After rice is flooded, attention must be paid to the three prevention measures

From mid-to-late June to mid-to-late July, southern regions are often hit by heavy rain, and some areas are prone to flooding disasters. If flooding occurs, in addition to carrying out conventional remedial measures, attention must also be paid to preventing outbreaks of bacterial diseases and mass outbreaks of migratory pests.

Prevent the spread of bacterial brown stripe disease. As floodwaters overflow, the pathogen spreads and is transmitted and infects through wounds on rice plants caused by rain and floodwaters. The resistance of submerged rice plants declines, which is more conducive to disease spread. There is a process from after flooding to disease spread, therefore, middle-season rice and single-crop late rice in flooded areas must be inspected frequently, and one must not be negligent. In mid-June 2003, in villages such as Tuziping in Niangxi, Xinshao County, heavy rain fell continuously. After the heavy rain, plots of late-maturing middle-season rice in the village developed bacterial brown stripe disease, and the heart leaves of some late-maturing middle-season rice turned yellow and curled, showing "dead heart seedlings." Some farmers treated them as stem borers, but the result was of no avail. Unlike stem borers, dead heart seedlings caused by bacterial brown stripe disease have no insect holes, no insect frass, and no insects can be found; the base is yellow, withered, and rotting, with a foul odor. The entire plant is affected and grows slowly, and severely affected plants die entirely. These are the symptoms often seen when damage occurs at the tillering stage; when disease occurs at the seedling stage, it often appears as water-soaked green stripes on the leaf base or leaf sheath, which later turn light yellow and extend up and down along the leaf veins, finally gradually becoming dark brown long stripes; when disease occurs at the heading stage, brown stripes or heart rot appear on the flag leaf and the 1-2 leaves below it and the leaf sheath. Diseased plants head 3-5 days earlier than healthy plants and are noticeably taller than healthy plants. Brown stripes appear on the panicle neck, and in severe cases the panicle neck turns brown in segments above and below, forming blighted panicles, and some or all of the branchlets turn brown and curve, becoming deformed panicles, unfilled, and sometimes showing half-exserted panicles or dead embryo phenomena. All diseased plants can produce yellow-white bacterial ooze when humidity is high, and when the disease is severe there is a fishy odor in the field. To control bacterial brown stripe disease, on the basis of draining water and exposing the field, choose 20% Yeqingshuang 600-800 times solution or 5% Junduqing 300-400 times solution for spraying, once every 5-7 days, for 2-3 consecutive times.

Prevent the spread of bacterial leaf streak after heavy rain. Heavy rain is often accompanied by strong winds that cause a large number of wounds on rice plants, which is conducive to pathogen invasion; high temperature promotes lesion expansion, while high humidity is conducive to pathogen spread. When disease occurs, yellow-brown stripes form between the leaf veins of the leaves, can reach more than 1 cm in length, are semi-transparent against light, and have many waxy yellow bacterial ooze on the lesions. To control this disease, prevent continuous irrigation. When disease occurs, use 20% Yeqingshuang 600-800 times solution and 5% Junduqing 300-400 times solution alternately, generally applying 2 times, once every 5-7 days, and also control white blight.

Prevent sudden increases in migratory pests. Third-generation and fourth-generation rice leaf roller larvae (often with overlapping generations) damage middle-season rice from the booting stage to the heading stage; third-generation brown planthopper (the main type of rice planthopper) damages rice in August. In addition to local insect sources, these two migratory pests also have insect sources that descend from the north to the south with wind and rain, especially with the inverted trough airflow during heavy rain. Therefore, during heavy rain, sudden increases in these migratory pests often occur. After heavy rain, close attention must be paid to investigation. When the leaf rolling rate at the tillering stage reaches 7%-9% and the leaf rolling rate at the booting stage reaches 5%-7%, use 5% Regent 600-800 times solution for spray control; when rice planthopper nymphs reach 1000-1500 per 100 hills, use 10% Yashijing (Yibianjing, Dagongchen, imidacloprid, Kangfuduo) 2500-3000 times solution for control.