Control of Fruit Rots of Processing Tomato Using Cover Crop Mulch and Tom-Cast

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  • 1 1Former Graduate Research Assistant, Department of Plant Pathology, The Ohio State University, Columbus, OH 43210
  • | 2 2Associate Professor, Department of Plant Pathology, The Ohio State University, Columbus, OH 43210
  • | 3 3Professor, Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH 43210
  • | 4 4Professor Emeritus, Department of Plant Pathology, The Ohio State University, Columbus, OH 43210

The effects of three bed systems [conventional (bare soil), chemically killed, or mechanically killed winter rye (Secale cereale) + hairy vetch (Vicia villosa) cover crop mulch] and five fungicide programs (no fungicide, 7-day fungicide application program, and Tom-Cast-timed fungicide applications at 15, 18, or 25 disease severity values) on marketable yield and soil-borne fungal fruit rot development in processing tomato (Solanum lycopersicum) production were studied. In 1997, marketable yield was higher in both cover crop systems compared with the conventional bed system. In 1997, percentage of anthracnose- (Colletotrichum coccodes) and ground rot-infected fruit (caused by Pythium spp. or Phytophthora spp.) were lower in both cover crop mulch systems compared with the conventional bed system. In 1998, marketable fruit yields were lower in both cover crop mulch systems compared with the conventional bed system. Percentage of anthracnose-infected fruit was lower in 1998 in the chemically killed cover crop mulch system compared with mechanically killed bed system. There were no differences in ground rot-infected fruit between bed systems in 1998. In 1998, percentage of total molded fruit in the chemically killed cover crop mulch system was reduced compared with the mechanically killed cover crop mulch system.

Abstract

The effects of three bed systems [conventional (bare soil), chemically killed, or mechanically killed winter rye (Secale cereale) + hairy vetch (Vicia villosa) cover crop mulch] and five fungicide programs (no fungicide, 7-day fungicide application program, and Tom-Cast-timed fungicide applications at 15, 18, or 25 disease severity values) on marketable yield and soil-borne fungal fruit rot development in processing tomato (Solanum lycopersicum) production were studied. In 1997, marketable yield was higher in both cover crop systems compared with the conventional bed system. In 1997, percentage of anthracnose- (Colletotrichum coccodes) and ground rot-infected fruit (caused by Pythium spp. or Phytophthora spp.) were lower in both cover crop mulch systems compared with the conventional bed system. In 1998, marketable fruit yields were lower in both cover crop mulch systems compared with the conventional bed system. Percentage of anthracnose-infected fruit was lower in 1998 in the chemically killed cover crop mulch system compared with mechanically killed bed system. There were no differences in ground rot-infected fruit between bed systems in 1998. In 1998, percentage of total molded fruit in the chemically killed cover crop mulch system was reduced compared with the mechanically killed cover crop mulch system.

Cover crops such as rye, hairy vetch, and subterranean clover (Trifolium subterraneum) have been used in no tillage and reduced tillage vegetable and agronomic crop production systems to reduce soil erosion, improve organic matter content, increase crop yield, supply nitrogen to subsequent crops, increase soil water-holding capacity, control weeds, and reduce competition and damage caused by pests (Abdul-Baki and Teasdale, 1993; Blevins et al., 1990; Creamer et al., 1996a, 1996b; Mills et al., 2002; Mitchell and Teel, 1977; Price and Baughan, 1987; Vaughan and Evanylo, 1998).

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Soil splashing can help disseminate important fungal pathogens of tomato such as anthracnose fruit rot, early blight (Alternaria solani), and septoria leaf spot (Septoria lycopersici). Cover crop mulches left on the soil surface may help break disease cycles and suppress the dissemination of soil-borne plant pathogens (Creamer et al., 1996a), and provide a more cohesive soil in which soil particles are less likely to be dislodged and splashed onto crop foliage (Mills et al., 2002). Soil splashed onto foliage as a direct result of rainfall or overhead irrigation may disseminate pathogen inoculum that acts to initiate primary infections early in the growing season. An intact cover crop mulch on the soil surface may intercept splashed soil and thus reduce the amount of soil that reaches the plant canopy. Coverage of tomato leaflets with soil was reduced in plots with polyethylene or hairy vetch mulches versus bare soil or compost in 2 years of assessment (Mills et al., 2002). Surface topography of groundcover and plant canopy were major factors controlling splash dispersal of anthracnose (Colletotrichum acutatum) of strawberry (Fragaria ×ananassa) through effects on splash droplet trajectories and loss of inoculum (Yang et al., 1990). Straw mulch alone provided 95% to 99% control of leather rot (Phytophthora cactorum), and straw mulch between the rows was equally or more effective than fungicides for controlling leather rot of strawberry (Ellis et al., 1998).

