Development and commercialization of rust (Puccinia canaliculata) for biological control of yellow nutsedge (Cyperus esculentus L.)

388 Development and commercialization of rust (Puccinia canaliculata) for biological control of yellow nutsedge (Cyperus esculentus L.)

Sharad C. Phatak Department of Horticulture, Coastal Plain Experiment Station, University of Georgia, Tifton, Georgia 31793, U.S.A.

Summary Yellow nutsedge (Cyperus esculentus L.) and purple nutsedge (C. rotundus) (Cyperaceae) are difficult to control weeds in many crops in more than 30 countries (9). One of these two species occur in every state in the United States of America and in several provinces in Canada (11) . Nutsedges have been listed among the ten worst weeds of field crops in the United States (10) and "Enemy #1" by the editors of Weed Control Manual (1). This paper summarizes stages from first observation of nutsedge rust [Puccinia canaliculata (Schw.) Lagerh.] (Uredinales) in the field, research, patenting and commercialization

of nutsedge rust for biological control of yellow nutsedge.

Introduction Attempts at controlling Cyperus spp. encompasses a wide variety of techniques using chemical, cultural, and biological methods. Over 150 organisms have been associated with C. esculentus and C. rotundus (16, 17). Of these, nutsedge rust offers the most promising method for controlling nutsedges (17) . Nutsedge rust was first reported in 1832 and indigenous to many countries. After various scientific classifications the present scientific name was assigned in 1894 (3). P. canaliculata is a macrocyclic, heteroecious rust on Cyperus sp. with cocklebur (Xanthium canadense L.) as an alternate host (2). Other confirmed alternate hosts are X. strumarium and Helianthus annus L. (7) . These and other alternate host belong to the family Compositae (14).

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Research and Patent An epiphytotic of nutsedge rust was first observed on yellow nutsedge in September, 1978 on one of the research farms of the Coastal Plain Experiment Station, College of Agricultural and Environmental Sciences, University of Georgia, Tifton, Georgia, U.S.A. (18). In August - September, 1979 severe

epiphytotic developed on the nutsedge at the same location. Since these observations, extensive research has been done towards the development and commercialization of this rust as augmentation method for control of yellow nutsedge. The nutsedge rust strain that attacks C. rotundus was located in India (14) but the search for an indigenous strain on C. rotundus in the United States continues. After preliminary research in 1980, rust was over - wintered in the greenhouse and efficacy studies were conducted in 1982 -1983. The first scientific report on this work was published in Science (18) . Application for patent was filed in 1984 and "Patent Number 4,731,104" "Method of controlling yellow nutsedge using Puccinia canaliculata" was issued by the U.S. Patent Office on March 15, 1988 (19). Extensive research on efficacy, application technology, and collection, storage and retrieving of uredinial spores, and the infection process have been conducted (4, 5, 6, 7, 8, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27). Uredinial spores of nutsedge rust

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are very sensitive, thus, it was essential to study the effect of various surfactants on efficacy of rust (15). Information on various studies involving surfactants will be presented. Some non -ionic surfactant were most effective. License and registration

In 1989, rust patent was licensed to Tifton Innovation Corporation (TIC) , 1009 North Central Avenue, Tifton, Georgia 31794, U.S.A. In 1989 TIC initiated the registration process with the United States Environmental Protection Agency (EPA) . Ecological Effects Branch (EEB) of EPA insisted on wide range of studies The following Nontarget Organism Studies were conducted to satisfy EPA-EEB: 1. Acute Pulmonary Toxicity /Pathogenicity Study in rats. 2. Acute mammalian toxicity test with mice. 3. 4. 5. 6.

7.

The oral toxicity and pathogenicity testing with bobwhite quail. The Avian Oral Pathogenicity and Toxicity study in mallard duck. 21 day static renewal test with Daphnia magna. 30 day static renewal test with rainbow trout. A dietary pathogenicity and toxicity study with the honeybee.

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Even though the existence of nutsedge rust has been known since 1832 and that the uredinial stage, (a self - perpetuating stage) has been observed only on plants belonging to genus Cyperus, EPA -EEB insisted on host range studies for Non - Target Plant, Tier I, data requirements. EPA's insistence was based on the experience with "Collego" [Colletotrichum gloeosporioides f. sp. aeschynomene (CGA) ] which was registered on the basis of its known host range

in 1982 which included northern jointvetch, indian jointvetch, jointvetch (three species) and sensitive jointvetch. By 1988 the host range for "Collego"

extended to several cultivated food crops, forage and cover crops, and

ornamental crops. According to EEB, susceptible plants by 1988 included garden pea, lentil, broadbean, garbanzo bean, winged bean, purple vetch, bitter vetch, narbone vetch, common vetch, white lupine, sweet pea, tree lupine, sky lupine,

bigleaf lupine, hybrid lupine, lupine, Texas bluebonnet, indigo (two species) vetch and rough peavine. Host range studies on nutsedge rust were conducted in 1990 -1991 on one cultivar each of cucumber, broccoli, soybean, wheat, corn and cotton, and on 10 cultivars of sunflowers. These crops represented major crop families based on economic and agricultural values. None of the crops studied showed any infection. Nutsedge biotype -rust strain interactions have

been observed and it will influence commercialization. Nutsedge biotype reaction ranged from most susceptible to most tolerant.

