Fresh-market Tomato Production Research Articles

An all-out assault on a dominant resistance gene: Local emergence, establishment, and spread of strains of tomato spotted wilt orthotospovirus (TSWV) that overcome Sw-5b-mediated resistance in fresh market and processing tomatoes in California.

Tomato spotted wilt orthotospovirus (TSWV) causes substantial economic loss to tomato production, and the Sw-5b resistance gene is widely deployed for management. Here, we show (i) the emergence of resistance-breaking (RB) TSWV strains in processing and fresh market tomato production in California over the past ten years, and (ii) evolutionary relationships with RB strains from other areas. A specific RT-PCR test was used to show the C118Y RB strain that emerged in Fresno County in 2016 quickly became predominant in the central production area and remained so through this study. In 2021, the C118Y strain was detected in the Northern production area, and was predominant in 2022. However, in 2023, the C118Y strain was unexpectedly detected in fewer spotted wilt samples from resistant varieties. This was due to emergence of the T120N RB strain, previously known to occur in Spain. A specific RT-PCR test was developed and used to show that the T120N RB strain was predominant in Colusa and Sutter counties (detected in 75-80% of samples), and detected in ~50% of samples from Yolo County. Pathogenicity tests confirmed California isolates of the T120N strain infected Sw-5b tomato varieties and induced severe symptoms. Another RB strain, C118F, was associated with spotted wilt samples of Sw-5 varieties from fresh market tomato production in southern California. Phylogenetic analyses with complete NSm sequences revealed that the C118Y and T120N RB strains infecting resistant processing tomato in California emerged locally, whereas those from fresh market production were more closely related to isolates from Mexico. Thus, widespread deployment of this single dominant resistance gene in California has driven the local emergence of multiple RB strains in different tomato production areas and types. These results further emphasize the need for ongoing monitoring for RB strains, and identification of sources of resistance to these strains.

Field performance of paper and plastic mulches for fresh market tomato production

ABSTRACT Plastic mulch is used for agricultural production to improve crop performance and mediate local environmental concerns. Paper mulch is an alternative to plastic mulch, it is effective and more biodegradable. The performance of plastic and paper mulch materials in agricultural production varies according to climatic environments, production practices, and crops. The objective of this study was to investigate the performance of paper mulch compared with plastic mulch and bare soil for tomato (Solanum lycopersicum L.) field production in 2018 and 2021. Data on weed control, soil temperature, and tomato yield were recorded. Weed coverage and weeding time were reduced in paper and plastic mulch treatments compared to bare soil. Soil temperature in 2021 was lower in paper and plastic mulch treatments than in bare soil. Tomato yield was greater in plastic mulch than paper mulch and bare soil. Tomato yield for paper mulch treatments was not different from that of bare soil treatments. Paper mulch offered comparable weed control benefits as plastic mulch, and comparable tomato yield as bare soil.

Field evaluation of CRISPR-Cas9-driven brachytic and jointless pedicel tomatoes identifies an association between the high extra-large-sized fruit yield of the brachytic-mediated shortened tomato and the jointless2

Fresh-market tomato is one of the most important vegetables in the United States (US), and novel, cost-effective labor solutions are an important issue in current fresh-market tomato production. The shortened stem driven by the brachytic (br) and the jointless pedicel driven by the jointless2 (j2) are two important traits that would contribute to knowledge-based breeding; based on these traits, an appropriate plant architecture can be designed for ground cultivation systems that will ultimately enable mechanical harvesting. We aimed to evaluate the effect of CRISPR-Cas9-driven shortened plant architecture and jointless pedicel on the yield and horticultural performance of fresh-market tomatoes using a ground cultivation system in an open field. We conducted field trials during three successive seasons in 2020 and 2021 using the fresh-market tomato variety Fla. 8059 (a non-brachytic jointed pedicel tomato; BR/BR:J2/J2; wild-type) and its three different CRISPR-Cas9-driven mutants, a brachytic jointed pedicel Fla. 8059 (br/br:J2/J2), a non-brachytic jointless pedicel Fla. 8059 (BR/BR:j2/j2), and a brachytic jointless pedicel Fla. 8059 (br/br:j2/j2). Field evaluations confirmed that the total yield of the mutants was not significantly different from the yield of the wild-type. However, there was a significant association between the high extra-large-sized fruit yield of the br mutant and the j2 mutation. Field evaluations also revealed a clear positive impact of the br mutation on the high proportion of fruits laying on the raised plastic bed. Our results contribute to the optimization of fresh-market tomato architecture for developing shortened jointless pedicel varieties and the adoption of low input management practices.

