US Plant Quarantine Regulations and Operations

[Moderators Note: In discussing the current situation, Dr. Curtis felt this paper was still relevant and brought to light quarantine issues which need to be addressed. Dr. Curtis is now retired and living in Fort Collins, Colorado. He spent many years working as an agronomist at CIMMYT, in Mexico]

Chairman Bentley and members of the Board:

I appreciate the opportunity to present again my views on what I consider to be a very significant impediment to the international exchange of germ plasm. The impediment I am referring is the result of highly restrictive plant quarantine systems which seem to be out of place in today's modern world. I could have chosen to discuss the plant quarantine systems of a number of countries, because the problem is truly international in scope. However, I have chosen to focus on the US plant quarantine system because 1) I am a citizen of the USA, and 2) the US plant quarantine system serves as a model to plant quarantine organizations in many other countries, particularly in the developing world.

My comments are offered in a positive manner in an attempt to increase the awareness of the importance of the problem, and in the hope that this Board can play a leadership role in finding more effective and beneficial ways to enhance the international exchange of germ plasm and to bring our national quarantine system more in step with the changing world in which we live.

I am employed by the International Maize and Wheat Improvement Center (known by its Spanish acronym, CIMMYT which is a non-profit international agricultural research organization responsible for improving wheat and maize production an a global basis, but with particular emphasis on Third World countries. CIMMYT is only one of a number of centers engaged in such research, all of which rely to varying degrees on the free exchange of experimental germ plasm among international networks of agricultural scientists.

The advent of international testing, in which the USDA played a pioneering role, opened a modern era in plant breeding. Prior to the establishment and rapid growth of these international networks, agricultural research tended to occur in relative isolation with very little sharing of improved germ plasm. During the early 1950s, however, devastating stem rust epidemics, caused in the USA and Canada by the highly virulent race 15B and in Latin America by a race similar to 15B, forced scientists to search for new solutions, and out of this crisis came initiatives which are still benefiting world agriculture. In order to speed up the identification of germ plasm resistant to the new race of pathogen, the USDA appealed to scientists in Mexico, Colombia, Ecuador, Peru, Chile, Argentina and Canada to join the USA in testing 1,000 lines of wheat selected as possible sources of resistance to 15B. These lines were exposed to the stem rust populations in the participating countries. The results of this 1st International Stem Rust Nursery exceeded expectations and today, much of the stem rust resistance in the commercial wheats of the USA and other countries can be traced to resistant breeding materials identified from those early international trials.

There were other benefits of even greater importance. A new mechanism for the widespread distribution and testing of experimental wheat germ plasm-early generation materials as well as advanced generation unnamed lines--was in the process of creation. This, in turn, dramatically accelerated the introduction of materials with genetic variability into national breeding programs. While the initial emphasis of international testing was to identify new sources of disease resistance, other benefits also emerged. The inclusion of advanced lines and cultivars from all parts of the world afforded cooperators the opportunity to observe the adaptation of materials to widely differing local conditions, generating data in one cycle that would have taken years to collect had this mechanism not existed.

Because of these international germ plasm testing and exchange networks, high-yielding cultivars with wide adaptation and disease resistance have been developed at an accelerated pace. Indeed, international testing has served as a unifying thread to bring together the work of thousands of scientists and hundreds of organizations worldwide and has been fundamental to the rapid advances made by agricultural science during the 1960s and 1970s. These networks became the hallmark of the Green Revolution, and remain vital to the long-term success of plant breeding research the world over.

The continuing importance of these research efforts is perhaps best described by way of example, and I'll use the example of wheat, with which I'm most familiar. Since its inception in 1966, CIMMYT has served as the hub of a very large international network of collaborating scientists working to improve wheat production around the world. Hundreds of high-yielding, disease-resistant bread wheat cultivars have been released by national programs that have been based, at least in part, on germ plasm developed and distributed through the CIMMYT-coordinated international testing programs. Today, approximately 45 million hectares in the developing world (50% of the total wheat area) and 15 million hectares in the developed world, much of it in the USA (25% of the total US wheat area according to a 1984 survey) are planted to cultivars based on germ plasm obtained through the CIMMYT-coordinated international wheat testing program.

My intention here is not to belabor the successes of international germ plasm testing and exchange networks; rather, I wish to emphasize that these production increases would not have been possible without a smoothly functioning global network comprising hundreds of responsible agricultural scientists seeking solutions to the world food problem. This network relies upon the free and efficient exchange of germ plasm on an international scale, a process that embraces wholly reasonable procedures to ensure the safe movement of healthy experimental materials.

