Bradbrook - 2012 - Rice Farming complete with methods to increase ric

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a. Water management Alternately flooding and draining the riee field is a good practice to discourage insects that inhabit the soil, viral diseases, and virus vectors. b. Weed management Weeds can be either good or bad for rice plants. Many weeds act as alternate hosts of pests and pathogens, but they also provide shelter to beneficial insects that are natural enemies of insect pests. The best course of action to take in terms of weed management is to remove weeds that grow within the rows of plants but allow weeds to grow near the rice field to serve as habitats for natural enemies of pests. c. Fertilizer management As previously mentioned, avoid providing too much nitrogen as this encourages heavy growth that attract insect pests. d. Biological control Although insect infestation might convince farmers to spray pesticides, it is not advisable because pesticides indiscriminately kill all insects. In the process, beneficial insects such as natural parasites and predators of the target insect pest are also eradicated. Furthermore, eradicating one insect pest might leave an opening for another insect (i.e. secondary pest) to attack the plants. Following proper cultural management practices is the best course of action to take. e. Planting time Planting at the earliest possible time is more desirable than planting later when insect population is higher. f. Cropping pattern It is better to plant the entire rice-growing area at the same time than leave gaps in the schedule of planting. If rice plants in one field mature earlier than those in another field, insect pests can relocate to that other field and continue their damage. The result is higher yield losses over a wider area from insect pests. 5. Disease management The most damaging diseases attacking rice plants are sheath blight, blast, stem rot, bacterial panicle blight, grain smuts, the Cercospora complex, seed rot, and water mold. 39
Combating disease attack involves host resistance (disease-resistant varieties), cultural management practices, and chemical control. As with insect pests, disease prevalence differs by region. It is better to check with local agricultural authorities regarding which diseases are prevalent in the area where rice will be grown. Planting resistant varieties is the first line of defense in crop protection when it comes to disease management. No single rice variety has resistance to all or most diseases, but new varieties with improved resistance to many diseases have been bred. Crop rotation is one method to break the cycle of disease infestation but it is possible only in upland rice culture: when disease outbreak occurs in one season, it is advisable to plant a different crop in the next growing cycle to prevent the outbreak from spreading. When a disease outbreak occurs, using chemical control is the best way to limit crop damage. But application of pesticides should be a last resort because, as with insect pests, fungi and bacteria develop resistance to chemicals used in their control. Early detection and targeted use of chemicals is the best approach to take in controlling diseases. Major diseases in rice plants The two major diseases in rice are leaf sheath blight and rice blast. Management practices for both diseases are similar: plant varieties that show at least moderate resistance, avoid planting late in the season, and do not apply too much nitrogen fertilizer. a. Sheath blight Causal fungi: Rhizoctonia solani Sheath blight usually attacks the rice plant from the intemode elongation phase (during the vegetative stage) to the ripening stage. The pathogen is spread through the field during flooding and the first signs of infection appear on the stems along the water line. Symptoms appear as brown oval lesions on the stem that can spread through the entire plant except the roots. High nitrogen rates result in thick stands and thicker canopies which increase moisture levels in the plant thereby encouraging the development of the disease. The rice field should be inspected from intemode elongation to heading stage for signs of blight infestation. To
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Bradbrook - 2012 - Rice Farming complete with methods to increase ric

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