LoRaWAN based internet of things (IoT) system for precision irrigation in plasticulture fresh-market tomato

Precision irrigation with sensors has proven to be effective for water saving in crop production. An Internet of Things (IoT) system is necessary for monitoring real-time data from sensors and automating irrigation systems. Long-range wide-area network (LoRaWAN), a type of low-power wide-area network (LPWAN), is a low-cost and easily implemented IoT system which can be used for precision crop irrigation. In this study, a LoRaWAN based IoT system was developed and evaluated as a precision irrigation tool on fresh-market tomato production in a plasticulture system. Four irrigation scheduling treatments were designed and tested, including irrigation based on crop evapotranspiration (ET), soil matric potential sensors (Watermark 200SS-5) at -60 kPa (MP60) or -40 kPa (MP40), and GesCoN fertigation decision support system (DSS). The treatments were arranged based on a randomized complete block design with four replicates. System feasibility, irrigation water use efficiency (iWUE), and crop yield were evaluated. Throughout the season, the overall water use efficiencies were 22.2, 26.5, 27.9, and 28.4 kg·m−3 for ET, MP60, MP40, and GesCoN, respectively. The results indicated that treatment MP60 and GesCoN had 15.2 and 22.1% higher marketable fruit yield than ET, while, MP40 had 12.5% lower marketable yield compared to ET. Overall, the LoRaWAN-based IoT system performed well in terms of power consumption, communication, sensor reading, and valve control. These results suggested that the IoT system can be implemented for precision and automatic irrigation operations for vegetable and other horticultural crops with enhancing crop's water use efficiency and sustainability.

Optimizing Tomato Growth and Productivity Using Nitrogen and Irrigation Application Timing

Soil nutrients and water management practices according to the concept of 4R nutrient stewardship (right rate, right timing, right placement, and right source) can have significant benefits on crop productivity and reduce the negative effects of agricultural practices on the environment. Therefore, this present study evaluated the effects of nitrogen (N) application timing under different irrigation regimes on open-field, fresh-market tomato production in Florida. In this study, 2 N application timings applied at 25% pre-plant with 75% fertigation (BM), and 0 pre-plant with 100% fertigation (NB), were evaluated. The two N application methods were evaluates using three irrigation regimes: full irrigation (FI, 100% ETc), deficit irrigation (DI, 66% ETc), and regulated deficit irrigation (RDI, 66% ETc during the first 4 weeks after transplanting and 100% ETc afterward). The results showed that BM treatment significantly improved early-season tomato growth compared to NB treatment. The results also indicated that under RDI and DI irrigation conditions, tomato root length was lowest (average value of 13%) within the first 15 cm compared to 40% within 15–30 cm and 47% at 30–40 cm soil depths. Similar to plant growth, BM treatment significantly increased tomato yield (average valued 56.00 Mg ha−1) compared to the NB (average value 40.23 Mg ha−1). The application of DI throughout the growing season reduced tomato yield; however, there were no differences in yield under the RDI and FI irrigation regimes. Therefore, based on the results from this study, it can be concluded that, under Florida growing conditions, pre-plant N application is essential for tomato growth and productivity. Additionally, irrigation application using the RDI method could be successfully adopted in Florida tomato production for improved water savings without any negative effects on tomato growth and productivity.

