DDT ad from 1947
Color print magazine advertisement for Pennsalt DDT products. This ad appeared in Time Magazine, June 30, 1947.

By Mike McCoy
Executive Director, Kern County Museum

Mike McCoy
Mike McCoy Executive Director, Kern County Museum

Anyone who has had a home garden knows the struggle of trying to grow fruit or vegetables without completely dousing the tree or vines with insecticide. This year we tried to go completely organic with our tomatoes and squash. The end result was some success with hot peppers but a complete disaster for the other veggies. Two sad withered tomatoes stare back at me from the kitchen sink. Now, imagine trying to raise a livelihood of vegetables, nuts or fruit over thousands of acres.

The fight against ag pests is centuries old. There are reports of ancient Romans covering their grape leaves with sulfur and charcoal before fruiting. Going back through the back issues of the periodical California Agriculture is a constant reminder of the changing battle against insects and bio pests. One issue in 1947 heralded the development of organic phosphates to battle pests. Post war America led the world in expanding agriculture led by university research. Historians claimed a second Agricultural Revolution with cover crops, new fertilizers, soil treatments and mechanization. The real revolution was the control of pests and crop diseases.

The development of DDT and other chemical pesticides were considered a major breakthrough in pest control. This was also the new era of crop dusting by airplanes so that entire fields could be efficiently treated. Through the 1940s though, scarce mention was made of the possible negative side effects of these chemicals. One lonely article in 1948 at the University of California questioned if these new miracle treatments might be negative to human consumption. It also asked about the residue level on vegetables and fruit.

A Belgian ad for the DDT-powered insecticide, Insectoline

The excitement however of finally getting a strong handle on these pests overshadowed any question of their safety with “Supervised Control” being the mantra of farmers. With mechanization, intelligent water use and new pesticides, yields were up all over the United States. In the mid-1950s, however, scientists at U.C. Davis and U.C. Berkeley began to look at “biological control of pests instead of a complete reliance on chemicals. As people began to move into California in the late 19th century, they also imported more than 600 parasites and pests. By the mid 1950’s more than 100 serious agricultural pests were in evidence per U.C. Davis. Now that urban and suburban housing developments in California were bumping up against farms, more questions arose about what was being sprayed from planes.

1962s revolutionary book Silent Spring by Rachel Carson revealed that the miraculous synthetic pesticides had unintended consequences by harming non-target species and killing off secondary populations such as birds and amphibians. When DDT started showing up in milk, this completely changed the conversation and the public demanded that changes be made immediately.

The 1970s sparked another agricultural revolution with the control of synthetic pesticides, the exploration of organic solutions and the move toward de-chemicalization. The other big push was to use genetically modified crops to withstand pests. Over the next 50 years, control of pests while protecting the public’s health has been a difficult balancing act. The industry has gotten creative with mating disruption and the introduction of pest predators. The navel orange worm, the number one nut tree pest in our region, is being treated by cleaning up orchards and removing old mummy nuts where they were nesting.

There are at least a dozen insect pests that currently threatens Central California agriculture with effective control measures constantly being re-evaluated and put on the regulatory no-list. Scientists are trying to keep one step ahead and are continually battling new pests that show up from Asia and South America. The battle is centuries old and appears that it will be a war that will never be won. The best farmers can hope for are occasional victories and better technology.

Thank you to U.C. Davis and the U.C. Berkeley Department of Natural Resources for information.