In contrast, another study showed that soil diseases affecting tomato were not controlled by mulches. Soil populations of verticillium wilt (Verticillium dahlia) and Fusarium wilt (Fusarium spp.) in processing tomato production were unaffected by overwintered mustard (Brassica hirta) cover crops, and there was no evidence of soil-borne disease suppression on subsequent tomato crops (Hartz et al., 2005).

Fruit quality is especially important in processing tomato production because of stringent requirements imposed by the U.S. Food and Drug Administration and processors (i.e., local) regarding acceptable mold counts and fruit rot incidence (Byrne et al., 1997). To help reduce mold and fruit rots, fungicides are applied to nearly 100% of the processing tomato crop grown in the midwestern region of the United States, with applications occurring every 7 to 10 d starting from a few weeks after transplanting and continuing until harvest (Precheur et al., 1992). Even with a good fungicide program, fruit rot caused by anthracnose can be as high as 15% (Dillard et al., 1997; Sherf and MacNab, 1986).

The disease forecasting system, Tom-Cast, was developed to help tomato grower's time fungicide applications for the control of early blight, anthracnose fruit rot, and septoria leaf spot (Pitblado, 1992). Tom-Cast predicts fungal disease development by recording field data on leaf wetness and temperature, which is then used to create disease severity values (DSV) that correspond to the severity of disease pressure affecting the tomato crop. Fungicide applications are then recommended based on the accumulation of those DSV. In several years of field trials, the Tom-Cast disease-forecasting system reduced fungicide applications by 34% and was widely adopted by processing tomato growers in the midwestern United States (Gleason et al., 1995). In other studies, Tom-Cast consistently reduced the amount of fungicide applied to tomato crops by 50% compared with 7-d spray programs (Kienath et al., 1996; Sikora et al., 1994). Tom-Cast has been evaluated and modified for managing diseases in tomato crops in North America and Australia (Cowgill et al., 2005; Fulling et al., 1995; Minchinton et al., 2006; Patterson et al., 2001; Pitblado et al., 2006), and has been tested for use in other crops such as carrot (Daucus carota), celery (Apium graveolens), and potato (Solanum tuberosum) (Bounds and Hausbeck, 2007; Bounds et al., 2006, 2007; Grunwald et al., 2000; Rogers and Stevenson, 2006). In general, when fungicide applications to crops are reduced as a result of using Tom-Cast, grower costs are also reduced (Bounds et al., 2006, 2007; Sikora et al., 2002).

Combining cover crop mulches with disease-forecasting systems may help reduce the amount of fungicide needed during the growing season. A study evaluating the use of a zone-tilled cover crop mulch system combined with Tom-Cast had no effect on marketable yield or percentage of total molded fruit, and no consistent effect on defoliation caused by early blight (Louws et al., 1996). However, in this study, Tom-Cast–timed spray schedules required 45% to 80% fewer fungicide applications to limit fruit mold incidence caused by early blight, anthracnose fruit rot, and soil rot (Rhizoctonia solani) (Louws et al., 1996).

The objectives of this study were to determine the effects of a fall sown winter rye + hairy vetch cover crop mulch with the tomato disease-forecasting system, Tom-Cast, on the development of anthracnose- and ground rot-infected fruit in processing tomato production.

Materials and methods

Location and design of field experiments.

Field experiments were conducted in 1997 and 1998 at the Waterman Agricultural and Natural Resources Laboratory in Columbus, OH (Franklin County). In Sept. 1996, a randomized split block design with three bed systems (bare soil, and chemically or mechanically killed cover crop mulch) as main plot and five fungicide treatments (no fungicide, 7-d fungicide application program, and Tom-Cast-timed fungicide applications at 15, 20, or 25 DSV intervals) as subplots were established on a Crosby silt loam soil with a pH of 6.7 and organic matter less than 1%. Each main plot consisted of 20 5-ft-wide raised beds, each 30 ft long. Each main plot was divided into five fungicide treatment subplots. Each fungicide treatment subplot was four 25-ft-long beds (each 5 ft wide) with a 5-ft transition break. The outer two rows of each fungicide treatment subplot served as untreated guard rows. Similarly, in Sept. 1997, a split block design with bed systems as main plot and fungicide treatment as subplot with five replications was established on a different field at the same facility on a Kokomo silty clay loam soil with a pH of 6.7 and organic matter less than 1%. In 1998, each main plot consisted of 20 5-ft-wide raised beds, each 25 ft long. Each main plot was divided into five fungicide treatment subplots. Fungicide treatment bed lengths were 20 ft long with a 5-ft transition break with the outer two rows of each treatment serving as untreated guard rows.

