General Comments
This topic was meant for participants to raise subjects not specifically addressed in the primary forum areas. They were asked to recommend other issues that might be examined, or point to resources that could be referenced from this symposium.
Robert Bowden - 03:36pm Jun 29, 1996 EDT (#2 of 27)
Kansas State University
In his introduction (Jackie Rudd "Introduce Yourself"), Jackie Rudd wrote "I hope
that this symposium will help bring science and public policy
closer together." That is certainly our goal. Which public
policies are demonstrably unscientific? Perhaps they are better
described as extremely cautious. When data are lacking, why is a
cautious policy unscientific?
Kim C. Shantz - 10:25pm Jul 2, 1996 EDT (#3 of 27)
IT'S THE WEATHER STUPID!
After the initial discovery of KB in Arizona a very intense effort was put forth to find the villain that caused this unprecedented disaster. First it was one lot, one variety, one company, then it was more than one lot, then it was found in another variety that contaminated the original variety but the original variety was not contaminated, then it was found in a variety of a second company in another area. These were private varieties and the varieties were named in the press but the owners of the varieties were not named to "protect their identity". Then it was found in another area in a public variety of hard red wheat at high levels and the variety was not named in the press. KB was still being characterized as a "localized find". The ranch where the first KB was found was disclosed but later names of ranches with KB were not disclosed. Until of course the ranch with the highly positive hard red wheat was identified as being a large ranch owned by a religious organization in Blythe, California. Then it was lack of seed treat by unscrupulous seed companies who were in the severest part of the epidemic. But seed treatment is only about 80% effective so while it might slow an epidemic down it certainly wouldn't stop one. Then it was because of an infestation found in variety "A" that was brown bagged and not treated. The problem with this theory was that this variety has very limited acres.
I suppose it may be human nature to want to place blame on someone, some company, or some religion, but it was obvious two weeks after the initial find, when KB was found in the Durum Quality Survey samples, that KB was widespread and epidemic to Arizona. But the quest to find the villain went on. When Johnny Buntseed could not be found, then it was contaminated equipment that goes back and forth from Mexico and the USA. The problem with this theory is that most of the equipment exchange takes place in the Yuma and Imperial Valleys. These two valleys however are at the very edge of the epidemic.
But the most plausible theories of how KB traveled to Arizona were continually downplayed by APHIS because they did not involve a culprit. During the mid seventies and again in 1980, large amounts of durum seed were imported from the Yaqui Valley of Mexico. The 1975 seed distribution was over the entire state of Arizona but the 1980 seed distribution was mostly in the Imperial Valley of California. This seed in all likelihood had some KB teliospores and perhaps even bunted kernels.
The second method that could have given wide spread spore inoculation to Arizona would be windblown teliospores. Fields are routinely burned in Mexico and spores are known to rise at least 3000 meters. At that height they could easily reach all of the irrigated areas of Arizona to a greater or lessor extent. The theory was debunked by an APHIS administrator as being "just a theoretical model". Other possible methods of long range spore dispersal would also include white wing doves which migrate in large numbers from Mexico to Arizona in May and are found in most wheat fields. This occurs right after the Mexican harvest and just prior to the Arizona harvest. Also there is a constant flow of people, farm workers, trucks, produce and cars from the Yaqui valley.
If Arizona was possibly inoculated so easily and consistently, why was the epidemic so delayed in happening? For years we thought Arizona was protected from KB by our dry environment and rotational practices. The Yaqui Valley is close to the Sea of Cortez and has much higher relative humidity than Arizona and their crop rotations include wheat every calendar year. Our environment and rotations did protect us for many years from a KB epidemic.
We have weather data at our research plots beginning in 1987. (AZMET) My notes indicate that in 1985 we had no rain in March, but in March 1986, we had at least 2 periods favorable for KB development. However in 1987, 1988, 1989, and 1990, we were very dry during late February and March. Starting in 1991 we had three straight years that had multiple days that were favorable for KB development over much of the state. Favorable weather for KB includes at least two days in a row of measurable precipitation (at least .1 inch) with total precipitation exceeding .4 inches and average relative humilities above 70%. High average RH above 90% seems to be equivalent to a rainy day. Irrigation timing may influence the KB development as well but it is definitely secondary to weather conditions. The temperatures during rainy days during this time of year fall easily within the parameters of KB spore germination and infection. KB can infect wheat any time from 2 weeks before anthesis to about 5 days after. Depending on the planting date and variety, wheat flowers from early March to mid April in Arizona.
