Development Of Phoma Herbarum WG And Its Control Effect Against Commelina Communis L.

Duckweed is a malignant weed in the field and has a strong hazard.Phoma herbarum is a pathogenic fungus isolated from diseased comfrey,which can infect the comfrey and cause death.The test was carried out with Phoma herbarum as the research object,and the suitable carrier and auxiliary agent were selected and processed into water-dispersible granules,and the obtained microbial herbicide was used to control the comfrey.Through the biocompatibility test,the initial screening of the carrier with good compatibility with Phoma herbarum is talc powder and white carbon black,the wetting agent is pull-open powder and sodium lauryl sulfate,and the dispersing agent is NNO and Oleic acid amide,the binder is polyethylene glycol and CMC-Na,the disintegrants are sodium sulfate,sodium chloride and ammonium sulfate,the stabilizers are calcium carbonate and dipotassium hydrogen phosphate,and the above reagents are all good with Phoma herbarum.Biocompatibility.Through the performance test of the auxiliary agent,the carrier white carbon black,the wetting agent pulling powder,the dispersing agent NNO,the disintegrant ammonium sulfate,the binder polyethylene glycol and the stabilizer calcium carbonate are the best reagents.Through the dosage optimization test,the formula of the water-dispersed granules of Phoma herbarum was determined by the direct formula repeated test method: the Phoma herbarum was 2.57×108cfu/g,and the wetting agent was opened 6%(mass fraction,thesame below).Dispersing agent NNO 4%,disintegrant ammonium hexafluoride 6%,binder PEG 6%,stabilizer calcium carbonate 5%,carrier silica to make up to 100%.The granulation method was used,and a rotary granulator was used to select a pore size of 1 mm for granulation,and finally the Phoma herbarum water-dispersed granules was obtained.The serial dilution method was used to determine the viable bacterial rate.The final viable rate was 2.55×108cfu/g.The wetting time was about 28.16 s using the graduatedcylinder test method.The disintegration was determined by the graduated cylinder test method to be 70.50 s.According to the recommended national standard,the suspension rate of the preparation is about 88.90%,the p H is about 6.97,and the water content is about 1.47%.The indexes are in line with national standards.The storage of the Phoma herbarum water-dispersed granules was carried out at room temperature(10~ 25?)for 80 days.The storage stability results showed that at 80 days,the live bacteria rate was 94.69% at the beginning,and after 80 days,the live bacteria rate was large.The amplitude was reduced.At 160 days,the viable rate was 72.85% at the beginning;after 180 days,the viable rate was 68.36%.After 180 days,the indexes such as wetting time,suspension rate and disintegration time were not significantly different from those before storage.The results of potted test of the water-dispersed granules of the Phoma herbarum showed that when the live bacterium of the water-dispersed granules was 2.55 ×108cfu/g,thecomfrey was 3~4 leaves,and when the agent was sprayed 3 times,The best control effect.The results of colonization test on the leaves of A.serrata showed that the colonization of the active ingredient Phoma herbarum on the comfrey grass gradually decreased with the prolongation of time,the first 35 days,the strain The amount was greatly reduced.After 35 days,the amount of bacteria changed little.Until 61 days after spraying,no strain of Phoma herbarum was detected on the leaves of the comfrey.The field efficacy test results of the Phoma herbarum water-dispersed granules showed that the dosage of 1305 g a.i./hm2,1740 g a.i./hm2,2175 g a.i./hm2,3480 g a.i./hm2 was 21 d,and the fresh weight control was 50.89% and 55.97% respectively,60.67% and 69.88%.