The Fungicide Resistance Action Committee - ACS Publications

Chapter 22

The Fungicide Resistance Action Committee

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 11, 2017 | http://pubs.acs.org Publication Date: February 23, 1990 | doi: 10.1021/bk-1990-0421.ch022

An Update on Goals, Strategies, and North American Initiatives 1

2

M. Wade and C. J. Delp 1

Shell Research, Ltd., Sittingbourne Research Centre, Sittingbourne, Kent, ME9 8AG, England Consultant, 145 Kentucky Avenue, SE, Washington, DC 20003 2

FRAC is an inter-company committee dedicated to prolonging the effectiveness of fungicides liable to encounter resistance problems and to limit crop damage due to resistance. Through educational and research programs, FRAC communicates information on resistance and fungicide-use strategies to agricultural, academic, industrial and regulatory sectors worldwide and promotes cooperative action to solve resistance problems. FRAC coordinates four Working Groups for fungicides at risk (phenylamides, dicarboximides, demethylation inhibitors, benzimidazoles). Through resis tance monitoring and research programs, Working Groups develop and recommend technical resistance management strategies. FRAC stays alert to developments in the field of fungicide resistance and is constantly reviewing situations and updating strategies and educational programs. Current FRAC strategies for resistance management are described along with a review of recent FRAC educational and policy initiatives in North America. FRAC is an inter-company committee dedicated to prolonging the effectiveness of fungicides liable to encounter resistance problems and to limit crop damage during the emergence of resistance. For 8 years, FRAC and its Working Groups have assumed an important international role in effective fungicide resistance management. The Working Groups have been successful in developing and promulgating TECHNICAL strategies designed to delay or prevent the onset of resistance to the four major classes of fungicides at risk--the phenylamides, benzimidazoles, dicarboximides, and demethylation inhibitors (DMIs). 0097-6156/90/0421-0320$06.00A) © 1990 American Chemical Society Green et al.; Managing Resistance to Agrochemicals ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

22. WADE AND DELP

The Fungicide Resistance Action Committee 321

The FRAC Steering Committee coordinates a c t i v i t i e s of the Working Groups and takes a leading r o l e i n educat i o n a l a c t i v i t i e s i n and p o l i c y i n i t i a t i v e s with respect to r e s i s t a n c e . At a l l l e v e l s , FRAC enjoys the close c o l l a b o r a t i o n and support of u n i v e r s i t y and government s c i e n t i s t s throughout the world. Only through cooperation may sound s t r a t e g i e s be developed and implemented.


Objectives FRAC was formed i n 1981 i n responsee to a growing awareness by the Industry that the complex problems posed by fungicide r e s i s t a n c e could only be tackled e f f e c t i v e l y through cooperation. Of p a r t i c u l a r concern were issues r e l a t i n g to c r o s s - r e s i s t a n c e . One company's e f f o r t s to safeguard the e f f e c t i v e n e s s s of a product, by promoting s e n s i b l e usage, could be n u l l i f i e d by the abuse of a r e l a t e d product through c r o s s - r e s i s t a n c e . Other concerns included the lack of education or awareness of the causes and consequences of r e s i s t a n c e with users, d i s t r i b u t o r s , marketing managers and r e g i s t r a t i o n o f f i c i a l s . This lack of awareness was a major obstacle to the adoption of anti-resistance strategies in practice. There was a need to standardise d e f i n i t i o n s of r e s i s t a n c e and monitoring methods so as to avoid confusion and unnecessary alarm and problems to growers, advisors and manufacturers. FRAC was e s t a b l i s h e d to t a c k l e these problems and set the gene r a l o b j e c t i v e : to prolong the e f f e c t i v e n e s s s of f u n g i cides l i a b l e to encounter r e s i s t a n c e problems, and to l i m i t crop damage during the emergence of r e s i s t a n c e . To do t h i s FRAC e s t a b l i s h e d Working Group for four fungicide types considered to be at r i s k , i d e n t i f i e s e x i s t i n g and p o t e n t i a l r e s i s t a n c e problems , c o l l e c t s and generates i n f o r m a t i o n , communicates to those involved in fungicide r e s e a r c h , d i s t r i b u t i o n and use. P r i n c i p a l Functions of FRAC are

to:

-

I n i t i a t e , stimulate and monitor the Working Groups. Provide guidance and c o o r d i n a t i o n of Working Groups. Help Working Groups communicate their conclusions. P u b l i c i z e g u i d e l i n e s on p r o c e d u r e s / d e f i n i t i o n s of p r a c t i c a l resistance research. - Provide t e c h n i c a l counsel for r e s i s t a n c e courses and research.

FRAC had set i t s e l f and the Working Groups a very ambit i o u s set of o b j e c t i v e s . However, i t i s pleasing to r e port that by and large the o b j e c t i v e s are being achieved. Accomplishments of Working Groups A common feature of the Working Groups i s the close c o l l o b o r a t i o n with advisory o f f i c e r s and i n s t i t u t e s . This

Green et al.; Managing Resistance to Agrochemicals ACS Symposium Series; American Chemical Society: Washington, DC, 1990.

