Monitoring Pests and Disease from Satellite data

Various factors such as intensive cultivation, monocropping, changing weather conditions and indiscriminate use of pesticides have resulted in frequent outbreaks of crop pests and diseases causing huge crop losses. Minimising these losses is one way of enhancing grain production and remote sensing tool has been found very useful in monitoring large areas frequently. The Earth observing systems are useful in monitoring weather and ecological conditions favourable for crop pests and diseases. Weather conditions such as temperature, humidity (moisture), sunshine hours (light) and wind play major influence on the densities of pest population and their natural enemies. Among the weather parameters that can be remotely sensed, type of cloud, extent of cloud cover, cold cloud duration (a surrogate for rainfall) are the most easily retrievable. Such information was used by phytopathologists to study rust diseases of wheat crop.

An aircraft fitted with a camera loaded with colour infrared films and flown over Kerala state (India), identified coconut areas severely affected by 'wilt' which could not be easily detected from the ground. This gave a clue to the area that could be viewed from satellite altitude.

Understanding the magnitude of crop losses is necessary to appreciate the importance of plant protection in crop production programmes. Losses can be due to biotic factors such as pests/diseases/weeds and abiotic factors such as drought, floods, cyclones and hailstorms. Damage caused by pests may be quantitative (overall reduction in yield), or qualitative such as change in colour and offensive odour. The regional disparities in crop condition assessment, the complex Centre-State relationships in handling relief measures and the introduction of crop insurance scheme, call for an unbiased, objective and timely information system to give early warning, to indicate the intensity of such hazards and to assess the loss.

FAO had organized an international training programme at National Remote Sensing Agency (NRSA) in India a decade ago, involving countries like India, Pakistan and Tanzania in the use of various remote sensing data to identify locust-breeding areas. The directorate of plant protection handles such issues. There is no proper information about the area affected by pests and diseases and other yield reducing factors on an all-India basis.

It is stated that the brown plant hopper (BPH) of rice is one of the dreaded insect pests in Asia. BPH is stated to be associated with synoptic weather conditions (depressions). Double cropping, extensive rice cultivation in the command area and indiscriminate use of fertilizers and pesticides aid the occurrence of BPH.

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