International Journal of Biometeorology

, Volume 49, Issue 6, pp 363–370 | Cite as

Spatial variability of leaf wetness duration in different crop canopies

  • Paulo C. Sentelhas
  • Terry J. Gillespie
  • Jean C. Batzer
  • Mark L. Gleason
  • José Eduardo B. A. Monteiro
  • José Ricardo M. Pezzopane
  • Mário J. PedroJr
Original Article


The spatial variability of leaf wetness duration (LWD) was evaluated in four different height-structure crop canopies: apple, coffee, maize, and grape. LWD measurements were made using painted flat plate, printed-circuit wetness sensors deployed in different positions above and inside the crops, with inclination angles ranging from 30 to 45°. For apple trees, the sensors were installed in 12 east-west positions: 4 at each of the top (3.3 m), middle (2.1 m), and bottom (1.1 m) levels. For young coffee plants (80 cm tall), four sensors were installed close to the leaves at heights of 20, 40, 60, and 80 cm. For the maize and grape crops, LWD sensors were installed in two positions, one just below the canopy top and another inside the canopy. Adjacent to each experiment, LWD was measured above nearby mowed turfgrass with the same kind of flat plate sensor, deployed at 30 cm and between 30 and 45°. We found average LWD varied by canopy position for apple and maize (P<0.05). In these cases, LWD was longer at the top, particularly when dew was the source of wetness. For grapes, cultivated in a hedgerow system and for young coffee plants, average LWD did not differ between the top and inside the canopy. The comparison by geometric mean regression analysis between crop and turfgrass LWD measurements showed that sensors at 30 cm over turfgrass provided quite accurate estimates of LWD at the top of the crops, despite large differences in crop height and structure, but poorer estimates for wetness within leaf canopies.


Dew Rainfall Microclimate Plant disease Warning systems 



This project was funded in part by a fellowship to the first author from CNPq, a Brazilian Government Institution (Proc. 202536/02-5), and by the United States Department of Agriculture. The first and sixth authors are supported by a fellowship from CNPq and the fourth and fifth from FAPESP. The authors wish to thank two anonymous reviewers for their constructive criticism and helpful comments. The experiments of this project comply with current laws of the Brazilian, Canadian, and American Governments


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Copyright information

© ISB 2005

Authors and Affiliations

  • Paulo C. Sentelhas
    • 1
  • Terry J. Gillespie
    • 2
  • Jean C. Batzer
    • 3
  • Mark L. Gleason
    • 3
  • José Eduardo B. A. Monteiro
    • 4
  • José Ricardo M. Pezzopane
    • 5
  • Mário J. PedroJr
    • 5
  1. 1.Agrometeorology Group, Department of Exact Sciences, ESALQUniversity of São PauloPiracicabaBrazil
  2. 2.Agrometeorology Group, Department of Land Resource Science, Ontario Agricultural CollegeUniversity of GuelphGuelphCanada
  3. 3.Department of Plant PathologyIowa State UniversityAmesUSA
  4. 4.Agrometeorology Group, Department of Physical Science, Agricultural College “Luiz de Queiroz”University of São PauloPiracicabaBrazil
  5. 5.Agrometeorology GroupAgronomic Institute of CampinasCampinasBrazil

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