Late summer organic tomato production with heat tolerant tomato cultivars

Field production of organic fresh-market tomatoes in the U.S. Desert Southwest is desired by local producers and consumers. Tomato yield and fruit quality can be seriously impacted by heat stress (HS) and beet curly top virus (BCTV) infection of the main-season crop. We examined delayed planting of HS tolerant cultivars as a strategy for avoiding and mitigating these abiotic and biotic stressors. In 2016, seven putative HS tolerant cultivars, and one considered to be heat susceptible, were transplanted to the field in mid-summer to avoid peak populations of beet leafhopper (Circulifer tenellus), the vector of BCTV. In 2017, seven HS tolerant cultivars, one heat-susceptible, and two hot-set hybrid cultivars were transplanted in mid-summer. Fruit set was above 75% for most entries, including the heat-susceptible checks. Open-pollinated (OP) and hybrid cultivars exhibited a range of yields from 21.3 to 148.6 Mg/ha and fruit quality ratings from poor to excellent. The OP check ‘Super Sioux’ displayed consistently good yield and quality across years. The correlation between fruit set and yield was low (R2 = 0.29) and significant only at the 0.10 level (P<0.09). The incidence of curly top (incited by BCTV infection) was less than 10% in both years, indicating mid-summer planting aided disease avoidance. ‘Flamenco’, the earliest variety, and two later maturing varieties ‘Florida 91’ and ‘Skyway 687’, are recommended for further evaluation. Mid-summer planting of small and medium-fruited tomato cultivars appears to be a viable option for organic fresh-market tomato production for the fall market in the Southwest USA

Tomato Growth, Yield, and Root Development, Soil Nitrogen and Water Distribution as Affected by Nitrogen and Irrigation Rates on a Florida Sandy Soil

Effective nutrient and irrigation management practices are critical for optimum growth and yield in open-field fresh-market tomato production. Although nutrient and irrigation management practices have been well-studied for tomato production in Florida, more studies of the current highly efficient production systems would be considered essential. Therefore, a two-season (Fall 2016 and Spring 2017) study was conducted in Immokalee, FL, to evaluate the effects of the nitrogen (N) rates under different irrigation regimes and to determine the optimum N requirement for open-field fresh-market tomato production. To evaluate productivity, the study investigated the effects of N rates and irrigation regimes on plant and root growth, yield, and production efficiency of fresh-market tomato. The study demonstrated that deficit irrigation (DI) targeting 66% daily evapotranspiration (ET) replacement significantly increased tomato root growth compared with full irrigation (FI) at 100% ET. Similarly, DI application increased tomato growth early in the season compared with FI. Therefore, irrigation applications may be adjusted downward from FI, especially early during a wet season, thereby potentially improving irrigation water use efficiency (iWUE) and reducing leaching potential of Florida sandy soils. However, total marketable yield significantly increased under FI compared with DI. This suggests that although DI may increase early plant growth, the application of DI throughout the season may result in yield reduction. Although N application rates had no significant effects on biomass production, tomato marketable yield with an application rate of 134 kg·ha−1 N was significantly lower compared with other N application rates (179, 224, and 269 kg·ha−1). It was also observed that there were no significant yield benefits with N application rates higher than 179 kg·ha−1. During the fall, iWUE was higher under DI (33.57 kg·m−3) than under FI (25.57 kg·m−3); however, iWUE was similar for both irrigation treatments during spring (FI = 14.04 kg·m−3; DI = 15.29 kg·m−3). The N recovery (REC-N) rate was highest with 134 kg·ha−1 N; however, REC-N was similar with 179, 224, and 269 kg·ha−1 N rates during both fall and spring. Therefore, these study results could suggest that DI could be beneficial to tomato production only when applied during early growth stages, but not throughout the growing season. Both yield and efficiency results indicated that the optimum N requirement for open-field fresh-market tomato production in Florida may not exceed 179 kg·ha−1 N.