322

MANAGING RESISTANCE

TO AGROCHEMICALS


c o l l a b o r a t i o n i s an e s s e n t i a l f e a t u r e o f e f f e c t i v e r e s i s t a n c e management. Each o f t h e Groups has been s u c c e s s f u l i n c o m i n g t o g r i p s w i t h t h e i r p a r t i c u l a r p r o b l e m s by e s t a b l i s h i n g t r u s t , p o o l i n g i n f o r m a t i o n , and f o r m u l a t i n g use r e c o m m e n d a t i o n s t h a t a r e r e p o r t e d b e l o w . Phenylamides (formerly acylalanines) . The phenylamides are r e c o g n i s e d as having a h i g h p o t e n t i a l f o r i n d u c i n g resistance. T h e y h a v e a s p e c i f i c mode o f a c t i o n , a n d r e s i s t a n t s t r a i n s can have a h i g h l e v e l s o f r e s i s t a n c e and fitness. The p r e - p a c k a g e d m i x t u r e s o f p r o d u c t s b a s e d on phenylamide and r e s i d u a l f u n g i c i d e s have g i v e n e n c o u r a g ing r e s u l t s i n recent years allowing the reintroduction of p h e n y l a m i d e s where t h e y had been w i t h d r a w n . The Worki n g Group recommendations a r e t o use: - Only pre-packed mixtures f o r f o l i a r use. - Three q u a r t e r s t o f u l l r a t e of the partner a p p l i e d at i n t e r v a l s n o t t o e x c e e d 14 d a y s . - L i m i t e d number o f s p r a y s p e r s e a s o n . - No c u r a t i v e u s e . - No s o i l t r e a t m e n t s f o r c o n t r o l o f a i r b o r n e p a t h o g e n s ( w i t h the e x c e p t i o n of Tobacco Blue Mold). Benzimidazoles. tance p o t e n t i a l

The b e n z i m i d a z o l e s h a v e a h i g h w i t h many p a t h o g e n s because:

resis-

- T h e y h a v e a s p e c i f i c mode o f a c t i o n t h a t c a n l e a d t o the s e l e c t i o n of s t r a i n s w i t h high r e s i s t a n c e l e v e l s . - Pathogen p o p u l a t i o n s have n a t u r a l l y o c c u r r i n g r e s i s t a n t strains. - R e s i s t a n c e i s not u s u a l l y a s s o c i a t e d w i t h a s i g n i f i c a n t l o s s of f i t n e s s of the pathogen. When occur part tinue tions tact used

benzimidazoles are abused, r e s i s t a n c e i s l i k e l y to a n d o f t e n h a s . H o w e v e r , when u s e d j u d i c i o u s l y a s of w e l l considered s t r a t e g i e s , benzimidazoles conto give excellent control. M i x t u r e s and combinao f m i x t u r e s and a l t e r n a t i o n s w i t h m u l t i - s i t e c o n f u n g i c i d e s have proved very e f f e c t i v e , e s p e c i a l l y i f b e f o r e p r o b l e m s become a p p a r e n t . To c o p e w i t h p r o b l e m s o f c e r e a l eyespot resistance, the B e n z i m i d a z o l e W o r k i n g Group recommends t h e f o l l o w i n g : - Use a m i x t u r e o f a b e n z i m i d a z o l e and n o n - b e n z i m i d a z o l e i n f i e l d s t h a t have a h i g h r i s k from eyespot o r have reeceived benzimidazole treatments f o r several years. - A b e n z i m i d a z o l e s h o u l d n o t be u s e d w h e r e p r e v i o u s d i s e a s e c o n t r o l f a i l u r e h a s been due t o r e s i s t a n c e .

Dicarboximides. Acute problems of r e s i s t a n c e t o d i c a r b o x i m i d e s c a n a r i s e when t h e p r o d u c t s a r e i n t e n s i v e l y a n d e x c l u s i v e l y u s e d o v e r many s e a s o n s . Resistant isolates a r e m o d e r a t e l y r e s i s t a n t a n d t e n d t o be l e s s f i t t h a n



22. WADE AND DELP


s e n s i t i v e s t r a i n s i n the absence of the f u n g i c i d e s . The D i c a r b o x i m i d e Working Group recommends t h e f o l l o w i n g : - Grapes. Two s p r a y s o f d i c a r b o x i m i d e s , a p p l i e d a s a m i x t u r e w i t h a downy m i l d e w f u n g i c i d e h a v i n g a d d i t i o n a l a c t i v i t y a g a i n s t B o t r y t i s , may b e a p p l i e d o n c e at bunch c l o s i n g and once a t b e g i n n i n g o f r i p e n i n g . In s e a s o n s when b a d w e a t h e r e x t e n d s the f l o w e r i n g per i o d and p r o v i d e s c o n d i t i o n s s u i t a b l e f o r i n f e c t i o n , t h e f i r s t a p p l i c a t i o n c a n be b r o u g h t forward. - Glasshouse crops. Growers a r e a d v i s e d t o r e s t r i c t t h e number o f d i c a r b o x i m i d e t r e a t m e n t s t o no more than t h r e e per c r o p i n s i t u a t i o n s where r e s i s t a n c e i s present. Where r e s i s t a n c e h a s n o t b e e n a p r o b l e m p r e v i o u s l y , a f o u r t h a p p l i c a t i o n may b e u s e d i f i n f e c t i o n pressure i s very high. When i n f e c t i o n p r e s s u r e i s h i g h , ensure t h a t d i c a r b o x i m i d e s a r e used either i n a l t e r n a t i o n s or i n mixtures with contact fungicides l i k e c h l o r o t h a l o n i l , captan, or thiram. - Strawberries. A l i m i t e d number ( 3 - 4 ) o f a p p l i c a t i o n s per s e a s o n i s recommended i n m i x t u r e s and a l t e r n a t e d with c o n t a c t f u n g i c i d e s such as thiram. - Stone/pome f r u i t . F o r t h e c o n t r o l o f S c l e r o t i n i a and M o n i l i n i a , a l i m i t e d number o f t r e a t m e n t s i s r e c o m mended i n m i x t u r e s a n d a l t e r n a t i o n s w i t h c o n v e n t i o n a l p r o d u c t s and d e m e t h y l a t i o n inhibitors. Demethylation I n h i b i t o r s ( D M I s ) . G e n e r a l l y w i t h t h e DMIs, the need f o r e a r l y p r e - e m p t i v e s t r a t e g i e s i s not so c l e a r for many c r o p - p a t h o g e n combinations a s w i t h some o t h e r classes of fungicides. Less s e n s i t i v e s t r a i n s appear to be a t a s e l e c t i v e d i s a d v a n t a g e i n the absence of the fungicides. Gradual "step-by-step" s h i f t s i n the pathogen p o p u l a t i o n toward decreased s e n s i t i v i t y occurs. T h i s s h i f t c a n be r e v e r s e d b y l i m i t i n g t h e u s e o f D M I s i n f a v o r o f non-DMI f u n g i c i d e s . In t h e c a s e o f c u c u r b i t p o w d e r y m i l d e w , a c l e a r c o r r e l a t i o n has been e s t a b l i s h e d between t h e i n t e n s i t y of DMI u s e a n d r e d u c e d e f f i c a c y o f t h i s c l a s s o f f u n g i c i d e s . This i s the only crop-pathogen combination f o r which this c o r r e l a t i o n has been c l e a r l y shown. F o r t h e s e situations, t h e F R A C DMI W o r k i n g G r o u p r e c o m m e n d s t h e u s e o f a l t e r n a t i o n s or mixtures. In grape powdery mildew, isolates w i t h lower l e v e l s o f s e n s i t i v i t y have been d e t e c t e d i n Portugal. R e c o m m e n d e d s t r a t e g i e s i n c l u d e t h e u s e o f DMI a n d s u l p h u r m i x t u r e s , l i m i t i n g DMI i n p u t t o c r i t i c a l p e r i o d s i n t h e growing season and a v o i d i n g c u r a t i v e a p p l i c a t i o n s o f DMI's w h e r e v e r possible. No p r o b l e m s i n t h e f i e l d p e r f o r m a n c e o f D M I s h a v e been observed yet f o r the c o n t r o l of apple scab, although s t r a i n s of Venturia i n a e q u a l i s with reduced sensitivity t o DMIs h a v e b e e n o b s e r v e d i n a few f i e l d plots. B a s e d o n t h e s e f i n d i n g s t h e F R A C DMI W o r k i n g G r o u p r e c o m m e n d s t h a t r e p e a t e d a p p l i c a t i o n o f DMI f u n g i c i d e s a l o n e f o r t h e c o n t r o l o f c e r e a l d i s e a s e s i n t h e same 1


