Anthracnose disease caused by Colletotrichum spp. makes heavy losses for post-harvest mangoes of Cat Hoa Loc variety during storage, packaging, and transportation. The synthetic fungicides are commonly used to control the disease, but they are not safe for consumers’ health and environment. This study was aimed to investigate the use of essential oils (EOs) as the safe alternative control. Pathogen was isolated from the infected Cat Hoa Loc mangoes and identified by morphology and DNA sequencing of the ITS region. Six EOs (cinnamon, basil, lemongrass, peppermint, coriander, and orange) were chemically analyzed by GC–MS. The antifungal activity of EOs was studied in vitro and in vivo. The results showed that the isolated pathogen was Colletotrichum acutatum. Cinnamon, basil, and lemongrass EOs effectively inhibited the growth of C. acutatum in descending order of cinnamon, basil, and lemongrass. However, they (except basil oil) severely damaged fruit peels. The antifungal activity was closely related to the main compounds of EOs. Basil EOs effectively controlled anthracnose development on Cat Hoa Loc mangoes artificially infected with C. acutatum, and its effectiveness was comparable to that of fungicide treatment. Consequently, basil EOs can be used as a biocide to control anthracnose on post-harvest Cat Hoa Loc mangoes.

Bacterial leaf blight, which is caused by Xanthomonas axonopodis pv. allii, annually causes significant yield losses to Welsh onion in many producing countries, including Vietnam. In this study, we isolated and characterized lytic phages Φ16, Φ17A and Φ31, specific to X. axonopodis pv. allii and belonging to a new phage species and genus within the Autographiviridae, from four provinces in the Mekong Delta of Vietnam. Moreover, we evaluated their efficacy for the biocontrol of leaf blight in greenhouse and field conditions. When applying the three highly related phages individually or as a three-phage cocktail at 10⁸ PFU/mL in greenhouse conditions, our results show that treatment with Φ31 alone provides higher disease prevention than the two other phages or the phage cocktail. Furthermore, we compared phage concentrations from 10⁵ to 10⁸ and showed optimal disease control at 10⁷ and 10⁸ PFU/mL. Finally, under field conditions, both phage Φ31 alone and the phage cocktail treatments suppressed disease symptoms, which was comparable to the chemical bactericide oxolinic acid (Starner). Phage treatment also significantly improved yield, showing the potential of phage as a biocontrol strategy for managing leaf blight in Welsh onion.

A huge amount of orange peel waste is annually discharged into the environment. Processing of this waste for the control of post-harvest fruit diseases can reduce environmental pollution. Essential oils (EOs) from fruit peels of Citrus reticulata × sinensis (Sanh cultivar) and Citrus sinensis (Xoan, Mat and Navel cultivar) were investigated for their ability to control anthracnose caused by Colletotrichum gloeosporioides and Colletotrichum scovillei on mangoes. EOs were extracted by hydro-distillation and analyzed by GC-MS and GC-FID. The antifungal activity of the EOs was determined by in vitro and in vivo assays. The Mat cultivar had the highest extraction yield of 3% FW, followed by Xoan (2.9%), Sanh (2.2%), and Navel (1%). The chemical composition of the EOs was similar, with limonene as the main compound (around 96%). The antifungal activity of EOs was not different, with a minimum fungicidal concentration of 16% for both fungi. The disease inhibition of EOs increased with their concentration. The highest inhibition of anthracnose caused by both fungi on mangoes was achieved at 16% EO. EOs had no adverse effect on mango quality (pH, total soluble solids, total acidity, color and brightness of mangoes), except firmness and weight loss at high concentrations (16%). Orange EOs can be used as bio-fungicides to control mango anthracnose at high concentrations.

The study on the procedure of applicating bacteriophage (or phage) to prevent rice bacterial grain rot caused by Burkholderia glumae was conducted in the greenhouse conditions. The first experiment investigated the effect of different phage titers (i.e. 105 PFU/mL, 106 PFU/mL, 107 PFU/mL, 108 PFU/mL) in controlling bacterial grain rot of rice. The results showed that all four titers gave disease reduction with different levels, among these were the titer of 108PFU/mL expressed highest efficacy in disease reduction with the lowest percentage of infected grains compared to the rest treatments. The second experiment examined the effect of phage application times (i.e. spraying phage at 2 hours before pathogen inoculation, 2 hours before and 5 days after pathogen inoculation, and 5 days after pathogen inoculation) in suppressing bacterial grain rot disease. The results found that two treatments (i.e. one time spraying at 2 hours before pathogen inoculation, and two times spraying at 2 hours before and 5 days after pathogen inoculation) expressed high efficacy in reduction of grain rot disease through percentage of infected grains and improved yield parameter regarding rate of filled grains.

The objective of the study was selection promising bacteriophages for lysis Ralstonia solanacearum in vitro and evaluation their ability to prevent bacterial vascular wilt on eggplants under greenhouse conditions. Primary selection of promising bacteriophages from four bacteriophages as Φ54, Φ60, Φ67, and ΦBT on Ralstonia solanacearum isolated from eggplant based on plaque diameter and phage multiplication in in vitro, the result found that three bacteriophages (Φ54, Φ67, and ΦBT) expressed plaque diameter over 7.00 mm at 48 hours, and phage titer with log (pfu/ml) reach over 7.00. Continuing the survey, the efficacy of these phages in controlling bacterial wilt on eggplants in greenhouse conditions through applying each bacteriophage or cocktail of three phages suspension two times (1010 pfu/ pot/ each time) before pathogen inoculation and 7 days after pathogen inoculation through soil drenching. As a result, all bacteriophages either single or mixture of three phages were effective in the prevention of bacterial wilt disease. Especially, phage Φ BT showed the highest disease reduction and was better than bacteriocide treatment applied with Starner 20 WP.

Bệnh đạo ôn lúa là một trong những bệnh ảnh hưởng năng suất lúa nghiêm trọng tại Việt Nam.Trong nghiên cứu,vi khuẩn Bacillus 55, Bacillus 61 được sử dụng là vi khuẩn vùng rễ kích thích cây trồng tăng trưởng được phân lập từ vùng rễ lúa,được ghi nhận mang lại hiệu quả giảm bệnh đạo ôn thông qua xử lý ngâm hạt và tưới đất với vi khuẩn Bacillus 55,hoặc phun lá với vi khuẩn Bacillus 61.Nghiên cứu được tiến hành nhằm xác định hiệu quả của việc phối hợp hai chủng vi khuẩn này với tỷ lệ 1:1,trong phòng trị bệnh đạo ôn lá,đạo ôn cổ bông trên lúa thông qua các biện pháp xử lý ngâm hạt kết hợp tưới đất,hoặc phun lá,hoặc ngâm hạt kết hợp tưới đất,phun lá trong quản lý bệnh đạo ôn lá,phun vi khuẩn vùng rễ quản lý bệnh đạo ôn cổ bông.Kết quả cho thấy hỗn hợp vi khuẩn ở mật số tương ứng 106, 107 và 108 cfu/mL đều có hiệu quả phòng trị bệnh đạo ôn lá tương đương nhau.Tuy nhiên,các biện pháp xử lý hỗn hợp vi khuẩn vẫn chưa ghi nhận được sự khác biệt thống kê với nhau. Bên cạnh đó, kết quả ghi nhận hỗn hợp huyền phù vi khuẩn ở mật số 107 và 108cfu/mL có hiệu quả phòng trị bệnh đạo ôn cổ bông và duy trì năng suất tương đương so với các nghiệm thức có xử lý thuốc Beam 75 WP.