Increasing Air Temperatures and Its Effects on Growth and Productivity of Tomato in South Florida.

Florida ranks first among US states in fresh-market tomato production with annual production exceeding one-third of the total annual production in the country. Although tomato is a signature crop in Florida, current and future ambient temperatures could impose a major production challenge, especially during the fall growing season. This problem is increasingly becoming an important concern among tomato growers in south Florida, but studies addressing these concerns have not been conducted until now. Therefore, this study was conducted to determine the impacts of the present ambient temperature conditions and planting dates on tomato productivity in south Florida. The study was conducted using crop simulation model CROPGRO-Tomato of DSSAT (Decision Support System for Agricultural Transfer) version 4.7. Five treatments were evaluated, and included AT (simulated treatment using 14 years of actual daily weather conditions at the study location) while other treatments were conducted based on a percentage (−20%, −10%, +10%, +20%) of AT to simulate cooler and warmer temperature regimes. The results suggested that under the current temperature conditions during the fall growing season in south Florida, average tomato yield was up to 29% lower compared to the cooler temperature regimes. Tomato yield further decreased by 52% to 85% at air temperatures above the current condition. Yield reduction under high temperature was primarily due to lower fruit production. Contrary to yield, both tomato biomass accumulation and leaf area index increased with increase in temperature. Results also indicated that due to changes in air temperature pattern, tomato yield increased as planting date increased from July to December. Therefore, planting date modification during the fall season from the current July–September to dates between November and December will reduce the impacts of heat stress and increase tomato productivity in south Florida.

Management of bacterial spot of tomato caused by copper-resistant Xanthomonas perforans using a small molecule compound carvacrol

Bacterial spot of tomato (BST), caused by Xanthomonas perforans, is one of the most serious diseases in fresh market tomato production in Florida, and currently available management measures are largely ineffective or insufficient. Using small molecule compounds has been shown to be promising in management of BST. Carvacrol is a plant-derived small molecule, which is effective against many human and plant pathogens. In this study, we evaluated the efficacy of carvacrol for control of BST in vitro, in the greenhouse and in field trials. In the laboratory, X. perforans strain used in this study was able to grow on nutrient agar (NA) amended with CuSO4 at 400 mg L−1, which proved that this X. perforans strain was copper resistant. Our results also showed that the minimum inhibitory concentration (MIC) of carvacrol was 32 mg L−1 and its minimum bactericidal concentration (MBC) was 64 mg L−1. Carvacrol increased the sensitivity of the copper-resistant X. perforans strain to copper. In the leaf disc assay, carvacrol combined with copper reduced recovery of X. perforans from tomato leaf discs. Seed priming with carvacrol at 32 mg L−1 was found to be effective in promoting seed germination and seedling vigor of tomato. In greenhouse assays, carvacrol foliar applied alone or in combination with copper significantly (P < 0.05) reduced BST severity. Moreover, carvacrol at 32 mg L−1 combined with copper at 76.8 mg L−1 was most effective in reducing BST severity, which was significantly greater than either treatment alone and also greater than copper at 153.6 mg L−1. In field trials during 2018 and 2019, control efficacy of carvacrol at 32 mg L−1 was significantly greater than copper. Results from this study indicate that carvacrol significantly reduces BST severity and enhances the efficacy of copper against copper resistant X. perforans. There is potential for the small molecule compound carvacrol to be integrated into BST management programs for copper resistant X. perforans and provide a more environmentally sustainable approach for controlling BST.

