REMOTE-SENSING FOR CROP PROTECTION

Research and technological advances in the field of remote sensing hav e greatly enhanced our ability to detect and quantify physical and bio logical stresses that affect the productivity of agricultural crops. R eflected light in specific visible, near- and middle-infrared regions of the electromagnetic spectrum have proved useful in detection of nut rient deficiencies, disease, and weed and insect infestations. Multisp ectral vegetation indices derived from crop canopy reflectances in rel atively wide wavebands can be used to monitor the growth response of p lants in relation to measured or predicted climate variables. Any devi ation from the expected seasonal pattern signals a potential problem a nd warrants further investigation by agricultural resource managers. T he thermal infrared acquired from aircraft or satellite platforms can identify areas susceptible to frost damage, quantify crop water stress and provide some previsual discase detection capabilities. Continued research is needed to quantify the relationship between crop stress an d remotely sensed parameters. Techniques need to be developed to imple ment surveillance over large areas and deliver relevant information to growers and consultants in time for preventative action to be taken.