Rapid Molecular Diagnostic Technology,Occurrence Regularity And Control Of Phyllachora Dalbergiicola In Dalbergia Odorifera

At present,Dalbergia odorifera is one of the most precious native tree species in Hainan Province.Recent years,driven by the economic interests of Dalbergia odorifera,the market is getting higher and higher value.As the research results showed that,tar spot of Dalbergia odorifera caused by Phyllachora dalbergiicola is a common occurrence in plants of Dalbergia odorifera,and it seriously affected the rate of photosynthesis,caused host leaf shedding in advance.And it has become one of the main diseases of Dalbergia odorifera in Hainan,Guangdong,Guangxi and other provinces.The pathogen is highly parasitic,transmission routes is complex,and it can’t cultivated by traditional method.It can’t recognized by traditional disease diagnostic technology accurately.This experiment has designed a pair of specific primers for the ITS region of the Phyllachora dalbergiicola and therefore we can quarantine the pathogen before the disease breaks out spreads.So this technology provides some suggestion for the subsequent prevention and cure.Writer researched the occurrence of the disease,and conduct the fungicides test used 7 fungicides,the results are as follows:(1)A nested PCR procedure used ITS4/ITS5 as the first-round primers and followed with P1/P2 increased detection sensitivity 10 000-fold to 100ag.The results showed that the Nested-PCR technology could detect the pathogen more accurately and rapidly than the standard isolation method,it not only could detect P.dalbergiicola in its late pathogenesis,but also it is available to detect the pathogen during its latent period.(2)The occurrence regularity of tar spot of Dalbergia odorifera.The disease occured in mid-to-late March,there is yellow halo in sickness health junction,in the late stages,the diseased leaf surface produces black dots,the host plants extract abundant of tender leaves,at this time,the disease index is lower than mean level.From early June to the beginning of September,the results indicated that the disease index enhanced significantly,the number of tar spots on the host leaves extended fast.There were 62 percents tree infected by Phyllachora dalbergiicola.At the mid of November,the disease index appeared to the peak spreading,the host leaves covered black dots,seriously affected the photosynthesis,caused the leaves of Dalbergia odorifera to dry and brown,seriously the disease leads to early deciduous.From the end of November to the other March,as the temperature and humidity drop,the disease stopped to development.(3)Pollution-free prevention technicques of tar spot of Dalbergia odorifera.Dalbergia odorifera + Santalum album,Dalbergia odorifera + Pterocarpus macrocarpususe,under this two different planting patterns,there is no obvious difference between the start time of the disease,but the disease index are 3.1 and 6.5,At the late stage of the disease,the disease index are 51.8 and 21.6.This results showed that the planting pattern(Dalbergia odorifera +Santalum album)can prevent the infection of Phyllachora dalbergiicola effectively.The 7 antiseptic we used in this study are as follows:70%thiophanate-methyl WP,50%carbendazim WP,3%zhongshengmycin WP,80%mancozeb WP,50%azoxystrobin WP,60%Cabrio Top WG,75%chlorothalonil WP,we conducted the forest prevention efficacy trials.The results showed that,the control effect of single application are as follows:60%Cabrio Top WG>50%azoxystrobin WP>80%mancozeb WP>50%carbendazim WP>75%chlorothalonil WP>70%thiophanate-methyl WP>3%zhongshengmycin WP.And among these 7 fungicides we chosed three of them,they are 60%Cabrio Top WG,50%azoxystrobin WP and And 80%mancozeb WP.And we made a comparison between the continuous application of single fungicide and rotate to use 3 fungicides.And the single application control efficiency were 37.16%,34.11%,32.12%.Rotate to use the three fungicides,the efficiency was 72.27%,significantly higher than the other way around.And the morbidity after rotate to use 3 fungicides are 73.45%,53.25%,45.32%,34.24%,the disease index are 36.47,32.27,24.95,20.32,the control efficiency are 44.48%、55.31%、66.68%、72.27%.It is effective to use the three kinds of fungicides in turn,every 15days,application time:8:00～20:00am or 15:00～17:00pm,we should delay treatment in case of heavy rain.