How to manage water and fertilizer well after rice is hit by floods

What should be noted when righting and washing rice seedlings?

For flooded paddy fields, drain the standing water promptly and right the lodged seedlings; clear the ditches in time to lower the groundwater level. Where irrigation facilities have suffered heavy damage, organize forces promptly for emergency repairs. After the water in the paddy field recedes, open ditches to drain it, so that soil water in the field seeps into the ditches and is discharged, lowering the field moisture content as quickly as possible, so that the floating mud formed by flooding gradually settles and compacts, thereby promoting new root growth. For fields that have been submerged for a long time, the water can be drained off all at once in rainy weather; if there is scorching sun and high temperature, drain gradually, first letting the upper part of the rice plants emerge above the water surface, then dehydrating at night to aerate, and irrigating by day and exposing at night, so as to help the rice recover its growth.

Why is it emphasized that foliar topdressing should be carried out after flooding for double-cropping early rice?

At present, double-cropping early rice has entered the late growth stage of grain filling and ripening, and the physiological functions of leaves and roots are relatively weak; in addition, the rice plants have been submerged, and the vegetative organs have been damaged to varying degrees. Foliar topdressing helps the leaves absorb nutrients quickly, can maintain the leaves' functional period for a longer time, can prevent premature aging, raise the seed-setting rate, and increase the 1000-grain weight. For foliar topdressing, generally spray 150-200 grams of monopotassium phosphate per mu on the leaves; for those with lighter leaf color, 500-800 grams of urea can be added. Combined with pest and disease control, it can achieve twice the result with half the effort.

What should be noted in field management of middle and late rice after flooding?

During the period when rice is submerged, the vegetative organs of the rice plants are damaged to varying degrees. After emerging from the water, the roots, leaves, and tillers resume growth and need large amounts of mineral nutrients. In addition, much of the original fertilizer in the paddy field has been lost. Therefore, topdressing should be done quickly and in sufficient amount to promote the rice plants' recovery growth as soon as possible. For the production of middle and late rice after the disaster, carefully observe the growth process, growth vigor and appearance, leaf color, etc., and apply fertilizer and manage according to the seedlings.

First, for fields that have not yet entered panicle differentiation, apply panicle fertilizer at the 4th leaf from the top, with 6-8 kg each of urea and potassium chloride per mu. Second, for fields that have already entered panicle differentiation and whose leaf color has faded noticeably and turned bluish-yellow, as well as third-class seedlings, apply grain-filling fertilizer promptly, generally 3 kg each of urea and potassium chloride per mu. Third, after heading and flowering, carry out foliar topdressing, generally spraying 50 kg per mu of 0.5%-1% urea solution and 0.2%-0.3% monopotassium phosphate solution on the leaves. Fourth, for high-yield fields where the seedlings grow luxuriantly and appear deep green, no fertilizer should be applied, because excessive nutrient uptake by the seedlings will cause soft tissues, delayed maturity, susceptibility to pests and diseases, and easy lodging, and will also cause reduced yield. However, ditches must be opened promptly to drain the standing water, and wet irrigation should be practiced to reduce the field humidity of high-yield fields and improve the stress resistance and yield of rice.

What pests and diseases are likely to occur in rice after flooding?

After rice is submerged, the leaves are damaged, the plants' disease resistance is reduced, and the temperature and humidity in the field are suitable for the growth and spread of pests and diseases, which can easily cause major outbreaks of pests and diseases such as rice planthopper, rice leaf roller, rice stem borer, rice sheath blight, rice blast, and rice bacterial leaf streak, so special attention should be paid to their control.

How can the epidemic of rice bacterial leaf streak and bacterial leaf blight be prevented?

Spray pesticide at the early stage of disease onset. You can choose 20% zinc thiazole suspension concentrate 100-125 grams/mu, or 20% thiodiazole-copper suspension concentrate 100-130 grams/mu, or 20% bismerthiazol wettable powder 100-150 grams/mu.

How can rice sheath blight be controlled in the first season of ratoon rice?

All fields with a diseased clump rate of 15% are listed as target fields for pesticide spraying. Spray the first application 7 days before panicle emergence, and spray once more at full heading. For the pesticide, you can choose 5% validamycin aqueous solution 200 ml/mu, or 30% difenoconazole·propiconazole emulsifiable concentrate 15 ml/mu, or 24% thifluzamide suspension concentrate 13-23 ml/mu, and spray with 50-60 kg of water.

How can the control effect against the rice leaf roller be improved?

First, grasp the control timing. Spray pesticide during the peak of egg hatching to the second-instar larval stage, and applying pesticide in the evening gives the best effect.

Second, select the right pesticide. For example, 20% chlorantraniliprole suspension concentrate 10 ml/mu, or 15% indoxacarb emulsifiable concentrate 12-16 ml/mu, or 40% profenofos emulsifiable concentrate 80-100 ml/mu, or 1.8% abamectin emulsifiable concentrate 16-30 ml/mu; pyrethroid pesticides are prohibited.

Third, choose new plant protection machinery. New pesticide application equipment can reduce drifting, leaking, dripping, and spilling and improve the control effect. For example, "Guard" brand manual sprayers and mist sprayers.

Fourth, use sufficient water. When spraying pesticide, add enough water; manual sprayers should use at least 50 kg of water per mu, and mist sprayers should use no less than 25 kg of water per mu. During pesticide application, a water layer should be maintained in the field.