The West Phoenix area (the reported center of the epidemic) had 10 favorable days for KB development in 1991, 8 in 1992, 4 in 1993, 4 in 1994, 2 in 1995, and 2 in 1996. Maricopa (south of Phoenix 40 miles), which has a moderate level of KB, had 4 in 1991, 8 in 1992, 3 in 1993, 0 in 1994, 2 in 1995, and 0 in 1996. Coolidge which is outside the epidemic area near Casa Grande had weather conditions very similar to Maricopa except that in 1996 it was much drier than Maricopa. So Coolidge could very well have as much KB as Maricopa (40 miles apart) but it certainly did not manifest itself on a biological indicator in 1996.
Parker and Yuma Arizona are on the Colorado River about 100 miles apart. Parker has a severe epidemic and Yuma has a light infestation. Parker had 4 favorable days for KB development in 1991, 11 in 1992, 2 in 1993, 2 in 1994, 2 in 1995 and 0 in 1996. Yuma had 4 in 1991, 5 in 1992, 0 in 1993, 0 in 1994, 0 in 1995 and 0 in 1996. Both Parker and Yuma grew hard red wheat until 1992. Wheat is generally more susceptible than durum. The positives for KB at Parker in 1996 were likely caused by soil contamination because the weather was very unfavorable for KB development. On irrigated land, farmers put in soil checks on their border ridges to spread the irrigation water. The combine operators usually drive right through them with their headers.
Aguila, another hot spot for KB had 2 favorable days in 1990, 6 in 1991, 9 in 1992, 5 in 1993, 2 in 1994, 0 in 1995, and 2 in 1996.
In Arizona we normally have about 100,000 acres of wheat out of about 1 million total acres of irrigated land. In 1996 we have about 180,000 acres of wheat.
I believe we have had a steady source of KB teliospores coming from Mexico ever since the epidemic started in the Yaqui Valley. For many years our environment protected us. The conditions favorable for KB development are quite abnormal for us, but do occur. I believe our current epidemic started in 1991, built up locally in 1992 (KB was detected in 1992 wheat samples), peaked in 1993, maintained in 1994 and 1995, and decreased in 1996. What kept the epidemic alive in 1996 is that our rotations are bringing wheat back to fields that had infested wheat in 1991, 1992 and 1993.
Once the initial
windblown teliospores completed their life cycle in Arizona, KB
became a localized perpetuated epidemic in most areas of the
state. If this occurred once, it can and will occur again as long
as Arizona and Mexico grow wheat. Imposing a quarantine did not
prevent the spread of KB into Arizona. Quarantines seldom work
unless the regulatory officials are clever enough to draw the
quarantine lines at the natural boundaries of the disease
epidemic. Whether this eradication will be successful or not
without removal of the host crop depends, well, on the weather.
It's the weather, stupid!
Richard Smiley - 05:24pm Jul 8, 1996 EDT (#4 of 27)
Oregon State University
I find the climatic
conditions cited by Kim Shantz to be more definitive than
presented in other summaries that I have read. This is of great
interest to those of us who work in areas where the pathogen is
not known to occur, and where it has been found as a contaminant
in the absence of disease. I have an excellent weather data base
and am running "what if" scenarios for our industry and
regulatory agencies. First, though, I need to assemble a list of
citable references with information like that in this section.
Kim, could you send me the list of references used to assemble
the data you presented in your comment. Please email it to Dick
Smiley at smileyr@ccmail.orst.edu , or fax it to me at
541-278-4188. Thanks
Gerald Holmes - 03:05am Jul 9, 1996 EDT (#5 of 27)
Univ. Calif. Coop. Ext. Imperial Co.
Kim, I would also be interested in how you assessed disease in past years, what criteria were used, etc. I put together a section in the UC risk assessment for Imperial and Palo Verde Valleys, but could not find definitive criteria to predict disease outbreaks.
As you may know, no
teliospores were found in Imperial Valley preharvest samples, but
23% of fields in PV were positive. The main weather difference
between the two areas in '96 was rainfall (IV-3 mm; PV-109 mm).