The five fungicide treatment programs consisted of no fungicide applied all season long, fungicide applied every 7 d, or fungicide applications applied at 15, 18 or 25 DSV intervals calculated according to the tomato disease forecasting system, Tom-Cast (Gleason et al., 1995; Pitblado, 1992). Beginning on 20 June in 1997 and 1998, 2.75 lb/acre chlorothalonil (Bravo Ultrex WDG 82.5; Syngenta Crop Protection, Greensboro, NC) was applied according to each fungicide program weekly or according to each fungicide program DSV threshold value. Benomyl at 2 lb/acre (Benlate 50WP; DuPont Agricultural Products, Wilmington, DE) was added to all fungicide spray programs on 3 Aug. 1997 and 2 July 1998 for control of septoria leaf spot. All fungicide applications were done at 60 psi with 50 gal/acre water using a tractor mounted, carbon dioxide-pressurized boom sprayer with five conejet visiflo hollow cone spray tips (TXVS-12) nozzles (TeeJet Technologies, Wheaton, IL) with the spray boom height maintained at 1 ft above the tomato canopy during the production season.

Field preparation, cover crop establishment, and kill.

Before cover crop establishment in Fall 1996 and 1997, granular fertilizer (0N–20.1P–0K and 0N–0P–50.6K) at 50 lb/acre each was broadcast and incorporated in a field that had been in tomato the same season. On 12 Sept. 1996 and 27 Sept. 1997, a cover crop mix consisting of hairy vetch + winter rye seed was sown at 50 lb/acre each on preformed 5-ft-wide raised beds. Water was applied by overhead irrigation on 14 Sept. 1996 and on 1 Oct. 1997 and 6 Oct. 1997 to promote cover crop establishment.

On 16 May 1997, and 29 Apr. and 23 May 1998, 2 pt/acre 2,4-D (Weedone; NuFarm, Burr Ridge, IL) + 4 pt/acre glysophate (Roundup Gold; Monsanto, St. Louis) was applied to kill the winter rye and hairy vetch in the chemically killed bed system. On 21 May 1997, mechanically killed cover plots were mowed to a height of 2 ft before mechanical undercutting, and on 23 May 1997 and 29 Apr. and 11 May 1998, a mechanical undercutter previously developed and described by Creamer et al. (1995) was used to cut the cover crop at about a 2-inch soil depth with minimal soil intrusion and then rolled flat on the surface of raised beds. On 23 May 1997 and 12 May 1998, all chemically killed cover crop plots were flat rolled with a 10-ft-wide cultipacker. A rainfall event on 29 Apr. 1998 (on the day of herbicide application and undercutting) resulted in incomplete desiccation in the chemically killed cover crop bed system and regrowth in the mechanically killed cover crop bed system, therefore, a second herbicide application and undercutting was done.

Tomato transplanting and fertilizer application.

In 1997 and 1998, 5-week-old seedlings of ‘Peto 696’ processing tomato (Seminis, Oxnard, CA) in 288-size plug trays obtained from a local greenhouse transplant producer were set outside and allowed to harden-off for 7 to 10 d before transplanting. On 27 to 28 May, 30 to 31 May, and 1 to 2 June 1997, and 26 to 28 May 1998, tomatoes were transplanted 1 ft apart in single rows using a RJV 600 Plug Planter Unit (RJ Equipment, Blenheim, ON, Canada), and by hand where necessary. At transplanting, each seedling received 8.0 fl oz of 10N–4.4P–8.3K solution in 1997, and 8.0 fl oz of 10N–52P–10K solution in 1998. On 12 June 1997, urea (46N–0P–0K) and 7 and 20 July 1998, urea (34N–0P–0K) was broadcast at 50 lb/acre each.

Assessment of cover crop residue.

At transplanting in 1997 and 1998, cover crop biomass samples (1-m2 area) were collected from each of three replications in the chemically killed and mechanically killed cover crop mulch systems. Before removal, a 1-m2 area of cover crop from the center of treatment was visually rated on a scale of 0 to 1 (using 5% increments) to determine the percentage (0%–100%) of soil covered by cover cop biomass. A 1-m2 area of cover crop biomass from the bed surface of each replication was collected at transplanting and harvest, placed in brown paper bags, dried for 48 h at ≈160 °F, and weighed to determine the cover crop biomass (dry weight) of all aboveground plant parts. Cover crop biomass was collected by hand by clipping off (if necessary) all biomass from each sample section at the soil surface.

Tomato harvest and assessment of marketable yield.

Tomatoes were harvested 12 to 13 Sept. 1997 and 8, 10, and 11 Sept. 1998. All fruit from a 5-ft-long section from the two center rows of each fungicide treatment subplot (10 ft of row total) were harvested to determine marketable yield, which included all marketable red, green, and pink fruit (i.e., not diseased), as well as the weight of fruit infected by ground rots or anthracnose fruit rot. Each fruit was individually evaluated for symptoms of anthracnose fruit rot or ground rot lesions, and was separated and weighed. Additionally, total molded fruit weight was calculated by combining the weights of anthracnose- and ground rot-infected fruit for statistical analysis.

