Common Rice Diseases and their Control

In the whole growth period of rice, the common diseases are rice blast, bacterial leaf spot, bacterial blight, sheath blight, rice false smut and so on.

(1) Rice blast

Rice can occur from seedling to heading. According to the symptoms of the disease in different growth stages and different parts, it can be divided into five types: seedling rice blast, leaf rice blast, node rice blast, panicle rice blast and grain rice blast.

1. Main symptoms

(1) Seedling rice blast: the diseased seedlings turn gray-black at the base of the stem near the soil surface, and the upper part is reddish brown, which makes the whole seedling curl and die.

(2) Leaf rice blast: it can occur on both seedlings and adult leaves. There are four different shapes of plaques:

A, acute disease spot: generally oval, but also irregular, disease spot dark green, watery, dense gray mildew layer

B, chronic disease spot: the disease spot is brown and spindle-shaped, the outer yellow is the toxic part, the inner brown is the necrotic part, and the central gray is the collapsing part. when the weather is wet, there is a gray-green mildew layer on the back of the disease spot.

C, brown disease spot: the spot is brown, very small, limited to between leaf veins, and is common in disease-resistant varieties.

D, white spot: the spot is white, nearly round, with a size of about 2 to 4 veins.

(3) Rice blast: mainly occurred on the stem node, easy to occur at the jointing stage, needle-sized brown spots appeared at the initial stage, and then extended to the whole node or part of the node became dark brown, the tissue was destroyed and the stem was easy to break.

(4) panicle rice blast: also known as panicle neck blast, commonly known as broken neck disease, mainly occurs on panicle neck and branches. Ear neck disease, the disease spot brown or gray-black, spread from the ear neck up and down, can be as long as 3-4 cm. When the disease is early and serious, it will cause white ear, and panicle neck blast will often cause panicle stem and branch break.

(5) Rice blast: mainly occurs on grains, brown or dark brown.

two。 Occurrence characteristics

The pathogen overwintered on rice straw and diseased grain, mainly through air flow and Rain Water. It is easy to occur with high temperature and high humidity. The disease was serious when nitrogen fertilizer was applied in the later stage.

3. Prevention and cure measures

(1) selecting resistant varieties, such as Yixiangyou series and Mian Ⅱ You838, which are more resistant to rice blast.

(2) for seed disinfection, carbendazim, formalin and strong chlorine can be selected for seed disinfection.

(3) strengthen cultivation management, achieve reasonable fertilization, pay attention to the combined application of nitrogen, phosphorus and potassium, reasonable close planting, reasonable irrigation and so on.

(4) insecticide control, we can choose Daoyaojing, tricyclazole, Fuji No.1, Daokang, plague and so on for spray control, once every 7 days, pay attention to alternate use of drugs, control for 2 or 3 times.

(2) Rice bacterial leaf streak

1. The main symptoms are damage to the leaves and sometimes to the leaf sheath. The disease spot occurs between the leaf veins, which is initially a dark green water stain-like speck. after expansion, it is limited by the leaf vein to form a dark green strip, which is transparent to the light, about 10 mm long and 1 mm wide. the surface of the disease spot often secretes a lot of yellow bacterial pus, showing yellow gum-like particles after dry knot.

two。 The pathogen overwintered mainly on rice seeds and straw and became the primary infection source of the disease. the transmission routes were wind and rain, airflow and the introduction and export of diseased seeds. The disease is a bacterial disease, which is one of the main diseases harmful to rice production. If it is not controlled in time, it can cause large-scale spread and destructive losses.

3. Control methods: (1) selecting disease-resistant varieties; (2) seed disinfection, soaking seeds with agricultural streptomycin for 2 hours, then sowing seeds; (3) chemical control, agricultural streptomycin, cutting bacteria, Shiduqing, Yekuning, Shidaoling, and other anti-bacterial diseases can be used alternately, spray for one or two times, and then be controlled according to the disease.

(3) Rice bacterial blight

Symptoms: there are two types of symptoms: leaf wilt type and wilting type. Among the symptoms of leaf blight type, the most common is that the disease spot starts from the leaf tip or leaf edge, at first it is a dark green linear short spot, then spreads along both sides to form long stripe disease spot with wavy lines on the edge; the wilting type symptom often occurs 3-4 weeks after seedling transplanting, the first one or two seedlings wilt, then develop to each leaf, and develop to other tillers, and finally the whole plant or even the whole clump wilts, loses water and dies.

Bacterial blight is a bacterial disease, and its control method is the same as that of bacterial leaf spot.

(4) Rice Bad Seedling Disease

Symptoms: the disease can occur from seedling stage to heading stage, the color of diseased seedlings is yellowish green, the growth of diseased seedlings is higher and weaker than that of healthy seedlings, the leaves are long and narrow, and the roots are poorly developed.

Characteristics of the disease: the pathogen overwintered on diseased rice straw or the seed itself carried bacteria, which became the source of primary infection. The pathogen was immersed into the base of seedling stem from the wound and spread through irrigation water and Rain Water.

Prevention and control methods: 1. Select non-diseased varieties to avoid leaving seeds in diseased fields and nearby fields; 2. Seed disinfection can be carried out with carbendazim, Quan Baike, strong chlorine, etc., the key is disinfection; 3. If you find a diseased plant, remove it immediately.

(5) Rice sheath blight, commonly known as flower foot disease, rotten foot blast, etc.

Symptoms: the edge of the spot is brown, the center is light brown or grayish white, when wet, the spot is grayish green, water stains are translucent, and the spot develops from bottom to top.

Characteristics of the disease: the pathogen overwintered in the soil and invaded directly from the stomata or lenticels. After the rice was closed, the disease was easy to occur due to high humidity in the field, excessive close planting, poor ventilation and light transmission.

Prevention and control methods: 1. Eliminate the source of bacteria; 2. Reasonable close planting, reasonable irrigation, frequent irrigation in shallow water, moderate drying of fields and reduction of field humidity can reduce the occurrence of sheath blight. Chemical control, spraying Jinggangmycin 3 times before maturity can effectively prevent and control the occurrence of sheath blight.

(6) Rice false smut, commonly known as Gudan

Harm to individual grains, the initial formation of mycelium in the grain, gradually increased, so that the inner and outer glumes open, revealing a yellowish mass, that is, the spore seat of the pathogen.

Prevention and control methods: 1. Select disease-resistant varieties; 2. Seed disinfection, same as rice blast and sheath blight; 3. Combined with the control of sheath blight, Jinggangmycin was sprayed for 3 times from closing to maturity for 4 times.

(7) physiological diseases of rice (element deficiency)

Symptoms: mainly due to malnutrition, lack of trace elements, leaves green fade, do not grow, after pulling up more black root, less white root.

Disease characteristics: mainly caused by zinc deficiency, poor soil permeability, deep-water irrigation, poor drainage of cold-soaked field root poisoning and other symptoms are obvious.

Prevention and control methods: 1. In the early stage, the shallow water was irrigated frequently, and the field was drained. Sprinkle or spray zinc sulfate or magnesium zinc fertilizer 1 kg / mu.