Environment-Friendly Control of Cucumber Downy Mildew Using Chlorine Dioxide

Pseudoperonospora cubensis (downy mildew) is highly virulent to various Cucurbitaceae crops, including cucumber (Cucumis sativus). We tested chlorine dioxide application in a plastic greenhouse for environmentfriendly control of downy mildew disease. Spraying diluted chlorine dioxide suppressed downy mildew disease with 41.2% control efficacy. Thermal fogging with chlorine dioxide had a high control efficacy of 80.9%, confirming that this approach is useful for environment-friendly downy mildew control. Using thermal fogging to control diseases that are greatly affected by humidity, such as downy mildew, may be more effective compared with conventional dilution spray control methods.

Biocontrol of Large Patch Disease in Zoysiagrass (Zoysia japonica) by Bacillus subtilis SA-15: Identification of Active Compounds and Synergism with a Fungicide

Bacillus subtilis SA-15 is a plant growth-promoting bacterium isolated from non-farming soil. We aimed to identify lipopeptides produced by B. subtilis SA-15 and evaluate the control efficacy of B. subtilis SA-15 against large patch disease caused by Rhizoctonia solani AG 2-2 (IV) in zoysiagrass (Zoysia japonica). Bacillus subtilis SA-15 inhibited mycelial growth of R. solani AG 2-2 (IV) in vitro and produced fengycin A and dehydroxyfengycin A, which are antifungal compounds. Fengycin A and deghydroxyfengycin A inhibited R. solani mycelial growth by 30.4 and 63.2%, respectively. We formulated B. subtilis SA-15 into a wettable powder and determined its control efficiency against large patch in a field trial. The control efficacy was 51.2–92.0%. Moreover, when B. subtilis SA-15 powder was applied together with half the regular dose of the fungicide pecycuron, the control efficacy was 88.5–100.0%. These results indicate that B. subtilis SA-15 can be used to control soil-borne diseases, including large patch caused by R. solani, because of lipopeptide production. The use of this bacterium can also reduce the amount of fungicide needed, providing an eco-friendly management option for turfgrass.

Combination of yeast antagonists and Acibenzolar-S-Methyl reduced the severity of Fusarium head blight of wheat incited by Fusarium graminearum sensu stricto

The combination of yeast antagonists and Acibenzolar-S-Methyl (ASM) was tested against Fusarium graminearum on a spring wheat cultivar PAN3471. Two strains of Papiliotrema flavescens (Strains WL3 and WL6) and a strain of Pseudozyma sp. (MGO1) were combined with full strength ASM at anthesis, half strength ASM at anthesis and quarter strength ASM at late boot stages. The yeast and ASM treatments were applied prior to F. graminearum inoculation and disease progress was assessed over time. The combination of yeast and ASM treatments effectively reduced Fusarium Head Blight (FHB) severity and deoxynivalenol (DON) concentration compared to when the treatments were used alone. A positive correlation was observed between the Area Under Disease Progress Curve (AUDPC) and Percentage Seed Infection (PSI) (r = 0.44) whereas a negative correlation was observed between AUDPC and Hundred Seed Weight (HSW) (r = -0.77) and PSI and HSW (r = -0.44). The best combination treatment providing the highest reduction in final disease severity (41.83%), high HSW and moderate PSI was 0.075 g/l ASM at anthesis plus P. flavescens strain WL3. The highest DON reduction (19.35%) was by the treatment 0.075 g/l ASM at anthesis plus P. flavescens strain WL6. The best treatment was P. flavescens combined with 0.075 g/l ASM at anthesis. Although Pseudozyma sp. strain MGO1 did not provide the best FHB and DON reduction, its combination with ASM application improved disease control efficacy. To the best of our knowledge, this study presents the first report of the combination of P. flavescens and ASM in the management of FHB caused by F. graminearum in wheat plants.

Minimizing Occupational Exposure to Pesticide and Increasing Control Efficacy of Pests by Unmanned Aerial Vehicle Application on Cowpea

Pesticide operators are often exposed to high levels of contaminants, leading to potential adverse health impacts on these agricultural workers. In tropical regions, pesticide applicators are more vulnerable to dermal exposure than their counterparts in temperate regions. Thus, it is highly desirable to develop new spraying methods to minimize the pesticide exposure level without sacrificing the pest control efficiency. Due to their flexibility, high efficiency, and lower labor intensity, unmanned aerial vehicles (UAVs) have attracted considerable attention in precision pest management. However, the pesticide operator exposure assessment during the spraying application with UAVs, especially the comparison with conventional ground sprayers, has not been well investigated. In this work, the control effect against thrips on cowpea and operator exposure determination by aerial and ground spraying in Hainan Province were carried out and compared. When biopesticide spinetoram with the same dosage was applied, the field control efficacy against cowpea thrips sprayed by UAVs was higher than that of knapsack electric sprayers. Moreover, UAV spraying could greatly reduce water consumption and working time. For UAV spraying, when the amounts of water applied per hectare were 22.5, 30, and 37.5 L, the control effects on thrips on the first day were about 69.79%, 80.15%, and 80.58%, respectively. When Allura Red as a pesticide surrogate was applied under similar spraying scenarios with the field control against thrips on cowpea, the average total unit exposure of the knapsack operator (1952.02 mg/kg) was greatly higher than that of the UAV operator (134.51 mg/kg). The present research indicates that plant protection UAV is the direction of development of modern intensive sustainable agriculture.

Advanced Copper and Copper Alternatives for Crop Protection – a minireview

: Copper (Cu) has been used in agriculture for centuries as a standard bactericide/fungicide due to its low cost, superior disease control efficacy, and relatively low toxicity to humans. However, the extensive use of copper as a pesticide has caused the development of Cu-tolerant microorganisms as well as negative environmental impacts due to the accumulation of copper in soil and bodies of water. Therefore, there is a strong demand for advanced Cu products and alternatives to minimize the Cu footprint in the environment. This minireview will cover the limitations of Cu usage and the strategies being investigated to develop advanced Cu materials and alternatives for crop protection using nanotechnology.