Ministry of Agriculture issues technology for preventing cold dew wind damage and promoting early maturity of double-cropping late rice in the south

Rice Expert Steering Group of the Ministry of Agriculture

National Agricultural Technology Extension Service Center

(July 31, 2014)

At present, the early rice harvest is nearing completion, and the transplanting of double-cropping late rice has entered the peak period. Affected by low-temperature, overcast, rainy and low-light weather, the maturity period of early rice in some areas of the middle and lower reaches of the Yangtze River has been delayed, affecting the timely transplanting of the subsequent late rice crop. In view of the possible occurrence this year of a moderate-or-higher-intensity El Nino event, low temperatures and excessive rain in autumn in the south, and the increased risk of cold dew wind overlapping with disease and insect damage, which affects the safe maturity of late rice, the Ministry of Agriculture organized experts to formulate technical guidance for field management of double-cropping late rice in the south, emphasizing the focus on “transplanting in good time to promote early development, scientific fertilization to promote early maturity, and strengthening disaster resistance to secure a good harvest”, so as to effectively strengthen field management and strive for a good late rice harvest.

(1) Transplant in good time, and use dense planting to compensate for delay. Most late rice currently planted consists of indica rice varieties with strong temperature sensitivity and little flexibility in seedling age; transplanting beyond the proper seedling age easily causes stunted seedlings that fail to develop. For fields that cannot be transplanted in time because of delayed early rice harvest, all localities should transplant in good time, use dense planting to compensate for delay, and establish sufficient basic seedlings to prevent insufficient panicle number caused by reduced tillering. For seedling-throwing fields where seedlings have been scattered by heavy rain, timely transplanting from dense areas to fill sparse areas should be carried out. For late rice fields where seedlings have been destroyed by rainfall and timely transplanting cannot be carried out, dryland grain crops such as miscellaneous grains, miscellaneous beans and tuber crops should be replanted as soon as possible to prevent the land from being left abandoned.

(2) Fertilize rationally to increase panicles and preserve grains. Apply tillering fertilizer early, appropriately increase the proportion of tillering fertilizer, and raise the amount of basal fertilizer and tillering fertilizer to 75% of the total fertilization amount. Generally, apply tillering fertilizer 3-5 days after transplanting at 5-7 kg of urea per mu to promote early growth and rapid development. Skillfully apply panicle fertilizer: when the second leaf from the top emerges and the top leaf tips appear, apply 2-3 kg of urea per mu to promote strong stems and large panicles. Supplement grain fertilizer: for fields with smaller populations, during the flowering and grain-filling stage, apply 2-3 kg of urea per mu, or use 1.5-2 kg of urea plus 150-200 g of potassium dihydrogen phosphate sprayed on the leaves after dilution with water, to prevent premature senescence and promote grain filling and maturity.

(3) Manage water scientifically to promote roots and prevent lodging. Follow the principles of shallow-water transplanting, deep-water establishment, shallow-water tillering promotion, and alternating wet and dry conditions to carry out field water management. For transplanted rice, maintain a shallow water layer within 15 days after transplanting to promote tillering. For seedling-throwing fields, use intermittent shallow water to promote seedling establishment; after establishment, adopt moist management with periodic exposure of the field to promote tillering and root development. Drain the field at the proper time to control the population: for transplanted fields with low fertility and weak seedlings, drain lightly and expose appropriately; for those with high fertility and vigorous seedlings, drain somewhat more heavily. For plowed seedling-throwing fields, drain earlier and more heavily as appropriate; for no-till seedling-throwing fields where establishment is relatively late, drain more often and lightly. After field draining is completed, rewater in time and adopt alternating irrigation with dry and wet conditions to promote root development and enhance the plant's lodging resistance. Stop water 5-7 days before harvest, and strictly prevent stopping water too early.

(4) Move the threshold forward to prevent disease and control insects. Closely monitor the dynamics of rice diseases and insect pests, focusing on the control of major migratory and epidemic diseases and pests such as rice planthopper, rice leaf roller, rice blast and sheath blight, scientifically select appropriate pesticides, and carry out emergency control and unified control at the proper time. For rice planthopper control, emphasize “suppressing the early to control the later”, select pesticides such as etofenprox, pymetrozine and nitenpyram at the peak of young nymphs, and apply by spraying to strictly prevent outbreak and disaster during the panicle stage. For stem borers and rice leaf roller, select pesticides such as chlorantraniliprole, tetrachlorantraniliprole and metaflumizone, focus on protecting functional leaves, and according to the principle of “loose earlier and tight later, apply when the threshold is reached”, control the main damaging generation in the middle and late stages of rice. For rice blast and rice false smut, focus on implementing preventive measures at the breaking and heading stage; for sheath blight, focus on control at the peak tillering stage and jointing stage; use high-content single agents as much as possible, avoid high-content compound agents, prevent the development of pesticide resistance, and improve control efficiency.

(5) Respond early and guard against “autumn cold”. In view of the increased probability this year of low temperature, overcast rain and cold dew wind in southern rice areas, preventive plans should be formulated early, and on the basis of doing a good job in promoting early development in the earlier period, technical and measure preparations for response in the later period should be made in advance. For fields that have not yet headed when the cold dew wind arrives, irrigate with deep water to protect the “booting” stage; for those that develop more slowly and have already begun heading before the cold dew wind arrives, combine foliar spraying of potassium dihydrogen phosphate with an appropriate amount of “920” to promote earlier heading; for rice fields that are at the heading and flowering stage when the cold dew wind arrives, irrigate with deep water to preserve warmth and resist cold, and where conditions permit spray a warming agent to enhance cold resistance, reduce low-temperature damage, and ensure safe full heading.