Abstract
In general, leaf wetness duration (LWD) is a key parameter influencing plant disease epidemiology, since it provides the free water required by pathogens to infect foliar tissue. LWD is used as an input in many disease warning systems, which help growers to decide the best time to spray their crops against diseases. Since there is no observation standard either for sensor or exposure, LWD measurement is often problematic. To assess the performance of electronic sensors, LWD measurements obtained with painted cylindrical and flat plate sensors were compared under different field conditions in Elora, Ontario, Canada, and in Piracicaba, São Paulo, Brazil. The sensors were tested in four different crop environments—mowed turfgrass, maize, soybean, and tomatoes—during the summer of 2003 and 2004 in Elora and during the winter of 2005 in Piracicaba. Flat plate sensors were deployed facing north and at 45° to horizontal, and cylindrical sensors were deployed horizontally. At the turfgrass site, both sensors were installed 30 cm above the ground, while at the crop fields, the sensors were installed at the top and inside the canopy (except for maize, with a sensor only at the top). Considering the flat plate sensor as a reference (Sentelhas et al. Operational exposure of leaf wetness sensors. Agric For Meteorol 126:59–72, 2004a), the results in the more humid climate at Elora showed that the cylindrical sensor overestimated LWD by 1.1–4.2 h, depending on the crop and canopy position. The main cause of the overestimation was the accumulation of big water drops along the bottom of the cylindrical sensors, which required much more energy and, consequently, time to evaporate. The overall difference between sensors when evaporating wetness formed during the night was around 1.6 h. Cylindrical sensors also detected wetness earlier than did flat plates—around 0.6 h. Agreement between plate and cylinder sensors was much better in the drier climate at Piracicaba. These results allow us to caution that cylindrical sensors may overestimate wetness for operational LWD measurements in humid climates and that the effect of other protocols for angling or positioning this sensor should be investigated for different crops.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Armstrong R, Barthakur NN, Norris E (1993) A comparative study of three leaf wetness sensors. Int J Biometeorol 37:7–10
Barr A, Gillespie TJ (1987) Maximum wetness duration for water drops on leaves in the field. Agric For Meteorol 41:267–274
Bathakur NN (1985) A comparative study of radiometric and electronic leaf wetness sensors. Agric For Meteorol 36:83–90
Camargo AP, Sentelhas PC (1997) Performance evaluation of different potential evapotranspiration estimating methods in the state of São Paulo, Brazil. Braz J Agrometeorol 5:89–97
Davis DR, Hughes JE (1970) A new approach to recording the wetting parameter by the use of electrical resistance sensors. Plant Dis Rep 54:474–479
Geisler LJ, Horst GL, Yuen GY (1996) A site-specific sensor for measuring leaf wetness duration within turfgrass canopies. Agric For Meteorol 81:145–156
Getz RR (1991) Report on the measurement of leaf wetness. WMO–CIMO 10p
Gillespie TJ, Kidd GE (1978) Sensing duration of leaf moisture retention using electrical impedance grids. Can J Plant Sci 58:179–187
Gillespie TJ, Duan R-X (1987) A comparison of cylindrical and flat plate sensors for surface wetness duration. Agric For Meteorol 40:61–70
Gillespie TJ, Srivastava B, Pitblado RE (1993) Using operational weather data to schedule fungicide sprays on tomatoes in Southern Ontario, Canada. J App Meteorol 32:567–573
Highes RN, Brimblecombe P (1994) Dew and guttation: formation and environmental significance. Agric For Meteorol 67:173–190
