| Recently, potato gangrene (Phoma foveata) was found as an entry quarantinepest. It is the major factor to cause rotten potato during storage. It was firstlydiscovered in2009in Gansu Province, China. In this study, the symptoms, pathogenmorphological, physiological and biochemical characteristics, ITS sequences ofpotato gangrene, as well as the disease resistance of cultivars and chemical controlmethods were systematically studied. We evaluated the suitability and risk of thepotato gangrene. The main contribution were summarized as following:1. Potato gangrene damages its leaves and stems. Firstly, dehydration like wiltingoccurred on the plants. Then the low stem of the plants become browning. Smallblack particles, pycnidium, were formed at the diseased parts. Finally, the whole plantdies gradually. After infected during the storage, the sunken deceased patches with theshape of round, oval, or irregular, light brown or brown, occurred gradually on thepotato tuber. Small black bodies (gathered piles of pycnidium) were observed in thecenter of the lesions. The tuber rotten eventually.2. The fungal isolate were identified as Phoma foveata Foister according itsmorphologic characteristics, pathogenicity, symptoms, biochemical characteristics andITS sequence analysis.3. We tested the factors, such as temperature, humidity, solar irradiation andnutrient and their influence to the growth of the Phoma foveata Foister. The optimumtemperature for mycelial growth and conidia germination is20℃. There weredifferent performance in the color, size and edge of colony on the8different media,such as PDA, OA. The PDA medium was founde to be optimum for mycelial growth.The conidia could germinate among pH3-10. The optimum pH value for conidiagermination was pH=6. The requirements of humidity were strict, and relativehumidity100%was the bestconditions for the spores’s germination.5%sucrosesolutions can promote spore germination. The solar irradiation treatment for thehyphae has not produce any significant difference.4. Before infected by P. foveata, there is no regularity for five defense enzymes (SOD, POD, β-1,3-glucanase, CAT, PPO) activity and the protein content in six potatovarieties. However, their contents are increased after infected. In contrast, the relativeactivity of Zhuangshu No.3and Dingshu No.1increased significantly. Variation ofdefense enzyme activity infected by P. foveata in six potato varieties were closelyrelated to their resistance. The lesion volume of Dingshu No.1and Zhuangshu No.3were57.21mm3and64.63mm3respectively, disease incidence of them were5.40%and0.81%respectively during maturity, the potato disease’s total rate after storage ofthem were5.76%and1.57%respectively, those showed that they had the strongestresistance of potato gangrene. The lesion volume of Qingshu No.9was652.27mm3,which showed that Qingshu No.9had the weakest resistance. Although the diseaseincidence of Longshu No.10, No.3No.6were11.34%,11.34%and11.79%respectively, their yield were higher than other species, which showed their betterpatience.5.30%propiconazole difenoconazole,35%Carbendazim sulfonate,5%Junduqing,10%difenoconazole and32.5%difenoconazole azoxystrobin had a betterinhibiting action to Phoma foveata and the EC50were0.000024mg/L,0.01767mg/L,0.07395mg/L,0.13151mg/L and0.23054mg/L, respectively. The efficacy in fieldof10%difenoconazole,25%Azoxystrobin and32.5%difenoconazole azoxystrobin were94.87%,100%,92.31%, respectively, and the increase rate were16.96%,8.73%,7.98%, respectively, also their control effect on rot tuber after storage were all above85%, which were better than others. The efficacy of32.5%difenoconazole azoxystrobin onpotato gangrene was80.88%, which was better than others. Bacillus subtilis couldhave a higher efficiency as80.02%. The efficacy of0.1%Salicylate on potatogangrene was64.96%.6. Based on this research, we published one official document titled as “Theregulations for potato gergrene integrated prevention and control technology in Gansuprovince”. The document can be used to guide agricultural production in Gansu.7. P. foveata can survive in the11provinces of China, including Gansu, Yunnan,Guizhou, Sichuan, Xinjiang, Ningxia, Jiangsu, Anhui, Hubei and Hunan. It could beplanted in the most areas of10Provinces, including Inner Mongolia, Shaanxi, Shanxi, Henan, Hebei, Shandong, Beijing, Liaoning, Jilin and Heilongjiang. Comprehensiverisk value of P. foveata was estimated as0.792. It suggested that P. foveata would be arisk microorganism in China and need to be monitored as a key target.This research laid the foundation for effective inspection and prevention theintrusion and proliferation of potato gangrene disease in China. The findings providtheoretical basis for breeding of disease resistance varieties. |
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