Other contributing factors were % red wheat planted and the
amount of contaminated seed used in planting.
William Brown - 06:57pm Jul 9, 1996 EDT (#6 of 27)
Bob and Jackie--regarding
public policy making and science. During the Alar crisis the
Kiplinger Newsletter had a quotable quote that I feel sums policy
making and science up. "In the world of public policy making
there is no truth, only perception." My question--is who is
creating the preception and how do we change it? Kim Shantz--you
mention an epidemic--I was under the impression from Kelly's
paper that only 2 infected grains had been found and that
everything else was positive for KB spores----the survey and
laboratory proceedure is not measuring KB disease but rather
finding KB spores. Spores a disease do not make! What is the
Arizona and Imperial Valley situation? Is there a detectable
field level impact (i.e., epidemic) on yield and quality?
Guillermo Fuentes-Davila - 10:49am Jul 10, 1996 EDT (#7 of 27)
To Cindy Ash: the symposium paper touches very briefly the aspect of resistance-susceptibility of the plant species affected by T. indica "...Wheat cultivars differ in susceptibility...". The most important activity of CIMMYT related to KB for the last 12 years has been to breed wheat for genetic resistance and to develop synthetic hexaploids with resistance to KB. The following are references about these activities which include methodology for screening, identification of sources of resistance, genetic studies, advanced lines and synthetics: Salazar et al. 1990. Revista Mexicana de Fitopatolgia 8:145-153
Fuente-Davila. 1992. Karnal bunt and durum wheat. In: Durum wheat:challenges and opportunities, wheat special report No. 9, CIMMYT
Fuentes-Davila et al. 1992. Annual Wheat Newsletter 38:157-162
Fuentes-Davila and Rodriguez-Ramos. 1993. Revista Fitotecnia Mexicana 16:172-178
Fuentes-Davila and Rajaram. 1994. Crop Protection 13:20-24
Villareal et al. 1994. Plant Breeding 112:63-69
Fuentes-Davila et al. 1995. Plant Breeding 114:250-252
Rajaram and Fuentes-Davila. 1995. Proceedings of the 9th smut workshop, CIMMYT, pages 47-58
Villareal et al. 1995. Cereal Research Communication 23:127-132
Singh et al. 1995. Euphytica 81:117-120
Singh et al. 1995. Plant Breeding 114:439-441
Autrique et al. 1995. Plant Genome III, San Diego, CA. page 24
Villareal et al. 1996. Crop Science 36:218
Villareal et al. 1995.
Plant Breeding 114:547-548
Kim C. Shantz - 11:36am Jul 10, 1996 EDT (#8 of 27)
Gerald Holmes - APHIS in the course of investigating Western Plant Breeders, tested seed samples from 1991-1996 for teliospores at my insistence. The teliospore count ranged from 1 per 50 grams to over 400. Bunted kernels were found in some of the samples. I only looked for bunted kernels in the samples with the highest teliospore counts. I suddenly realized I had 6 years of KB data to relate to weather, anthesis date and planting date.
Two sources of definitive criteria to predict infection are:
1. "1992 Wheat News Letter", page 117-118, D. V. Singh outlines weather in relation to bunted kernel counts in India. You must realize that Arizona would have had zero KB in 1996 if analyzed like this. Thus the higher relative humidity that is reported here. (85%-95% with intermittent rainfall)
2. Schall, Robert A. 1987. Karnal Bunt, The Risk to the American Wheat Crop. Internal. APHIS paper
I wish APHIS would put this on the symposium because Dr. Schall predicted in 1987 and epidemic of KB almost like it is unfolding in 1996.
I would be interested in good weather data from the Palo Verde Valley as it is half way between Parker and Yuma. You can not draw any conclusions from one year of weather data. KB epidemics need time to develop with consecutive years of favorable weather because it only goes through one cycle per year. I would go back at least to 1991 for a weather analysis. Obviously, weather is not the only contributing factor for KB development, but very necessary.