324

MANAGING RESISTANCE TO AGROCHEMICALS

season should be avoided. The use of mixtures (DMI/nonDMI's) for reducing the s h i f t to lower s e n s i t i v i t y should be p r a c t i s e d . Recently, the DMI Group held i t s f i r s t Banana subgroup meeting i n Miami. At t h i s meeting, the agrochemi c a l manufacturers along with the major banana growers of C e n t r a l and Southern America and government s c i e n t i s t s agreed on a monitoring method and the following p o l i c y for the use of DMI s on bananas for Sigatoka c o n t r o l :


1

- Limit the t o t a l number of DMI sprays to 8 per year. - Schedule a p p l i c a t i o n s i n blocks of 2-4 consecutive DMI treatments. - Intersperse the blocks with non-DMI treatments. FRAC

Accomplishments

Industry takes the lead i n e s t a b l i s h i n g s t r a t e g i e s , i n a d v e r t i s i n g them, and i n organizing educational programs to foster an awareness of the causes and consequences of resistance. Companies are working hard to ensure good communications and c l e a r e r l a b e l i n g of products to reduce the chance of c r o s s - r e s i s t a n c e . Industry bears the major r e s p o n s i b i l i t y for monitoring of r e s i s t a n t s t r a i n s i n pathogen populations - an expensive overhead. But industry cannot and should not face the common problems of r e s i s t a n c e alone. Only through cooperation with a shared w i l l to use fungicides i n t e l l i g e n t l y can e f f e c t i v e s t r a t e g i e s for r e s i s t a n c e management be s u c c e s s f u l . The FRAC Steering Committee meets r e g u l a r l y to review the a c t i v i t i e s of the Working Groups and to deal with the wider aspects of r e s i s t a n c e . These include publ i s h i n g d e f i n i t i o n s of r e s i s t a n c e , g u i d e l i n e s for containment of r e s i s t a n t s t r a i n s , conclusions and recommendations of Working Groups, minutes of FRAC meetings, a r t i c l e s and posters on i n d u s t r y ' s responsee to r e s i s tance, and a book and brochure based on proceedings of the North American workshop. FRAC also provides advice and funds for research ( v i a companies), and cooperates with the FAO and ISPP i n running courses on r e s i s t a n c e for developing n a t i o n s . It developed a code of e t h i c s to avoid i n a p p r o p r i a t e use of r e s i s t a n c e i n advertisements. FRAC i s a l e r t to fungicide r e s i s t a n c e developments in the f i e l d and laboratory and to issues r e l a t i n g to the use, r e p o r t i n g , r e g u l a t i o n and a d v e r t i s i n g e t c . FRAC cons i d e r s education to be most important. Without a firm understanding of the problem and the r a t i o n a l e behind usage s t r a t e g i e s i t i s impossible to gain acceptance within companies, by a d v i s o r s , d i s t r i b u t o r s and users. For t h i s reason, FRAC has a concerted educational p o l i c y to take the "message" to a l l people involved i n fungicide use. This i s being done through a c t i v e support of f r i e n d s and colleagues i n u n i v e r s i t i e s , advisory s e r v i c e s and government i n promulgating sound t e c h n i c a l s t r a t e -


22. WADE AND DELP


gies. Together we can continue to make r e a l progress toward preserving the i n v a l u a b l e option of chemical d i s ease c o n t r o l for crops.


