In its worst and most widespread form is that which occurs during August and September. During this period the hay fever victims in the United States can be counted in the millions. The severity of attacks of late summer hay fever is generally much more intense and prolonged than those of the spring or early summer type. At the present time when production man-hours are of vital importance, this type of hay fever must be considered a national problem. A conservative estimate of the working time lost to industry because of hay fever effects would be in the neighborhood of two hundred million hours.
Late summer hay fever, was referred to as autumnal catarrh in the early days of its recognition. The “catarrh” being descriptive of the profuse mucous secretion from the nose and throat which accompanies the hay fever symptoms. It is often called ragweed hay fever because the rag-weed plant is the most frequent cause of hay fever at this time. While it is true that ragweed is by far the worst offender, it is not the sole cause of autumn hay fever. Other related and unrelated species of weeds are known to produce hay fever symptoms during August and September in areas where ragweed does not grow. For instance in many mountainous regions of Colorado, the inhabitants suffer from hay fever in towns at an altitude of 9000 feet. These cases are due to mountain sage rather than ragweed.
The instance just cited dispels the often repeated misinformation that in order to avoid fall hay fever you merely have to go to a town having an altitude above i ,00 feet. Nothing could be farther from the truth. Many of the western towns in Colorado, Idaho and Montana, having altitudes above three and four thousand feet, have favorite citizens who suffer from late summer hay fever. Easterners should not travel to these areas of high altitude indiscriminately to obtain relief from ragweed hay fever. In many cases the offending weeds belong to the ragweed family to which the persons are probably equally sensitive.
WEEDS IN GENERAL
There are two general kinds of weeds; absolute weeds and relative weeds. An absolute weed is one which is harmful to cultivated crops and of no value in itself. These are the plants we shall be referring to when we use the term weed.
Weeds are the least known of the entire plant kingdom. There is less written about them than about any other plant group. This is so because they have always represented a negative factor in the plant world. Before the weeds were known to plague society with hay fever, they were known to every farmer for their harmful and evil nature.
In the period of planting and caring for his crops the farmer has always had to labor to prevent damage by weeds. Many and varied are the annoyances of the weeds. They molest the farmer by usurping the soil reserved for crops, by entangling crops, by interfering with the machinery in the harvesting, and by stealing the water needed for crops when the rainfall is meager.
After the crops are harvested the weeds have a free rein. An entire wheat field can be seen filled with a perfect stand of ragweed within a week after the wheat has been cut. If we can induce the farmer to spray the ragweed in its early stages with iron sulphate it might effect a reduction in the ragweed pollens in some areas.
The time of harvesting crops is related to ragweed hay fever symptoms. Evidence of this may be recognized from the occurrence of hay fever a week and two weeks later in many northern parts of New York, Canada and the New England states. In these areas common crops of corn, and garden vegetables ripen later than in the southern parts of the states. Thus, reduced hay fever symptoms which are noted in these regions may be partially explained on a dual basis. First, the delayed growth of weeds in general because of the colder temperatures, and secondly, the delayed growth of ragweed in the cultivated fields because of the presence of unharvested crops.
SEEDS AND WEEDS
Since weeds have long been a blight to farmers, you may ask, “Why have they been permitted to grow and even increase in abundance?” The answer to this question lies in the nature of the seeds that are responsible for producing weeds, and in the methods by which these seeds are spread. This answer may also serve as a partial explanation of the fact that, to date, none of the ragweed eradication campaigns has proved effective.
All of the weeds that cause hay fever reproduce by bearing seeds. The stories of how famous scientists, including Darwin, were duped into believing that wheat seeds obtained from the wrappings of Egyptian mummies two thousand years old, were able to produce wheat plants makes interesting reading. Although many fantastic tales have been told about the ability of seeds to live thousands of years and still reproduce a plant, none has been proven to be true. However, recent scientific experiments have yielded some accurate and interesting information about seeds.
It has been found that in general seeds do not live more than a few years. Very hardy seeds can live twenty years or longer. And more woe to the hay feverite, of all the seeds, those of wild plants and weeds have the greatest length of life. Ragweed seeds have been shown to develop full grown ragweed plants after being buried for forty years. Plowing the ground under, during the period of crop rotation, will not destroy the seeds of weeds.
Information such as this is of benefit in attempting to control weeds. Above we recommended that the farmer spray the ragweed with iron sulphate which kills the weed. In the past the farmer has been advised to plow under the early ragweed, but as has been indicated, this will permit the weed to grow some other time. To add to the difficulty of eradicating weeds, there are the many ingenious ways in which their seeds are spread from one place to another.