William Brown - You can't
believe everything you read on the net. Kelly's paper was written
quite early in the 1996 harvest and had a certain amount of
"spin". I believe in both 1995 and 1996, bunted kernels
have been found in 3 out of the 4 major agricultural counties in
Arizona. The incidence of bunted kernels was higher in 1995 (as
high as 3%) than in 1996. We don't know how bad KB was in 1993
because very few samples remained from that year. The incidence
of KB teliospores in my 1993 breeding nursery was far higher than
in 1995. (100-400 teliospores per 50 GMs with over 90% of the
samples infested) The APHIS criteria for an outbreak is 1
teliospore so I don't think it is a stretch to call 3.5% positive
preharvest samples, found in all major agricultural areas of
Arizona an epidemic. There has been no detectable field level
impact on yield and quality in any year. In 1996 without the
teliospore test, I don't think any bunted would have been found.
We were probably one storm system away from having zero bunted
kernels in 1996. The situation we have here in Arizona is a
resistant (not immune) reaction of a host crop (durum wheat) in
an environment that is somewhat marginal for KB development KB is
here, widespread and real - a real "wimp",
Gerald Holmes - 11:38am Jul 11, 1996 EDT (#9 of 27)
Univ. Calif. Coop. Ext. Imperial Co.
Kim Shantz - I could certainly get Palo Verde weather data to look at. We looked only at 1996 weather in the UC report. I would like to see how Imperial and Palo Verde Valleys measure up to the criteria you used.
William Brown - Look in discussion on "what's happening in your region" under my name for update on quarantined areas of Calif. There were no cases of detectable yield reduction, even in Palo Verde Valley (Blythe) where 23% of preharvest samples were positive. The only way KB has been found in Calif. is by the wash-sieve technique or in some cases they found bunted kernels in storage (Blythe). Regulatory people working in Calif. would know the details. You almost have to be like a pesty journalist to find out what's going on.
Kim C. Shantz - 10:54am Jul 12, 1996 EDT (#10 of 27)
In the July 7, 1996 Arizona Republic, staff writer Jane Larson states "The fact that southern Arizona is relatively free from the fungus although western Maricopa County shows the state's highest rates of infection shoots holes in the theory that wind alone spread karnal bunt from Mexico to Arizona, regulators say".
So I checked the weather
records for Marana and Eloy, the only significant wheat areas in
Southern Arizona. In 1991 Marana had 0 days favorable for KB
development, 6 in 1992, 0 in 1993, 2 in 1994, 0 in 1995, and 0 in
1996. Eloy had 0 in 1991, 5 in 1992, 4 in 1993, 2 in 1994, 0 in
1995, and 0 in 1996. This compares to western Maricopa County
with 10 in 1991, 8 in 1992, 4 in 1993, 4 in 1994, 2 in 1995, and
2 in 1996. This shoots holes in the APHIS supporting argument for
a single source infection (fateful sample) theory.
Jack Riesselman - 10:11am Jul 14, 1996 EDT (#11 of 27)
In reading the comments and discussing the issue with several people its evident that most of us have some sympathy for AZ & CA but down deep we all say "thank God it didn't happen to us" or "as long as it stays in the SW and doesn't affect us, let they deal with the problem.
But, in reality it has affected many of the northern states, more directly than most realize. For example, many northern states and Canada use the desert for producing extra generations. When a desirable, high yielding, special quality or pest resistant line is brought to the grower two or three years faster by utilizing the SW it does adversely affect northern producers. An example, during the l990's, scab caused a reported billion dollar loss during the single growing season in the upper midwest. We know that scab is not a "wimpy disease". but when a line developed in AZ that has good resistance to scab was contracted for seed increase in ND the state refused to allow entry even though it tested negative for KB. The plan was to have nearly a million bu of this seed ready for Red River valley producers by the l999 growing season. But, KB derailed these plans even though the potential that KB could survive a ND winter is highly unlikely.
Some quick figuring, given only a mild scab outbreak in l999 suggests that this decision could cost ND growers a conservative 25 M in lose income. If I were a ND grower, who had lost most of my crop to scab, two or the last three years, I'd be more than displeased.
This type of over
reaction, plus numerous quarintine inconsistencies, really
challenge the credability of quarintines in general, especially
for a pathogen like T. indica. I work in a region that has low
levels of dwarf bunt, a smut that causes minor damage and is
severely limited by environmental parameters. Does AZ or ND
quarintine Montana or Washington wheat from dwarf smut areas? Of
course not, why?, the environment of those states is not
favorable for the pathogen. Sound familar?