Statistical analysis.

Analysis of variance [ANOVA (PROC GLM, P = 0.05)] using SAS (version 7.0; SAS Institute, Cary, NC) was done to examine the effects of cover crop mulch and fungicide treatment on marketable yield and the development of fruit rots with significant interactions noted between cover crop main plots and fungicide treatment subplots. ANOVA was done to determine significant differences in the weight (kilograms) of marketable yield (healthy red and green fruit), the weight of ground rot-infected fruit and anthracnose-infected fruit, the percentage (based on weight) of fruit infected with ground rot or anthracnose, and the percentage of total mold (ground rot + anthracnose-infected fruit) per plot.

Results and discussion

DSV accumulation, fungicide applications, and rainfall for 1997 and 1998.

Total DSV accumulation for the 1997 and 1998 production seasons were 96 and 114, respectively (daily data not shown). In 1997, the Tom-Cast–advised spray intervals of 15, 18, and 25 DSV received 5, 4, and 3 fungicide applications season long, respectively. When compared with the 7-d spray schedule, which required 11 fungicide applications season long in 1997, Tom-Cast–advised spray programs using 15 DSV (TC-15), 18 DSV (TC-18), and 25 DSV (TC-25) received 55%, 63%, and 72%, respectively, fewer fungicide applications compared with the standard 7-d fungicide program. The average DSV accumulation between fungicide applications for the Tom-Cast–advised spray programs in 1997 were 19.2 DSV for the TC-15-advised program, 24 for TC-18, and 32 for TC-25, respectively. In 1997, the estimated DSV interval for the 7-d spray schedule based on the number of fungicide applications was 8.7.

In 1998, the TC-15, TC-18, and TC-25 programs received 7, 6, and 4 fungicide applications, respectively. When compared with the 7-d spray schedule, which required 11 fungicide applications in 1998, the Tom-Cast–advised spray programs resulted in 36%, 45%, and 63% fewer fungicide applications for TC-15, TC-18, and TC-25, respectively. The average DSV accumulation between fungicide applications for the Tom-Cast–advised spray programs in 1998 were 16.3 DSV for TC-15, 19 for TC-18, and 28.5 for TC-25. In 1998, the estimated DSV interval for the 7-d spray schedule based on the number of fungicide applications was 10.7.

In 1997 and 1998, total rainfall for the production season (June, July, and August) was 51.4 and 24.7 cm, respectively. Overall, in 1997, rainfall was 9.2 cm above average, while in 1998, rainfall was 17.5 cm below average for the 3-month production season at the Waterman Agricultural and Natural Resources Laboratory in Columbus, OH.

Cover crop mulch.

In each year, a winter rye + hairy vetch cover crop mulch was successfully established in the fall and was killed by herbicide application or undercutting the following spring before processing tomato transplanting. In both years, chemical kill immediately followed by rolling and mechanical undercutting of the winter rye and hairy vetch cover crop resulted in uniform mulch distribution over bed surfaces. The percentage of groundcover of chemically and mechanically killed cover crop mulch plots immediately after chemical or mechanical desiccation before tomato transplanting was >90% in each year. At harvest in 1997 and 1998, the percentage of soil coverage by mulch litter visually estimated from chemically and mechanically killed cover crop plots was 63% to 66% at harvest, respectively (data not shown).

Cover crop effects on marketable fruit yield.

Marketable yields were higher in both cover crop mulch systems in 1997 and lower in 1998 compared with the conventional bed system, respectively (Tables 1 and 2). In 1997, marketable yield in both no fungicide/cover crop mulch systems (26.9 and 26.2 kg) were similar to yield in 7-d/cover crop mulch systems (26.6 and 24.3 kg), which received 11 fungicide applications season long, respectively (Table 1). There was no significant effect of fungicide program (P = 0.9457), nor fungicide program by bed system treatment interaction effect (P = 0.6197) on marketable fruit in 1997 (Table 1).

Table 1.

Influence of bed system and fungicide schedule on weight of total marketable fruit, total mold, ground rot-infected, and anthracnose-infected fruit of ‘Peto 696’ processing tomato in 1997.

Table 1.
Table 2.

Influence of bed system and fungicide schedule on weight of total marketable fruit, total mold, ground rot-infected, and anthracnose-infected fruit of ‘Peto 696’ processing tomato in 1998.

Table 2.

In 1998, with the exception of TC-25 program, marketable yield in the conventional bed system was significantly higher compared with both cover crop mulch systems (Table 2). There was no significant effect of fungicide program (P = 0.2703), nor fungicide program by bed system treatment interaction effect (P = 0.5239) on marketable fruit in 1998 (Table 2).