NORTH AMERICAN INITIATIVES FRAC, i n cooperation with the Department of Plant P a t h o l ogy at Pennsylvania State U n i v e r s i t y , organized and sponsored the North American Fungicide Resistance Workshop and Conference, held September 20-25, 1987, at U n i v e r s i t y Park, Pennsylvania. The o b j e c t i v e s of the Workshop and Conference were to: - Develop North American fungicide r e s i s t a n c e research goals. - Prolong the usefulness of fungicides at r i s k from r e s istance i n North America. - Promote a n t i r e s i s t a n c e use s t r a t e g i e s for fungicides i n North America. - Stimulate North American research p o t e n t i a l i n the area of fungicide r e s i s t a n c e . - Improve c o l l a b o r a t i o n among i n d u s t r y , government, academia, and p r i v a t e o r g a n i z a t i o n s for determining and implementing appropriate fungicide use s t r a t e g i e s . - Encourage and demonstrate the commitment and leadership of Industry i n the accomplishment of the foregoing objectives. Research and Management Goals A major o b j e c t i v e of the 1987 North American Fungicide Resistance Workshop was to develop goals for fungicide r e s i s t a n c e research and management and to ensure that the goals are implemented i n North America. S p e c i f i c goals were developed for each of the four fungicide groups, i n a d d i t i o n to general g o a l s . The 60 p a r t i c i p a n t s were encouraged to c o n t r i b u t e t h e i r suggestions, to modify proposed goals, and to a r r i v e at a consensus. General goals l i s t e d below are followed by goals for each of four fungicide groups at r i s k from r e s i s t a n c e . Neither goals nor recommendations are presented i n a s p e c i f i c order implying importance or sequence of execution since many a c t i v i t i e s are r e l a t e d and interdependent. Non-North American experiences have been incorporated i n t o these goals and should be given c o n s i d e r a t i o n i n the f u t u r e . Many of the goals for one group apply to other fungicide c l a s s e s as w e l l . Their s u c c e s s f u l implementation r e l i e s on the constant awareness and cooperation of a l l involved with fungicide use, from the manufacturing company to the end user. The ultimate s o l u t i o n i s c a r e f u l and r e s p o n s i ble use of fungicides i n an e f f e c t i v e manner that w i l l preserve t h e i r usefulness for future needs.


326


General

MANAGING RESISTANCE TO AGROCHEMICALS Goals

I. P r o v i d e E d u c a t i o n a l and T r a i n i n g A i d s . T h e r e a r e many misconceptions c o n c e r n i n g r e s i s t a n c e p r o b l e m s , e v e n among agricultural professionals. E d u c a t i o n a l and t r a i n i n g a i d s s h o u l d be r e a d i l y a v a i l a b l e t o a w i d e v a r i e t y o f audiences t o overcome these difficulties. - U s e FRAC v i d e o t a p e s , s l i d e s e t s , a n d R E S I S T A N - t y p e r e s i s t a n c e development models - D e v e l o p s p e c i a l a u d i o v i s u a l s and handouts f o r e x t e n s i o n a g e n t s and c o n s u l t a n t s . - Promote and use a i d s d e v e l o p e d by i n d u s t r y f o r u s e r s o f individual products. II. Improve Communication o f R e s i s t a n c e S t r a t e g i e s a t the User L e v e l . Improved mechanisms a r e needed f o r r e a c h i n g a c o n s e n s u s on u s e s t r a t e g i e s . In a d d i t i o n , s t r a t e g i e s are often misunderstood by u s e r s a n d , t h e r e fore, inadequately applied. There are a l s o problems of abuse d e s p i t e w e l l - d e f i n e d s t r a t e g i e s . - U s e FRAC W o r k i n g G r o u p s t o a t t a i n agreements. - Obtain concurrence o f i n d u s t r y management (marketing/ s a l e s a n d r e s e a r c h ) a n d t h o s e who make r e c o m m e n d a t i o n s . - F i l e w r i t t e n documents (recommendations, l a b e l s , advert i s e m e n t s ) w i t h FRAC W o r k i n g G r o u p . - Report c o n c e r n s o f m i s u s e t o FRAC W o r k i n g G r o u p s . - Promote s t r a t e g i e s and educate users. III. Strengthen Basic Research on F u n g i c i d e R e s i s t a n c e B a s i c r e s e a r c h on f u n g i c i d e r e s i s t a n c e h a s been insuff i c i e n t i n North America, and g r e a t e r support i s needed. - Conduct or c o n t r a c t b a s i c r e s e a r c h through i n d u s t r y as cooperative industry/academic projects. - D e v e l o p and c o o r d i n a t e g r a n t s from m u l t i p l e s o u r c e s ( i n c l u d i n g U.S. D e p a r t m e n t o f A g r i c u l t u r e , N a t i o n a l S c i e n c e F o u n d a t i o n , and i n d u s t r i e s ) t h r o u g h North Ameri c a n s u b g r o u p s o f FRAC W o r k i n g G r o u p s . - D e f i n e and study e p i d e m i o l o g i c a l f a c t o r s c r i t i c a l t o the development of r e s i s t a n c e . - D e t e r m i n e g e n e t i c c o n t r o l and b i o c h e m i c a l modes o f a c t i o n / r e s i s t a n c e f o r DMIs a n d d i c a r b o x i m i d e s . - Study b i o c h e m i c a l i n t e r a c t i o n s of candidate f u n g i c i d e s with other fungicides, negatively cross-resistant fung i c i d e s , and n o n f u n g i c i d e compounds w i t h physiological a c t i o n s i n c l u d i n g e f f e c t s on h o s t resistance. - D e v e l o p new b i o t e c h n o l o g y t o o l s t o s t u d y resistance. - Encourage nonchemical a p p r o a c h e s t o manage r e s i s t a n c e . I V . A v o i d E s t a b l i s h m e n t o f R e s i s t a n t S t r a i n s i n New Areas. I t may be n e c e s s a r y t o e x p e r i m e n t with introduced or c r e a t e d s t r a i n s , b u t o n l y w i t h p r o p e r precautions. - A v o i d t h e i n t r o d u c t i o n o f r e s i s t a n t s t r a i n s i n a manner w h e r e t h e y may b e r e l e a s e d i n t o a v i r g i n environment.


