About the Author
Frederic Flewelling grew up on a potato farm in Crouseville, Maine. He graduated in 1971 from Washburn District High School and received his B.S. in agricultural and resource economics from the University of Maine in 1974. He farms in partnership with his father, raising seed potatoes, oats, barley, and hay. Seed varieties raised include Russet Burbank, Superior, Norwis, Shepody, Snowden, Idole, and Atlantic. Seed is sold to growers along the Eastern Seaboard from Florida to Maine and as far west as Michigan. Flewelliong is currently serving as chairman of the Late Blight Ad Hoc Committee for the National Potato Council. He served two years as Vice President of Grower Relations for the National Potato Council. He is chairman of the Maine Seed Potato Board, on the University of Maine Agricutural Advisory Committee, a supervisor on the Central Aroostook Soil and Water Conservation District, a Director for the Maine Potato Growers Cooperative, and was the chairman of the National Potato Council Seed Seminar Committee for five years.
What the Grower Needs
Fred Flewelling
Flewelling Seed Farms
The introduction of new more virulent strains of the late blight fungus into the North American potato industry has wreaked economic havoc on many potato growers. The resistance to metribuzin, a very effective systemic fungicide widely used to combat late blight, and the very aggressive movement of the fungus through both vines and tubers once infected, has left the potato industry scrambling to find effective control measures. The cost of increased fungicide application rates, more frequent applications, and new chemicals used to attempt to control the disease has driven potato production costs up dramatically at a time when profit margins are already very slim.
In the November 26, 1996, issue of "Spud Topics" from Washington State an article entitled "The Cost of Managing Late Blight in the Columbia Basin" describes the cost increases experienced by the State of Washington. The mean cost of application and fungicides in 1994 for late season potatoes was $47.53 per acre. In 1995 that cost had risen to $179.28 per acre. They estimate the cost of managing late blight in Washington State in 1995 at $30,000,000.
In Maine the cost per acre for late blight control has risen in excess of $100.00 per acre. In 1995 application for EPA Section 18 the Cooperative Extension estimated the cost of crop losses in 1993 and 1994 at $20,000,000 each year. When you add to these losses the cost of management in both field and storage, the cost of vine desiccation and resulting reduction in yield and the cost of handling distressed material, it becomes apparent why this Late Blight Workshop is necessary.
There are five major areas that will be looked at for their contribution to controlling late blight. These are regulation, research, breeding, genetic engineering and education. Within each of these categories there are both long- and short-term needs.
Regulation is not a popular topic among most potato growers. Unfortunately, late blight is a community disease since it is spread by spores blowing in the wind. Regulation must be a part of an area’s control strategy. Certified seed laws should be enacted in all states to help ensure that seed transmission of the disease is minimized. Proper cull disposal and volunteer control should be mandatory to reduce these common sources of late blight inoculum. Nursery operations should be regulated to prevent the spread of late blight on plants. The A2 strain of blight probably moved into the U.S. on tomato plants being shipped long distances from areas having the new strain. Home gardeners should be forced to take responsibility to control late blight in their gardens. Commercial potato farms cannot be allowed to let infected fields go without proper control measures to limit spread. In addition, a notification system should be set up so that other growers in the area can take proper measures to protect their crop. Finally, should we allow varieties to be planted that have shown no resistance to the disease and end up infected year after year?
Research is needed to answer some questions in the near term. We need to separate the myth from the science in the use of both Section 18 materials and some of the more common chemicals. Money is being wasted due to a lack of information on the proper use of the chemicals we have available to us.
Since there are several application methods that are used in applying fungicides, research is needed as to their effectiveness. New spray technology is very expensive and beyond the reach of many growers, so we need to know what can be done to optimize the effectiveness of the older equipment.
The role of seed in the transmission of late blight must be understood better. What is the actual contribution of seed in the spread of late blight? How is the fungus transmitted from the seed piece to the plant and what management practices can be applied that will reduce the chance of transmission in a particular seed lot? A screening program to detect late blight in seed lots prior to shipping point should be developed and used as routinely as a winter test for virus.
Research is needed to develop a quick, inexpensive test for tuber late blight for use by growers and inspection personnel. Current tests are not practical for shipping point applications.
Finally, basic research is needed that will lead to the "silver bullet". We all long for the systemic compound that will put late blight back on the shelf.