Overall, in 1997 and 1998, the disease-forecasting system Tom-Cast advised for fewer fungicide applications compared with the 7-d spray schedule without compromising yield of marketable fruit within a given bed system. The results of this study are similar to other studies where Tom-Cast–advised spray programs resulted in fewer fungicide applications without compromising tomato yield (Gleason et al., 1995; Kienath et al., 1996; Louws et al., 1996), although in this study, the presence of a cover crop increased marketable yield in one year and decreased marketable yield in a second year.

Cover crop effects on weight of anthracnose-infected fruit.

The cover crop mulch alone may have also been responsible for reducing the amount of anthracnose-infected fruit in this study. In 1997, the weight of anthracnose-infected fruit in the no fungicide/conventional bed system (0.41 kg) was about three times higher than in both no fungicide/cover crop mulch systems (0.12 kg) (Table 1). When fungicides were applied weekly or according to Tom-Cast, there were no differences in anthracnose-infected fruit across bed systems within each fungicide program, with the exception of TC-18 (Table 1). In 1998, the weight of anthracnose-infected fruit rot was lower in both no fungicide/cover crop mulch systems compared with the no fungicide/conventional bed system (Table 2). When fungicides were applied weekly or according to Tom-Cast, there were no differences in anthracnose-infected fruit across fungicide programs, with the exception of the 7-d fungicide program (Table 2).

Cover crop effects on weight of ground rot-infected fruit.

The cover crop mulch alone may have been responsible for reducing the amount of ground rot-infected fruit in 1997. In 1997, with the exception of TC-15, weights of ground rot-infected fruit were significantly lower in both cover crop mulch systems compared with the conventional bed system (Table 1). Because a fungicide for control of fruit rot pathogens caused by Pythium spp. and Phytophthora spp. was not included in any fungicide program, the differences in weight of ground rot-infected fruit between the conventional bed system and both cover crop mulch systems may have been due to the presence of the chemically or mechanically killed cover crop mulch left intact on the soil surface during the production season. In 1998, a considerable drier year than 1997, there were no differences in weight and percentage of ground rot-infected fruit between the conventional and both cover crop mulch systems (Table 2).

Cover crop effects on the percentage of anthracnose- and ground rot-infected fruit.

There was no fungicide program by bed system treatment interaction effect on percent total molded fruit, ground rot- or anthracnose-infected fruit in 1997 and 1998 (Tables 1 and 2). The percentage of ground rot- and anthracnose-infected fruit was significantly lower in both cover crop mulch systems compared with the conventional bed system in 1997 (Table 3). In 1998, there were no significant differences in the percentage of ground rot-infected fruit between the conventional and cover crop mulch bed systems. The percentage of anthracnose-infected fruit was lowest in the chemically killed cover crop mulch system in 1998, but was not significantly different from the conventional bed system, and was highest in the mechanically killed cover crop mulch system (Table 3).

Table 3.

Influence of bed system on percentage of total molded fruit, and ground rot- and anthracnose-infected fruit of ‘Peto 696’ processing tomato in 1997 and 1998.

Table 3.

The presence of a cover crop mulch in 1997 (chemically or mechanically killed mulch system) reduced the percentage of total molded fruit (Table 3). In the conventional (bare soil) bed system in 1997, total molded fruit was 13.6%, which was higher than a local processors rejection threshold of 4% (Table 3). Total molded fruit was less than 2% in both types of cover crop mulch systems in 1997, where a large percentage of total molded fruit was from ground rot-infected fruit (Table 3). In 1998, total molded fruit in the conventional bed system was considerably lower (3.1%) when compared with 1997 (13.6%), suggesting lower disease pressure (Table 3). In 1998, total molded fruit in chemically killed mulch (2.7%) and mechanically killed mulch (4.6%) was higher than in 1997 (1.6% and 1.0%, respectively) (Table 3). Importantly, cover crop mulch systems in both years were at or below a common rejection threshold level of 4% for total allowable molded fruit according to local processing standards.

Conclusions

A cover crop mix consisting of winter rye + hairy vetch used in this study was successfully established in the fall following previous tomato plantings. Winter rye and hairy vetch were chosen for this study because both are commonly grown in the midwestern region of the United States as winter cover crops. Previous research in Ohio indicates that winter rye left on the soil surface provides large amounts of aboveground biomass, and hairy vetch supplies adequate amounts of nitrogen to subsequent crops, making each an excellent candidate in cover crop/tomato production systems (Creamer and Bennett, 1997; Creamer et al., 1996a).

