Plant Diseases

The Yearbook of Agriculture 1953

UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.

For sale by the Superintendent of Documents, Washington 25, D. C. Price $2.50 THE UNITED STATES GOVERNMENT PRINTING OFFICE

Costs and Causes

Three Billion Dollars a Year

Jessie L Wood.

A farmer in Pennsylvania in 1928 sprayed his apple orchard with materials other than those tested and recommended by the experiment station.

The result was an attack of apple scab that caused the loss of 80 percent of his crop. He had expected 1,500 bushels, but he got only 300 bushels of poor apples.

Furthermore, the trees were so badly weakened that yields in after years were low. Because of their poor condition, 15 percent of the trees died during drought in 1930 and 1932. Even 20 years afterward, the orchard had not returned to its original healthy, profitable state.

But that is not all. The financial setback forced the farmer to borrow heavily every year in order to produce a crop. As a result, the farm became so debt-ridden that he would gladly have sold it for the amount of indebtedness. In order to make a living, he had to seek outside employment and finally became a full-time worker at another occupation. Thus one bad attack of a plant disease turned a debt-free enterprise into a liability and wrecked the owner's independence and security.

Another instance: A farmer had owned his farm in South Dakota all his life. In 1914-1918, leaf and stem rust caused losses to small grains. The yield of barley was reduced from 50 bushels an acre to 10; oats dropped from 40 to 60 to 5 to 15 bushels; wheat, from 20 to 30 bushels to 2 to 5 bushels an acre.

The financial loss amounted to $1,000 to $3,000 every year. He borrowed money during this time of crop failure. A series of years of low prices added to his loss. The debt caused foreclosure in 1934, when the depression was at its worst. Here again, a plant disease gave the downward push that decided the fate of this farm home and business.

Stem rust caused almost 60 percent loss to the wheat crop in Minnesota and some of the neighboring States in the epidemic year of 1935, and the loss for the whole country was almost a quarter of the crop. Obviously, that heavy reduction in over-all yield means that some individual farmers sustain disastrous losses. Witness the following accounts of farm losses due to stem rust in Minnesota that year. In one county a $4,000 loss was the final factor, although not the only one, in foreclosure on one farm; a $2,000 loss caused foreclosure of a 400-acre farm valued at $16,000; a $4,000 loss caused foreclosure of a 1,100-acre farm worth $25,000. In another county the wheat crop on some 700 farms was practically a complete failure because of stem rust. The average yield expected was 20 bushels to the acre, but the actual yield ranged from nothing at all to about 10 bushels an acre. The total loss for the area amounted to about $400,000. Some farmers had to give up farming. Others did not recover financial stability for 5 years or longer.

About 50 years ago Granville wilt, or bacterial wilt, of tobacco appeared in the southern part of Granville County, N. C., where about 7,000 acres of tobacco were grown on 1,500 farms, some of which had been owned and operated by the same families for generations. The disease increased until it was destroying 20 to 50 percent of the crop each year; the loss amounted to 1 to 2 million dollars annually. All attempts at control failed. Many farmers lost their farms, farmsteads deteriorated, the morale of the farm population dropped, education was neglected, and living and health standards went down. Between 1920 and 1940, when the disease was at its peak, total loss from forced sale of farms at sacrifice and from reduced tobacco production amounted to 30 to 40 million dollars. All this because of one plant disease in one community!

Those are some of the cases reported by county agents. By no means were all of the losses involved so severe or lasting as the ones I have mentioned, but in many other instances a plant disease was partly or wholly the cause of serious difficulty.

Possibly you think that those farmers must not have been very skillful, that good farmers would not have such trouble, or perhaps that they did not arrange their financial affairs very well. Undoubtedly poor judgment was a factor sometimes.

But how about the tobacco farms that had been owned by the same families for generations, only to be lost when a disease-producing organism invaded the soil and could not be checked? The obvious remedy would have been to change to some other main crop or to vary the crops, but a region that is suited to and derives most of its income from one major profitable cash crop does not easily make such a change, for the change involves much more than just growing a different plant. Moreover, the bacterium that causes the disease has so many other hosts besides tobacco (such as peanuts and potatoes) that a change might merely be from the frying pan into the fire.

With farming, as with any occupation, many factors make success or failure. The farmer, no less than everyone else, is affected by the ups and downs of the general economic situation. In good times he can absorb or recover quickly from large losses due to any cause. In hard times small losses may be enough to shove him under. As for the individual economic circumstances, good financial management is as essential as fertile soil and skillful farming to be sure of leeway enough to meet all chances of loss and take advantage of all opportunities for profit. Lacking any of those qualities, a farmer may barely make a living in the best of times and certainly will possess no margin for emergencies.

Granted all that: The fact remains that agriculture is subject to numerous risks, which at times endanger the prosperity of the best of farms or of whole areas. Economic fluctuation is just one of the risks; it is shared with the rest of the population. Others are peculiarly agricultural. Among them are plant diseases.

Weather, insects, and plant diseases are the three great natural hazards of crop production. Weather is perhaps the chief one, but the order of importance is not certain. The interrelation between weather and disease and between weather and insects and among all three, if the disease is caused by a pathogen carried by insects, is so close and so complicated that sometimes it is hard to determine the actual origin of trouble. Moreover, the causes of plant diseases are mostly not obvious to the unaided eye, and loss due to them may be ascribed to the more conspicuous insects or to weather conditions. In any event, the relative importance of the three factors is not fixed but varies according to season and location, and the total loss due to each one by itself is quite enough to make comparisons superfluous.

In the United States the average annual loss from plant diseases is estimated to be about 3 billion dollars.

We have no way of establishing a precise figure, and this one is based on many assumptions but it could well be under rather than over the real amount. Without the control measures we do have, the loss would be much greater.