The Investigation Of Pathogens,Occurrence Regularity And Control Of Panax Notoginseng Fungal Diseases In Guangxi

Panax notoginseng fungal diseases were rated as one of the important factors on Panax notoginseng production in Guangxi. During 2014-2015, the pathogens and occurrence regularity of Panax notoginseng fungal diseases were investigated and control experiment was conducted. The results were shown as follows:1. Species and pathogens of Panax notoginseng fungal diseasesFungal diseases of Panax notoginseng in Guangxi were known based on field investigation, which included Panax notoginseng black spot (Alternaria panax Whetzel), Panax notoginseng round spot [Mycocentrospora acerina (Hartig) Deighton], Panax notoginseng powdery mildew (Erysiphe panacis Bai et Liu), Panax notoginseng grey mould(Botrytis cinerea Pers.), Panax notoginseng blight [Phytophthora cactorum (Leb. et Cohn) Schroet], Panax notoginseng root rot and Panax notoginseng anthracnose. Panax notoginseng black spot, Panax notoginseng root rot and Panax notoginseng round spot were main fungal diseases of Panax notoginseng in Guangxi. Panax notoginseng round spot and Panax notoginseng powdery mildew were found as new diseases in Guangxi. It showed that Fusarium proliferatum and Fusarium incarnatum were the pathogens of Panax notoginseng root rot, which were determined for the first time in Guangxi based on the results of pathogenicity test, morphological observation, homology comparison of ITS and TEF-la sequence and phylogenetic analysis. Seventeen Colletotrichum isolates isolated from samples collected from different areas were identified as Colletotrichum fructicola, Colletotrichum alienum, Colletotrichum truncatum and Colletotrichum gloeosporioides based on the results of pathogenicity test, morphological characters and multigene (Internal Transcribed Spacer-ITS, β-tubulin-2 gene-TUB2, glyceraldehydes-3- phosphate dehydrogenase gene-GAPDH, chitin synthase A gene-CHS Ⅰ, Actin gene-ACT) homology comparison and phylogenetic analysis.2. The occurrence regularity of Panax notoginseng fungal diseases was investigatedThe investigation of the occurrence regularity of Panax notoginseng fungal diseases was made and it was found that Panax notoginseng black spot and Panax notoginseng round spot were more serious in high altitude area than low altitude area, otherwise Panax notoginseng root rot was more serious in low altitude area. Panax notoginseng black spot and Panax notoginseng round spot were decreased significantly under rain shelters than ordinary net sheds, while Panax notoginseng powdery mildew were more serious under rain shelters than ordinary net sheds and ventilated rain shelters. Leaf disease rates were reduced as Panax notoginseng grew up after the survey on incidence of leaf spots on one-year to three-year Panax notoginseng were made.3. The monthly variation of Panax notoginseng round spotThe observation of monthly variation of Panax notoginseng round spot was made and it indicated that June and July were the infection peak of Panax notoginseng round spot. The disease index gradually increased before June and the upward trend gradually slowed down after July.4. The results of the test of seed-carrying fungi on Panax notoginsengThe test of seed-carrying fungi on Panax notoginseng was conducted with seed samples and the result showed that spores of Colletotrichum spp., Alternaria spp., Penicillium spp., Rhizopus spp., Mucor spp., Fusarium spp., Aspergillus spp. and Cladosporium spp. sticked on surfaces of seeds, among which Fusarium spp., Penicillium spp. and Aspergillus spp. were dominiant species and Fusarium spp. accounted for the largest proportion. Colletotrichum spp., Penicillium spp., Rhizopus spp., Mucor spp., Fusarium spp., Aspergillus spp. and Cladosporium spp. were isolated from tissues of seeds, among which Penicillium spp. and Fusarium spp. were dominiant species. Colletotrichum isolates were pathogen, only 10% of which successfully infected through wounds which were identified as Colletotrichum fructicola based on morphological characters and analysis of ITS sequence, part of Fusarium isolates were opportunistic pathogen of root rot after koch’s postulates were completed with isolates of Colletotrichum spp., Alternaria spp. and Fusarium spp.；Alternaria spp. and other fungi isolated from seeds were non-pathogen on Panax notoginseng.5. Control experiment of major Panax notoginseng fungal diseasesThe control effects of 5 kinds of fungicides and 1 biocontrol bacteria on Panax notoginseng round spot were tested in the field. The results showed that Panax notoginseng round spot was significantly controlled by propiconazole, prochloraz and A16 (biocontrol bacteria).The test of chemical treatment of Panax notoginseng seeds was done before sowing and it indicated that the disinfection effect of thiram and prochloraz were the best among 6 fungicides. Prochloraz and thiram were the best based on effect and side-influence on the Panax notoginseng seed. It was suggested that when thiram was used to treat Panax notoginseng seeds, soaking was the best method to Panax notoginseng seeds.The investigation of Panax notoginseng fungal diseases also showed that Panax notoginseng lesf spot were controlled significantly by the way of combining rain shelter cultivation and drop irrigation in soil.