The positive and negative effects of a killed cover crop mulch on tomato yield determined in this study is consistent with other research. In a study evaluating the effects of bed strategy and fungicide programs, marketable yield of fresh market tomatoes was similar among bed strategies except for higher yields in covered verses uncovered and unamended beds in a relatively wet year and lower yields in vetch versus polyethylene beds in a dry year (Mills et al., 2002). In the same study, there were 40% to 50% fewer sprays using Tom-Cast (Mills et al., 2002). In a study evaluating the effects of growing an overwintered mustard cover crop preceding processing tomato, the mustard cover crops increased tomato yield in one field, and reduced yields in two fields (Hartz et al., 2005). In another study, fresh market tomato grown in a hairy vetch mulch produced yields more than double those in nonmulched plots (Abdul-Baki and Teasdale, 1993). Once-over mechanically harvested red fruit yield of ‘OH8245’ processing tomato produced in integrated and organic production systems were significantly less when compared with the conventional system at one field site, and showed no difference at another field site in an Ohio study evaluating cover crop use in four processing tomato production systems (Creamer et al., 1996a). Yield differences between sites were attributed to soil type, weather differences, and percentage of red fruit values (Creamer et al., 1996a). Weather conditions, particularly rainfall, may have played a significant role in the differences in yield between production systems in both years of the study. In 1997, rainfall was slightly above normal and tomato yield in cover crop mulch systems was higher than the conventional bed system, which suggests that in this study, in the year with normal rainfall, the presence of a cover crop mulch may have helped retain adequate soil moisture for longer periods than the bare soil system. However, in 1998, rainfall amount was well below normal (−17.5 cm) during the entire production season. The lack of rainfall in 1998 may have reduced soil fertility and tomato growth. Cover crop mulches on the soil surface tend to tie up available nitrogen, which may have been exacerbated by the dry production season, resulting in lower yields. Thus, the lack of water and available nitrogen combined may have significantly reduced tomato yield in both cover crop mulch systems in 1998.

The use of fall sown, spring-killed winter rye + hairy vetch cover crop mulch in processing tomato production for the control of important fungal diseases was evaluated in this study. The two important pathogens at our site were anthracnose fruit rot and ground rots, which survive on plant debris found in field soil between production seasons. Although initial inoculum levels were not determined in this field experiment research, results are in agreement with other research reports. The use of a killed organic mulch may help to reduce disease incidence of foliar and fruit rot pathogens by acting as a physical barrier by preventing fruit from coming into direct contact with soil, by disrupting the rain splash distribution of inoculum of soil-borne fruit rotting pathogens of tomato, and may help to reduce the amount of fungicide input needed to control these pathogens during the tomato production season (Ellis et al., 1998; Ristaino et al., 1997; Thayer et al., 2001).

By combining a winter rye + hairy vetch cover crop mulch with a disease-forecasting system such as Tom-Cast, tomato growers in midwestern region of the United States may reduce the amount of fungicide input needed to control important fungal pathogens in tomato production without drastically increasing production cost or jeopardizing the quality of their crop. Although the effects of the hairy vetch + winter rye cover crop on soil fertility and microbial populations was not examined in this study, their importance in the development of the processing tomato crop and marketable yields in both years were distinguishable by the fact that in a wet year (1997) yields were significantly higher in the winter rye + hairy vetch cover crop mulch bed systems and lower in a dry year (1998) versus conventional (bare soil) beds. The influence of cover crop mulches such as winter rye and hairy vetch on microbial populations and subsequent soil fertility needs to be carefully evaluated under field condition in processing tomatoes for cover crops such as these to be fully integrated in commercial production systems. Other techniques, such as site-specific weather data collection (Gleason et al., 1997; Kim et al., 2006) and model predictions of chlorothalonil residual on tomato foliage (Patterson and Nokes, 2000), have been developed in conjunction with Tom-Cast to develop a more precise forecasting system and can be further evaluated with cover crops to determine the best practice for reducing fungicide applications in processing tomatoes.

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  • Hartz, T.K., Johnstone, P.R., Miyao, E.M. & Davis, R.M. 2005 Mustard cover crops are ineffective in suppressing soil-borne disease or improving processing tomato yield HortScience 40 2016 2019

    • Search Google Scholar
    • Export Citation
  • Kienath, A.P., DuBose, V.B. & Rathwell, P.J. 1996 Efficacy and economics of three fungicide application schedules for early blight control and yield of fresh-market tomatoes Plant Dis. 80 1277 1282

    • Search Google Scholar
    • Export Citation
  • Kim, K.S., Gleason, M.L. & Taylor, S.E. 2006 Forecasting site-specific leaf wetness duration for input to disease-warning systems Plant Dis. 90 650 656