David Hole - 05:55pm Jul 14, 1996 EDT (#12 of 27)
I agree with Jack (posting #11 of 12), only in my area TCK has the capability of being severe and chronic. It is not unusual to get 85% bunted kernels on susceptible lines in an artificially innoculated nursery and 40% bunted kernels in suceptible lines under natural infection, and this is after growing resistant cultivars in these areas for decades. The spores have proven they can survive for 20 years or more.
I have thought a lot
recently about the seed that I send out in response to requests
and for regional nurseries. There is no way that I can produce
seed that I can say is free of TCK spores. Why hasn't APHIS put
quarantines in place for state to state travel like they have for
KB? The disease is certainly a trade issue just like KB. My only
answer is that seed has moved for so long and they still don't
get TCK in Kansas that APHIS recognizes that the disease won't
occur everywhere. Now what do we have to do to convince them the
same thing is true of KB?
Scott Yates - 11:52am Jul 15, 1996 EDT (#13 of 27)
Elevator companies in the
Northwest, especially Washington, are taking a long hard look at
participating in what APHIS has described as a voluntary survey.
They see no advantages. No Northwest grain customer has asked for
Karnal bunt free wheat. Meanwhile, there are disadvantages.
Although APHIS has agreed to pay for half the cleaning costs of
sanitizing elevators, up to $20,000 and to pay the difference in
wheat price received, there is no provision for reimbursement for
the downtime elevators will suffer during the quarantine and
cleaning process. Although I have asked APHIS about this
specifically, I've gotten no response. Of course, the agency
could easily get samples of wheat by going through the grain
inspection system, but that would violate the protocol they have
set out. To a great extent, elevator companies here are in the
foot dragging stage, hoping they aren't asked to participate.
Others feel there really isn't an option. As one said: Voluntary?
I've heard that before. I wonder.
Jack Riesselman - 11:25am Jul 16, 1996 EDT (#14 of 27)
Response to Scott: Montana proposed that the survey be conducted at on farm sites, one site for every 250,000 bu of production. The reason, to protect elevators, eliminate the potential for contamination, if found the location would be known and finally to prevent a possible positive from another state or country moving grain out of Montana. APHIS still wanted elevator samples but with some county parameters also accepted.
The risk for elevators is high, especially with a zero tolerance in place. I personally do not blame them for not being proactive participants. An example, Montana's contaminated elevator where 3,000 bu of contaminated durum was stored was decontaminated this spring. The cost which included tarping the entire facility, removing 30,000 gallons of contaminated water (broken pipe) etc was nearly 80K. The 20K does not go far in covering the total cost. Additionally, this seed cleaning/treatment facility was down during the spring season with no income. If these rules are placed on cooperating businesses, then they need to be fully compensated.
Even though the potential
for actual field infections in most of the U.S. is low I do feel
that the survey is still an important function, if for no other
reason than to show that this pathogen is probably contained by
the environment.
James A. Hoffmann - 09:02pm Jul 21, 1996 EDT (#15 of 27)
ARS/USDA Retired
With typical USDA
short-sightedness, the ARS Cereal Disease Unit at Logan, UT was
closed upon my retirement in 1986. Goates, Smilanick and myself
had a productive research program on KB in the only approved
containment lab in the US other than the facility at Frederick,
MD. We also had a collaborative research program with CIMMYT in
Mexico. Had this lab and collaboration been allowed to continue,
much information could have been obtained and we would have been
better prepared to cope with the inev itable introduction of this
disease. Sour grapes? You bet! But true, nevertheless. Regards
and aloha, Jim Hoffmann
Dan Biggerstaff - 12:01am Jul 23, 1996 EDT (#17 of 27)
Western Plant Breeders
To: Dr. Stephen Poe
In your introduction you make a comment about steering an honest course in dealing with KB ..... best scientific information available. I realize that you and other APHIS scientists are in a very difficult position with regard to speaking-out on KB issues. Even so, how can you defend the present APHIS position of "eradication of KB" when it is obviously not feasible on the basis of available information? KB teliospores are certainly widespread in the Southwest and are also present outside the quarantine area.
Please explain (on the basis of honest, scientific information) the APHIS rationale of quarantining 2000 lb. of 1995 breeder's seed after 9 million pounds of seed from the same production area had already left that quarantine area as planting seed? (See section 8 of my Symposium paper for details.)
