Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/30/2001
Publication Date: N/A
Citation: Interpretive Summary: Effective application of protective pesticides requires spray deposits at efficacious levels across a plant canopy. During most applications, it is difficult for the equipment operator to see how effectively the plant canopy has been treated. Unless the operator is following the application, it is not possible to observe the fate of spray on the canopy. Unprotected canopy will be at more risk for damage by insects or diseases. This study was designed to study the feasibility of detecting and quantifying leaf surface moisture content. Non-contact, non-destructive and quantitative techniques were used to provide information on leaf surface moisture. Spectral reflectance information was used as an indicator of leaf surface wetness and was correlated with contact sensing approaches. Tests and simulations found that leaf reflectance decreased with the addition of water spray onto the leaf surface. The development of a rapid, non-destructive technique for assessing leaf surface wetness provides a means of giving the spray equipment operator real-time feedback on the effectiveness of the application and will help operators make adjustments to spray applications to avoid over-spray or change application parameters to ensure better canopy spray coverage.
Technical Abstract: The objective of most pesticide applications is to provide as much deposit material on foliage in a manner that provides as much protection against pest damage as possible. Unprotected foliage may result in crop damage and may require follow-up treatments. No feedback systems or sensors are available currently that provide spray applicators with real-time assessment of their spraying practices. A rapid, non-contact, non-destructive and quantitative detection technique would help provide feedback that could be used to adjust equipment operation to improve the effectiveness of applications. Remote sensing techniques can be used to determine the water content of leaves. Spectral reflectance properties of leaves are a good indicator of the presences of spray droplets or water on leaf surfaces. Research with New Guinea impatiens leaves indicates that the presence of moisture on the surface of a leaf causes a change of spectral reflectance of the leaf surfaces. Results of using a radiative transfer computer model and sensor readings have been useful for interpreting whether or not leaves have intercepted spray droplets.