    • Search Google Scholar
    • Export Citation
  • Louws, F.J., Hausbeck, M.K., Kelly, J.F. & Stephens, C.T. 1996 Impact of reduced fungicide and tillage on foliar blight, fruit rot, and yield of processing tomatoes Plant Dis. 80 1251 1256

    • Search Google Scholar
    • Export Citation
  • Mills, D.J., Coffman, C.B., Teasdale, J.R., Everts, K.L., Abdul-Baki, A.A., Lydon, J. & Anderson, J.D. 2002 Foliar disease in fresh-market tomato grown in differing bed strategies and fungicide spray programs Plant Dis. 86 955 959

    • Search Google Scholar
    • Export Citation
  • Minchinton, E.J., Warren, M., Watson, A., Hepworth, G. & Tesoriero, L. 2006 Evaluation of the Tom-Cast model for prediction of early blight, septoria leaf spot and anthracnose fruit rot in processing tomatoes in south-eastern Australia Acta Hort. 724 137 143

    • Search Google Scholar
    • Export Citation
  • Mitchell, W.H. & Teel, M.R. 1977 Winter-annual cover crops for no-tillage corn production Agron. J. 69 569 572

  • Patterson, J.M. & Nokes, S.E. 2000 Incorporation of chlorothalonil persistence on processing tomato into TOM-CAST Agr. Systems 64 171 187

  • Patterson, J.M., Nokes, S.E., Bennett, M.A. & Riedel, R.E. 2001 Evaluation of residual chlorothalonil levels on processing tomato foliage using the TOM-CAST spray program Appl. Eng. Agr. 17 445 448

    • Search Google Scholar
    • Export Citation
  • Pitblado, R.E. 1992 Development and implementation of Tom-Cast Ontario Ministry of Agriculture and Food, Ridgetown College Ridgetown, ON, Canada

    • Search Google Scholar
    • Export Citation
  • Pitblado, R.E., Nichols, I. & Winter, J. 2006 Modernizing the delivery of TOM-CAST Acta Hort. 724 121 128

  • Precheur, R.J., Bennett, M.A., Riedel, R.M., Wiese, K.L. & Dudek, J. 1992 Management of fungicide residues on processing tomatoes Plant Dis. 76 700 702

  • Price, H.C. & Baughan, R.A. 1987 Establishment of fresh market tomatoes in a no-till system Acta Hort. 198 216 268

  • Ristaino, J.B., Parra, G. & Campbell, C.L. 1997 Suppression of phytophthora blight in bell pepper by a no-till wheat cover crop Phytopathology 87 242 249

    • Search Google Scholar
    • Export Citation
  • Rogers, P.M. & Stevenson, W.R. 2006 Weather-based fungicide spray programs for control of two foliar diseases on carrot cultivars differing in susceptibility Plant Dis. 90 358 364

    • Search Google Scholar
    • Export Citation
  • Sherf, A.F. & MacNab, A.A. 1986 Vegetable diseases and their control 2nd ed Wiley New York

  • Sikora, E.J., Bauske, E.M., Zehnder, G.W. & Hollingsworth, M.H. 1994 Evaluation of low-input fungicide spray programs for control of early blight on tomatoes Highlights Agr. Res. 41 15

    • Search Google Scholar
    • Export Citation
  • Sikora, E.J., Kemble, J.M., Zehnder, G.W., Goodman, W.R., Andrianifahanana, M., Bauske, E.M. & Murphy, J.F. 2002 Using on-farm demonstrations to promote integrated pest management practices in tomato production HortTechnology 12 485 488

    • Search Google Scholar
    • Export Citation
  • Thayer, B., Riedel, R.M., Bennett, M.A., Welty, C., Jasinski, J.R. & Precheur, R.J. 2001 Complementing TOMCAST by developing a comprehensive tomato integrated pest management (IPM) program J. Veg. Crop Prod. 7 57 73

    • Search Google Scholar
    • Export Citation
  • Vaughan, J.D. & Evanylo, G.K. 1998 Corn responses to cover crop species, spring desiccation time, and residue management Agron. J. 90 536 544

  • Yang, X., Madden, L.V., Wilson, L.L. & Ellis, M.A. 1990 Effects of surface topography and rain intensity on splash dispersal of Colletotrichum acutatum Phytopathology 80 1115 1120

    • Search Google Scholar
    • Export Citation

Contributor Notes

Funding for this research was provided by the National Research Initiative Competitive Grants Program (NRICGP 96-35313-3620).

Corresponding author. E-mail: wyenandt@aesop.rutgers.edu.

