Symposium Discussion Forum

Annual Meeting: Notes & Comments

(Ed. Note) This section includes notes from related presentations at the 1996 Annual Meeting and comments from attendees.

Greetings from Indianapolis.

This is where you'll read comment from people attending the meeting...and who add comments from the PC's set up in the Tech Center for demonstrations of APSnet.

Notes on Presentations

A quick synopsis of several presentations given at the APS Annual Meeting in Indianapolis this week is given below.

Readers were asked, "Please feel free to add comments, additions or corrections directly by posting a message or contact Cindy Ash"

Cynthia L. Ash - 12:25pm Jul 30, 1996 EDT (#1 of 11)

Director of Scientific Services

Discussion Session: Innovative Techniques in Pathogen Detection and Their Role in Agriculture.

Development of disease detection methods for Karnal bunt of wheat in anticipation of the disease. G. Peterson and M. Bonde.

Detection of Karnal bunt spores in wheat is done by a method Peterson and Bonde developed using size selective sieves. They are always able to get a positive test when there are at least 5 spores per gram present, using either PCR or microscopic examination.

To prevent contamination all laboratory equipment is washed between samples with a 30% bleach solution. This kills spores and also changes their form and/or color to prevent false positives.

Spore morphology and size is used is make a microscopic identification. A logistics index determines the probability that a particular spore is Tilletia indica and not T. barclayana.

There was some concern about T. barclayana on Panicum species but it was felt that is would not be a problem due to limited distribution of the grass host and flowering at a different time than wheat.(See the paper presentation by R.W. Stack for more information)

Dan Biggerstaff- 09:07pm Jul 30, 1996 EDT (#2 of 11)

Western Plant Breeders

In reference to Cynthia Ash's note above:

Do you mean 5 spores per gram, or 5 spores per fifty grams of grain (or seed)?

One (1) teliospore per fifty grams of sampled grain/seed was the most common teliospore count in the Southwest this year in pre-harvest field samples, post-harvest samples, and rail car samples declared "positive for KB teliospores." Is it possible to use a logistics index or PCR on a single spore?

In reference to the last paragraph, what difference does it make that Panicum spp. may flower at a different time than wheat? The important consideration is: Do Panicum species flower at an opportune time (temperature, humidity, free water, etc.) for effective germination and sporulation ofTilletia spp.? Keep in mind that some host crops escape KB infection in the Southwest because they flower at an inopportune time for effective KB teliospore germination, not because there are no KB teliospores present. KB teliospores are certainly present in some host crop fields that had no KB infection this year.

Cynthia L. Ash - 01:48pm Aug 1, 1996 EDT (#3 of 11)

Director of Scientific Services

Dan, You are right, the text should read 5 spores per 50 gram sample. I would really welcome any other comments or corrections.

Cynthia L. Ash - 11:49am Aug 4, 1996 EDT (#4 of 11)

Director of Scientific Services

Discussion Session: Innovative Techniques in Pathogen Detection and Their Role in Agriculture. A Large-scale Detection Survery for Karnal Bunt of Wheat. Tom Sims, Kansas Department of Agriculture.

Disease survey data are used to support regulatory issues. The 1995 wheat disease survey in Kansas included 410 sites in 85 counties. A Karnal bunt survery was initiated in 1991 with Kansas, Nebraska and Oklahoma joining the survey in 1993 and South Dakota, North Dakota, Nebraska, and Texas in 1995. All samples have been negative for Karnal bunt. Ergot and common bunt were found in some states. As a result of this survey markets have remained open for these states.

Plans are to check 2,000 to 2,500 harvest samples for Karnal bunt this year. T. pulcherima is not expected to be a source of confusion as Panicum is in the boot during harvest. Panicums are common in corn and contamination of combines may be from combined corn not wheat.

As a last note, Sims mentioned that freezing and thawing won't kill Karnal bunt spores but the environmental conditions which impact the spores are very complex.

Cynthia L. Ash - 05:01pm Aug 4, 1996 EDT (#5 of 11)

Director of Scientific Services

Discussion Session: Karnal Bunt. Biology and Epidemiology. Morris Bonde, USDA-ARS, Frederick, Maryland.

Karnal bunt was initially identified in northwest India, near the city of Karnal in 1930. In 1969/70, it became more prevalent due to the widespread planting of susceptible wheat cultivars. In 1972, Karnal bunt was identified in Mexico.

In 1982, Dr. Bonde began a research program on Karnal bunt in a disease containment facility at Fort Detrick, Maryland. Cooperators include scientists at CIMMYT in Mexico and in India. Karnal bunt and other diseases known to occur in other parts of the world but not in the United States are studied at Fort Detrick to determine what should be done if they are introduced into the United States.

Wheat infection occurs by primary and secondary sporidia but there is some controversy as to whether the fungus goes directly from soil to the wheat heads or "monkey jumps" up the foliage.

The disease is very weather dependent with moisture being the most important factor. [Editors note: Many of the presenters reinforced the idea that the disease is "weather driven"].

