Each year, California strawberry nurseries transplant “mother” plants into 1,000 ha to produce over one billion runner plants (daughters) for either out-of-state sale or for 15,620 ha of California fruit production, valued at ≈$1.8 billion (Calif. Dept. of Food and Ag., 2010). Nearly all (greater than 95%) transplants originate from individual axenic tissue-culture plants that are used to produce daughters in hanging pots in a greenhouse followed by a generation in pathogen-free soil in a screenhouse and finally a series of field-grown generations in conditions that promote runner plant production. In early generations of vegetative propagation, mothers produce ≈100 daughters each, which declines to ≈30 daughters each in the final multiplication in a high-elevation (greater than 1000 m) nursery. At high elevation, the shortening days in August and September stimulate flower bud initiation and facilitate dormancy, and the cool fall temperatures stimulate vigor for early transplantation into coastal fruit production areas in California (Strand, 2008).
Colletotrichum acutatum Simmonds causes anthracnose of strawberry in California and is an internationally regulated pest (EPPO, 2004). The disease is generally asymptomatic in the nursery, but after planting infected transplants into fruiting fields, the plants can be stunted and die. Also, fruit can develop lesions and be unmarketable (Koike and Browne, 2008; Smith, 2008). Consequently, although strawberry anthracnose is only an intermittent problem in California fruiting fields, it is of constant concern in nurseries because nursery plants with the pathogen cause disease outbreaks in fruiting fields for which fruit growers demand compensation from nurseries.
Hot water dips of mother plants are sometimes used in early nursery generations to control nematodes and C. acutatum, but the strategy is not used in the high-elevation generation destined for fruiting fields because hot water inhibits vigor (Koike and Browne, 2008) and has the potential to spread Xanthomonas fragariae, an internationally regulated pest (Clover et al., 2010). Fungicide dips or water-wash treatments may reduce severity of C. acutatum but do not completely eliminate the pathogen (Daugovish et al., 2008; Johnson et al., 2006; Paredes and Munoz, 2002). Because almost all nurseries use sprinkler irrigation, which is conducive for dissemination and infection of Colletotrichum species, nurseries routinely spend over $1200 per ha for fungicides as a preventive treatment for C. acutatum.
Anthracnose in strawberry caused by C. acutatum is difficult to control, partly because some isolates have a wide host range on crops and weeds (Freeman et al., 2001; Peres et al., 2005) and the pathogen can survive in soil on crop debris (Feil et al., 2003; Urena-Padilla et al., 2001). Because C. acutatum conidia are transported by splashing water (Ntahimpera et al., 1997), and water on the leaf surface provides a conducive environment for germination and infection, we postulated that drip irrigation in the nursery would reduce the impact of C. acutatum in fruiting fields. The objective of this study was to evaluate the impact of irrigation method and the presence of pathogen pressure in a high-elevation strawberry nursery on subsequent performance of transplants in fruiting fields in California.
Bhat, R.G. & Browne, G.T. 2010 Specific detection of Phytophthora cactorum in diseased strawberry plants using nested polymerase chain reaction Plant Pathol. 59 121 129
Brandfass, C. & Karlovsky, P. 2008 Upscaled CTAB-based DNA extraction and real-time PCR assays for Fusarium culmorum and F. graminearum DNA in plant material with reduced sampling error Intl. J. Mol. Sci. 9 2306 2321
Calif. Dept. of Food and Ag 2010 Calif. Ag. Res. Dir.: 68. 31 Mar. 2011. <http://www.cdfa.ca.gov/Statistics/>.
Calif. Irrigation Management Information System 1982 8 Oct. 2011. <http://wwwcimis.water.ca.gov/cimis/>.
