Identification and Control of Rice Black-streaked Dwarf Disease in South China

Rice black-streaked dwarf disease in southern China is a rice virus disease occurred in southern rice region, which has the characteristics of strong outbreak, rapid spread, difficult prevention and control, heavy damage and so on. After comprehensive prevention and control in 2011, a total of 8500 mu of rice black-streaked dwarf disease occurred in Lianyuan City, including 6500 mu of middle rice, 1600 mu of late rice and 400 mu of corn and other crops. A total of 25.93 tons of rice was lost, of which the most serious mound loss rate was less than 3%.

First, identify:

1. Typical symptoms

The main results are as follows: (1) the leaves of diseased rice plants are dark green, and uneven wrinkles can be seen on the upper leaves (mostly at the base of leaves).

(2) there are inverted fibrous roots and high node branches in the aboveground nodes of the diseased plant; there are milky tumor-like protuberances on the stem surface of the diseased plant (obvious roughness on the hand), which are longitudinally arranged in the shape of wax dots, milky white in the early stage and brownish black in the later stage; the nodes produced by the diseased tumors are easy due to different susceptible periods, and the diseased rice plants in the early stage, the diseased tumors occur in the lower nodes, the later the susceptible period, the higher the nodal position.

2. Symptoms in seedling stage: the diseased plant was short and small, the color was dark green, the heart leaf was slowly drawn, the heart leaf was short and stiff, and the leaf occipital spacing was shortened.

3. Symptoms in the parting stage: the diseased plants were clustered, the pillows of the upper leaves were overlapped, and the leaf tip was slightly distorted. The plant is short, and the main stem can still ear as early as possible, but the ear head is difficult to bear fruit, or the ear is small, like dwarfism.

4. symptoms of heading stage: the whole plant was dwarfed and clumpy, the flag leaves were short and stiff, the longitudinal folds could be seen at the base of the middle and upper leaves, and the short strips of vein swelling with wax white or dark brown protuberance could be seen on the lower internodes and nodes of the stem. White wax-like vein swelling spots can be seen on the stems of susceptible japonica glutinous rice, which is the most prominent symptom of the disease at present. The roots of susceptible plants are underdeveloped, the whisker roots are few and short, and the roots are yellowish brown in severe cases.

Second, prevention and control:

The pathogen of rice black-streaked dwarf disease in southern China is southern rice black-streaked dwarf virus, and its transmission vector is mainly migratory pest white-backed planthopper. It is mainly transferred to the infected white-backed planthopper to feed on early rice or weeds, to the infected white-backed planthopper or the local white-backed planthopper and then to the medium rice, late rice seedling field and Honda. In order to control rice virus diseases such as rice black-streaked dwarf disease in South China, the comprehensive control strategy should be based on agricultural control, focusing on lice control and dwarf control, and supplemented by emergency remediation.

The key is to do a good job in the prevention and control of rice planthopper and other virus-transmitting insects, and to do a good job in the three key periods of rice seedling field and early field control: one is from one leaf to two leaves and one heart, and the other is three days before transplanting. Third, at the beginning of rice tillering, insecticides were sprayed once to control rice planthopper, and the virus transmission was controlled before the transmission of virus vector insects. On this basis, fertilizer and water management should be strengthened to improve the resistance of rice itself. To achieve the purpose of preventing and controlling rice black-streaked dwarf disease in southern China.

1. Do a good job of seed dressing with 10% imidacloprid wettable powder 300-500 times solution for 12 hours or 10% imidacloprid wettable powder 15-20 grams with 1-2 kg seeds (in terms of dry seeds). Sow seeds after the agent is fully absorbed

2. The "marriage medicine" should be applied 3-5 days before transplanting rice seedlings. You can use 25% pyramidone wettable powder 40 g / mu or 25% thiazinone wettable powder 50 g / mu plus 48% chlorpyrifos EC 80g 100ml / mu, add plant gene activator 20 g / mu (or antiviral agents such as Ningnanmycin) and foliar fertilizer 30-45 kg of water.

3. Strengthen field inspection and take emergency remedial measures: first, for diseased seedling fields, diseased plants should be easily removed in time (buried in mud) Second, if the incidence of the tillering clump in the field is less than 2%, step directly into the mud in time, and the field with the incidence rate of 22% should be removed in time, and the diseased plants (clumps) should be removed in time and deeply buried in the mud, and then the tillers should be broken to replenish the seedlings from the healthy clumps. At the same time, the management of fertilizer and water should be strengthened to promote early onset and ensure the number of effective tillers and effective panicles. Third, for the hills where the disease is particularly serious, it is suggested that ploughing in time should be changed to the next crop of rice or other crops.