Efficient spray equipment and power-packed pest controls are ours for the asking, yet despite them, we spend more effort protecting our plants from pests than our forefathers ever did.
Many of our pest problems have been solved thanks to technical knowledge and skill. But there are many reasons why we can’t wipe out all pests once and for all and why fighting plant ailments takes up more time than it did years ago.
What Intensifies Plant Troubles
Modern horticultural methods create and intensify plant troubles. We bypass natural plant evolution and take the tastiest, nourishing, or most beautiful of our plants and improve, reproduce, and grow them not as nature does in scattered units among competing plants but all by themselves, sometimes hundreds of acres of a single species.
Even a row of beans or a bed of roses is a concentration of plants, which applies to home gardeners too. This concentration of plants and the shaping of evolution to suit our needs are contrary to nature.
As our population grows, we are forced to these practices even though they invite food-hungry organisms to multiply, attack, and possibly destroy our crops.
Given this, it is a small wonder that pests not too numerous in our ancestors’ time have increased in numbers, regardless of the new pesticides available. And many pests which formerly lived only on wild plants have turned to or adapted themselves to live on related cultivated crops.
The Mexican bean beetle is a case in point. It once confined itself to eating wild leguminous plants of the Southwest but now gives its attention to cultivated beans growing in gardens everywhere.
Foreign Pests That Plague Us
Adding to our problems, foreign pests hitchhiked here to plague us. Their natural enemies left behind flourish and spread rapidly where the climate is favorable and their food supply plentiful.
Japanese beetles are a good example. Brought here on roots of plants imported from Japan, they were first observed in 1916, consuming many deciduous foliages. The history of their spread and devastation is well known, and it took many years to bring them under reasonable control.
The corn borer came from Europe; the chestnut blight, which wiped out our native chestnut trees, arrived around 1900 on some innocent-looking Chinese chestnut trees.
The Plant Quarantine Act was passed to meet the problem of controlling the entry of alien plant pests, and plant inspection stations were set up. Research in pest control was intensified at agricultural experiment stations and in commercial laboratories.
Some markedly effective insecticides and fungicides resulted, but the research in insect controls is not without disappointments.
Ineffective Insecticides
Some 15 years ago, it was predicted that DDT would cause the housefly and many other insects to become extinct. But nature fought back, and resistant strains of flies and insects once susceptible to DDT appeared.
Other insecticides similarly became ineffective for some insects, which partly explains the ever-changing recommendations for pest control.
Work on insect problems goes hand in hand with breeding plants resistant to specific diseases. In many instances, success is attained. But often, nature outwits us by producing a new race or strain of a disease organism that can overcome a plant’s inherent resistance.
Plant Varieties Resistant To Diseases
A wheat variety, Ceres, was resistant to stem rust for 10 years, but then a new race of this rust began to attack it.
Complicating matters even further, some plant varieties bred to resist one disease are often more susceptible to other diseases. For example, Kentucky bluegrass is subject to leaf spot, while a new strain, Merlon Kentucky bluegrass, is highly resistant.
The Merlon strain, however, is subject to leaf rust. So as one disease problem is solved, another takes its place. But, along the way, effective controls are found so the task is not as hopeless as it may sound.
We cannot return to nature’s way of growing crops, edible or ornamental. Instead, as our population increases, intensive cultivation is the rule, and we become increasingly dependent on chemical control of plant pests.
One Price To Pay For Civilization
Unavoidably, we sometimes kill the natural enemies and parasites of the pests we are attempting to control; and in clearing and eliminating wild areas, we force out birds and animals that prey on plant pests, still further complicating our pest control problems. It is one price we pay for civilization.
Finally, in comparing our problem with that faced our forefathers, let us not forget that our way of life has made us more particular than our grandfathers were. Years ago, there was little grading of fruit, vegetables, or flowers.
Everyone expected the bad with the good, and a few wormy apples or chewed-up flowers were nothing to get excited about.
Today, only perfect fruits and flowers appeal to us, so through economic necessity or pride in achievement, commercial growers and homeowners are making vigorous efforts to control pests that they had formerly come to accept.
44659 by Dr. Louis Pyenson