High Tunnel and Grafting Effects on Organic Tomato Plant Disease Severity and Root-knot Nematode Infestation in a Subtropical Climate with Sandy Soils

The U.S. fresh-market tomato industry faces increasing competition from Mexico, which achieves greater productivity and quality due to the use of protected structures. Protected agriculture is limited in humid, subtropical regions of the United States. Although grower interest in high tunnel production has increased in recent years, systematic high tunnel research has not yet been conducted in subtropical Florida. Additionally, although tomato grafting has shown the potential to overcome biotic and abiotic stresses, research of high-tunnel, grafted tomato production in subtropical conditions is lacking. During this 2-year study (Citra, FL), a side-by-side comparison of open field and high tunnel organic tomato production was conducted using a split-split plot design. The most significant benefit of high tunnel production was season extension achieved through the reduction of foliar disease severity, which reduced the area under the disease progress curve by 64% across two seasons. This may be largely attributed to the pronounced reduction in the duration of leaf wetness during the wet months of the growing cycle. Grafting with ‘Multifort’ rootstock reduced the root-knot nematode soil population density by 88% as well as root galling severity, both of which demonstrated the potential for increased levels in the high tunnel production system compared with open field production. The more severe root-knot nematode infestation in high tunnels was likely due to the modification of soil temperatures, which were 2 °C greater during the early part of the season but were reduced after shadecloth application. Compared with the open field, solar radiation was reduced by 23% in the high tunnel before shadecloth application and by 51% after shadecloth application; however, due to the high radiation levels in subtropical Florida, daily light integral levels indicated that light was not limiting for high-quality tomato production. The average wind speed was reduced by 57% in the high tunnel and, together with the reduction in solar radiation, indicated the potential reduction in summer abiotic stress and evapotranspiration within high tunnels. These results revealed that the integrated use of high tunnel and grafting technologies may be important for enhancing fresh-market tomato production in the humid subtropics, especially in organic systems.

Economic Analysis of Anaerobic Soil Disinfestation for Open-field Fresh-market Tomato Production in Southwest and North Florida

With the phase-out of methyl bromide due to its impact on ozone depletion, research has focused on developing alternative chemical and biologically based soil disinfestation methods. Anaerobic soil disinfestation (ASD) was developed to control plant-parasitic nematodes, weeds, and soilborne pathogens. However, whether farmers will adopt ASD methods on a large scale is unknown. This study evaluates the economic viability of using ASD in open-field, fresh-market tomato (Solanum lycopersicum) production, drawing on data from field experiments conducted in 2015 in Immokalee, FL, and Citra, FL. The experiment included three treatments: chemical soil fumigation (CSF), ASD1 [the standard ASD treatment with 1482 gal/acre molasses and 9 tons/acre composted poultry litter (CPL)], and ASD0.5 (the reduced rate ASD treatment with 741 gal/acre molasses and 4.5 tons/acre CPL). Results from the economic analysis show that ASD treatments require higher labor costs than CSF regarding land preparation and treatment application. However, yields from ASD treatments are higher than those resulting from CSF, and the improvement in yield was enough to offset the increased labor costs. Relative to CSF, ASD0.5, and ASD1 achieved additional net returns of $630.38/acre and $2770.13/acre, respectively, in Immokalee, FL. However, due to unexpected conditions unrelated to soil treatments, the net return of ASD1 was lower than that of CSF in Citra, FL. Breakeven analysis indicates that ASD treatments would remain favorable even with an increase in the molasses price. However, when the tomato price is low, ASD could potentially lose its advantage over CSF.

Polyhalite as a sulfur source for fresh market tomato production in Brazil

Polyhalite (PH), a naturally occurring multinutrient fertilizer containing potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), has improved tomato (Solanum lycopersicum L.) production in Brazil but a specific response by tomato to the S in PH is not confirmed. We compared four S sources – PH, sulfate of potash (SOP), sulfate of potash magnesia (SOPM), and single super phosphate (SSP) – applied at a target application rate of 40 kg S ha−1 to fertilizers with no S (muriate of potash, MOP), and no K or S at commercial application rates in three commercial fields in Brazil with nitrogen (N), phosphorus (P), and K applied at recommended rates of 355, 500, and 200–300 kg ha−1, respectively. Consistent across locations, PH increased total yields over the control, MOP, and SSP, with SOP and SOPM higher than the control but not MOP or SSP. Only PH increased marketable yields compared to the control. Yields increased linearly with fruit numbers per plant which were higher for PH than the control or MOP, indicating higher fruit set in PH contributed to yield differences. While fertilizers increased leaf K and S concentrations and soil test K and SO4–S, yield differences did not appear to be related solely to either K or S fertilization, nor to Mg fertilizers to which there was no response. Leaf and fruit Ca concentrations were higher in PH than the control and MOP at some locations suggesting Ca improved fruit set in PH. Results suggest tomato likely responded to the multinutrient content or solubility pattern of PH.