22. WADE AND DELP


-


Ensure the containment of experimental f i e l d strains when t e s t i n g r e s i s t a n c e management s t r a t e g i e s .

V. A n t i c i p a t e t h e I m p a c t o f New C a n d i d a t e F u n g i c i d e s on Resistance Problems. The methods ( e s p e c i a l l y f i e l d studies) for evaluating r e s i s t a n c e p o t e n t i a l o f new c o m p o u n d s m u s t be i m p r o v e d a n d u s e d . - D e t e r m i n e t h e r e s i s t a n c e and c r o s s - r e s i s t a n c e potential o f e a c h new c a n d i d a t e w i t h m a j o r f u n g i c i d e groups. - D e t e r m i n e t h e i n f l u e n c e o f new c a n d i d a t e s o n p a t h o g e n populations r e s i s t a n t t o p r e v i o u s l y used fungicides. - D e t e r m i n e mode o f a c t i o n / r e s i s t a n c e o f new c a n d i d a t e s . - D e v e l o p and v a l i d a t e r e l i a b l e m o n i t o r i n g methods. - Establish baseline s e n s i t i v i t y levels i n wild strains. - B u i l d on t h e " G i s i m o d e l " f o r r i s k a s s e s s m e n t . VI. Coordinate Industry, Government, and Academic A c t i v ities. - E s t a b l i s h N o r t h A m e r i c a n s u b g r o u p s o f t h e F R A C DMI a n d dicarboximide working groups. - Develop cooperation among i n d u s t r y , g o v e r n m e n t , a n d a c a d e m i a , i n c l u d i n g e n t o m o l o g i s t s a n d weed scientists. VII. I m p r o v e U n d e r s t a n d i n g a n d C o o p e r a t i o n o f EPA t o I m p l e m e n t FRAC R e s i s t a n c e M a n a g e m e n t Strategies. - Regulation and l a b e l i n g c a n p r o v i d e more u s e f u l functions i n resistance management. - Coordinate labeling f o r cross-resistant products. - P e r s u a d e EPA o f t h e n e e d f o r t h e r e t e n t i o n o f p r o d u c t s for u s e a s c o m p a n i o n s i n r e s i s t a n c e management s t r a t e g i e s , the use of r e s i s t a n c e f a c t o r s i n r i s k - b e n e f i t a n a l y s i s f o r compounds under s p e c i a l r e v i e w , and t h e consideration o f mode o f a c t i o n a s w e l l a s e f f i c a c y i n r e g i s t r a t i o n o f new p r o d u c t s . VIII. D i s c o v e r and D e v e l o p F u n g i c i d e s w i t h New M o d e s o f Action. The d i s c o v e r y o f new f u n g i c i d e t a r g e t s i t e s i s required t o c o m p e n s a t e f o r t h e l o s s o f p r o d u c t s due t o d e - r e g i s t r a t i o n and r e s i s t a n c e . - P r o v i d e a c c u r a t e market value d a t a . - Promote "orphan drug" l e g i s l a t i o n t o encourage d e v e l o p ment o f c o m p o u n d s w i t h i n s u f f i c i e n t e c o n o m i c p o t e n t i a l for unsubsidized development. Benzimidazole Resistance and T h e i r I m p l e m e n t a t i o n

Research i n North

and Management America

Goals

I. D e t e r m i n e O p t i m a l B e n z i m i d a z o l e Use S t r a t e g i e s . S t r a t e g i e s f o r f u n g i c i d e use a r e c r i t i c a l i n p r e v e n t i n g and managing r e s i s t a n c e . Evaluation of use s t r a t e g i e s c a n be f a c i l i t a t e d t h r o u g h f i e l d r e s e a r c h e x p e r i m e n t s and computer models. Investigation of strategies w i l l focus on t w o e c o n o m i c a l l y i m p o r t a n t diseases.



328

MANAGING RESISTANCE

TO AGROCHEMICALS

Apple Scab. The computer simulation model RESISTAN, with the use of c u r r e n t l y a v a i l a b l e f i e l d data, can aid d e v e l opment of management recommendations t a i l o r e d to r e g i o n a l situations. The following procedure can be used to t r a n s l a t e the data i n t o recommendations and evaluate the management s t r a t e g i e s : - Set parameters of the model with a v a i l a b l e f i e l d data.y V a l i d a t e and r e f i n e model by comparing f i e l d data with simulation output. - Run model to s e l e c t best management options for spec i f i c situations. Stone F r u i t Brown Rot ( F r u i t Rot and Blossom B l i g h t ) . F i e l d and laboratory i n v e s t i g a t i o n s can provide useful information i n s e l e c t i n g disease management t a c t i c s : - Develop rapid r e s i s t a n c e monitoring systems. - I n v e s t i g a t e biology of r e s i s t a n t fungal i s o l a t e s . - Evaluate integrated disease management s t r a t e g i e s . II. Implement Optimal Fungicide Use S t r a t e g i e s Through Cooperation and E d u c a t i o n . Cooperation and education are needed to d i s t r i b u t e information and implement a p p r o p r i ate fungicide use s t r a t e g i e s . - Promote t e c h n i c a l cooperation within industry to recommend appropriate use of fungicides through FRAC. - Promote s t r a t e g i e s with growers through cooperation among i n d u s t r y , academia, extension, and regulatory agencies. III. Use Resistance Monitoring to Study Resistant Populations . S e n s i t i v i t y monitoring used to determine the l e v e l and frequency of r e s i s t a n t s t r a i n s i s needed i n guiding fungicide use s t r a t e g i e s . - Improve, exchange, and standardize monitoring t e c h niques and data i n t e r p r e t a t i o n among i n d u s t r y , academia, and extension through FRAC. Dicarboximide Resistance Research and Management Goals and Their Implementation i n North America I. Identify the Most E f f e c t i v e Use S t r a t e g i e s to Delay or Prevent Resistance Development This i s the guiding goal for a l l r e s i s t a n c e r e s e a r c h . - Determine the e f f e c t s of r a t e , t i m i n g , and spray depos i t i o n on r e s i s t a n c e development on strawberry, stone f r u i t , grape, and greenhouse c r o p s . - Determine the e f f i c a c y of dicarboximides i n the presence of various proportions of r e s i s t a n t s t r a i n s . Degrees of continued e f f i c a c y have been noted despite the occurrence of s u b s t a n t i a l r e s i s t a n c e . - Explore the e f f e c t s of companion materials on r e s i s t a n t population dynamics and disease c o n t r o l . - Develop and implement d i s t i n c t r e g i o n a l s t r a t e g i e s for strawberry, stone f r u i t , grape, and greenhouse c r o p s .


