The United States is the largest producer of strawberries in the world, with over 85% of fresh market fruit produced in California (U.S. Department of Agriculture, 2005). Anthracnose, caused by Colletotrichum acutatum, is a major disease in strawberry production in the United States (Gunnell and Gubler, 1992) and continues to be a problem elsewhere worldwide (Bobev et al., 2002; Dai et al., 2006; Denoyes and Baudry, 1995; Freeman and Katan, 1997; Henz et al., 1991; Stensvand et al., 2001). The pathogen can infect all parts of the strawberry plant, resulting in substantial losses in fruit production (Freeman and Katan, 1997; Henz et al., 1991). Severe anthracnose infections from nursery-grown planting stocks caused loss of marketable yield up to 40% during the 2001–02 season in some fall-planted strawberry fields in Ventura County, CA; losses were estimated at $3000 per acre (Daugovish et al., 2004). Thus, management strategies that include preventive measures are needed to control anthracnose on plants before transplanting to production fields.
There are many potential sources of inoculum. Eastburn and Gubler (1990) showed the presence of inoculum in soil particles that were adhering to the roots and crowns of strawberry plants from the nursery. In addition, nursery surveys and greenhouse studies clearly indicated that anthracnose inoculum may come from diseased strawberry volunteers, rotation crops, and weed hosts in neighboring fields (Gubler et al., 2006). Infected nursery plants are generally asymptomatic except for a few petiole or stolon lesions. However, after digging and trimming the plants, the disease is difficult to see and the pathogen can be carried long distance on transplants from nurseries to the production fields where it then causes plant stunting or collapse of young plants (Eastburn and Gubler, 1990).
Because the inoculum is usually water-splashed and wind-blown to adjacent fields by sprinkler irrigation or rain, new plants would be ideally grown away from recently harvested fields. However, because of limited land availability, a single site rotation is common in California. Because C. acutatum could survive in buried plant tissues for up to 9 months (Eastburn and Gubler, 1990), and soil moisture and temperature could also affect pathogen survival (Feil et al., 2003), new plantings may be subject to potential infection for several months.
Currently, regular foliar application of fungicides is a common practice to reduce this disease in strawberry nurseries (Koike et al., 2005), but this does not affect crown rot resulting from inoculum in infested soil (Eastburn and Gubler, 1990; Gubler et al., 2006). Control options in fruit production fields are also very limited. Foliar sprays of strobilurin fungicides and captan have suppressed disease incidence of fruit rot (Black et al., 1990; Freeman et al., 1997; Su and Gubler, 2006). However, infections of the root system were not controlled by aboveground fungicide applications.
Additional control measures for transplants could reduce the infection on transplants or infestation of soil attached to transplants to minimize the risk of disease epidemics. Eastburn and Gubler (1990) reported that infested plants and soil adhering to transplants directly contributed to disease epidemics in fruit production fields, and that washing of transplants with running tap water removed soil and fungal spores and resulted in excellent disease control. Fungicide dipping may also suppress the pathogen. The objectives of this study were to evaluate the effects of preplant fungicide dips and water washing of nursery plants for anthracnose control in fruit production fields.
Black, L.L., McInnes, T.B. & Gatti J.M. Jr 1990 Evaluation of fungicides for control of strawberry fruit rots in Louisiana Adv. Strawberry Res. 9 33 36
Dai, F.M., Ren, X.J. & Lu, J.P. 2006 First report of anthracnose fruit rot of strawberry caused by Colletotrichum acutatum in China Plant Dis. 90 1046
Daugovish, O., Takele, E., Klonsky, K.M., DeMoura, R.M.2004 Sample costs to produce strawberries: South coast region, Ventura County 1 Nov. 2008 <http://coststudies.ucdavis.edu/files/strawscvent2004.pdf>.
Denoyes, B. & Baudry, A. 1995 Species identification and pathogenicity study of French Colletotrichum strains isolated from strawberry using morphological and cultural characteristics Phytopathology 85 53 57
Eastburn, D.M. & Gubler, W.D. 1990 Strawberry anthracnose: Detection and survival of Colletotrichum acutatum in soil Plant Dis. 74 161 163
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. & Sharon, A. 2001 Pathogenic and non-pathogenic lifestyles in Colletotrichum acutatum from strawberry and other plants Phytopathology 91 986 992
Freeman, S. & Katan, T. 1997 Identification of Colletotrichum species responsible for anthracnose and root necrosis of strawberry in Israel Phytopathology 87 516 521
Freeman, S., Nizani, Y., Dotan, S., Evens, S. & Sando, T. 1997 Control of Colletotrichum acutatum in strawberry under laboratory, green house, and field conditions Plant Dis. 81 749 752
Gubler, W.D., Su, H. & Feliciano, A.F. 2006 Detecting potential sources of Colletotrichum acutatum for infection of new strawberry plantings in California Phytopathology 96 S43 (Abstr.)
Henz, G.P., Boiteux, L.S. & Lopes, C.A. 1991 Outbreak of strawberry anthracnose by Colletotrichum acutatum in central Brasil Plant Dis. 76 212
King, W.T., Madden, L.V., Ellis, M.A. & Wilson, L.L. 1997 Effect of temperature on sporulation and latent period of Colletotrichum spp. infecting strawberry fruit Plant Dis. 81 77 84
Koike, S.T., Gubler, W.D. & Browne, G.T. 2005 University of California pest management guidelines: Strawberry anthracnose 1 Nov. 2008 <http://www.ipm.ucdavis.edu/PMG/r734101011.html>
Ntahimpera, N., Madden, L.V. & Wilson, L.L. 1997 Effect of rain distribution alteration on splash dispersal of Colletotrichum acutatum Phytopathology 87 649 655
Stensvand, A., Strømeng, G.M., Langnes, R., Hjeljord, L.G. & Tronsmo, A. 2001 First report of Colletotrichum acutatum in strawberry in Norway Plant Dis. 85 558
Su, H. & Gubler, W.D. 2006 Fungicidal control of botrytis and anthracnose fruit rot in strawberry in California, 2006 Plant Dis. Mgt Rpt. SMF021
Su, H., Gubler, W.D. & Dell, K. 2005 Fungicidal control of anthracnose and botrytis fruit rot in strawberry in California, 2005 Fungicide and Nematicide Tests 61:SMF041
U.S. Department of Agriculture 2005 Commodity highlight 1 Nov. 2008 <http://www.ers.usda.gov/briefing/fruitandtreenuts/>.
Wilson, L.L., Madden, L.V. & Ellis, M.A. 1990 Influence of temperature and leaf wetness duration on infection of immature and mature strawberry fruit by Colletotrichum acutatum Phytopathology 80 111 116