A multi-point aggregation trend of the outbreak of pine wilt disease in China over the past 20 years

BACKGROUND: Aerial application, a spraying method with aircraft as the application platform, is one of the most important methods of pest control in pine forests. This work aimed to investigate the movement and distribution patterns of droplets and the pest control effectiveness of helicopter spraying on Masson pine (MP) and Korean pine (KP) trees. In particular, three nozzle types (CP02, CP03 and CP04) were evaluated and compared at the same spray volume rate (15 L ha −1 ) in both wind tunnel and field trials.RESULTS: The CP04 nozzle with a larger orifice size showed significantly better deposition and penetration, but the precision of flight operation parameters must be strictly controlled when using this type of nozzle. The majority (≥48%) of the droplets produced by the three nozzle types were concentrated in the range of <200 ∼m, and the spray performance of each nozzle type was more stable in the range 201-300 ∼m. The final pest correction control rate (CR) of MP was in the range 59.24-95.74% and that of KP was 45.41-54.39% by helicopter spraying.CONCLUSION: This study confirmed that it is necessary to select the appropriate nozzle type and ensure accurate flight parameters for aerial application in mountain pine forests. Meanwhile, it also confirms the importance of the timing of operation which can lead to incorrect implementation, resulting in poor control effectiveness.

Section: Resultsmentioning

confidence: 55%

Section: Distribution Characteristics Of Droplet Sizementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Droplet deposition and pest control efficacy on pine trees from aerial application

Yao

Guo

Wang

et al. 2022

“…Pine wilt disease (PWD) is a dangerous and destructive disease in global forest ecosystems that has strong diffusion. 1 The pinewood nematode (PWN), Bursaphelenchus xylophilus, is an invasive species that originated in North America and has spread to Asia and Europe. 2 After being infected with PWN, pine trees die quickly and infect other pine trees through Monochamus insects.…”

Section: Introductionmentioning

confidence: 99%

Selenium nanoparticles are effective in penetrating pine and causing high oxidative damage to Bursaphelenchus xylophilus in pine wilt disease control

Shang

Zhang

Zhao

et al. 2022

BACKGROUND: Research on selenium nanoparticles (SeNPs) in chemical defense and chemotherapy of plants has developed rapidly owing to their high microbial toxicity, environmental safety, and degradability. Pine wilt disease (PWD) threatens pine forests worldwide; however, it is difficult to kill the nematodes (Bursaphelenchus xylophilus) inside the tree that cause PWD using traditional pesticide formulations. SeNPs could be the key to controlling PWD.RESULTS: In this study, approximately 50 nm SeNPs were prepared using a simple and green method, and chitosan was used to increase their biocompatibility and stability. The preparation and characterization results showed that the prepared SeNPs coated with chitosan (SeNPs@CS) were spherical and evenly dispersed. The bioassay results showed that SeNPs@CS had an LC 50 of 15.627 mg L −1 against B. xylophilus. In addition, the killing mechanism of SeNPs@CS against B. xylophilus was studied. Confocal microscopy and transmission electron microscopy demonstrated that B. xylophilus were killed by reactive oxygen species, and the penetration of nano-form materials to B. xylophilus was higher than that of non-nano-form materials. To verify the effective penetration of SeNPs in pine tissues, Cy5-labeled SeNPs@CS was observed inside pine needles and branches using frozen sections and confocal microscopy. In addition, the cytotoxicity of SeO 2 and SeNPs@CS was tested, and the results showed that the cytotoxicity of SeNPs@CS to MC3T3-E1 cells was reduced.CONCLUSION: These results show that SeNPs are expected to be used as a new strategy for the control of PWD with oxidative damage and high penetration to B. xylophilus and effective target penetration and biosafety.

Impact of stand‐ and landscape‐level variables on pine wilt disease‐caused tree mortality in pine forests

Zhan

Ren

et al. 2023

BACKGROUND: Pine wilt disease (PWD) outbreaks have affected extensive areas of South China's forests, but the factors explaining landscape patterns of pine mortality are poorly understood. The objective of this study was to determine the relative importance of stand structure, topography, landscape context, and beetle pressure in explaining PWD severity. During 2020-2021, we identified 66 plots based on mapped PWD infestation severity. We built PWD infestation maps for 2019-2021 through field surveys. Stand structure and topography were obtained from Forest Resources Management 'One Map' and elevation raster data. We then used 'One Map' and PWD infestation maps to determine landscape context and beetle pressure variables at different spatial scales. The relative importance of 12 explanatory variables was analyzed using multi-model inference.RESULTS: In this study, we show that: (i) 1 km was the best spatial scale related to pine mortality, and (ii) models including landscape context and beetle pressure were much better at predicting pine mortality than models using only stand-level variables.CONCLUSION: Landscape-level variables, particularly beetle pressure, were the most consistent predictors of subsequent pine mortality within susceptible stands. These results may help forest managers identify locations vulnerable to PWD and improve existing strategies for outbreak control.