22. WADE AND DELP

The Fungicide Resistance Action Committee329


- Develop models of population dynamics to i n t e g r a t e above f a c t o r s and help a n t i c i p a t e the e f f e c t s of r e s i s t a n c e management s t r a t e g i e s .

the

II. C h a r a c t e r i z e F i e l d Populations of DicarboximideResistant S t r a i n s of B o t r y t i s and M o n i l i n i a . A thorough understanding of dicarboximide r e s i s t a n c e behavior would permit more accurate p r e d i c t i o n and i n t e r p r e t a t i o n of the e f f e c t s of p o t e n t i a l use s t r a t e g i e s . It could also d i r e c t e f f o r t s toward the most f r u i t f u l areas of research. Note that despite the advantages of generating r e s i s t a n c e i n the l a b o r a t o r y , these studies become more meaningful to subsequent i n t e r p r e t a t i o n for strategy development i f f i e l d - r e s i s t a n t i s o l a t e s are employed. It i s prudent, however, for the responsible researcher to avoid developing f i e l d r e s i s t a n c e i n experimental plots or i n t r o d u c i n g laboratory or greenhouse-derived r e s i s t a n t i s o l a t e s i n t o the f i e l d . - I d e n t i f y the genetic c o n t r o l and biochemical mode of resistance. - Determine the l e v e l s of r e s i s t a n t populations and t h e i r relative virulence. - Further define the o v e r a l l f i t n e s s and f i t n e s s f a c t o r s ( s p o r u l a t i o n , l a t e n t p e r i o d , pathogen s u r v i v a l , p a t h o g e n i c i t y , e t c . ) of r e s i s t a n t populations selected from the f i e l d r e l a t i v e to wild type ( s e n s i t i v e ) populations . - Determine the e f f e c t s of dicarboximides and/or companion fungicides on the pathogenicity of s e l e c t e d r e s i s tant i s o l a t e s . III. E s t a b l i s h Comprehensive Monitoring Programs. Without t i m e l y , e f f i c i e n t , and r e l i a b l e monitoring, no r e s i s tance program can be properly developed or evaluated. - Simplify monitoring techniques to be more r a p i d , l e s s expensive, and l e s s labor-consuming. - E s t a b l i s h r e s i s t a n c e monitoring programs for B o t r y t i s i n strawberry, grapes, and greenhouse crops and M o n i l i n i a i n stone f r u i t . These can be implemented by i n d u s t r y , regulatory agencies, U. S. Department of A g r i c u l t u r e , grower groups, academia, or p r i v a t e a d v i sors to v a l i d a t e r e s i s t a n c e cases, assess r i s k , and estimate e f f i c a c y before a treatment i s a p p l i e d . This includes expanding r e s i s t a n c e "indexing" programs that monitor for r e s i s t a n t pathogens on propagation material to be broadly d i s t r i b u t e d . - V a l i d a t e methods. It i s very important that any monit o r i n g method be reproducible and that the r e s u l t s r e l a t e d i r e c t l y to the a c t u a l f i e l d s i t u a t i o n . - Link some product uses to monitoring programs. Label r e s t r i c t i o n s could prevent the use of dicarboximides in h i g h - r e s i s t a n c e areas.



