Detection Of Phytophthora Capsici From Pepper Seeds And Treatment Technology Research

As a worldwide devastating disease, Pepper Phytophthora Blight can cause significant yield losses for growers and has become a serious threat to the agricultural production of China and other countries in the world. In order to provide a basis for integrated control, the initial infection sources and channel of spreading disease, detection and treatment technologies were intensively studied in this paper.1. Pepper seeds can successfully be infected by Phytophthora capsici through injection, under the inoculation concentration of 104 sporangia/mL suspension, and we can effectively obtain pepper seeds with pathogen. Different inoculation methods and inoculation concentrations were used to treat with pepper fruits. The disease index of pepper fruits, carriage rates of pepper seeds and so on were investigated. The results showed that pepper seeds can successfully be infected with pathogen through injection. Under the inoculation concentration of 104 sporangia/mL suspension, seeds can be infected easier.2.We are clear about seeds and soil were the main initial infection sources and important routes of transmissions of Pepper Phytophthora Blight. Two inoculation methods, injecting sporangia to pepper fruits and mixing Phytophthora capsici with soil were used in the experiment. Along with the disease index of pepper plants and survival rate of pathogen in the inoculating soil, whether seeds can be infected when the pepper fruits were inoculated with pathogen and the infected seeds can transmit the disease were investigated. We injected sporangia to pepper fruits, which can infect the seed and significantly reduced the germination and emergence rate and the seedling will sustainability happen Phytophthora capsici at the whole growth stage. Pepper plants grown in the soil were continued happen disease at the growth period, and the disease incidence of pepper plants became steady in 105 days, meanwhile, Phytophthora capsici in the soil was still alive.3. A selective medium for isolating Phytophthora capsici from pepper seeds was prepared, which can effectively detect pathogen from pepper seeds. Basing on the research of Phytophthora selective media at home and abroad, and combing with screening test of fungicides, a selective medium for Phytophthora capsici, which contained Pimaricin 10 mg/L, Ampicillin 250 mg/L, Rifampicin 10 mg/L, PCNB 100 mg/L, Hymexazol 100 mg/L, and Carbendazim 10 mg/L, was prepared. The medium can effectively inhibite the development of Fusarium spp. et al. Phytophthora capsici was successfully isolated from pepper seeds that had been kept for120,150 days with the selective medium, and the separation rate was 2% on the 150 d.4. A Real-time quantitative Polymerase Chain Reaction detection technology of Phytophthora capsici was established, which can quantitatively detect pathogen from 10 million pepper seeds had 1 infected seed. DNA of pepper seeds were amplified by Real-time PCR technology, and the survival time of Phytophthora capsici in pepper seeds and the detection limit of Real-time PCR were analysed. After artificial simulation test, this detection technology can be successfully detected 1 infected seed in 10 million when the minimum content of pathogen DNA was 0.17 fg; Phytophthora capsici was successfully detected from pepper seeds that had been kept for 120,150 days with this technology, and the minimum content of pathogen DNA was 21.3 fg on the 120 d.5. A treatment technology for pepper seeds disease control was advanced. On the basis of fungicides in vitro and in vivo Screening against Phytophthora capsici, we chose 50% dimethomorph WP and 20% flumorph WP to treat pepper seeds with different concentrations and different time. The safety of two fungicides were assessed at seedling stage. The results showed that 50% dimethomorph WP or 20% dimethomorph WP soaked 3 h under the concentration of 250 mg/L can effectively control Phytophthora capsici in pepper seeds. First time preparated pepper seeds infected by Phytophthora capsici and established the selective medium, Real-time PCR to detecte Phytophthora capsici from pepper seeds in this study, which had important practical significance for detection of pepper seeds and control the seed disease.