The latest control measures of leaf tip blight in the process of rice planting

Rice leaf tip blight is also called rice leaf tip bacterial blight. It is mainly harmful to the leaves, the disease begins to occur at the leaf tip or leaf edge, and then extends downward along the leaf edge or middle, forming stripes. The disease spot is dark green at first, gradually changes to grayish brown, and finally withered. There are brown stripes at the junction between the disease and the health, and the disease is easy to be longitudinally cracked. In severe cases, the leaves can wither and die. Damage to rice, after the formation of dark brown spots on the edge of the glume, the center showed grayish brown disease spots, and the diseased grain was thin.

Pathogen

Rice stem mildew is a subphylum fungus. The conidium was initially buried under the epidermis of rice leaves, then slightly exposed, dark brown. The sporogenic cell is unbranched, and the sporulation mode is the whole-wall budding monogamy. Conidia ovoid, unicellular, colorless, conidia with 1-2 oil globules. The character is rice small sunken shell, which belongs to ascomycetes subphylum fungi.

Route of transmission and conditions of onset

The pathogen overwintered in diseased leaves and glume shells by conidia. There are more than 10 species of Gramineae weeds on pathogen hosts, so bacteria-carrying weeds can also spread. Under suitable conditions, the overwintering conidium releases conidia, spreads to rice leaves by wind and rain, and invades through leaves, leaf margin or leaf central wound. The obvious disease center was formed from jointing to booting stage, and the second peak appeared at the early filling stage. During this period, low temperature, heavy rain and many typhoons are beneficial to the occurrence of diseases. After the storm, rice leaves cause a large number of wounds and diseases are easy to occur. Too much nitrogen application, too late disease is serious, and silicon fertilizer application is less serious. The rice did not dry the field in time in the late tillering stage, there was more stagnant water and the disease was serious. The density in the field is high and the disease is serious. The optimum temperature for the disease was 25-28 ℃, the temperature limit for mycelium growth was 10-35 ℃, the optimum temperature was 22-25 ℃, the temperature limit for conidia formation was 15-30 ℃, the optimum temperature was 25 ℃, the temperature limit for spore germination was 10-35 ℃, and the optimum temperature was 30 ℃.

Prevention and cure method

1. Strengthen seed quarantine to prevent it from spreading into disease-free areas.

2. Disease-resistant varieties were selected, and japonica rice was more resistant than indica rice. The varieties with long stalks and long leaves were more susceptible to disease. Indica rice Lu Yangdao 3, 4, 3037, Nannong 3005 and Xingxian 1 were more resistant to disease.

3. Apply enough organic fertilizer and increase phosphorus and potassium fertilizer and silicon fertilizer. The tillering stage should be timely and moderate drying, and the late growth stage should be dry and wet. Cultivation should not be too dense to reduce the humidity in the field.

4. Chemical control. The seeds were treated with 50% carbendazim or 50% thiophanate methyl wettable powder 250-500 times solution for 24-48 hours, and 40% he Kuling wettable ultra-fine powder 250 times solution for 24 hours, and the effect was good. From booting to heading and flowering stage, 40% carbendazim gel suspension 40ml or 40% Hekuling wettable powder 60-75g was selected after the central diseased plant was found. 60L spray on water per 667m2. 40% Hekuling can also treat fungal diseases such as rice false smut, cloud disease, sheath rot, purple stem disease, and so on.