Chemicals of the Past

Occasionally I receive very old agriculture books. Looking through them gives me an opportunity to compare agriculture practices of the past. In some cases, we talk about how better things were in the good old days. That is not always an accurate statement when we look at the pesticides of the past.

The book I was recently looking at was printed in 1945 and was an individual compilation of many people’s ideas. They refer to it as “The Book of a Thousand Authors.”

One of the first remedies was a sheep dewormer. Parasitic worms are a serious issue in sheep and goats that have caused many deaths. Since 1945, several dewormers have been developed that can be used on livestock. Unfortunately, it seems almost as quickly as they are developed, the parasite builds up a resistance to these miracle products and treated animals may die.

The worm reduction product of the past that is no longer is Black Leaf 40, a 40% solution of nicotine sulfate. As a child, I would see people feed an eager goat a cigarette or cigar and pronounce them dewormed. Nicotine is an insecticide that can be very harmful if not given at the proper dosage. The actual dosage of the product needed to control the parasites is near the toxic level for the animal. Giving the animal a cigarette may kill a few worms but there is no scientific determination of the actual dosage or just how many cigarettes it takes to kill most of the worms.

Today’s insecticides are designed to be less toxic to animals and more toxic to pests. The old days of DDT, lead arsenic, and mercury chloride are thankfully behind us. Today’s pesticides are safer for humans than those of 70 years ago. But they still need to be treated with respect. Even products that are relatively low in toxicity might, over time, result in other human or environmental issues.

The 1945 book also recommended a change in pasture for sheep every year. A great idea but further research now has sheep producers rotating several times a year and keeping sheep off pastures for over a month. This keeps the plant tall and the worms less available to the animals that would naturally graze grass to the ground.

With all pest control, it is not just about the chemicals, it starts with other cultural changes. We need to bring in the chemicals as the last resort.

Mark Kepler

Purdue Extension Educator, ANR

Fulton County