A Study On Microcupsule Formulation Of Bioherbicide QZ-2000

The pathogen strain(Curvularia eragrostidis)QZ-2000 of crabgrass(Digitaria sanguinalis)was developed as a bioherbicide Disancu for biocontrol of main grassy weeds,such as crabgrass,barnyard grass,china leptochloa in rice,soybean,corn,vegetable,fruit and other major crop fields.However,the control effect of the product has been constrained by environmental factors.Previously-developed water-in-oil formulations have improved its control effect of the bioherbicide,but it is still limited to environemntal factors in practical applications.Therefore,the development of new oil-in-water microcapsule formulations is important for the industrialization of this product.In this paper,through the improvement of complex coacervation process,the microcapsules formulation of QZ-2000 was developed,and further the shelf life was observed and field efficacy trials were conducted to evaluate the quality of microcapsule formlation.The preparation procedure of complex coacervation for microcapsule formulation of QZ-2000 was as:spore pre-germination-the additives added-stir-acidize-cohesion-freeze-drying-powdery microcapsules.Filtering water and oil volume ratio of 1:1.67,the quality of the oil and volume of lecithin ratio of 1:10;gelatin,gum arabic to determine the concentration of 2%(mass fraction),mixing and acidification time effect the forming microcapsule.As the mixing and acidification time prolonged,microcapsule formed better.The use of pre-germination of spore and addition of cryoprotectant successfully solved the problem that the loss or weakening of spore virulence.Trehalose and glycerol in 5%and 3%(mass ratio)determined as cryoprotectant.The shell freezing was adopted to shorten the time for dry.the detect of microcapsule suspension rate,dispersion,wetting properties and pathogenicity,and microcapsule spore germination and morbidity tests showed that the microcapsules formulation of QZ-2000 has the commercialization potential.To determine the shelf life of the microcapsules formulation for QZ-2000,the microcapsules were stored at 4 ?,room temperature,N2,vacuum under four different preservation conditions respectively.The continuous 12 months' shelf life stability of the microcapsule was checked every half month.The results showed that the two preservation conditions of 4? and vacuum,microcapsules spore germination rate remains above 84%,demonstrating strong virulence.Since it is easy to implement in practice,and at low cost,the vacuum preservation may be used as an alternative mean of storage for the microcapsule formulation of QZ-2000.A field trial of the microcapsule formulation of QZ-2000 for biocontrol of grass weeds in corn and soybean fields showed that complexing with concentrations of 8000ppm oxalate,microcapsule concentrations at 8×105 spores/ml,7×105 spores/ml demonstrated good control efficacy separately.In conclusion,making bioherbicide QZ-2000 into microcapsule formulation can enhance the efficacy of bioherbicide QZ-2000,improve biological stability and safety,and extend period of preserving effect.