How does APHIS defend the description of KB in the 1983 and 1996 quarantines (as printed in the Federal Register) on the basis of "good science." Can APHIS explain the present quarantine inconsistencies using "good science"? (See section 10 of my Symposium paper.)
At the risk of sounding impertinent, I do not believe the terms "good science" and the present "risk-basis quarantine" should be used together. It appears to me that USDA/APHIS are ignoring "good science" in this 1996 episode, just as they did in 1982-83.
These comments and
questions are not a personal attack on you or any other
USDA/APHIS scientist, but I, and many other scientists, are
frustrated by the lack of scientific justification for APHIS
policies. Let's be honest and refer to KB as the political
disease that it is, and skip the pretense that the quarantines
are based on scientific information. I look forward to your
response.
blair goates - 11:50am Jul 23, 1996 EDT (#18 of 27)
In response to the July 14 comments by Jack Riesselman and David Hole. The effects of KB on the movement of germplasm have been been severe in some cases; mostly depending on the decisions from individual states. Even if the germplasm passes through the rigorous protocol of the APHIS compliance agreement which includes 1) testing negative for teliospores with the seed wash assay technique, 2) disinfesting seed with a soak in clorox, and 3) treating seed with high rates of fungicides, some states have taken the route of extreme caution by excluding the germplasm.
We have had about a hundred years of experience with dwarf bunt in the U.S. and have learned (mother nature taught us) where the disease can and can not occur. Can we say the same for KB? When I read the climatic conditions that favor scab, they do not seem too far from the conditions that favor KB. Certainly, experience with KB in other parts of the world indicate climatic limitations (Jessie Dubin's article in this symposium). Perhaps climatic conditions will limit yield losses in the U.S. due to KB, but will they exclude slight traces of infection that can result in a few spores in a grain shipment that can be extremely problematic? Can we undo the world-wide mind set of this KB "problem"? There are a few wheat diseases that "don't occur" in my area that we find rarely in slight trace amounts. We never see common bunt anymore, unless we wash some seed.
Since the first discovery of KB in the U.S., I have heard many people say that spores can't survive the winters in the Northern U.S.. I believe most, if not all, of these opinions come from the results of a single study (Zhang, Lange, and Mathur. 1984. EPPO Bull. 14:119-128) which showed total inhibition of teliospore germination after prolonged exposure to -18C. However, later, and in my opinion more complete studies (Chahal and Mathur, 1992. FAO Plant Prot. Bull. 40:31-35) showed only slight effects of -18C after 20 weeks of exposure when teliospores were "thawed" for 20 days prior to plating. Both these studies were done under laboratory conditions and may not relate to what occurs in the field. I hope scientists in the northern areas, and elsewhere, are currently designing field experiments (and going through a lot of "red tape" for proper containment and permits) to test the survival question. Of course, spore survival does not necessarily mean disease establishment.
In addition, I've heard
the argument that spores have been distributed throughout the
U.S. already, and we haven't seen the disease, so it can't occur
in other places. I remember when this same argument was used for
the Southwestern U.S. and parts of Mexico that were previously KB
free.
Douglas Prasher - 01:49pm Jul 23, 1996 EDT (#19 of 27)
USDA, APHIS
New Karnal bunt newsgroup?
The APHIS computer people have created a Karnal bunt newsgroup (sci.bio.plantpests.karnalbunt) but, unfortunately, the newsserver of my local Internet provider does not yet offer it. If people do not subscribe to the newsgroup, it will be terminated. Are any of you KB Netters able to 'subscribe'? If so, please send me a note (dprasher@capecod.net) or post a reply at this Symposium. This KB newsgroup will be an excellent medium to address KB issues once the Symposium terminates.
I also asked that two
other 'plantpests' newsgroups be created:
'sci.bio.plantpest.fruitflies' and
'sci.bio.plantpests.aphismethods'. Are you also able to subscribe
to those?
