Mode Of Action And Mechanism Of Picoxystrobin On Colletotrichum Gloeosporioides Of Mango And Preparation Of Microemulsion

In this paper,the virulence,mode and mechanism of action of strobilurin fungicide picoxystrobin against Colletotrichum gloeosporioides of mango were systematically studied.At the same time,the intake transportation function and rainfastness in the mango plant and the preparation process of 10%picoxystrobin microemulsion and index and activity of the microemulsion were evaluated.The results were as follows:1.Picoxystrobin could inhibit the mycelial growth,spore germination and spore production on C.gloeosporioides of mango.As the concentration of the picoxystrobin increased,the inhibitory effect becomed more obvious,and the effective medium concentration(EC₅₀)for mycelial growth was 3.30 mg/L.When the concentration was10 mg/L,the spore germination rate was 29.03%,and the inhibition rates of mycelial growth and spore production were 68.38%and 87.60%,respectively at 16 h.Electron microscopy and scanning electron microscopy observations revealed that the mycelia appeared enlarged,branched,deformed,and dried out after treated with picoxystrobin.2.Picoxystrobin showed better protection and therapeutic on leaves and fruits,When the concentration of picoxystrobin was 10 mg/L,the protective and therapeutic effects of picoxystrobin on leaves were 97.32%and 92.84%,respectively.And on the fruit were 94.35%and 82.00%,respectively.Overall,the protection effect of picoxystrobin on C.gloeosporioides of mango was slightly better than that of therapeutic effects.3.Picoxystrobin had good upward,downward,and lateral conduction in mango plants,and could be quickly absorbed into mango tissues in a short time.The conduction speed were upward conduction>downward conduction>lateral conduction.Rainfall had a certain effect on the absorption of picoxystrobin.When the absorption time of the medicament was less than 12 h,which has a greater impact to the leaching rate,the leaching ratet was between 24.34%and 41.94%.When the absorption time was 24 h and 48 h,the leaching rate was less than 20%.It showed that rainfall had little effect on the absorption of medicine.4.Picoxystrobin had a strong destructive effect on the cell membrane of anthracnose mango and can increased cell membrane permeability.With the extension of the processing time,the destruction rate gradually decreases and tended to a stable state.Picoxystrobin had a certain effect on the synthesis of ergosterol from C.gloeosporioides,but the overall effect was small..Picoxystrobin could quickly inhibit the respiration of the anthracnose mycelia.The inhibitory effect slowed down with the extension of the treatment time.By added malonic acid,iodoacetic acid,sodium sulfate,and salicylic acid respirator,the respiratory oxygen consumption rate of anthracnose mango was lower than that of picoxobin.The superposition rate of picoxystrobin and malonic acid were lower than the respiratory superposition rate of adding salicylic acid,iodoacetic acid and sodium phosphate.This showed that picoxystrobin mainly inhibited the tricarboxylic acid cycle pathway on C.gloeosporioides of mango.5.Through researched on the preparation process of 10%picoxystrobin microemulsion,the formulation formula was 10%picoxystrobin,20%ethyl acetate,NP-10 16%,34^#4%,silicone 1.5%and ionized water added 100%.The determination of physical and chemical properties showed that all the indicators of the preparation were qualified,and the preparation diluent had better wettability and spreadability and higher retention.6.10%picoxystrobin microemulsion had good indoor virulence and field control effect on mango anthracnose pathogen,and the effective medium concentration(EC₅₀)of indoor virulence was 1.68 mg/L.The field control effect showed that when 10%picoxystrobin microemulsion was applied twice,the control effect was between52.15%and 66.37%after 10 days and could effectively inhibit the occurrence of C.gloeosporioides.