Huber L, Gillespie TJ (1992) Modeling leaf wetness in relation to plant disease epidemiology. Annu Rev Phytopathol 30:553–577
Jacobs AFG, Heusinkveld BG, Klok EJ (2005) Leaf wetness within a lily canopy. Meteorol Appl 12:193–198
Jacobs AFG, Heusinkveld BG, Kruit W, Berkowicz SM (2006) Contributing of dew to the water budget of a grassland area in the Netherlands. Water Resour Res 42:W03415, DOI 10.1029/2005WR004055
Lau YF, Gleason ML, Zriba N, Taylor SE, Hinz PN (2000) Effects of coating, deployment angle, and compass orientation on performance of electronic wetness sensors during dew periods. Plant Dis 84:192–197
Madeira AC, Kim KS, Taylor SE, Gleason ML (2002) A simple cloud-based energy balance model to estimate dew. Agric For Meteorol 111:55–63
Magarey RD (1999) A theoretical standard for estimation of surface wetness duration in grape. PhD Dissertation. Cornell University, Ithaca, NY, USA
Magarey RD, Seem RC, Russo JM, Zack JW, Waight KT, Travis JW, Oudemans PV (2001) Site-specific weather information without on-site sensors. Plant Dis 85:1216–1226
Malek E, McCurdy G, Giles B (1999) Dew contribution to the annual water balances in semi-arid desert valleys. J Arid Environ 42:71–80
Miranda RAC, Davie TD, Cornell SE (2000) A laboratory assessment of wetness sensors for leaf, fruit and trunk surfaces. Agric For Meteorol 102:263–274
Pedro Jr MJ (1980) Relation of leaf surface wetness duration to meteorological parameters. Ph.D. dissertation. University of Guelph, Guelph, ON, Canada
Rosenberg NJ, Blad BL, Verma SB (1983) Microclimate–The Biological Environment. John Wiley and Sons, Inc., New York, p 495
Schuepp PH (1989) Microstructure, density and wetness effects on dry deposition to foliage. Agric For Meteorol 47:179–198
Sentelhas PC, Gillespie TJ, Gleason ML, Monteiro JE, Helland ST (2004a) Operational exposure of leaf wetness sensors. Agric For Meteorol 126:59–72
Sentelhas PC, Monteiro JE, Gillespie TJ (2004b) Electronic leaf wetness duration sensor: why it should be painted. Int J Biometeorol 48:202–205
Sentelhas PC, Gillespie TJ, Batzer JC, Gleason ML, Monteiro JE, Pezzopane JR, Pedro MJ (2005) Spatial variability of leaf wetness duration in different crop canopies. Int J Biometeorol 49:363–370
Sharma ML (1976) Contribution of dew in the hydrological balance of a semi-arid grassland. Agric Meteorol 17:321–331
Smith CA, Gilpatrick JD (1980) Geneva leaf-wetness detector. Plant Dis 64:286–288
Wei YQ, Bailey BJ, Stenning BC (1995) A wetness sensor for detecting condensation on tomato plants in greenhouses. J Agric Eng Res 61:197–204
Weiss A, Hagen AF (1983) Further experiments on the measurements of leaf wetness. Agric Meteorol 29:207–212
Weiss A, Lukens DL (1981) Electronic circuit for detecting leaf wetness and comparison of two sensors. Plant Dis 65:41–43
Weiss A, Lukens AF, Steadman JR (1988) A sensor for the direct measurement of leaf wetness: construction techniques and testing under controlled conditions. Agric For Meteorol 43:241–249
Willmott CJ, Akleson SG, Davis RE, Feddema JJ, Klink KM, Legates DR, O’donnell J, Rowe CM (1985) Statistics for the evaluation and comparison of models. J Geoph Res 90:8995–9005
Acknowledgment
The authors wish to thank Ontario Weather Network, from Ridgetown College of the University of Guelph, and Prof. Mark Gleason, from Iowa State University, for providing the LWD sensors used in this study. The experiments of this project comply with current laws of the Brazilian and Canadian governments.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Sentelhas, P.C., Gillespie, T.J. & Santos, E.A. Leaf wetness duration measurement: comparison of cylindrical and flat plate sensors under different field conditons. Int J Biometeorol 51, 265–273 (2007). https://doi.org/10.1007/s00484-006-0070-7
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00484-006-0070-7