Roland F. Line - 12:55pm Jul 24, 1996 EDT (#20 of 27)
This symposium has certainly been successful. For many years I have been concerned about the quarantine regulations related to the smuts of wheat and have suggested that we reassess the need for quarantines at both the national and international level. I am convinced that quarantines for control of wheat smuts need to be modified or eliminated and the purchasers of wheat need to be educated on the lack of danger from purchasing grain from countries where the diseases may occur. However, as long as those laws exist and the purchasers want smut free grain, we must comply with those regulations. I have had a long dialogue with regulatory personnel at APHIS, and I hope that I contributed to some positive changes in the implementation of those regulations. It is easy to pass a quarantine law and very difficult to eliminate or change that law. We not only must convince a regulator that the law is not biologically sound, ineffective, and unnecessary, but we need to persuade lawyers and politicians that they should accept the responsibility for removing the regulation. Not an easy task. It is now time for APS to take a stand on this issue. The following is a brief summary of some information from past talks on the quarantine situation from flag smut to Karnal bunt.
QUARANTINES FOR CONTROL OF WHEAT SMUTS -- ARE THEY EFFECTIVE OR NECESSARY? Roland F. Line, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA 99164-6430.
There are three wheat smut diseases that are affected by quarantine laws, flag smut, dwarf bunt, and Karnal bunt. Each disease has been restricted to certain geographic regions for centuries ecause each has certain environmental requirements, not because quarantines keep them there. Each can be controlled by methods that are more economical than quarantines. In each case, once the quarantines regulations were implemented, efforts to remove the quarantines have been futile, and modification of the laws has been resisted.
Flag smut Quarantine No. 39, which was aimed at preventing the introduction of flag smut into the United States from other countries, has existed since 1919 when flag smut was first discovered in Madison County, Illinois near St. Louis, MO. National quarantine actions to prevent spread of flag smut from Madison County to other regions of the United States were proposed in 1919. The state of Illinois convinced the federal government that they had ample legal powers to control the disease and prevent interstate movement of diseased products. The following actions were implemented: 1) treatment of harvested grain with formaldehyde, 2) burning all straw and stubble after threshing, 3) disinfection of threshing machines, 4) sowing no wheat in infested fields for several years, 5) sowing no wheat in land with wheat the previous year, 6) using seed from areas that did not have flag smut, 7) treatment of seed with copper sulfate or copper carbonate, and 8) growing resistant cultivars. By 1924, flag smut was detected in 10 counties of Illinois and Missouri near St. Louis and six counties of Kansas and Missouri near Kansas City. The quarantine actions within the United States were discontinued in 1923, because they were ineffective in preventing spread of the disease. Without any quarantine within the United States, flag smut of wheat disappeared from central United States by 1934 and has never been detected in that region since then. Reasons for the decline of flag smut in central United States were a change in the environment and use of seed treatments, resistant cultivars, and crop rotation.
As predicted, flag smut was reported in the Pacific Northwest in 1940. The disease subsequently increased in severity and spread to other areas in the Pacific Northwest. There was no major attempt to control the disease until 1968. By that time, flag smut had become the most important disease of wheat in Moro County, Oregon and Klickitat County, Washington and was an impending problem in international marketing of wheat from the Pacific Northwest. In less than four years, the epidemiological and managerial factors that affected flag smut had been determined, and the disease was controlled by Vitavax seed treatment. Resistant cultivars and improved management also controlled the disease. Since then, flag smut has declined to the point where it is difficult to detect. It has not spread to other regions of the nation, even though wheat seed and grain from the Pacific Northwest has been distributed throughout the United States without any restriction. The "flag smut problem" resulted from growing highly susceptible cultivars in a favorable environment made more favorable by crop management. World-wide, flag smut is not as damaging as once thought, it occurs only in certain regions and has not spread to other areas because it has unique environmental requirements, and it is easily controlled by seed treatments, resistant cultivars, and preventative management. In retrospect, quarantine regulations did not control flag smut and were and are not necessary. However, Flag Smut Quarantine No. 39 still exists unchanged.
The quarantine regulations for control of dwarf bunt and Karnal bunt have already been discussed. Like the flag smut quarantine, those regulations should be reassessed. Dwarf bunt occurs only in certain regions because it has unique environmental requirements, and it has not spread to other regions even though it has had ample opportunity. With the development of Dividend, dwarf bunt can now be controlled with seed treatments as well as resistant cultivars and modifying the managerial methods. Karnal bunt also occurs under certain unique environmental conditions; can be controlled by seed treatments, foliar sprays, and modifying the managerial methods; and it seldom causes major losses. Even before this recent excitement, the quarantine regulations had a major negative impact on the free and easy exchange of germplasm and the development of improved wheat cultivars. Now, the quarantines are causing additional and unnecessary seed distribution and marketing problems.
