Species Identification,biological Characteristics Study,and Screening Of Control Strain Of Parasitic Weed Cuscuta In Shihezi

Objective: To clarify the species and infection cycle of Cuscuta in Shihezi,Xinjiang Province,and to select the biocontrol fungus and highly effective herbicide,which provide theoretical basis and technical support for control the Cuscuta in Xinjiang Province.Method: Stems,flowers and seeds of the Cuscuta were collected and identified according to the morphology and molecular biology(ITS,rbc L,trn L-F sequence analysis)from Shihezi city,the biology characteristicand occur rule of C.campestris and C.monogyna were studied through both pot and field;The natural diseased samples of cuscuta stems were collected for tissue isolation,pathogenicity,morphological and molecular identification;The isolates were screened for strong pathogenic bacteria,biological characteristics studied and field efficacy test were carried for the strong pathogenic isolates were screened.Efficient chemical fungicide were screened by field efficacy spray test using different concentrations.Results:1.A total of 37 samples were collected from Shihezi,and identified as C.campestris and C.monogyna.Besides the C.campestris are parasitic to the herbs,while the C.monogyna parasitic to both the herbs and xylophyta.2.Seeds water-absorption test of cuscuta showed that most of the seed coat of the 2species of cuscuta are impermeable,and the seeds have physical dormancy;The germination rate of the scratified seeds of C.monogyna can be germinated at-4-35?,which total germination rate was the highest at 30?.The germination rate of scratified seeds of C.campestris can't germinate under 10?,which total germination rate was the highest at25?.Both of the C.campestris and the C.monogyna have longest seed bud at 25?;Different light conditions onseed germination rate and final seedling length of the 2 species of cuscutahave no significantly different,but to the young plants color of C.monogyna has.The sprouts show pale lavender under the continuous light tretment and the alternation of light and dark tretment(16/8 h),however they arewhite(colorless)under the continuous darkness,even show pale yellow under the continuous dark;There were no significant effects of different light conditions on the young plants color of C.campestris;Both C.campestris and C.monogyna have a highest seed germination rate and longest spouse when the soil humidity arrived 30%.3.The seeds of Cuscuta germinate sharply in late April to early May after the continuous spring rain,which bloom during the June to August.The 40 d was needed for C.monogyna from bear to ripen,but 20 d was needed for C.campestris.4.A total of 159 diseased samples were collected,and separated to three typical symptoms,123 isolates were obtained in the end.After screen on pathogenicity,96 pathogens was obtained,including 62 strains of A.alternata as dominant species accounting for 64.5%;13 strains of C.inaequalis accounting for 13.5%;2strains of C.chrysosperma accounting for 2.08%;17 strains of F.verticillioides accounting for17.7%;2 strains of the other fungus accounting for 2.08%.After inoculation in vitro and plot experiment,3 strains of pathogenic bacteria were screened out,that is Alternaria Alternaria k4-1,Fusarium oxysporumm5 and inequal Curvularia d1-3.The C.monogyna was diseased after 15 d in the treatment with 3 strains of pathogenic fungus respectively,and the control effect arrived 100%.5.The 4 biocontrol fungus k4-1,d1-3,m5 and Canker fungusy 2-3 suitable temperature for mycelia growthof four strains were 25?-30?,and the optimum temperature were 25?.The temperature for the highest spore germination rate of m5 was 25?,k4-1 and d1-3 were30?,and the higher relative humidity the greater spore germination rate.The suitable p H for mycelial growth of m5 was 7-11,d1-3 and k4-1 were 5-10,and y2-3 was 4-6.And suitable p H forspore germination were 6-9.Screening on host security test show that all four fungus are safe to intact hosts of C.monogyna,such as Ulmus pumila L.,Ulmus pumila L.,Rosa chinensis Jacq,Syzygium buxifolium Hook.et Arn,Syringa Linn,that show non-pathogenic.6.Chemical selecting test results showed that: 41% glyphosate isopropylammonium AS410(820 mg/L),10.8% quizalofop-p-ethyl EC(67 mg/L),and benzene-2-sodium(275 mg/L)are ideal herbicide,which highly against C.monogyna,and safe to one of hosts of C.monogyna,elm.