Identification Of Three Diseases Of Dendrobium Officinale And Screening Of Control Measures

Dendrobium officinale Kimura et Migo,belongs to Orchidaceae Dendrobium Sw.and herbaceous perennid.Modern pharmacology studies have proved that its components are of a variety of efficacy,show a certain value in edible,medicinal and other aspects.However,Dendrobium officinale is very demanding on growth environment and climate conditions,and grow slowly,so the wild resource is very scarce.In the 1990 s,Zhejiang was the first province to start the large-scale planting and industrialization development of Dendrobium officinale in the whole country,and now is the main distribution of Dendrobium officinale planting and deep processing industry.However,the artificial cultivation of Dendrobium officinale is often a greenhouse and high-density cultivation.The humidity in the shed is high,the ventilation is poor,and it is relatively sultry,which is very conducive to the occurrence of the diseases.What’s more,Zhejiang Province is located in the subtropics,high temperature and high humidity in Summer,with the long-enduring mould rains,leading to the more lasting and widespread occurrence of diseases.In order to clarify the pathogens of several common diseases of Dendrobium officinale in Zhejiang Province,and find out the control measures suitable for the green growth of Dendrobium officinale and the chemical emergency technology with high efficiency,low toxicity and low residue,some preliminary research and exploration have been carried out in this paper.The main results are as follows:(1)The disease occurrence rules at the planting base of Dendrobium officinale were investigated.Samples with typical symptoms of the diseases were collected and then the pathogens were isolated and purified.A series of experiments were conducted subsequently,including pathogenicity test,observation on morphological characteristics and analysis of rDNA-ITS sequence.The pathogen of Dendrobium officinale southern blight is Sclerotium rolfsii,and the peak of disease occurouce is the high-temperature and high-humidity mould rain season or the summer and the autumn high-temperature seasons.The pathogen of Dendrobium officinale ring rot is Myrothecium roridum,the peak of disease occurouce is from June to July.According to the investigation,the occurrence of Dendrobium officinale ring rot is obviously related to the air humidity in the shed.The pathogen of Dendrobium officinale anthracnoseon is Colletotrichum gloeosporioids,and the peak of disease occurouce is the high-temperature and high-humidity mould rain season or the summer and the autumn high-temperature seasons.(2)The fungi inhibitions of the three diseases were assayed by selecting of several fungicides in the laboratory.The results showed pyraclostrobin 25% EC 2000 times,pyraclostrobin 25% EC 3000 times and isopyrazam·azoxystrobin 29% SC 1500 times had 100.0% inhibitory effect to the mycelium growth of the pathogen S.rolfsii.The inhibitory effect of kasugamycin 6% WP 1000 times,fluopyram·trifloxystrobin 42.8% SC 3500 times,isopyrazam·azoxystrobin 29% SC 1500 times and thiophanate-methyl 70% WP 1000 times on mycelium growth and conidium germination of the pathogen M.roridum reached 100.0%.Kasugamycin 6% WP 1000 times,thiophanate-methyl 70% WP 1000 times had strong inhibition action to the pathogen,with the inhibitory ratio 96.4%,96.3% On the basis of laboratory fungicides selecting,the field efficacy experiments of Dendrobium officinale southern blight and Dendrobium officinale anthracnoseon were carried out.The results showed pyraclostrobin 25% EC 2000 times,difenoconazole 10% WP 1000 times controlled the occurouce of Dendrobium officinale southern blight effectively.Biological control preparation 1 billion spores / g zinc trichoderma SP was also used to the control of Dendrobium officinale southern blight,with a certain control effect,although slightly lower than the chemical preparations.It is recommended to use kasugamycin 6% WP 1000 times for the control of Dendrobium officinale anthracnoseon.Through the investigation of the occurrence of Dendrobium officinale southern blight and anthracnose under different cultivation methods,the results showed that the occurrence of these two diseases could be significantly reduced by using two innovative ecological cultivation methods,transverse bamboo frame and vertical bamboo frame.In addition,adjust the temperature and humidity in the greenhouse could obviously control the spread and expansion of the diseases.