Dissemination of teliospores occurs mostly via seeds but wind, vehicles, animals and water are also involved. Regarding the survival of teliospores; research conducted in Maryland indicates that the fungus will survive freezing/thawing and cold temperatures for at least 3 years. The lowest soil temperatures reached were -4 to -5 degrees centigrade.

Cynthia L. Ash - 06:19pm Aug 4, 1996 EDT (#6 of 11)

Director of Scientific Services

Discussion Session: Karnal Bunt. Research in Mexico. John Dubin, CIMMYT, Cuauhtemoc, Mexico.

1. Breeding for Karnal bunt resistance. There are 9 ecological niches or mega environments that are considered in a breeding program. The biggest and most important region bred for is mega Environment 1. This program has resulted in over 100 wheat lines with resistance to Karnal bunt. Four synthetics have been registered with immunity to Karnal bunt. Most wheat lines with resistance to Karnal bunt have at least 2 resistance genes from a pool of at least 10 resistance genes. A new wheat cultivar just released in 1995 is Borlaug 95.

2. Disease control. Research is being done, at CIMMYT, on the thresholds necessary for disease. Greater than 90% control of Karnal bunt is achieved with two applications of propiconazole. Seed treatment is not as effective. Some control is achieved with carboxin and other fungicides, some of which prevent the germination of spores for a given amount of time. Experiments using solarization are underway in the Yaqui Valley.

Cynthia L. Ash - 06:55pm Aug 4, 1996 EDT (#7 of 11)

Director of Scientific Services

Discussion Session: Karnal Bunt. Experience of Quarantine Matters in Seed Health. Dennis McGee, Iowa State University, Ames, Iowa.

Dennis discussed the quarantine standards for export. All export lots need phytosanitary certificates and there are two ways to get them. The most common method is field inspection. Unfortunately, this is based on the premise that if the plant is infected so is the seed. This is not always true for plant diseases. The second method involves testing the seed for pathogens on the seed surface or interior using incubation tests, seed grow-outs, ELISA and DNA technologies.

Until 1988, field crop certification was based only on field inspections then it shifted to lab tests. In 1994, Mexico established new regulations which impacted the United States as Mexico is the United States' biggest trading partner for seeds.

Some of the problems include unjustifiable regulations. These may be due to a lack of information, especially in third world countries, or poorly organized information. There are also trade barriers which are often used to replace tariffs. Things seem to be getting worse with the new trade agreements such as NAFTA. There is also an inadequate intelligence system to deal with phytosanitary certification systems.

CABI, The Danish Institute for Seed Pathology and Iowa State University have proposed a worldwide seed borne data base--which is currently being pulled together. The first module, due in early 1997, will contain information on 100 seed borne diseases. Another 150 are planned for release in 1998.

Protocol differences can also be a problem. To help with that problem a seed health committee has been established and will publish a rule in the Federal Register, probably in February.

Cynthia L. Ash - 07:19pm Aug 4, 1996 EDT (#8 of 11)

Director of Scientific Services

Discussion Session: Karnal Bunt. Federal Management Programs. Steven Poe.

USDA/APHIS/PPQ, Hyattsville, Maryland.

The Federal Plant Protection and Federal Plant Quarantine Acts of 1910 gave the authority to establish PPQ (Plant Protection and Quarantine) to prevent the introduction, spread and establishment of plant pests. These regulations have allowed for the successful eradication or containment of several pests and diseases including white rust of chrysanthemum, the golden nematode on potato, citrus canker, Med fly and potato wart disease.

The wheat quarantine against Mexico was established after extensive consultation between APHIS and the United States wheat industry.

Poe was the lead author for a 1992 emergency response plan written to deal with Karnal bunt. This process involved a collaborative effort between APHIS, industry representatives, state regulators, University scientists and others.

Once an exotic pest is detected a "trace back, trace forward" analysis is done. When Karnal bunt was found in March in Arizona, a survey was conducted to check the wheat seed not planted. Second, a combine survey was initiated and sampled 5,000 wheat fields in Arizona. About 250 fields tested postive for the presence of Karnal bunt spores. Most of which can be attributed to "infestations".

Cynthia L. Ash - 07:30pm Aug 4, 1996 EDT (#9 of 11)

Director of Scientific Services

Discussion Session: Karnal Bunt. Consequences of the Karnal Bunt Quarantine on the Seed and Grain Industry. Robert Barkley, Barkley Seed, Inc., Yuma, Arizona.

Mr. Barkley reviewed what had happened beginning with the positive identification of Karnal bunt on March 8, 1996. The delay in or prevention of shipment has cost the industry a lot of money. He presented information on the costs of delaying shipment of grain such as an additional $50/day/train car for delay from sampling or cleaning. Also, the price of transportation increases when the unit number of cars per train is reduced. It costs $50/train car to sanitize the cars with a bleach solution

Dan Biggerstaff - 02:35pm Aug 5, 1996 EDT (#10 of 11)

Western Plant Breeders

To Cindy Ash and Morris Bonde:

In message #5 above you indicate that Karnal bunt was identified in 1972 in Mexico. Other reports indicate that Karnal bunt was identified in commercial wheat fields (not adjacent to CIMMYT) in the Yaqui and Mayo valleys in the 1969-70 crop year. (See Dr. G. Fuentes-Davila's paper in this Symposium.) Our knowledge of the disease suggests that KB must have been present in Mexico before 1969 in order to have a detectable infection in 1996-70.

