What is this disease?
Judging from the picture, it is the leaf sheath rot disease, the leaf sheath appears brown spots, forming a cloud-like disease spot, and even extends to most of the leaf sheath, the young spikes in the leaf sheath, partially or completely dead, become dry pregnant spikes. If it occurs more severely, it can be combined with the prevention and control of rice blast and aspergillosis, with pyrazole ether ester or azoxystrobin, plus pentazole or imidazine, plus carbendazim or methylthioxine. The following small series briefly introduces this new disease.
In recent years, this new disease, the southern rice area often occurs in the late field of the second night, the disease can only be found in the rice break to the filling stage, the initial appearance of brown spots in the lower part of the sheath of the sword leaf, and then expand upwards, sometimes in the leaf occipital area also has a symptom, and some will spread upwards to the leaf, appearing needle-sized brown spots. After the ear extraction, hemp shells, black straws, and panicle shafts appear on the ying husks, which are dried up and appear white ears, which have a greater impact on the yield when severe, and the quality of rice is reduced, and the rice grains are black and brown.
1. Cases
The occurrence of rice leaf sheath rot disease in Donghai County, Jiangsu Province, was found in 2009 in the course of disease and pest investigation, which was limited to individual farmers at that time, and the specific varieties are unknown: the area of occurrence in 2010 has expanded accordingly, but it has only occurred on varieties with late panicle extraction, and the disease cluster rate is 10%; in 2011, it occurred in a large area, and the degree of occurrence also expanded, more than 10% of the county's fields were diseased, the loss of light incidence was 8%-10%, and the incidence of severe field disease was more than 80%. Almost extinct.
2. Pathogenesis hazards
Rice leaf sheath rot disease, also known as sheath rot disease, is a fungal disease, with Fusarium graminearum accounting for the absolute majority, followed by Fusarium beads and crospora, and the severely damaged rice ears appear brown. After the occurrence of the disease, there are many brown grains, high black rice rate, increased grain grain rate, decreased 1,000 grain weight, poor rice quality, yield loss of 10%-20%, and heavy ones reached more than 30%.
3. Climatic factors
Heavy rainfall during the gestational panicle period, or heavy fog and heavy exposure, are conducive to the onset of the disease.
4. Cultivation factors
Early rice and flapping varieties are severely diseased. When nitrogen fertilizer is applied in excess, too late, or when there is a lack of fertilizer in the field, the disease is severe. Fields with many insects and mites are susceptible to disease. The humidity in the field is high, the permeability is poor, and the incidence is severe.
5. Wintering and intrusion
Overwintering: Pathogens overwinter on diseased rice seeds and straw with mycelium and conidia. Invasion: Pathogens can be transmitted by air currents or small insects, mites and other vectors for initial infection. In the case of seeds with bacteria, after the seeds germinate, the pathogen invades from the growth point. After the onset of the disease, the diseased part forms conidia, which invade from the wound, stomata or water holes, etc., and re-infect.
6. Field management
Prevent early wilting of rice leaves, pay daily attention to fertilizer and water management, rationally apply nitrogen, phosphorus and potassium fertilizers, and improve soil fertility. The application of silicon fertilizer can improve the disease resistance of rice and reduce the incidence of disease.
7. Prevention and control methods
The disease and ear neck blast and rice aspergillosis control essentials are similar, to the week before the opening and the panicle 50-80% of the two key stages of the drug is preferred, the drug choice of chlormycin, pyrazole ether ester, imidamine two-two compound, the effect is more ideal.
Compiled by "Yun Zhongdi", for reference only, please indicate the source of the reprint! Yunzhongdi service purpose: an attitude, focus on rice and wheat planting technology of agricultural self-media, to help farmers popularize planting technology knowledge, to solve farmers planting problems. If there are any deficiencies, I hope my friends will comment.