In any crop production endeavor, it has been desirable to produce not only high quantities, but also disease-free yields. These goals can be fairly easy to achieve or may be quite difficult depending upon the specific plant types involved. Often the farmer need only plant the beneficial specimens in a nurturing environment. The cultivars themselves then may develop relatively free from disease with little outside assistance. This can be especially true for cultivars or propagules which are reproduced through seed propagation. Most of the time the seed coating itself acts as a protective environment which allows the juvenile propagule not only to be stored relatively disease free, but also to begin its growth in a somewhat protected environment. The problem of disease control is, however, much more challenging for propagules which do not have the benefit of some shell-like protective coating. One group of propagules which do not have a shell-like coating is called tubers. Tubers include crop plants such as potatoes. Of this group, much attention has focused upon the problem of disease control for the potato.
The potato is unique in several regards. While it is a crop plant which has great commercial demand, it is also a tuber which is very vulnerable to fungus, bacteria, and viral diseases and often has a relatively short growing season. As it relates to the present invention, the potato's short growing season makes its early development very important to a successful crop. Although the present invention may be applied to a great variety of propagules, the potato's often extreme sensitivity highlights the benefit and function of the present invention.
As mentioned, the potato is very vulnerable to a variety of diseases. This is in part due to the fact that the potato is tuber propagated. Its sensitivity may be so extreme that at times entire crops have been impacted by the presence of only one disease in a specific area. Because these diseases can be spread very easily, the entire agricultural system with respect to potatoes has evolved somewhat uniquely. For instance an entire regulatory system has evolved in order to minimize the risks posed by diseases for this particular crop plant. As one example, the concern over introducing a disease to a crop may be so extreme that regulations have been enacted which make it literally illegal to import used farming equipment for use with the potato crop from one state to another. Additionally, the regulatory system at times limits the number of reproductions that a particular farmer may allow. This in essence mandates that every few years an entirely new, test-tube grown potato crop must be utilized by the farmer.
Even these extreme precautions often break down. When this happens if even one potato tuber is discovered to be infected by a disease, typically the entire crop must be destroyed and the crop residue rendered sterile. Some crops are even gamma ray irradiated to avoid the spread of that disease. Once this is accomplished the farmer must purchase certified seed tubers to begin a new growing cycle. While naturally the purchase of these certified seed tubers could be used every season, it is not economical to do so. Instead the potato farmer typically plants the offspring of that first season and continues that cycle for several years until, by regulation, they must start again with seed tubers which have been grown in essence in laboratory conditions and therefore are certified to be disease free.
As can be seen with respect to potato crops, the problem of disease control can be acute. In spite of these needs, there is also a need to minimize one's utilization of chemicals, chemically-formulated pesticides, chemically-formulated additives, and the like with respect to food production. It has become very desirable for any crop production intended for consumptive use to be able to be grown organically, that is without employment of chemically-formulated substances or at least to be grown in an environment which minimizes the utilization of unnatural effects such as the use of chemically-formulated pesticides (fungicides, insecticides and herbicides), genetically engineered changes, irradiation, and the like. While the desirability of a completely naturally grown product can rarely be debated, the actual implementation of these desires has, on a large scale, been very difficult to realize until the present invention. This has been especially true for very sensitive crops such as the potato. The present invention presents a system for organically controlling disease which may have particular applicability, but not be limited to, potato crops.
As mentioned, the desire for disease control has existed for years. Until the present invention two key techniques were prevalent for crops such as the potato crop. The regulatory approach mentioned earlier attempts to minimize the spread of undesirable diseases. This approach has met with only limited success. There still exist outbreaks of disease. Naturally, these vary in location and time; at present several concerns are bacteria ring rot and potato virus Y for the potato crop. Basically it simply has not been possible to completely eliminate the spread of disease through regulatory approaches. In addition, as markets have evolved, the demand for crops which are less likely to contain any disease has increased. Thus, while most regulatory approaches permit the utilization of a crop such as the potato to be reproduced for up to six growing seasons before its replacement with new, test-tube grown seed tubers, the consumers themselves have pushed for earlier crops such as those occurring in the third year.