Comparison of Extractants for Calibrating Phosphorus Application Rates in a Calcareous Soil

Preplant soil testing is essential for optimizing phosphorus (P) fertilization and minimizing the potential for soil P losses. Currently, there is no effective soil P extractant for calcareous soils in Florida. This study was conducted to compare Mehlich-3, ammonium bicarbonate–diethylenetriaminepentaacetic acid (AB-DTPA), and Olsen for evaluating P availability, estimating soil-test P (STP) critical levels, and calibrating P application rates for fresh-market tomato (Solanum lycopersicum L.) production in a calcareous soil. Tomatoes were grown during Winter 2014 and 2015 with P application rates of 0, 29, 49, 78, 98, and 118 kg·ha‒1 P. Water-extractable P (water-P) and dissolved reactive P (DRP) in leachate were used to determine the STP change point of leaching potential. Results showed the greatest correlation occurred between Mehlich-3 and Olsen of the three STP extractants. For Mehlich-3-P, the medium STP level (producing 75% to 90% relative yield) was predicted from 76 to 89 mg·kg‒1 and the change point was predicted at 88 or 104 mg·kg‒1 by split-line models. The P requirement was calculated from 52 to 112 kg·ha‒1 when Mehlich-3-P was rated as low level (producing 50% to 75% relative yield), which was from 42 to 76 mg·kg‒1. The multiple regression models using AB-DTPA-P and Olsen-P could not predict either the medium STP level or the practical P application rates for the low level. Consequently, based on 2 years of data, Mehlich-3 was the most effective extractant for estimating soil P availability and calibrating P rates in calcareous soils with an extremely high calcium carbonate (CaCO3) content.

Reduced Use of Restricted and Danger-Labeled Pesticides in Florida Fresh Market Tomato Production (1992-2004)

Pesticide use values for 2004 compared to peak usage data for the period 1992 through 2004 demonstrate a 75% reduction in the application of restricted or “Danger”-labeled insecticides in fresh market tomato. Paraquat use was reduced by 31%. Fumigant use (17% reduction) was mainly influenced by rate reduction, rather than reduction of use (1-7). This document is PI-87, one of a series of publications of the Pesticide Information Office, Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published November 2005.

Evaluation of a small molecule compound 3-indolylacetonitrile for control of bacterial spot on tomato

Bacterial spot, caused by Xanthomonas perforans, is one of the major diseases in fresh market tomato production in Florida. It is reported that X. perforans has developed resistance to copper, an element of major bactericides used for management of this disease in Florida and worldwide. Continuous efforts are necessary for providing the tomato industry with new effective approaches to managing this important disease. A small molecule 3-indolylacetonitrile (IAN) that can inhibit biofilm formation has been reported to be effective against many medical bacterial pathogens. In this study, we evaluated the efficacy of IAN in planta for the control of bacterial leaf spot on tomato, the effectiveness of IAN when applied at different times from pathogen inoculation, how IAN efficacy compared to a copper bactericide (Kocide 3000), and if IAN could be applied as a tank mixture with copper bactericide. In vitro testing in liquid media was also completed to further investigate observations made in planta. Our results showed that IAN was effective in reducing disease severity of bacterial leaf spot on tomato between 0.5 and 1.0 mg/ml. However, phytotoxicity to tomato plants occurred when the concentration was higher than 1.0 mg/ml. IAN significantly (P < 0.05) reduced the disease when it was foliar applied during the period from 3 days prior to inoculation to 1 day after inoculation. When IAN was applied in combination with a copper bactericide Kocide 3000, additive effect was observed in reducing both disease severity and bacterial growth, compared to either IAN or copper alone, for both copper-sensitive and copper-resistant X. perforans strains. Results from this study indicated that IAN significantly reduced bacterial leaf spot on tomato and enhanced the efficacy of copper against X. perforans. Specifically, IAN significantly improved the control of bacterial leaf spot caused by a copper-resistant X. perforans strain.

