Studies On Chemical Control Of A New Fungicide-AF-12946 Against Phytophthora Parasitica Var.Nicotianae And Its Mechanism

Tobacco Black Shank is a destructive disease of tobacco and is a stumbling block to tobacco production. If the disease occurs on tobacco and is not managed on time,it will lead to serious economy loss.At present controlling Tobacco Black Shank raises some problems, for example the pathogen has been resistance to a series of fungicides ,for example metalaxyl.Therefore filtering some new fungicides,whose mechanism are unique ,is essential.The article studies the control effects of AF-12946 to tobacco black shank and its mechanism.These main results are followed:1.The method which determines the virulence of AF-12946 to Phytophthora parasitica var. nicotianae is the method of the growth velocity .The results show that AF-12946 can restrain Phytophthora parasitica var. nicotianae remarkably and the needed quantity is very little .The lowest concentration which the restraint rate reaches 100% is only 0.1 μg/ml,which is lower than the routine fungicides which control tobacco black shank at present. So AF-12946 can reduce the produce cost and can be popularized widely.2. After Phytophthora parasitica var. nicotianae is dealed with by AF-12946,we find these managed Phytophthora parasitica var. nicotianae give birth to very few sporangiums.The results show that AF-12946 restrains the produce of sporangiums obviously and these sporangiums are organs which produce zoosperms. Therefore zoosperms are cut off radically, which reduces the possibility of the second intrusion of pathogen.3.The field experiment result of AF-12946 to tobacco black shank is also very ideal.In the couse of the experiment, the highest proofreaded control effect reaches...