Marketing Nutsedge rust will be marketed in the United States under the trade name "Dr. Biosedge" as soon as the EPA approval is received. Application

rate will be 5 g/ha. Rust spore are highly sensitive to the impurities in water

and surfactants. Thus, pure deep well water and special surfactant will required as carrier to apply rust. Acknowledgements

I want to thank Jimmy Hornbuckle and Anthony Bateman for technical assistance and Mrs. Kathy Mullinix for typing the manuscript. I am grateful my wife, Mrs.

Swaran Phatak, son, Kush Phatak, and daughter, Sharmila Phatak, for their interest, encouragement and patience during these investigations.

390 References 1. Anon. (1992) Weed control manual. Meister Publishing Co., Willoughby, OH 44094, U.S.A. 2. Arthur, J.C. (1922) Uredinalés- collected by Fred J. Seaver in Trinidad. Mycologia 14:240. 3. Arthur, J.C. (1934) Manual of rusts in the United States and Canada. Purdue Res. Foundation, Lafayette, Indiana, p. 189. 4. Bruckart; W.L., Johnson, D.R. and Frank, J.R. (1985) Reduction of yellow

nutsedge stand and tuber set by Puccinia canaliculata and bentazon herbicide. Phytopathology 75:623. 5. Callaway, M.B. (1985) Effects of rust [Puccinia canaliculata (Schw.) Lagerh.) and rust- herbicide combinations on yellow nutsedge ( Cyperus esculentus L.). M.S. Thesis, Univ. of Georgia, 94 pp. 6. Callaway, M.B., Phatak, S.C. and Wells, H.D. (1985a) Effect of rust and rust - herbicide combinations on yellow nutsedge. Proc. South. Weed Sci. Soc., 14 -16 Jan., Houston, Tex. French, C.M.(ed.); South. Weed Sci. Soc. 38:131. 7. Callaway, M.B., Phatak, S.C. andWells, H.D. (1985b) Alternate host studies for the rust Puccinia canaliculata (Schw.) Lagerh., a potential biological control agent. Plant Dis. 69:924 -926. 8. Callaway,.M.B., Phatak, S.C. andWells, H.D. (1986) Yellow nutsedge control in soybeans with rust and rust - herbicide combinations. Proc. Northeast. Weed Sci. Soc. 40:109. 9. Holm, L.G., Plucknett, D.L., Pancho, J.W. and Herberger, J.P. (1977) The worlds worst weeds' . p. 609. Distribution and Biology. Univ. Press Hawaii, Honolulu. 10. Lewis, W.M. and Worsham, A.D. (1970) The ten worst weeds of field crops: Nutsedge. Crops and Soils Magazine 22:14 -16. 11. Mulligan, G.A. and Junkins, B.E. (1976) The biology of Canadian weeds: 17. Cyperus esculentus L. Can. Jr. Plant Sci. 56:339 -350. 12. Phatak, S.C. (1984) Knock out nutsedge. Amer. Veg. Grower 32(6):44 -46.

13. Phatak, S.C. (1985) Rust fungus suppresses yellow nutsedge. Ga. Young Farmer 10(2):16. 14. Phatak, S.C. (1987) Biological control of nutsedges. Proc. Beltwide Cotton Production Res. Conf., 4 -8 Jan. , Dallas, Tex. Nat. Cotton Council of Amer. , pp. 354 -456.

15. Phatak, S.C. (1989) Rust ( Puccinia canaliculata) and nutsedges ( Cyperus sp.). Proc. VII. Int Symp.Biol Contr. Weeds, 6 -11 Mar. 1988, Rome, Italy. Delfosse E.S. (ed.). pp. 539 -43. 16.

Phatak, S.C. and Callaway, M.B. (1985) Biological control and its ntegration in weed management systems for nutsedges ( Cyperus rotundus L. )

and yellow nutsedge ( Cyperus spp.). Abstr. Weed Sci. Soc. Amer. 25:57. 17. Phatak, S.Ç., Callaway, M.B. and Vavrina, C.S. (1987) Biological control

and its integration in weed management systems for purple nutsedge ( Cyperus rotundus L.) and yellow nutsedge (C. esculentus L.). Weed Technology 1(1):84 -91. 18. Phatak, S.C., Sumner, D.R., Wells, N.D., Bell, D.K. and Glaze, N.C. (1983)

Biological control of yellow nutsedge with the indigenous rust fungus