Fusarium fruit rot is an important soil-borne fungal disease of cucurbit crops (Zitter et al., 1996). Fusarium solani f. sp. cucurbitae race 1 was the most common species causing fruit rot of pumpkin in a survey of commercial fields in Ohio from 2000 to 2002 (Fig. 1) (Wyenandt et al., 2010) and was also confirmed as the causal agent of fusarium foot and fruit rot outbreaks in pumpkin in Connecticut, New York, and Missouri during 2001–03 (Elmer et al., 2007). Fusarium fruit rot can be extremely destructive in small roadside farm markets where “u-pick” pumpkins are planted in the same field each year. In some years in Ohio, yield loss was as high as 100% where pumpkin rotations are nonexistent, or every 1 or 2 years (Wyenandt et al., 2010). Using cover crop mulches in pumpkin production may play an important role in reducing soil-borne fungal diseases when proper crop rotations cannot be done. Cover crops have been used in low- or high-input agronomic and vegetable production systems to help reduce soil erosion, fungicide use, plant disease, and weed pressure (Ellis et al., 1998; Hoyt, 1999; Jones et al., 1969; Louws et al., 1996; Masiunas et al., 1995; Mills et al., 2002; Putnam, 1990; Ristaino and Johnston, 1999; Sumner et al., 1986). Cover crops have also been shown to increase soil organic matter (SOM), nitrogen availability, and soil moisture (Blevins et al., 1971; Gallaher, 1977; Hoyt and Hargrove, 1986; Teasdale and Daughtry, 1993). Cover crop mulches have been shown to have negative, no impact, or positive effects on vegetable yields (Abdul-Baki and Teasdale, 1993; Abdul-Baki et al., 1996a, 1996b; Creamer et al., 1996; Doss et al., 1981; Koike et al., 1997; Knavel and Herron, 1986; Louws et al., 1996; McKeown et al., 1998; NeSmith et al., 1994; Wyenandt et al., 2008a, 2008b). Cover crops may also increase disease in subsequent crops (Koike et al., 1997).
Traditional cover crops used in the midwestern United States, such as hairy vetch and winter rye that are killed and left on the soil surface, have been evaluated in pumpkin production (Everts, 2002; Galloway and Weston, 1996). Cover crops can be killed with herbicide applications or mechanically by roll chopping, crimping, flail mowing, or undercutting before no-till planting (Creamer et al., 1995, 1996). Vegetable production systems involving cover crop mulches, such as zone- or strip-tillage, are systems where planting strips are killed with herbicide or rotovated before vegetable seeding or transplanting. In other systems, such as hybrid mulch systems, cover crop mulches are seeded in the furrows between rows of plastic mulch in the early spring and then killed with herbicide before seeding or transplanting, or allowed to remain as living mulches during the production season (C.A. Wyenandt, R.M. Riedel, M.A. Bennett, and L.H. Rhodes, unpublished data).
Production problems may arise in small roadside farm operations trying to incorporate fall-sown cover crops such as winter rye, hairy vetch, or both in pumpkin production systems. These include having a field available in the fall for cover crop seeding, the proper timing of fall seeding, potential winter kill, timing of spring desiccation, and the potential for herbicide drift when killing the cover crop. In some cases, simply having too much aboveground cover crop biomass in the spring can make it difficult to strip- or no-till plant into the cover crop mulch if the proper no-till equipment is not used. Incorporating the use of spring-sown, living or spring-sown, spring-desiccated cover crop mulches, such as oat, may help alleviate some of the problems associated with incorporating the use of fall-sown cover crops in some small vegetable farm operations. Living cover crop mulches have been evaluated as cover crops in agricultural and vegetable production (Masiunas, 1998; Paine and Harrison, 1993). Spring-sown living cover crop mulches, such as annual medic, have been evaluated in the midwestern United States as emergency forage crops and as contributors of nitrogen to the soil (Shrestha et al., 1998; Zhu et al., 1996).
Very few field studies have been done to examine the role of cover crop mulches on the development of soil-borne fungal pathogens in pumpkin production. Everts (2002) determined that pumpkin grown on a fall-sown hairy vetch or a hairy vetch plus winter rye cover crop had an average of 36% less plectosporium blight (Plectosporium tabacinum) and 50% less black rot (Didymella bryoniae) than those grown with conventional tillage on bare ground. Although the mechanism by which disease was reduced was not studied, the hairy vetch + winter rye cover crop mulch resulted in a thick and long-lasting barrier between fruit and the ground and provided greater reduction in disease than hairy vetch alone (Everts, 2002). Rutledge (1999) in a review of conservation tillage vegetables in Tennessee suggested that crops that can be produced satisfactorily on cover crops can be harvested in cleaner condition, which can reduce cleaning costs to the packer, grower, or processor. Rutledge (1999) also suggested that with a residue cover, growers can get into fields sooner after a rain or irrigation event with reduced equipment slippage and with reduced soil erosion due to mechanical rutting of the land. Failure to obtain a good stand of the cover crop results in a very thin groundcover, increased weed problems, and unclean fruit due to adherence of soil particles (Rutledge, 1999).
The objectives of this study were to determine the effects of fall- and spring-sown cover crop mulches on pumpkin yield, aesthetic fruit quality (e.g., cleanliness), and development of FFR caused by F. solani f. sp. cucurbitae.
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