Also let me emphasize that the movement of healthy germ plasm is as important to CIMMYT as it is to any quarantine service, because international testing constitutes the central mechanism--the very heart of the system-for increasing food production, not only in the Third World but also in countries like the USA. Consequently, CIMMYT takes great pains to ensure that the experimental materials it handles (both in-coming and outgoing) are treated with an effective mix of chemicals to prevent the spread of pathogens and pests. Moreover, 15 of the Wheat Program's 29 international staff are trained primarily as plant pathologists, and we have very close working relationships with the Mexican plant quarantine service (Sanidad Vegetal) and with Mexico's national agricultural research organization (INIA). Mexico, along with the USA and Canada, is also a member of the North American Plant Protection Organization (NAPPO), whose purpose is to achieve greater coordination in plant protection activities among the countries occupying the North American continent. CIMMYT is also developing stronger working relationships with ARS and APHIS. and several collaborative projects are currently underway.

Let me now turn to an incident that for me brought into focus the issue of the benefits of certain US plant quarantine methods versus the costs that they might cause in terms of crop improvement. In 1983, an embargo was placed on all wheat coming into the USA from Mexico. For reasons not made readily clear, the minor disease of wheat known as Karnel bunt suddenly became important to US the plant quarantine service. This disease has occupied a very narrow environmental niche in parts of the States of Sonora and Sinaloa in northwest Mexico for at least 15 years. While the pathogen is confined to this very small geographic area, the US embargo banned all exports of wheat and wheat products from the entire country of Mexico regardless of their origin. As a result, large quantities of commercial wheat seed that normally move into California and Arizona were excluded as well as the very small quantities of experimental materials coming from CIMMYT.

After negotiations with Mexico and CIMMYT, the US plant quarantine service agreed to relax their embargo to allow for the importation of experimental material, but established 17 additional requirements for the handling of these materials. Some of these requirements were so restrictive that the effect of these so-called "safeguards" was to grind to a halt the movement of wheat germ plasm from CIMMYT to US wheat breeders. Canada followed suit and, as expected, a number of developing countries receiving germ plasm from Mexico were unduly alarmed.

My purpose here is not to plead the case of CIMMYT before this Board, but rather to raise a much larger issue of whether current US efforts to prevent plant disease introductions in wheat, largely through embargoes, are feasible for the world's number one cereal grain which has 100 million tons of its grain traded annually in international markets. Because most of this grain is used for human and animal food, it is not treated for diseases and it undoubtedly carries a full range of seed-borne disease pathogens.

The US plant quarantine service has at its disposal six basic types or categories of control measures. These are 1) avoidance, 2) exclusion, 3) plant resistance to disease agents or insects, 4) eradication, 5) protection, and 6) therapy. Of these six, it seems to me that the US plant quarantine system chooses to focus, perhaps unduly, on exclusionary measures, such as embargoes. While this method may work effectively for certain crops with limited acreage and for certain types of pathogens, it seems to be extremely ineffective for a crop such as wheat, for countries sharing contiguous borders, and for many of the pathogenic organisms in which air-borne transport is a major pathway of entry.

In his thoughtful publications on preventing plant disease introductions the USDA scientist, William McCubbin, closely reflects the views I hold on this subject. Let me quote from an article he published in 1946 in The Botanical Review: "in reviewing the factors involved in [disease entry], it is necessary at the outset to distinguish clearly between the possibilities for disease introduction from a contiguous land area, such as Canada or Mexico, and the prospects for invasion from other continents across ocean barriers, between continuous spread, where because of the ability to spread locally a pathogen may readily cross political land boundaries, and a discontinuous spread, where dissemination must surmount formidable barriers such as oceans. The risk of introducing disease from adjacent countries thus merits special attention. Land continuity not only connotes identity of crops and agricultural practices on both sides of a common border but encourages an intimate and extensive exchange of products. Along with these favorable conditions for disease transmission there must be associated the hopeless prospect of trying to prevent an actively spreading pest from crossing a purely imaginary line, either through the air itself or by way of a host of articles and materials impossible to bring under effective quarantine control."

A quote from Dr. Norm Borlaug, former Director of the CIMMYT Wheat Program, also puts the issue of the US embargo of Mexican wheat into proper perspective: "The US Border Patrols, and the US immigration and Customs Officials are unable to exclude either the introduction of thousands of tons of marijuana or the influx of hundreds of thousands of undocumented workers (not only from Mexico, but from many Latin American and Asian countries). Nor can they control the millions of birds that migrate back and forth between North and South America each year. That being the case, what are the chances that plant quarantine officials will be able to keep the spores of any number of diseases from crossing into the US from Mexico? The answer is obvious to any microbiologist."

Another case in point: Until recently, India imported in excess of one million tons of wheat for food purposes. This wheat arrives at several ports in India and is distributed throughout the country on all kinds of vehicles, including trains, trucks, waterways and even leaky oxcarts. Spilled untreated grain contaminated with pathogens surely have at least an equal chance (and probably a much higher chance) of spreading disease to the wheat forms of India as does the chemically treated seed being exchanged by breeders. Yet India has an ultra-strict quarantine on the very small amounts of wheat seed germ plasm entering the country from wheat breeders of any country. The seed must be grown in isolation for one full cycle and the resulting plants are carefully inspected by quarantine pathologists on a regular basis. This practice has been carried on since the lots 1950s, while at the same time millions of tons of imported food wheat grains were transported all over the country. How can one explain such an inconsistency in policy?