Fine Mapping of the brachytic Locus on the Tomato Genome

Mechanization of farm work is increasingly demanded for the current system of fresh-market tomato (Solanum lycopersicum) production. One essential element for the adoption of mechanical harvest of fresh-market tomatoes is modification of plant architecture so that the crop can be grown without staking. To address this in the current production system, the stem length should be reduced. The tomato brachytic (br) locus has been shown to be a primary source of reducing stem length. To improve the effectiveness of marker-assisted selection (MAS) for the br-mediated trait and to provide resources for cloning this gene, we fine-mapped br to the tomato genome. Fine mapping of br to chromosome 1 was initiated by a survey of genome-wide single-nucleotide polymorphisms (SNPs) shown to be polymorphic between the br phenotype and normal using the tomato array, identifying the interval that harbors br. Genetic markers that flank the locus further permitted saturation of the interval. Twenty-six fixed homozygous recombinant lines were identified together in two different populations and tested with those markers. These efforts resulted in the first report that the br is fine-mapped to a 763-kb physical interval of tomato reference genome. The identified markers close to the br in the present study will be significant resources for MAS and gene cloning research.

Hairy vetch becomes an alternative basal N fertilizer in low-input fresh-market tomato production in plastic high tunnel

Environment pollution is one of the major concerns in recent times. In order to establish low-input alternative production systems based on cover crops, the effectiveness of hairy vetch (Vicia villosa Roth; HV) incorporated as a basal nitrogen (N) fertilizer in fresh-market tomato production in plastic high tunnel was investigated in Sapporo, Japan. The treatments consisted of HV seeding rates (HV20, 20 kg ha-1; HV50, 50 kg ha-1) and ammonium sulfate (AS100, 100 kg ha-1) applied as basal N fertilizers, and the control with no basal fertilizer. In all plots, 150 kg ha-1 of N was added as topdressing slow-release N fertilizer (LPS100 41%-N) before transplanting. HV aboveground biomass (dry weight) was 5.85 t ha-1 in HV20 and 7.19 t ha-1 in HV50. Nitrate in petiole sap was found to be higher in HV20, HV50 and AS100 plots than in control plots throughout the cultivation period with the exception of the first 2 weeks after transplanting (WAT). The growth index (GI) was higher in HV20 (47971), HV50 (46285), and AS100 (43397) than in control (39847) at 7 WAT. Higher marketable yields were found in tomatoes grown in HV20 (68.7 t ha-1), HV50 (69.1 t ha-1) and AS100 (60.8 t ha-1), compared with control (51.9 t ha-1). The HV plots had greater soil organic nitrogen and soil carbon than AS100 and control after tomato production. From these results, the HV seeding rate of 20 kg ha-1 will be enough to support the growth of tomato planted after HV production if HV grows smoothly in greenhouse.