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  • Hartz, T.K., Johnstone, P.R., Miyao, E.M. & Davis, R.M. 2005 Mustard cover crops are ineffective in suppressing soil-borne disease or improving processing tomato yield HortScience 40 2016 2019

    • Search Google Scholar
    • Export Citation
  • Kienath, A.P., DuBose, V.B. & Rathwell, P.J. 1996 Efficacy and economics of three fungicide application schedules for early blight control and yield of fresh-market tomatoes Plant Dis. 80 1277 1282

    • Search Google Scholar
    • Export Citation
  • Kim, K.S., Gleason, M.L. & Taylor, S.E. 2006 Forecasting site-specific leaf wetness duration for input to disease-warning systems Plant Dis. 90 650 656

    • Search Google Scholar
    • Export Citation
  • Louws, F.J., Hausbeck, M.K., Kelly, J.F. & Stephens, C.T. 1996 Impact of reduced fungicide and tillage on foliar blight, fruit rot, and yield of processing tomatoes Plant Dis. 80 1251 1256

    • Search Google Scholar
    • Export Citation
  • Mills, D.J., Coffman, C.B., Teasdale, J.R., Everts, K.L., Abdul-Baki, A.A., Lydon, J. & Anderson, J.D. 2002 Foliar disease in fresh-market tomato grown in differing bed strategies and fungicide spray programs Plant Dis. 86 955 959

    • Search Google Scholar
    • Export Citation
  • Minchinton, E.J., Warren, M., Watson, A., Hepworth, G. & Tesoriero, L. 2006 Evaluation of the Tom-Cast model for prediction of early blight, septoria leaf spot and anthracnose fruit rot in processing tomatoes in south-eastern Australia Acta Hort. 724 137 143

    • Search Google Scholar
    • Export Citation
  • Mitchell, W.H. & Teel, M.R. 1977 Winter-annual cover crops for no-tillage corn production Agron. J. 69 569 572

  • Patterson, J.M. & Nokes, S.E. 2000 Incorporation of chlorothalonil persistence on processing tomato into TOM-CAST Agr. Systems 64 171 187

  • Patterson, J.M., Nokes, S.E., Bennett, M.A. & Riedel, R.E. 2001 Evaluation of residual chlorothalonil levels on processing tomato foliage using the TOM-CAST spray program Appl. Eng. Agr. 17 445 448

    • Search Google Scholar
    • Export Citation
  • Pitblado, R.E. 1992 Development and implementation of Tom-Cast Ontario Ministry of Agriculture and Food, Ridgetown College Ridgetown, ON, Canada

    • Search Google Scholar
    • Export Citation
  • Pitblado, R.E., Nichols, I. & Winter, J. 2006 Modernizing the delivery of TOM-CAST Acta Hort. 724 121 128

  • Precheur, R.J., Bennett, M.A., Riedel, R.M., Wiese, K.L. & Dudek, J. 1992 Management of fungicide residues on processing tomatoes Plant Dis. 76 700 702

  • Price, H.C. & Baughan, R.A. 1987 Establishment of fresh market tomatoes in a no-till system Acta Hort. 198 216 268

  • Ristaino, J.B., Parra, G. & Campbell, C.L. 1997 Suppression of phytophthora blight in bell pepper by a no-till wheat cover crop Phytopathology 87 242 249

    • Search Google Scholar
    • Export Citation
  • Rogers, P.M. & Stevenson, W.R. 2006 Weather-based fungicide spray programs for control of two foliar diseases on carrot cultivars differing in susceptibility Plant Dis. 90 358 364

    • Search Google Scholar
    • Export Citation
  • Sherf, A.F. & MacNab, A.A. 1986 Vegetable diseases and their control 2nd ed Wiley New York

  • Sikora, E.J., Bauske, E.M., Zehnder, G.W. & Hollingsworth, M.H. 1994 Evaluation of low-input fungicide spray programs for control of early blight on tomatoes Highlights Agr. Res. 41 15

    • Search Google Scholar
    • Export Citation
  • Sikora, E.J., Kemble, J.M., Zehnder, G.W., Goodman, W.R., Andrianifahanana, M., Bauske, E.M. & Murphy, J.F. 2002 Using on-farm demonstrations to promote integrated pest management practices in tomato production HortTechnology 12 485 488

    • Search Google Scholar
    • Export Citation
  • Thayer, B., Riedel, R.M., Bennett, M.A., Welty, C., Jasinski, J.R. & Precheur, R.J. 2001 Complementing TOMCAST by developing a comprehensive tomato integrated pest management (IPM) program J. Veg. Crop Prod. 7 57 73

    • Search Google Scholar
    • Export Citation
  • Vaughan, J.D. & Evanylo, G.K. 1998 Corn responses to cover crop species, spring desiccation time, and residue management Agron. J. 90 536 544

  • Yang, X., Madden, L.V., Wilson, L.L. & Ellis, M.A. 1990 Effects of surface topography and rain intensity on splash dispersal of Colletotrichum acutatum Phytopathology 80 1115 1120

    • Search Google Scholar
    • Export Citation
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