Exclusionary quarantine procedures remain in force today despite the rapid increase in global air travel that has occurred over the last four decades. Information obtained from the International Civil Aviation Organization (ICAO) reveals that in 1983 there were 2.3 million scheduled international airline departures carrying 173 million passengers, an average of 63 passengers per flight. It should come as no surprise that there are numerous documented cases of international travelers transmitting diseases.

For example, it was recently confirmed (Dubin and Stubbs) that the stripe rust race of barley that appeared in Colombia in 1975 is nearly identical to race 24 of stripe rust on barley found in Europe, Although nobody is being blamed, it is almost certain that a plant breeder attending a barley conference in the UK in 1975 transported race 24 urediospores on his clothing to a field in Colombia. Race 24 became rampant in South America, causing crop losses valued at millions of dollars. The carelessness of this one individual aside, in this highly mobile world of ours there is simply no practical way of guarding against the inadvertent spread of diseases (plant and animal alike). Even with a policy of exclusion, the hoped-for degree of protection is rarely attainable. This then raises the question whether the US quarantine service has taken this reality into consideration.

A second example, one with a happier outcome, involved the movement of stripe rust of wheat from Western Europe into Australia, which has one of the strictest plant quarantine systems in the world. Australia was fortunate to have on hand some now commercial cultivars, many derived from CIMMYT-based materials, that were resistant to this race of stripe rust; hence, the losses caused by the disease were minimized.

The Australian example points out a plausible alternative to the use of plant quarantine resources. I think everyone would be better served if the US plant quarantine service adopted a positive or anticipatory approach rather than the reactionary approach that currently seems to be the norm. In other words, they should try to anticipate the introduction of new pathogens and be prepared to cope with these problems when they arise. This means supporting research an resistant cultivars, verifying and ensuring the availability of effective chemical sprays, etc. It seems a much more sensible approach to me for plant quarantine resources to be used to anticipate disease problems, and to develop effective methods of control before problems arise. In this way, research could stay ahead of the disease problems that, regardless of efforts to exclude them, will eventually require action. CIMMYT's collaborative research activities on Karnal bunt--involving the participation of ARS, the California Department of Agriculture, and several Mexican institutions--is an example of such an effort.

It has often been said that while the US plant quarantine service cannot stop the entry of a pathogen or post, they may delay its entry for a significant period of time. The fact of the matter is that if a pathogen finds a compatible environment in which to grow and multiply, it will do so, and it will do so very rapidly. It is clear to me that exclusionary practices in this day and age simply are not effective. They represent a misallocation of scarce resources that could be better spent on the research necessary to cope with diseases and pests that pose a threat to American agriculture.

I believe that it is essential that the activities of US quarantine system become more integrated with the research efforts of other USDA agencies, with the land grant university system, as well as with national and international research institutions outside US borders. While exclusion and eradication can continue to be used as preventive measures in certain cases a much broader approach to controlling the introduction of foreign diseases must be implemented.

J.R. Morschel of Australia has eloquently enumerated the fundamental prerequisites upon which plant quarantine measures should rest. I quote:

1) the measure should be based on sound biological principles;

2) they should not be used for the furtherance of trade;

3) the quarantine must derive from adequate law and authority;

4) as conditions change, or further facts become available, quarantines should be modified;

5) the objective of preventing introduction and spread must be considered reasonable to achieve;

6) cooperation, both on an international scale and from the public, is required;

7) quarantine measures can be effective only if those responsible for them are well informed; and

8) quarantine measures are only one of the facets of domestic pest management programs. A careful integration of measures is needed to achieve maximum effect.

In closing Chairman Bentley, I wish to reaffirm my proposal that NPGRB take appropriate action to address this issue. Specifically, I propose the formation of a Blue Ribbon Panel, with broad representation, to conduct an in-depth study of both the philosophical underpinnings and the operational activities of the US plant quarantine service, and that this panel be charged with delivering recommendations to the highest policy making levels. My personal feeling is that such actions are long overdue.

References

Dubin, H.J., and R.W. Stubbs. 1986. Epidemic Spread of Barley Stripe Rust in South America. Plant Disease 70:141-144.

McCubbin, W.A. 1946. Preventing Plant Disease Introduction. The Botanical Review, p. 104-139.

McCubbin, W.A. 1954. The Plant Quarantine Problem: A General Review of the Biological, Legal, Administrative and Public Relations of Plant Quarantine with Special Reference to the United States Situation. Ejnar Munksgaard. Copenhagen.

Morachol, J.R. 1971. Introduction to Plant Quarantine. Canberra: Australian Govt. Public Service, 71 pp.