In New York, organic production of muskmelon (Cucumis melo) and other cucurbits is limited by pests, diseases, and weeds. Among the most important pests are striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata howardi) cucumber beetles that cause damage through feeding. Cucumber beetles also transmit the bacterium, Erwinia tracheiphila, the causal agent of bacterial wilt. Mesotunnels are a modified row cover system consisting of nylon mesh netting supported by hoops approximately 1-m high, which have potential for incorporation into organic muskmelon production systems. The netting is an effective barrier for pests and insect-vectored diseases and also prevents insect-mediated pollination and in-season weed management in inter-bed areas. Two separate experiments were conducted in 2021 and 2022 to: (a) evaluate mesotunnels for organic muskmelon production and methods to control weeds in inter-bed areas (experiment 1), and (b) evaluate selected pollination treatments for integration into a mesotunnel production system (experiment 2). In experiment 1, there were four treatments: (i) landscape fabric in the inter-bed area with a mesotunnel, (ii) landscape fabric in the inter-bed area without a mesotunnel, and a (iii) ryegrass/white clover in the inter-bed area with a mesotunnel; or (iv) ryegrass cover crop in the inter-bed area with a mesotunnel. In experiment 1, mesotunnels significantly reduced cucumber beetle populations and bacterial wilt epidemic progress but did not affect the incidence of the foliar diseases, powdery mildew, or Alternaria leaf spot. In the mesotunnel and non-covered treatments, landscape fabric, applied for weed control between beds, resulted in greater fruit weight and more marketable fruit compared to mesotunnels with cover crops in the inter-bed area. In experiment 2, treatments were on/off/on (removal of netting during flowering followed by replacement), open ends (open ends during flowering), and a closed mesotunnel (with the insertion of a commercial bumblebee hive). Although the on/off/on treatment increased cucumber beetle populations and bacterial wilt epidemic progress compared to the open ends and closed treatments, it conferred significant yield benefits in both years. These findings emphasize the importance of systems-level analysis for evaluating the suitability of mesotunnels in organic muskmelon production.

Tobacco (Nicotiana tabacum L.) bacterial wilt, caused by Ralstonia solanacearum, is indeed a highly destructive plant disease, leading to substantial damage in tobacco production. While biological control is considered an effective measure for managing bacterial wilt, related research in this area has been relatively limited compared to other control methods. In order to discover new potential antagonistic bacteria with high biocontrol efficacy against tobacco bacterial wilt, we conducted an analysis of the microbial composition differences between disease-suppressive and disease-conducive soils using Illumina sequencing. As a result, we successfully isolated six strains from the disease-suppressive soil that exhibited antibacterial activity against Ralstonia solanacearum. Among these strains, B4-7 showed the strongest antibacterial activity, even at acidic conditions with a pH of 4.0. Based on genome analysis using Average Nucleotide Identity (ANI), B4-7 was identified as Bacillus velezensis. In greenhouse and field trials, strain B4-7 significantly reduced the disease index of tobacco bacterial wilt, with control efficiencies reaching 74.03% and 46.88% respectively. Additionally, B4-7 exhibited plant-promoting abilities that led to a 35.27% increase in tobacco production in field conditions. Quantitative real-time (qPCR) analysis demonstrated that strain B4-7 effectively reduced the abundance of R. solanacearum in the rhizosphere. Genome sequencing and Liquid Chromatography-Mass Spectrometry (LC-MS) analysis revealed that strain B4-7 potentially produces various lipopeptide metabolites, such as microlactin, bacillaene, difficidin, bacilysin, and surfactin. Furthermore, B4-7 influenced the structure of the rhizosphere soil microbial community, increasing bacterial abundance and fungal diversity, while also promoting the growth of different beneficial microorganisms. In addition, B4-7 enhanced tobacco's resistance to R. solanacearum by increasing the activities of defense enzymes, including superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO). Collectively, these findings suggest that B. velezensis B4-7 holds significant biocontrol potential and can be considered a promising candidate strain for eco-friendly management of tobacco bacterial wilt.