Effects of fluensulfone combined with soil fumigation on root-knot nematodes and fruit yield of drip-irrigated fresh-market tomatoes

After the phase-out of methyl bromide (MeBr) and the constant challenges of root-knot nematodes (RKNs, Meloidogyne spp.), the need to evaluate the efficacy of additional alternatives in tomato (Solanum lycopersicum L.) production is vital. Fluensulfone (Nimitz, ADAMA Agricultural Solutions Ltd., Raleigh, NC) is a true, contact nematicide developed to target RKNs. Among available chemical soil fumigants, Pic-Clor 60 [1,3-dichloropropene plus chloropicrin (40:60, w/w)] has been identified as one of the main alternatives to MeBr; however, nematode management in sandy soils with drip irrigation has been unsatisfactory. During the fall of 2014 and the spring of 2016, two replicated field experiments were conducted in Myakka City, FL with the objective of evaluating the efficacy of pre-plant drip-injected fluensulfone at 1.96 and 2.80 kg a.i.·ha−1 combined with pre-plant fumigated Pic-Clor 60 at 280 kg ha−1 on plant vigor, RKN soil population density, root galling index, and fruit yield of fresh-market tomatoes. All treatments showed uniform plant growth during both seasons. In 2014 and 2016, at final harvest, Pic-Clor 60 combined with fluensulfone at 1.96 and 2.80 kg a.i.·ha−1 decreased RKN densities compared to Pic-Clor 60 alone by 96 and 85% and 81 and 94%, respectively. Similarly, during 2014 and 2016, at mid-season and final harvest, less root galling was observed with Pic-Clor 60 combined with both fluensulfone rates than with Pic-Clor 60 alone. However, the effect of the combination of fluensulfone and Pic-Clor 60 on tomato yield was significant only at the third harvest in 2014 when RKN infestation was high. Fluensulfone combined with Pic-Clor 60 could be a viable alternative for managing RKNs in fresh-market tomato production in sandy soils using drip irrigation and in fields with high RKN infestation.

Optimizing anaerobic soil disinfestation for fresh market tomato production: Nematode and weed control, yield, and fruit quality

Anaerobic soil disinfestation (ASD) has potential as an alternative to chemical-fumigation for controlling soilborne pathogens and pests. Previously, control of nutsedge was sub-optimal and the quantity of inputs for commercial production was an impediment to adoption. Field studies were conducted in Citra and Immokalee, Florida to assess the effects of ASD with reduced amendments and inclusion of a pre-emergent herbicide on weed and nematode populations, tomato yield, and fruit quality. Pre-plant soil treatments included ASD with 6.9m3ha−1 of molasses and 11Mgha−1 of composted poultry litter (CPL) (ASD0.5), ASD with 13.9m3ha−1 of molasses and 22Mgha−1 of CPL (ASD1.0), and chemical soil fumigation using Pic-Clor 60 (CSF). Subplot treatments were halosulfuron-methyl (Sandea®) herbicide and no herbicide application. ASD0.5 reached high and equivalent accumulation of anaerobic conditions as ASD1.0 during the three-week soil treatment in both locations. Root galling and plant-parasitic nematode population at harvest in ASD treatments were similar in nematode suppression to CSF in both locations, while ASD1.0 resulted in higher non-parasitic nematode populations in soil compared to CSF in Citra. In Citra, ASD treatments did not differ from CSF in total marketable fruit yield; however, ASD0.5 resulted in higher total yield of extra-large fruit than CSF and ASD1.0. In Immokalee, no difference was observed in total marketable yield between ASD0.5 and CSF, whereas ASD1.0 produced 26.3% and 20.4% higher total marketable yield than that of CSF and ASD0.5, respectively. ASD treatments had no impact on fruit quality attributes including color, firmness, pH, total soluble solids, and dry matter content. Herbicide application improved nutsedge control and had no negative impact on the development of anaerobicity in ASD-treated plots, while total marketable yield and fruit quality were not impacted by herbicide treatment in either location. Despite some variations between the two locations, reduced application rates of CPL and molasses produced results similar to the full rates of amendment as well as the fumigation treatment. Overall, combining ASD with an herbicide had no negative impacts on crop production and resulted in improved weed control.

Hairy Vetch Becomes an Alternative Basal N Fertilizer in Low-input Fresh-market Tomato Production in a Plastic High Tunnel

Hairy Vetch Becomes an Alternative Basal N Fertilizer in Low-input Fresh-market Tomato Production in a Plastic High Tunnel