In conclusion, current
information on the epidemiology and control of these smuts
suggests that the quarantines have not been effective in
preventing the spread of what smut diseases, many of the current
regulations are not necessary, and other control methods are more
effective and less expensive.
Goldie Waghalter - 06:30pm Jul 27, 1996 EDT (#21 of 27)
Hi, I am Marketing
Director for Accelerator Technology Corporation, a company which
designs and manufactures electron beam irradiation systems. We
are forming a working group to explorethe use of electron beam
irradiation for control of Karnal bunt in bulk grain, in grain
elevators, and transport equipment. Irradiation treatment on
Dwarf bunt shows promise. We are working on a design of a
field-portable high-power e-beam system capable of processing 40
tons per hour of infested wheat. The systems could be configured
in tandem to process up to 160 tons per hour. A similar system
could be configured on a tractor-towed trailer to disinfest the
surface ~ 3/4" of soil in a field at a rate of 2 acres per
hour. Several USDA officials are interested in pursuing this
possibility but have indicated that it is important for the wheat
industry to support this project. The first step is to perform
protocol tests on Karnal bunt which can be done at the electron
beam lab at Iowa State University. Interested industry people can
reach me at 713-666-4717 or email gwag@ix.netcom.com.
Berlin Nelson - 10:40am Jul 28, 1996 EDT (#22 of 27)
For those looking for
photos of T. indica the book on Tilletia by Duran and Fisher, and
Ruben Duran's Ustilaginales of Mexico have very useful photos.
There are several other papers on the biology of this fungus by
R. Duran. If you are just learning the biology of this smut these
publications are helpful
Douglas Prasher - 10:48am Aug 2, 1996 EDT (#23 of 27)
USDA, APHIS
Thank you APS for
extending the symposium.
Dan Biggerstaff - 02:41pm Aug 2, 1996 EDT (#24 of 27)
Western Plant Breeders
I too am pleased that this Symposium has been extended. Thank you to all who are making it possible, and a special thanks to Cindy Ash and Taylor Walsh for their long hours on this project.
I am disappointed that Symposium questions being asked of USDA and/or APHIS are not being answered. Why is there no response from the policy makers or regulators to specific questions?
If APS prepares a position paper on Karnal bunt, will it be posted here after it
is presented to the USDA?
Cynthia L. Ash - 11:15am Aug 4, 1996 EDT (#25 of 27)
Director of Scientific Services
Dan,
YES, both position
papers/statements being prepared by APS will be posted here if
they are released before August 16. Otherwise they will be archived with this symposium on APSnet. I have also received a
request from APHIS to post a paper in this symposium. We will get
it up as soon as we receive it.
Gerald Holmes - 08:48pm Aug 15, 1996 EDT (#26 of 27)
Univ. Calif. Coop. Ext. Imperial Co.
I just attended the USDA public forum on KB in Imperial Calif. There were about 20 testimonials given representing mostly industry and growers. The comment came after the forum that there is not enough input from scientists at these forums. I gave a brief testimonial from the perpective of a plant pathologist and mentioned the drafting of a statement from APS. Several people expressed interest in this statement including USDA officials who would like to see it submitted before the Sept 3 deadline for commentary.
I attended the APS meetings in Indianapolis and have a copy of the drafted statement. Given the discussion about the statement at the meetings, it seems that it may be difficult to arrive at concensus in order to ratify the statement as a society. Personally I would like to see APS issue a statement. I also believe that the draft distributed in Indianapolis needs considerable revision.
I would like to be more
specific regarding criticism of the statement. Maybe a separate
discussion group on this topic would work. Is it too late? If so,
maybe someone can tell me who to contact.
Robert Bowden - 02:30pm Aug 16, 1996 EDT (#27 of 27)
Kansas State University
I heard a rumor that KB was found in Alabama. This is a rumor, so it may be completely untrue. Perhaps someone from APHIS can respond. Have there been any new detections outside the quarantined area?
If KB is confirmed in Alabama, this may show that KB can survive on winter wheat in a high rainfall area. My understanding is that KB has heretofore been limited to spring wheat in low rainfall areas.
I wish the Symposium was not ending already. Does it cost APS a certain sum per day? Are we renting the Symposium software rather than buying it?
© Copyright 1996 by the American Phytopathological Society