Ajay Nair

Effectiveness of Broad-Spectrum Chemical Produce Sanitizers against Foodborne Pathogens as In Vitro Planktonic Cells and on the Surface of Whole Cantaloupes and Watermelons.

Over the past few years, foodborne disease outbreaks linked to enteric pathogens present on cantaloupe and watermelon surfaces have raised concerns in the melon industry. This research evaluated the effectiveness of commercially available produce sanitizers against selected foodborne pathogens, both in cell suspensions and on the outer rind surface of melons. The sanitizers (65 and 200 ppm of chlorine, 5 and 35% hydrogen peroxide, 5 and 50 ppm of liquid chlorine dioxide, various hydrogen peroxide-acid combinations, 0.78 and 2.5% organic acids, and 300 ppm of quaternary ammonium) were tested against Escherichia coli O157:H7, Listeria monocytogenes, Salmonella, and non-O157 Shiga toxin-producing E. coli (O26, O45, O103, O111, O121, and O145). The cell suspension study revealed the ability of all tested sanitizers to reduce all selected pathogens by 0.6 to 9.6 log CFU/ml in vitro. In the melon study, significant differences in pathogen reduction were observed between sanitizers but not between melon types. The most effective sanitizers were quaternary ammonium and hydrogen peroxide-acid combinations, with 1.0- to 2.2-log CFU/g and 1.3- to 2.8-log CFU/g reductions, respectively, for all pathogens. The other sanitizers were less effective in killing the pathogens, with reductions ranging from 0.0 to 2.8 log CFU/g depending on pathogen and sanitizer. This study provides guidance to the melon industry on the best produce sanitizers for use in implementing a broad-spectrum pathogen intervention strategy.

Biochar Rate and Transplant Tray Cell Number Have Implications on Pepper Growth during Transplant Production

Biochar, a carbon-rich material derived from the pyrolysis of organic matter, exhibits beneficial chemical and physical properties when added to a soilless medium. Research on the use of biochar to improve plant productivity and growth has increased over the past decade, and has focused on using biochar as an alternative to sphagnumpeatmoss.However, little work has been done to determine whether biochar can be used to partially replace commercially available sphagnum peatmoss–based greenhousemedium in vegetable transplant production. This study investigated the potential for supplementing a greenhouse growing medium with biochar for ‘Paladin’ pepper (Capsicum annuum) transplant production. Biochar was added to a soilless mix at rates of 0%, 20%, 40%, 60%, or 80% (by weight). Pepper seedlings were grown for 56 days in 50-, 72-, or 98-cell transplant trays at each of the five levels of biochar concentration. Germination increased in the 50and 72cell trays with 20%, 40%, and 60% biochar; however, biochar had no effect on germination in the 98-cell tray. Seedling height and dry weight decreased as biochar concentration and cell number increased. Seedling stem diameter also decreased with increasing cell number and biochar concentration. Leaf SPAD readings (indirect measurement of chlorophyll) decreased with increasing biochar rate. Medium pH increased with increasing biochar application rates. Higher rates of biochar (60% and 80%) increased pH well beyond 7.0 and negatively affected transplant growth. Overall results indicate positive effect of biochar in sphagnum peatmoss–based growing mix on seedling growth characteristics; although higher biochar concentrations could negatively affect seedling growth. Biochar can successfully replace up to 40% of sphagnum peatmoss–based growing medium and serve as a sustainable alternative medium in vegetable transplant production.

Composting, Crop Rotation, and Cover Crop Practices in Organic Vegetable Production

For nearly a decade, there has been an increased awareness toward food quality, health standards, and global environmental issues in our communities. In that context, adoption of organic production practices has been increasing rapidly in vegetable production. Organic farming is grounded in a holistic view of agriculture that aims to reflect a profound interrelationship between on-farm living biota, farm production, and the overall environment. Organic agriculture has emerged as a powerful tool in re-establishing production practices that are self-sufficient, promote biodiversity, and support practices that conserve soil, water, and the environment. Organic production systems utilize practices such as composting, crop rotation, and use of cover crops, all of which have a positive impact on soil physical, chemical, and biological properties. Although these practices are widely used, there is still uncertainty among growers when it comes to the actual process of composting, compost nutrient concentration and availability, use of compost in transplant mixes, and application rates. Similarly, other areas that need attention are crop rotation, sequence of crops within a rotation, and integration of cover crops in these rotations. Cover crops have an important role in reducing soil erosion, suppressing weeds, improving soil structure and water holding capacity, and increasing soil organic matter. This chapter will highlight the role of composting, use of compost, crop rotation, and cover crops in organic vegetable production systems. This chapter will discuss in detail the composting process, raw materials used, composting methods, quality assessment of compost, and potential avenues where compost can be used in organic vegetable production. The crop rotation portion of this chapter will highlight various crop rotation plans and strategies that growers could utilize to improve soil quality, break pest and disease cycles, and increase yields. The chapter will also provide information on cover crop types, their planting, management, benefits, and challenges in organic vegetable cropping systems. Organic production systems are complex and dynamic. Understanding techniques and practices that directly influence soil is critical in building a production system that is self-sustaining, strong, and resilient. A better understanding of such practices is of paramount importance to build, strengthen, and support organic vegetable production.

Principles and Practices of Sustainable Vegetable Production Systems

Our production systems are at a pivotal stage in terms of meeting consumer demand for affordable food while improving sustainability. Current intensive crop production practices designed to maximize yield have created an unstable, fragile, and non-sustainable production system. Such systems are prone to reduced soil quality, frequent insect and disease resurgence, emergence of resistant weed species, reduced food quality, and detrimental effects on the health and well-being of our communities. With increasing awareness among consumers of produce quality, nutritional value, methods of crop production and effects of production techniques on the environment, there has been a strong move to improve the quality of our production systems. Grower response to this change has been supportive. Growers have shown interest in developing resilient and stable production systems through the adoption of production practices that enhance soil health, crop productivity, and improve long-term farm sustainability and profitability. This chapter will highlight various production techniques, practices, and tools employed by vegetable growers to improve sustainability of their production systems. Such practices emphasize the use of natural processes within farming systems, often called ‘ecologically sound’ practices which build resilience through synergies and complementarities within the field, the farm, and across our landscape and communities. Some of the key practices include conservation (or reduced) tillage systems, cover cropping, crop diversity including crop rotations and intercropping, use of suitable crop cultivars, efficient water use, sound nutrient management plans, and integrated pest management. Sustainable production systems are complex and dynamic and can involve diverse number of production practices. This chapter will also illustrate inherent challenges and trade-offs that growers could face while adopting such practices.