The second approach to the problem of disease control has been very traditional--the use of pesticides. Often, this solution has not always been acceptable; consumers have expressed a desire for organically grown produce free of pesticides. In addition, the use of pesticides, although often fairly effective, has been accompanied by other problems. First, the pesticides need to be applied. This can be challenging in that broadcast application on a field basis may not provide the concentrated amount necessary at the particular plant. Second, to the extent the pesticide does not break down and remains in the soil, it may produce byproducts, or residual pesticide which can pose a problem of contamination. Thus pesticides can often result in unacceptable contamination of the remaining soils after the crop has been harvested.
The present invention takes an entirely different approach to the problem of the disease control. It presents a system which utilizes naturally occurring substances (like organic, substances which are not chemically-formulated) which are not harmful to the propagule and yet which trigger that propagule's own natural defense mechanisms. Thus, the propagule itself is prompted to provide a defensive substance in the vicinity of the propagule so that when a disease enters this vicinity, it is controlled even before the propagule may sense its presence. This is an entirely different approach from the main efforts in this field. By utilizing a known, naturally occurring trigger substance such as chitin, the invention acts in a manner to intensely trigger the plant's natural defensive mechanisms. Although the stimulating substances may have been known for years, by causing an intense stimulation the present invention is able to achieve an entirely different and unexpected result.
As mentioned, others may have utilized the particular substances involved. Even those inventions which utilize the chitin material have utilized it for vastly different purposes and had not applied it in the intense manner of the present invention. Their techniques have not been directed toward and have not achieved the unique results of the present invention. Rather they have sought completely different results. For instance, U.S. Pat. Nos. 4,812,159 and 4,964,894 to Freepons each sought to utilize chitosan (deacetylated chitin) to change the growth of specific plants. Contrary to the goals of the present invention, these references are aimed at altering a plant's natural growth and development; they also involve applying chitin at levels thousands of times less than the present invention. Similarly, the present invention takes an entirely different approach from that disclosed in U.S. Pat. No. 4,940,040 to Suslow in which genetically-altered bacteria were placed near a plant. The resultant man-made bacterial strains of Suslow take an entirely different direction from the organic approach of the present invention. Perhaps most illustrative of the vastly different directions taken by some is contained in U.S. Pat. No. 4,670,037 to Kistner. Somewhat like the Suslow reference, this reference involves intentionally placing a fungus near certain plants. Again it is directed away from the direction of the present invention as it is the separate organism, not the propagule, which accomplished the desired result. The Kistner reference also does not address the need for disease control; instead it might be characterized as tempting fate (let alone regulatory requirements) by purposefully placing a fungus near the a plant.
While there has unquestionably been a long-felt need to control diseases for potatoes, this need has not been completely satisfied even though the implementing substances and elements of the present invention had long been available. The inability of those skilled in the art to view the problem from the perspectives of the present inventors has, perhaps, been in part due to the fact that prior to the present invention those skilled in the art had not fully appreciated the nature of the problem. Rather than considering the possibility of an organic solution to the problem, the acute nature of the problem may have caused those skilled in the art to focus upon the pesticide approach mentioned earlier. They apparently had not fully appreciated that the problem of disease control could be achieved through organic means. While substantial attempts had been made by those skilled in the art to achieve disease control and to avoid the destruction of entire crops, the understanding which is the underpinning of the present invention and results it has been able achieve had not fully been understood.
Rather than taking the approach of utilizing a substance which stimulates the propagule's own natural defensive mechanisms, those skilled in the art actually taught away from this direction by utilizing an external substance which itself caused the disease control. Perhaps especially with respect to the present invention, the results achieved have been somewhat unexpected because those skilled in the art had utilized similar substances on similar propagules without the ability to achieve the results of the present invention. This has been attended by some degree of disbelief and incredulity on the part of those skilled in the art, however, by expanding the fundamental understanding of the mechanisms within the plant itself, the present invention may not only convince those skeptical of its approach, it may also cause further progress in this area.