Breeding programs will play a large role in late blight control. A uniform ranking system for North America must be developed for all varieties using a standard protocol. No susceptible varieties should be released. Late blight resistance should be a standard trait to be used in all new variety development.
Genetic research must be expedited to introduce late blight resistance into current commercial varieties.
Education is probably the most urgent need in the control of late blight. We must get the most current knowledge we have out to the industry in a continuous flow through a variety of channels. That will require coordination of research, collection of new data as progress is made, and development of new ways to get the message out. It also requires that we make sure we are answering the practical questions that growers are asking.
In summary, we need a coordinated, multifaceted approach to controlling the disease. In the near term we must apply our current knowledge base to; 1) regulation of sources of late blight inoculum, 2) educating the industry in the best control methods, and 3) directing research needs. Long-term goals include; 1) genetic research, 2) breeding in resistance in new varieties, and 3) maintaining a broad based approach to research the development of multiple control measures.
I would like to present the resolution adopted at the National Potato Council’s annual meeting in New Orleans this year. One year ago the Late Blight Ad Hoc Committee was appointed to help define the NPC’s role in the late blight issue. After a great deal of industry input, the attached resolution was developed. The goal was to improve the dissemination of information on the disease as well as encourage a holistic approach to late blight control. The cooperation of all facets of the industry will be necessary to control this disease and the NPC will do all it can to help facilitate the process.
F. Flewelling
La introduccion de nuevos estirpes mucho mas virulentos de tizon tardio en la industria papera de Norte America ha provocado un desastre entre la mayoria de los cultivadores de papa. Resistencia estandard como medida de control, movimiento de la enfermedad a areas donde tizon tardio no ha sido un problema, costos elevados de control, y las perdidas del producto provoco en la industria una confusion al tratar de controlar la enfermedad a traves de nuevos caminos.
Necestimos analizar cinco grandes areas para controlar tizon tardio. Estas areas son, regulacion, investigacion, mejoramiento, ingenieria genetica, y educacion. Dentro de cada una de estas areas hay necesidades a corto y a largo plazo.
Regulacion, aunque no siempre es un topico popular, es una necesidad desde que la enfermedad es una enfermedad mucho mas de comunidad. Las siguientes areas en su totalidad deberian mirar hacia una regulacion potencial: 1) Leyes sobre certifificacion de semilla a fin de controlar la calidad de la semilla ha sembrarse, 2) Leyes que gobiernen cull disposal y control voluntario, 3) Regulaciones sobre las operaciones de los semilleristas, 4) Control de la enfermedad en los jardines de las casas, 5) Leyes que gobiernen sobre las tranzaciones comerciales de los campos infectados, y 6) Control de los campos sembrados con cultivares suceptibles.
La investigacion juega un rol vital en el control de tizon tardio. Los registros y efectividad del material de la seccion 18 y los fungicidas mas comunes deben ser evaluados. Necesitamos investigaciones sobre la tecnologia de aplicacion, transmision por semilla, desarrollar un programa uniforme de seleccion para poder detectar tizon tardio en los tuberculos utilizados como semilla, y desarrollar un metodo no caro y rapido para identificar tizon tardio para uso de los agricultores y personal de inpeccion. Una investigacion de base amplia debe continuar a fin de abrir nuevos horizontes de control en el futuro.
Programas de mejoramiento deben tomar como prioridad resistencia genetica en el desarrollo de nueavas variedades. Un sistema de clasificacion uniforme debera ser establecido para clasificar todas las variedades resistentes a tizon tardio. Variedades suceptibles no deberan ser liberados. Investigacion genetica tiene que jugar un rol vital en las variedades actuales. Variedades alteradas geneticamente con resistencia a tizon tardio ofrecen un metodo de control promisorio.
Educacion es la necesidad mas urgente para controlar tizon tradio. La industria necesita de los conocimientos actuales disponibles a traves de un flujo continuo de varios canales.
En resumen, necesitamos propuestas coordinadas y multifaceticas para controlar la enfermedad. En un plazo cercano nosotros debemos aplicar nuestros conocimientos actuales en base a: 1) Regulaciones sobre las fuentes de inoculo, 2) Educacion de la industria con los mejores metodos de control, y 3) directrices sobre necesidades de investigacion. Las metas a largo plaso incluyen: 1) investigacion genetica, 2) Mejoramiento en base a resistencia de las nuevas variedades, y 3) mantener una propuesta de investigacion de base amplia para el desarrollo de medidas multiples de control.