Coelho, M.V.S., Palma, F.R. & Café-Filho, A.C. 2008 Management of strawberry anthracnose by choice of irrigation system, mulching material and host resistance Intl. J. Pest Mgt. 54 347 354
Daugovish, O., Gubler, W. & Su, H. 2008 Pre-plant fungicide dips of strawberry transplants to control anthracnose caused by Colletotrichum acutatum in California HortTechnology 9 317 323
Debode, J., Van Hemelrijck, W., Baeyen, S., Creemers, P., Heungens, K. & Maes, M. 2009 Quantitative detection and monitoring of Colletotrichum acutatum in strawberry leaves using real-time PCR Plant Pathol. 58 504 514
Feil, W.S., Butler, E.E., Duniway, J.M. & Gubler, W.D. 2003 The effects of moisture and temperature on the survival of Colletotrichum acutatum on strawberry residue in soil Can. J. Plant Pathol. 25 362 370
Freeman, S., Horowitz, S. & Sharon, A. 2001 Pathogenic and nonpathogenic lifestyles in Colletotrichum acutatum from strawberry and other plants Phytopathology 91 986 992
Galletta, G.J. & Bringhurst, R.S. 1990 Strawberry management, p. 83–156. In: Galletta, G.J. and D.G. Himelrick (eds.). Small fruit crop management. Prentice-Hall, Upper Saddle River, NJ.
Garrido, C., Carbú, M., Fernández-Acero, F.J., Boonham, N., Colyer, A., Cantoral, J.M. & Budge, G. 2009 Development of protocols for detection of Colletotrichum acutatum and monitoring of strawberry anthracnose using real-time PCR Plant Pathol. 58 43 51
Howard, C.M., Maas, J.L., Chandler, C.K. & Albregts, E.E. 1992 Anthracnose of strawberry caused by the Colletotrichum complex in Florida Plant Dis. 76 976 981
Johnson, A.W., Simpson, D.W. & Berrie, A. 2006 Hot water treatment to eliminate Colletotrichum acutatum from strawberry runner cuttings Acta Hort. 708 255 258
Koike, S.T. & Browne, G.T. 2008 Strawberry anthracnose. Univ. Calif. Intl. Pest Mgt. Guidelines: Strawberry. Agr. Nat. Res. Publ. 3468 9 July 2011. <http://ucipm.ucdavis.edu/PMG/r734101011.html>. Accessed July 9, 2011.
Larson, K.D., Daugovish, O. & Shaw, D.V. 2009 Optimizing strawberry production and fruit quality with use of protected culture in southern California Acta Hort. 842 171 176
Leandro, L.F.S., Gleason, M.L., Nutter, F.W. Jr, Wegulo, S.N. & Dixon, P.M. 2001 Germination and sporulation of Colletotrichune acutatum on symptomless strawberry leaves Phytopathology 91 659 664
Madden, L.V. & Wilson, L.L. 1997 Effect of rain distribution alteration of splash dispersal of Colletotrichum acutatum Phytopathology 87 649 655
McInnes, T.B., Black, L.L. & Gatti J.M. Jr 1992 Disease-free plants for management of strawberry anthracnose crown rot Plant Dis. 76 260 264
Mertely, J.C. & Legard, D.E. 2004 Detection, isolation, and pathogenicity of Colletotrichum spp. from strawberry petioles Plant Dis. 88 407 412
Ntahimpera, N., Madden, L.V. & Wilson, L.L. 1997 Effect of rain distribution alteration on splash dispersal of Colletotrichum acutatum Phytopathology 87 649 655
Paredes, B.S.G. & Munoz, F.R. 2002 Effect of different fungicides in the control of Colletotrichum acutatum, causal agent of anthracnose crown rot in strawberry plants Crop Prot. 21 11 15
Seijo, T.E., Chandler, C.K., Merteley, J.C., Moyer, C. & Peres, N.A. 2008 Resistance of strawberry cultivars and advanced selections to anthracnose and Botrytis fruit rots. Proc. Fla. State Hort. Soc. 121:246–248.
Strand, L. 2008 Integrated pest management for strawberries. 2nd Ed. Univ. of Calif. Statewide Intl. Pest Mgt. Project, Agr. Nat. Res. Publ. 3351.
Urena-Padilla, A.R., Mitchell, D.J. & Legard, D.E. 2001 Oversummer survival of inoculum for Colletotrichum crown rot in buried strawberry crown tissue Plant Dis. 85 750 754