| Humic acid substances are a type of complex organic matter formed by the remains of ancient organisms during the long geological movement.Fulvic acid potassium is a humic acid substance and is currently widely used as leaf fertilizer and functional water-soluble fertilizer in agricultural production.In this study,a 10%Abamectin B1a suspension with humic acid substances as a dispersant was prepared by wet grinding,and its grinding efficiency of the preparation and its stability under cold,hot,and normal temperature storage conditions were used as indicators.The dispersants,wetting agents,antifreeze agents,thickeners and other auxiliaries in the formulation were screened,and whether humic acid can be directly added to the formulation as pesticide dispersants was determined,the dispersibility of humic acid potassium and fulvic acid potassium to avermectin B1a were studied.The optimum formulation of 10%avermectin B1a was selected by using fulvic acid potassium,which has stronger dispersibility,and the physical and chemical indexes of the preparation were determined.Then,the avermectin B1a suspension was prepared with different contents of avermectin and fulvic acid potassium from different manufacturers,and the adaptability of the above optimized formulation to different sources of avermectin and fulvic acid potassium was investigated.In combination with laboratory toxicity test and field efficacy test,the differences in the application of avermectin B1a suspension concentrate prepared with potassium fulvic acid as dispersant and commercial avermectin suspension concentrate were evaluated.The main contents and results are as follows:1.Only added humate acid potassium,fulvic acid potassium or sodium lignosulfonate to prepare avermectin B1a suspension as dispersing agent.After observing the preparation under microscope,it was found that the granules of the three preparations were evenly distributed,indicating that both humate acid potassium and fulvic acid potassium had certain dispersion ability.After diluting the solution to 10 mg/L according to the dilution concentration recommended by abamectin,it was found that the granules of the two preparations using sodium lignosulfonate alone and fulvic acid potassium alone were still evenly distributed.However,serious agglomeration occurred in the granules of the diluents used alone with humic acid potassium.This suggests that humic acid potassium and fulvic acid potassium has a certain dispersion ability,but the dispersion ability of fulvic acid potassium is stronger than that of fulvic acid potassium.After dilution,it can still ensure the dispersion of the diluent of the preparation evenly,thus ensuring the application effect of the preparation.2.With fulvic acid potassium as dispersant,developed a 10%avermectin B1a suspension formula,the addition of the fulvic acid potassium as dispersant is 3%,the addition of the OP-10 as wetting agent is 1%,the addition of the xanthan gum as thickener is 0.15%,the addition of magnesium aluminum silicate as thickener is 0.5%,the addition of citric acid as p H regulator is 0.02%,the addition of glycol as antifreeze is 2%,the addition of X60 as defoaming agent is0.1%.The physical and chemical properties of the preparation also meet the requirements of the formula,the persistent foaming property of the preparation<10 m L,the dumping of the preparation is qualified,p H 6.9-7.1.The sifting rate（fineness）of the preparation≥99%,the suspension rate≥99%,the cold storage stability of the preparation is qualified,the thermal storage stability of the preparation is qualified,the effective component content of the preparation is 9.91±0.02%,the appearance of the preparation is brown opaque.Moreover,the optimal formulation has been proved by many experiments,and the avermectins B1a preparation with good properties can be prepared stably.3.Although the water evolution rate of the preparation after thermal storage is slightly different,the water evolution rate of the preparation obtained by using the original medicine with 98%active ingredient content is higher,but the water evolution rate of the two preparations meets the requirements,and the other physical and chemical indexes of the two preparations are not significantly different.The optimum formula selected three kinds of fulvic acid potassium from different manufacturers to prepare the suspending agent.The size of the prepared agent was different,and the rules were different under different storage conditions,but the particle size of the preparation is between 0.5-5μm,which meets the requirement of the preparation.And the water evolution rate of the three preparations after thermal storage is also different.The preparation prepared by fulvic acid potassium in Nongda fertilizer industry did not produce water evolution after thermal storage.The preparation prepared by using fulvic acid potassium produced by Lvlong biological production reached about 30%.The preparation prepared by Yinhai chemical industry was the most serious after thermal storage,reaching about 60%.The physical and chemical properties of the other three preparations meet the requirements.The formula is suitable for some manufacturers fulvic acid potassium produced.4.Laboratory virulence tests show,mixing fulvic acid potassium with avermectin B1a as dispersant will not effect the virulence of avermectin B1a to southern root knot nematodes,twelve hours after the test,the LC50 of avermectin B1a preparation prepared by fulvic acid potassium to southern root knot nematode was 0.96 mg/L,LC90 was 1.48 mg/L,the LC50 of conventional avermectin B1a preparation on southern root knot nematode was 0.86 mg/L,LC90was 1.54 mg/L;Twenty-four hours after the test,the LC50 of the preparation of fulvic acid potassium on southern root knot nematode was 0.51 mg/L,LC90 was 0.79 mg/L,the LC50 of routine avermectin B1a preparation was 0.51 mg/L,LC90 was 0.80 mg/L.The field experiments showed that 90 days after application,the control effects of avermectin B1a suspension concentrate prepared with fulvic acid potassium as dispersant and commercial abamectin suspension concentrate was 45.59±15.11%and 36.86±19.26%respectively.The root knot index of cucumber treated with the two preparations was 38.15±2.17%and 44.77±12.23%respectively. |
