6, "Earth's Green Mantle" she adds: "Selective spraying….takes advantage of the inherent stability of nature…the object is not to produce grass on roadsides…but to eliminate the tall woody plants…and to preserve all other vegetation". Sounds like Environmentally Sensitive Weed Control to me!

The Legacy of Agent Orange and DDT

Many people hold on-to the belief that pesticides are poisonous, and that they are harmful to humans and bad for the environment. They have come to this belief mostly through unfortunate mistakes made in the past and through generalized broad-brush thinking about a large group of chemical compounds with widely varying characteristics. Under the heading of pesticides, there are several sub-groups, and yes, some are poisonous to animals because they are meant to kill animals (rodenticides and insecticides). Others are poisonous to funguses (fungicides) or lice (pediculicides). Another grouping (biocides) includes antibiotics and antivirals routinely used in modern medicine. Herbicides kill plants by disrupting biologic processes that occur only in plants (more about that later). About the only statement that applies to all of these is that they are man-made chemicals. 

In criticizing herbicides, many people have been influenced by our horrible experience in Vietnam with Agent Orange.  Containing equal parts of 2,4-D and 2,4,5-T, Agent Orange was used to defoliate the jungles to expose Viet Cong troop movement. Many veterans in the U.S. and many more residents of southeast Asia  became sick after the war with illnesses ranging from several types of cancer to various respiratory diseases. After years of inquiries, it was learned that the 2,4,5-T in Agent Orange was contaminated with dioxin, a potent and known carcinogen, as a byproduct of the manufacturing process. Consequently, the production of 2,4,5-T has been banned by the US and numerous other countries. For a detailed discussion of this subject, see http://www.nap.edu/catalog/11242.html#orgs. Over 20 million gallons of herbicides (there we others besides Agent Orange) were spread in Southeast Asia between 1962 and 1972 and we can only speculate at the high concentrations that were probably used during a war-time action. Many soldiers on the ground must have had very high rates of exposure and the persistent nature of dioxin has affected many non-combatants in southeast Asia in the years since the war ended. 

DDT is an insecticide that was used heavily during WWII and as late as the early 1970s. The chemical is fat soluble and because of this it bio-accumulates in food chains. This means that the animals at the top of the food chain (including us) get the highest doses. DDT takes more than 15 years to break down in the environment, is a probable human carcinogen and can damage many parts of the human body. It also pushed the Bald Eagle to the brink of extinction. It is really bad stuff and its use was banned in the U.S. in 1972. It's important to note that DDT is an insecticide, not an herbicide.

 Dioxins and DDT are included on the EPAs "Dirty Dozen" list of banned Persistent Organic Pollutants (POPs). Many POPs were widely used during the boom in industrial production after World War II, when thousands of synthetic chemicals were introduced into commercial use. Many of these chemicals proved beneficial in pest and disease control, crop production, and industry, but had unforeseen effects on human health and the environment. Their use has been reduced or eliminated through a United Nations treaty agreed to by the U.S. and 90 other countries. For more on this go to http://www.epa.gov/oia/toxics/pop.html#stockholm.