Management of Soilborne Diseases in Strawberry Using Vegetable Rotations

Abstract

The influence of crop rotation on soilborne diseases and yield of strawberry (Fragaria × ananassa) was determined at a site infested with Verticillium dahliae microsclerotia and at another with no known history of V. dahliae infestation during 1997 to 2000. The rotations studied at the V. dahliae-infested site were (i) broccoli-broccoli-strawberry, (ii) Brussels sprouts-strawberry, and (iii) lettuce-lettuce-strawberry; the treatments at the site with no history of V. dahliae were (i) broccoli-broccoli-strawberry, (ii) cauliflower-cauliflower-strawberry, and (iii) lettuce-lettuce-strawberry. The effects of rotation on V. dahliae and Pythium populations, strawberry vigor, Verticillium wilt severity, and strawberry fruit yield were compared with a standard methyl bromide + chloropicrin fumigated control treatment at both sites. Rotations did not alter total population levels of Pythium spp. at either study site. However, V. dahliae microsclerotia were significantly reduced with br occoli and Brussels sprouts rotations compared with lettuce rotations at the V. dahliae-infested site. Reduced propagules led to lower Verticillium wilt severity on strawberry plants in the broccoli and Brussels sprouts rotations than in lettuce-rotated plots. Strawberry vigor and fruit yield were significantly lower in lettuce-rotated plots than in broccoli- and Brussels sprouts-rotated plots. Despite no detectable microsclerotia at the other site, strawberry vigor and fruit yield were greatest in plots rotated with broccoli, intermediate with cauliflower, and lowest with lettuce. None of the rotation treatments were better than the fumigated control for all variables measured. In the absence of fumigation, rotation with broccoli and Brussels sprouts is an effective cultural practice for managing Verticillium wilt in strawberry production; whereas, in fields with no detectable V. dahliae, broccoli is also a feasible rotational crop that enhances strawberry growth and yield. According to a cost-benefit analysis, the broccoli-strawberry rotation system could be an economically viable option provided growers are able to alternate years for strawberry cultivation.

Integrated Biological and Cultural Practices Can Reduce Crop Rotation Period of Organic Strawberries

“…For a specialized organic strawberry grower to rotate fields with other organic vegetable growers, choosing which vegetable crops will be used in rotation as done in the present study may not be an option. Further, if a host crop susceptible to V. dahliae (e.g., lettuce) was planted during the break period between strawberries, the level of yield decline can be greater than we found in this study (Subbarao et al 2007).…”

“…Although the trial was conducted in a field with a low baseline V. dahliae population and results may be different for fields with greater disease pressure, it should be noted that the V. dahliae population in the soil was kept low (<5 ms g −1 ) during the five-year study ( Figure 3) and no V. dahliae or other major pathogens were detected from strawberry plants at the end of year 5. The low V. dahliae population in the soil during the trial may be due to broccoli residue incorporations (Subbarao et al 2007) though the application rate of broccoli residues in this trial was lower than many farmers are using today. Nevertheless, a significant positive correlation of the break period between strawberries and the marketable fruit yield in year 5 existed (Figure 1), and marketable fruit yield in continuous strawberry plots (treatment A) was 20% lower than seven-year break plots (treatment E) ( Table 5).…”

“…), Sudan grass (Sorghum × drummondii), and other cover crops LaMondia et al 2002;Seigies and Pritts 2006); microbial amendments including vesicular arbuscular mycorrhizal fungi (VAM) (Werner et al 1990;Bull et al 2005); plant growth promoting rhizobacteria (PGPR) (Bull and Ajwa 1999;Eayre 2000); crop rotations with broccoli, lettuce (Lactuca sativa L.) or Brussels sprouts (Brassica oleracea L. (gemmifera group)) (Subbarao et al 2007); mustard seed meal (Mazzola 2011); soil-less trough production (Thomas and Legard 2013); and anaerobic soil disinfestation (Shennan et al 2012). Further, a minimum of a three-year rotation is recommended for strawberries that do not use chemical fumigants in Europe (Bevan et al 2001, Steffek et al 2004, the Northeast and Midwest United States, and in eastern Canada (Pritts and Handley 1998).…”

“…The adopted biological practices were: using broccoli residues for bio-fumigation (Koike and Subbarao 2000;Subbarao et al 2007); incorporating cover crops including mustard Seigies and Pritts 2006); and applying compost (Sances 2000;Duniway et al 2001;Millner et al 2004). These measures were combined with selecting strawberry cultivars less sensitive to pathogens (Bull et al 2005;Shaw et al 1996); and rotating with vegetables that do not host V. dahliae (Bhat and Subbarao 1999).…”

Anaerobic soil disinfestation (ASD): a strategy for control of soil borne diseases in strawberry production

“…The main approach used to control these pathogens is crop rotation, however, many of the vegetable crops that can economically be rotated with strawberry are also hosts to one or more of the pathogens. Brassica species, notably broccoli have been found to suppress V. dahliae Subbarao et al, 2007), but other key crops like lettuce are hosts. Furthermore, microsclerotia of V. dahliae can persist in the soil for many years.…”