This issue becomes important when wheat seed exports from Mexico to the US and other countries is considered.

Any comments from APHIS or our colleagues in Mexico?

Allan Simons - 11:45pm Aug 12, 1996 EDT (#11 of 11)

Arizona Grain Council

From: Al Simons, Arizona Crop Improvement Association and Arizona Grain Research and Promotion Council, Tucson

To: Cynthia Ash and Steven Poe, as cited in Note 8 of this section:

You state that an emergency response plan to deal with KB was developed in 1992 in a collaborative effort among APHIS, state regulators, industry representatives, university scientists and others. Steve or any APHIS employee who sees this: would you be so kind as to provide the names and affiliations of the individuals who participated in developing this plan?

The Open Microphone

This is the only discussion topic where meeting attendees using a demonstration account can add comments to the symposium. Please feel free to do so,and please identify yourself in the text. Just click in the box below and enter the comment.

Although the symposium is focused on Karnal bunt, any comments you have are welcome.

(Registered users can also add comments here.)

Gerald Holmes - 06:10pm Jul 29, 1996 EDT (#3 of 8)

Univ. Calif. Coop. Ext. Imperial Co.

Enjoyed the KB session this morning very much. Obviously there is more than science and "truth" to the KB issue. Someone called it "holistic plant pathology;" and we're not very prepared in this area. While I believe that a statement regarding the scientific basis of the quarantine is good, it will inevitably be viewed by others as political and biased. A statement from ISPP, if possible, would be better received by the international community.

Dan Biggerstaff - 10:39pm Jul 30, 1996 EDT (#4 of 8)

Western Plant Breeders

A Sincere Request to All APS Annual Meeting Participants

Please have the moral and scientific courage to speak out in favor of using "good science" to find workable solutions to the present Karnal bunt quarantine problem. Most of us recognize that the present Karnal bunt issue is political, not scientific, and requires political solutions. Without question, a strong, scientific position statement by APS will help shape suitable political solutions.

Read and consider the excellent presentations available here on the APS Karnal Bunt Symposium.

Pay particular attention to the quarantine comments of Dr. Robert Bowden, Dr. William Brown, and Dr. Byrd Curtis in "Zero Tolerance"; Dr. Robert Forster's letter to Secretary Glickman; Dr. Roland Line's presentation in "General Comments"; and the 1985 paper by Dr. Curtis.

In a speech to the U.S. Agricultural Development Council, July 18, Secretary Glickman made the following statements:

"And we must continue to fight political science with sound science. Science is being used as both a shield and a sword as more countries use so-called sanitary and phytosanitary concerns to restrict imports. Don't demand zero tolerance on something you can't have zero tolerance on. That's a phony barrier."

How can anyone disagree with these statements? However, this rhetoric rings a bit hollow when USDA/APHIS tries to maintain a zero tolerance on KB but argues that it is not fair for countries to ask for a zero tolerance on TCK.

It is time for the US to have the courage to admit that it was a mistake to impose a KB quarantine on Mexico in 1983. It will be a mistake to continue the present quarantines in the Southwest. All quarantines of this nature fail, cause tremendous problems in international trade, and cost far more than the problem they purportedly try to solve. Now is the best possible time to start the process of removing political ("phony") barriers to international trade.

Dan Biggerstaff - 10:55pm Jul 30, 1996 EDT (#5 of 8)

Western Plant Breeders

To Gerald Holmes:

I agree that a statement from ISPP would be well received by the international community.

Please do everything you can to get this accomplished. Let others know what they can do to assist you.

Thank you

Sheldon L. Epstein - 05:31pm Aug 1, 1996 EDT (#6 of 8)

Epstein Associates - K9APE

Thanks to all who extended their hospitality to me during the convention. As a 'first-timer', I certainly appreciate the information I received. It certainly will contribute to our work here to develop automatic inspection systems for the detection of karnal bunt teliospores.

Regarding comments on the political facet of the quarantine problem, it is my opinion that our collective efforts would be more profitably used on gaining a better understanding of the nature of this disease and demonstrating in the U.S.A. that we can control it effectively. Until that can be done, I do not believe that it is realistic to expect bureaucrats in other countries (especially third-world) to assume a professional risk of lowering their quarantine standards. To this end, perhaps some thought should be given to providing buyers with some assurance of technical assistance and economic compensation should they be willing to amend their stance on local quarantine regulations. Because of the U.S.A.'s past quarantine restrictions, I believe scientific and engineering advances will have to be demonstrated before others will find us credible.

Bonnie Fernandez - 07:41pm Aug 2, 1996 EDT (#7 of 8)

California Wheat Commission

To Gerald Holmes or other interested parties could you please explain what ISPP stands for( I am assuming it is an organization). Also a little background on this organization would be helpful.

Cynthia L. Ash - 11:28am Aug 4, 1996 EDT (#8 of 8)

Director of Scientific Services

ISPP is the International Society of Plant Pathology.

 


© Copyright 1996 by the American Phytopathological Society