330

MANAGING RESISTANCE TO

AGROCHEMICALS

IV. Incorporate Nonfungicide Disease C o n t r o l Measures with Dicarboximide Use. Methods other than chemical cont r o l c a n be u s e d t o r e d u c e d i s e a s e p r e s s u r e a n d subsequent l i k e l i h o o d t h a t r e s i s t a n c e w i l l develop. - F o l l o w recommended c u l t u r a l p r a c t i c e s and use resistant v a r i e t i e s to reduce d i s e a s e pressure. An e x a m p l e i s t h e p r a c t i c e o f p r u n i n g and l e a f r e m o v a l a r o u n d grape c l u s t e r s t o i n c r e a s e a i r movement and r e d u c e g r a y m o l d . - I n t e g r a t e r e s i s t a n c e models with other systems that p r e d i c t d i s e a s e , pests, plant growth, e t c . ( i . e . , an IPM s y s t e m i n c o r p o r a t i n g r e s i s t a n c e m a n a g e m e n t ) . - I n t e g r a t e a r e s i s t a n c e monitoring system i n t o other management/monitoring practices. V. P r o m o t e I n t e r i n d u s t r y C o o p e r a t i o n and Communication Among I n d u s t r y , I n s t i t u t i o n s , R e g u l a t o r y A g e n c i e s , and Academia. W i t h o u t c o o p e r a t i o n and c o m m u n i c a t i o n , existi n g s t r a t e g i e s w i l l r a r e l y be e f f e c t i v e l y implemented, a n d t h e d e v e l o p m e n t o f new i d e a s w i l l be g r e a t l y hindered . - Establish guidelines for cooperation. Traditionally c o m p e t i t i v e c o m p a n i e s must d e t e r m i n e how a n d when t o a c t i n c o n c e r t and must a g r e e t o a d h e r e t o c o n s e n s u s decisions. - E s t a b l i s h common u s e p a t t e r n s f o r d i c a r b o x i m i d e s on a l l c r o p s f o r w h i c h more t h a n one d i c a r b o x i m i d e i s o r may be r e g i s t e r e d . T h i s i n c l u d e s : number o f a p p l i c a t i o n s p e r m i t t e d , r a t e s u s e d , t i m i n g o f a p p l i c a t i o n s , and poss i b l e use o f c o m p a n i o n s and alternatives. - D e v e l o p common l a b e l s t a t e m e n t s t o warn o f r e s i s t a n c e and r e s t r i c t the use o f o t h e r d i c a r b o x i m i d e s with cross-resistance. - E s t a b l i s h a N o r t h A m e r i c a n d i c a r b o x i m i d e FRAC W o r k i n g Group. - Communicate to r e g u l a t o r y a g e n c i e s the importance of c o o p e r a t i o n i n r e s i s t a n c e management. - P r o v i d e e d u c a t i o n a l m a t e r i a l a b o u t r e s i s t a n c e management t h r o u g h t e c h n i c a l i n f o r m a t i o n b u l l e t i n s , brochures f o r grower meetings, and p r o m o t i o n a l m a t e r i a l . - P r o m o t e p r e s e n t a t i o n s a n d d i s c u s s i o n s e s s i o n s on resistance at p r o f e s s i o n a l meetings. Phenylamide Resistance Research and Management Their Implementation i n North America

Goals

and

I. P r i o r i t i z e A t t e n t i o n t o Two Diseases. L e t t u c e Downy M i l d e w ( c a u s e d by B r e m i a lactucae). - Make g r o w e r s a w a r e o f t h e t h r e a t o f r e s i s t a n c e t h r o u g h C a l i f o r n i a f a r m a d v i s o r s and Ciba-Geigy. - Fund r e s e a r c h to study the g e n e t i c r e s i s t a n c e i n C a l i f o r n i a l e t t u c e c u l t i v a r s to pathovar I I I , the metal a x y l - r e s i s t a n t s t r a i n of Bremia l a c t u c a e , at the U n i v e r s i t y of C a l i f o r n i a - D a v i s .


22. -


-

WADE AND DELP


E x p l o r e t h e v a l u e o f a l t e r n a t i n g f o s e t y l A l and metal a x y l p l u s maneb s p r a y s i n l i m i t i n g resistance. Investigate the f a c t o r s ( e s p e c i a l l y use p a t t e r n of meta l a x y l ) that l e a d to the development of resistance.

P y t h i u m B l i g h t on Turfgrass - I n t r o d u c e a p r e p a c k o f m e t a l a x y l and mancozeb to limit the development of resistance. - Breed p e r e n n i a l ryegrass with greater resistance to P y t h i u m , as most f u n g i c i d e r e s i s t a n c e has been i n r y e grass fairways. - C o n t i n u e to promote the a l t e r n a t i o n of m e t a l a x y l w i t h a non-cross-resistant Pythium f u n g i c i d e . Ciba-Geigy held a t u r f s y m p o s i u m on D e c e m b e r 4, 1987. II. Standardize Monitoring Programs. It takes d i f f e r e n t concentrations of m e t a l a x y l to c o n t r o l d i f f e r e n t s t a g e s i n the l i f e c y c l e s of P h y t o p h t h o r a spp. and Pythium spp. T h e r e i s a l s o a m a r k e d d i f f e r e n c e b e t w e e n t h e ED50 and ED95. Most c u r r e n t m o n i t o r i n g t e c h n i q u e s do n o t detect the p r o p o r t i o n of r e s i s t a n t i n d i v i d u a l s w i t h i n a population. The p o s s i b i l i t y t o make s u c h d e t e c t i o n s with DNA p r o b e s i s an e x c i t i n g challenge. - O r g a n i z e and standardize monitoring programs. - D e v e l o p and validate rapid (on-site i f possible) monitoring techniques. - Determine the impact of c a r r y o v e r inoculum. III. I m p l e m e n t Use of Management S t r a t e g i e s D e v e l o p e d by FRAC. S e l e c t use s t r a t e g i e s c o m p l e m e n t a r y t o the foll o w i n g FRAC r e c o m m e n d a t i o n s : - I n t r o d u c e prepacked m i x t u r e s w i t h r e s i d u a l or systemic f u n g i c i d e s w i t h a d i f f e r e n t mode o f a c t i o n . Use threef o u r t h s of the f u l l r a t e s of the m i x i n g partners. - L i m i t t h e n u m b e r o f s p r a y s t o two to f o u r per c r o p and season. - K e e p a p p l i c a t i o n s i n t e r v a l s u n d e r 14 days. - Prohibit curative/eradicative use. - P r o h i b i t s o i l a p p l i c a t i o n f o r c o n t r o l of airborne pathogens. (The exception i s w h e r e t h e r e a r e no availa b l e companion f u n g i c i d e s , e.g., tobacco blue mold.) - Provide educational materials about the p h i l o s o p h y and s t r a t e g y o f r e s i s t a n c e m a n a g e m e n t f o r i m p r o v e d commun i c a t i o n with government a g e n c i e s , p r o f e s s i o n a l socie t i e s , t r a d e a s s o c i a t i o n s , g r o w e r s , and academia. - S t r e n g t h e n b a s i c s t u d i e s of pathogen p o p u l a t i o n dynamics a s i n f l u e n c e d by c u l t u r a l s y s t e m s a n d resistant c u l t i v a r s . Determine c r i t e r i a f o r epidemic development. - D e v e l o p and use RESISTAN-type models t o p l a n antiresistance strategies. - Study the m o l e c u l a r g e n e t i c s o f t a r g e t f u n g i i n an attempt to develop d i a g n o s t i c tools.


