Etiology Of Fungal Disease Of Curcuma Kwangsiensis In Guangxi

Curcuma kwangsiensis S.G.Lee et C.F.Liang is one of the authentic medicinal materials that mailly grown in Guangxi province,which has high economic and medicinal value.In recent years,with the deepening research and application of C.kwangsiensis,the market demand has been increasing,and the planting area has been expanding.However,the frequent occurrence of fungal diseases has resulted in significant economic losses for growers.Currently,the species of the fungi causing disease on C.kwangsiensis in field remains unknown.Therefore,the research on the pathogenic fungi of C.kwangsiensis has important guiding significance for the accurate diagnosis,scientific prevention and control of C.kwangsiensis diseases.In this study,the pathogenic fungi isolated from C.kwangsiensis plants in Guangxi were identified,and their biological characteristics and the sensitivity of the pathogen to fungicides were determined.The results are as follows:1、Isolation and identification of Pathogenic FungiIn this study,tissue isolation and single cell separation methods were used to isolate the pathogenic fungi.Pathogenicity analysis was carried out according to Koch’s rule,and 18 strains were identified as pathogenic fungi causing disease on C.kwangsiensis.Based on preliminary analysis of morphology and ITS sequence,the 18 pathogenic fungi were identified as members from 5 genera,including Fusarium spp.（2 strains）,Epicoccum spp.（2 strains）,Bipolaris spp.（1 strain）,Curvularia spp.（5 strains）,and Diaporthe spp.（8 strains）.Combined with morphological observation and multi-gene co-analysis of the isolates and their related species,the results showed that F.oxysporum,E.latusicollum,B.bicolor,C.radicifoliigena,C.eragrostidis,and D.passiflorae are all pathogenic fungi causing diseases on C.kwangsiensis in Guangxi.2、Study on the Biological CharacteristicsThe results showed that the optimal growth medium of F.oxysporum,E.latusicollum,B.bicolor,C.radicifoliigena,C.eragrostidis and D.passiflorae were PSA,PSA,PSA,OA,OA and OA medium,respectively.The optimal growth temperatures were 25℃,28°C,30°C,30°C,30°C and28°C,respectively.The optimal growth p H values were 8,9,6,7,8,6 and7,respectively.The lethal temperatures of hypha were respectively 56°C,50°C,54°C,59°C,58°C and 52°C in a water bath for 10 minutes.3、Laboratory screening of fungicides against the pathogenAccording to the results of laboratory screening of fungicides,50%Carbendazim and 75%Trifloxystrobin·Tebuconazole had a better inhibitory effect on mycelia growth of F.oxysporum,the values of EC₅₀were 0.55 mg/L and 0.88 mg/L;50%Carbendazim and 10%Difenoconazole was more effective in controlling mycelia growth of E.latusicollum,the values of EC₅₀is 0.69 mg/L and 0.91 mg/L;75%Trifloxystrobin·Tebuconazole was the strongest inhibitor of B.bicolor,EC₅₀is 0.50 mg/L;75%Trifloxystrobin·Tebuconazole and 10%Difenoconazole had a strong inhibitory effect on C.radicifoliigena,the values of EC₅₀ were 0.10 mg/L and 0.19 mg/L;In addition,75%Trifloxystrobin·Tebuconazole and 10%Difenoconazole had a significant inhibitory effect on C.eragrostidis,the values of EC₅₀ were 0.14 mg/L and0.42 mg/L.Finally,50%Carbendazim,and 75%Trifloxystrobin·Tebuconazole had a significant inhibitory effect on D.passiflorae,the values of EC₅₀ were 0.15 mg/L and 0.17 mg/L.The results provide a theoretical basis for the effective prevention and control of fungal diseases on C.kwangsiensis in the field.