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Diurnal Release of Airborne Pathogen Spores in Greenhouses via the Synergistic Effects of Relative Humidity and Wind

Summary

In greenhouses, cucumber and vegetable diseases spread explosively due to the combined effects of changing humidity and wind. This research reveals that when humidity drops during the day, fungal spores shrink and detach from diseased leaves through jerking movements. Even gentle wind can carry these detached spores to healthy nearby plants, causing rapid disease spread. By understanding this mechanism, farmers can implement better disease control by managing humidity and ventilation strategically.

Background

Greenhouse vegetable cultivation faces increasing disease severity due to rapid pathogen spread in semiclosed environments. While humidity and wind are known to affect fungal spore dispersal, the cellular mechanisms underlying spore release remain poorly understood. This study examines how daily humidity fluctuations and wind synergistically drive explosive greenhouse epidemics.

Objective

To elucidate the mechanisms of Corynespora cassiicola spore detachment and dispersal in greenhouses by investigating how relative humidity changes trigger spore release and how wind facilitates pathogen spread. The study aims to identify cellular mechanisms and environmental thresholds governing spore transmission.

Results

Spores undergo jerking movements and detach when relative humidity drops below ~52%, with connection strength between spores 10-fold stronger at 100% RH than at 53.5% RH. Wind speeds as low as 0.5 m/s facilitate spore dispersal, with dispersal distance increasing with wind speed, duration, and spore source height. Similar humidity-dependent jerking behavior was observed across multiple hyphomycete species. Disease transmission required both humidity fluctuation and wind; wind alone or constant humidity without wind did not produce disease spread.

Conclusion

The synergistic effects of diurnal humidity fluctuations and wind drive rapid pathogenic spore dispersal in greenhouses. This mechanistic understanding enables development of targeted disease management strategies including timed ventilation protocols and localized dehumidification systems that maintain humidity above the 52% release threshold during high-risk periods.
  • Published in:Advanced Science,
  • Study Type:Experimental Laboratory Study,
  • Source: PMC12225011, PMID: 40349151, DOI: 10.1002/advs.202501500
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