Fungicidal Control of Garlic White Spot Caused by Stemphylium solani

Inhibition of mycelial growth of Stemphylium solani by nine fungicides was assayed on amended potato sugar agar medium.Flusilazole EC(40%) had the highest inhibitory effect with the 50% effective concentration(EC50) at 0.39 μg/mL.The next most inhibitory were 30% difenoconazole/propiconazole EC,50% carbendazim WP,10% difenoconazole WG and 20.67% flusilazole/famoxadone EC with EC50 values of 1.02,1.38,1.95,2.74 μg/mL,respectively.Zineb WP(65%),70% thiophanate-methyl WP,25% azoxystrobin EC and 75% chlorothalonil WP had lower mycelial inhibition with EC50 values of 83.05,273.63,411.49,646.91 μg/mL,respectively.Fungicidal efficiency against garlic white spot was surveyed at 5 days after inoculating the pathogen onto pot-grown garlic leaves.The pathogen had been inoculated onto the leaves 1 d before fungicide treatment.Disease suppression by 10% difenoconazole WG,40% flusilazole EC and 20.67% flusilazole/famoxadone EC was 92.0%,90.0% and 90.0%,respectively while efficiency of 20.67% flusilazole/famoxadone EC,10% difenoconazole WG and 40% flusilazole EC were 54.0%,45.7% and 41.4%,respectively in the treatment of spraying fungicides 2 days after inoculating.These three fungicides had better preventive and curative efficiency than 30% difenoconazole/propiconazole EC.However,the efficiency was much better when fungicides were sprayed on garlic leaves before inoculation.In field trail,40% flusilazole EC and 20.67% flusilazole/famoxadone EC,which differed with others significantly,had the highest efficiency at 62.3% and 56.6% disease suppression.