Research On The Yield Loss Evaluation Of Potato Early Blight (Alternaria Solani) And Chemical Control Techniques

Potato is the fourth largest food crops after the paddy rice、corn、wheat, and China has possessed of the most largest production. But Early Blight has always been one of the most serious blight in production of Murphy, which becomes even more violent and results in a great yield loss these years. In order to make explicit of the performances, extent of injury, control measures of Potato Early Blight, the toxicity determinations of fungicides inside and outside, assessments of that damage were carried out in this thesis, The results follow as:1. Through the comparison of preventive treatment with blank control using Early Blight disease assessment, we make it clear that the final loss rate in WeiChang of HeBei province in 2011 is 33.60%.2. The toxicities of eleven fungicides to Alternaria solani were determined by the method of growth rate in the lab. Azoxystrobin·Difenoconazole, Azoxystrobin, Difenoconazole and Polyoxin 4 kinds of toxicity powerful fungicides whose EC50 below 0.5μg?mL-1 were selected out; Propiconazole, Penconazole, Iprodione whose EC50 are between 0.5~1.5μg?mL-1 have the better toxicity.3. All the 11 kinds of fungicides were used out in the field in normal atomizing way and the result shown that they all have obviously positive functions in the prevention and cure ,also in production. Among the rest Azoxystrobin·Difenoconazole SC of 32.5% has the best performance against the potato Early Blight, and the lowest prevention effect is 77.37%, the highest rate can reach 96.93%. The yield of potato was increased 50.60%. The effect of Azoxystrobin, Mancozeb, Penconazole comes second, and the control efficiency is between 67.26%~95.43%. The effect of yield increasing are respectively 44.22%, 36.26%, 29.88%.4. The demostrate experiment result of Azoxystrobin against the potato Early Blight showed that it is safe to Solanum tuberosum, and it can increase 26.62% more of the final yields of potato crops than other normal preventive fungicides (Mancozeb, sandofan), and has a better prospect and great promotional value.