332

MANAGING RESISTANCE

TO AGROCHEMICALS


D e m e t h y l a t i o n - I n h i b i t o r Resistance Research and Management Goals and Their Implementation i n North America I. Organize Input to Determine Use S t r a t e g i e s for DMIs on Selected Crops i n North America. R e g i s t r a t i o n s of DMI fungicides i n North America are i n c r e a s i n g , and the number of EPA-approved a c t i v e i n g r e d i e n t s i s expected to continue to i n c r e a s e . The biochemical mode of a c t i o n of DMIs leads to the expectation of c r o s s - r e s i s t a n c e . A consensus use strategy for DMIs on a crop could maintain product usefulness and l o n g e v i t y . - E s t a b l i s h a U. S. subgroup of the FRAC DMI Working Group. - Focus e f f o r t s on grapes, c e r e a l s , apples, t u r f g r a s s , peanuts, and stone f r u i t . - B u i l d on and upgrade previously formulated s t r a t e g i e s . - Communicate recommendations through FRAC. I I . Determine Baseline S e n s i t i v i t y to DMIs of Selected Pathogens on Selected CROPS. Management s t r a t e g i e s and use patterns of DMIs i n c e r t a i n markets can be influenced by s e n s i t i v i t y changes i n the target fungus. Adequate warning of s i g n i f i c a n t s e n s i t i v i t y changes allows for prudent strategy d e c i s i o n s . - Define "baseline s e n s i t i v i t y . " - Emphasize powdery mildew on grapes, apple scab, Septor i a on wheat, l a t e l e a f spot of peanuts, d o l l a r spot of t u r f g r a s s , and brown rot of stone f r u i t . - Standardize monitoring methods. - Share data and communicate r e s u l t s through FRAC. - Cooperate with i n d u s t r y , academic i n s t i t u t i o n s , and government agencies to communicate e x i s t i n g and future monitoring techniques and i n t e r p r e t a t i o n of r e s u l t s . III. Determine Mechanisms of Resistance to DMIs and P o s s i b l e Differences Among Compounds Within the Class Is c r o s s - r e s i s t a n c e automatic across a l l members of the DMI c l a s s , and i f not, why not? - Document and d e t a i l methodology to allow s u b s t a n t i a t i o n of claims of "new" or " d i f f e r e n t " modes of a c t i o n . - Encourage and support u n i v e r s i t y research p r o j e c t s . Action Items for the Implementation of Fungicide R e s i s tance Research and Management Goals i n North America As a r e s u l t of the recommended g o a l s , the following actions should be taken: - E s t a b l i s h North American subgroups of the FRAC DMI and Dicarboximide Working Groups. - Organize C a l i f o r n i a l e t t u c e downy mildew a c t i o n group.


22. WADE AND DELP -


-


D e s i g n a t e members o f t h e f o l l o w i n g g r o u p s t o r e p r e s e n t and promote N o r t h A m e r i c a n Workshop (FRAC) g o a l s : APS C h e m i c a l C o n t r o l Committee APS I n d u s t r y C o m m i t t e e CPS C h e m i c a l C o n t r o l Committee ISPP C h e m i c a l C o n t r o l Committee ACS A m e r i c a n C h e m i c a l Society ESA I n s e c t i c i d e R e s i s t a n c e C o m m i t t e e USDA A g r i c u l t u r a l R e s e a r c h Service WSSA Weed S c i e n c e S o c i e t y o f A m e r i c a O r g a n i z e f i e l d d e m o n s t r a t i o n s and s e m i n a r s f o r t h e U.S. Department o f A g r i c u l t u r e and EPA. P u b l i s h s t a n d a r d i z e d m o n i t o r i n g methods.

Workshop

Proceedings

T h e F R A C s p o n s o r e d b o o k , F U N G I C I D E R E S I S T A N C E I N NORTH A M E R I C A , p u b l i s h e d b y APS P r e s s , i s b a s e d o n p a p e r s p r e sented a t t h e North American Workshop. Although the f o c u s o f t h e book i s on N o r t h A m e r i c a , t h e i n c l u s i o n o f i n t e r n a t i o n a l e x p e r i e n c e s expands t h e s t a t e o f t h e a r t and s c i e n c e o f f u n g i c i d e r e s i s t a n c e . T h e book__updates the a c t i v i t i e s o f academia, government, and e x t e n s i o n and a l s o documents t h e a c t i v e involvement o f i n d u s t r y scient i s t s i n f u n g i c i d e r e s i s t a n c e r e s e a r c h a n d management and t h e i r exemplary cooperative efforts to preserve the effectiveness of fungicides. I t r e m a i n s t o be s e e n i f the n e c e s s a r y c o o p e r a t i o n w i l l be d e v e l o p e d t o c a r r y o u t the t o u g h t a s k s o f r e s i s t a n c e management i n t h e f u t u r e .

Sponsorship FRAC i s s p o n s o r e d by G I F A P t h e i n t e r n a t i o n a l g r o u p o f national associations of the agrochemical manufacturers located i n Brussels, Belgium. Ac kno w l éd gmén t s This a r t i c l e

i s adapted from r e f e r e n c e s

(1) and ( 2 ) .

References 1. Wade, M. Plant Dis. 1987, 71, 652-653. 2. Wade, M. Tagungsber. Akad. Landwirtschaftswiss. D.D.R. 1987, 253, 411-416. RECEIVED September 1, 1989


The Fungicide Resistance Action Committee - ACS Publications

Recommend Documents