海南省火龙果溃疡病菌对吡唑醚菌酯敏感性分析

【目的】监测分析海南省火龙果溃疡病菌对吡唑醚菌酯的敏感基线及敏感性水平。【方法】采用菌丝生长速率法测定吡唑醚菌酯对海南省8个火龙果种植市(县)采集到的59株火龙果溃疡病菌的EC₅₀值,采用R语言进行数据分析。【结果】吡唑醚菌酯对供试菌株的EC₅₀范围为0.2540~2.2233μg·mL^-1,EC₅₀均值为0.9841μg·mL^-1;以58株菌株EC₅₀连续性正态分布时的均值0.9627μg·mL^-1作为海南省火龙果溃疡病菌对吡唑醚菌酯的敏感基线,海南省火龙果溃疡病菌均对吡唑醚菌酯表现为敏感;除乐东和白沙地区间敏感性差异显著外,其他地区间敏感性差异均不显著。【结论】海南省火龙果溃疡病菌对吡唑醚菌酯的敏感性差异较小,对吡唑醚菌酯仍较为敏感。     

戊唑醇和咯菌腈复配对火龙果褐腐病菌的联合毒力及田间防效

【目的】明确戊唑醇和咯菌腈复配对火龙果褐腐病菌联合毒力与田间防治效果。【方法】采用生长速率法测定戊唑醇、咯菌腈及其复配药剂对火龙果褐腐病菌的室内毒力,以Wadley法评价增效作用,并验证了复配药剂对火龙果褐腐病的田间防效。【结果】咯菌腈和戊唑醇对火龙果褐腐病菌均表现出良好的抑菌效果,EC_(50)值分别为0.0045、0.0671 mg/L。戊唑醇与咯菌腈不同配比对火龙果褐腐病菌表现为加和作用。有效浓度分别为100 mg/kg和500 mg/kg连续喷施3次时,末次药后7 d,戊唑醇和咯菌腈质量比8∶2复配对火龙果褐腐病平均防效分别为80.31%和89.44%,戊唑醇单剂平均防效分别为80.24%和89.71%,咯菌腈单剂平均防效分别为70.08%和76.29%;末次药后15 d,戊唑醇和咯菌腈质量比8∶2复配平均防效分别为76.80%和83.63%,戊唑醇单剂平均防效分别为74.63%和81.22%,咯菌腈单剂平均防效分别为54.53%和65.24%;复配药剂两种施药浓度的防效均比使用相同浓度单一药剂的防效高。【结论】戊唑醇和咯菌腈质量比为8∶2的复配药剂对火龙果褐腐病菌具有良好的抑菌效果,在田间防治效果好且对火龙果无药害,可以在火龙果生产上推广使用。     

Identification and pathogenicity of Botryosphaeriaceae species associated with root and stem rot of sweet potato in Brazil

The sweet potato (Ipomoea batatas) is characterized by the production of tuberous roots rich in starch and is one of the most produced and consumed vegetables in Brazil. Botryosphaeriaceae, among other fungi, are known to cause root and stem rot of sweet potato. However, no representative and accurate study has been performed for the correct identification of these fungal species in sweet potato in Brazil. Therefore, this study aimed to identify the Botryosphaeriaceae species associated with root and stem rot of sweet potato and confirm their pathogenicity. Tuberous roots and stems of sweet potato with rot symptoms were collected in production fields and markets and used for fungal isolations. The identification of fungi was based on the morphology of reproductive structures and phylogenetic analyses of the gene regions ITS, tef1-α, and rpb2. The following species were identified: Lasiodiplodia theobromae, L. hormozganensis, Macrophomina phaseolina, M. euphorbiicola, M. pseudophaseolina, and Neoscytalidium dimidiatum. For the pathogenicity test, one representative isolate for each species was inoculated in healthy tuberous roots and in 30-day-old healthy seedlings. Black and necrotic lesions on tuberous roots and stems were observed in all replications and resulted in the death of some seedlings. This is the first report of L. hormozganensis, M. pseudophaseolina, and M. euphorbiicola, as causal agents of the stem and root rot of sweet potato and N. dimidiatum as a causal agent of stem rot worldwide.     

火龙果溃疡病病原菌鉴定及生物学特性

为确定火龙果溃疡病病原菌,应用柯赫氏法则测定了从病样中分离的纯培养物的致病性,根据形态学特性和ITS序列分析对病原菌进行鉴定,并采用菌落生长法和玻片法研究了其生物学特性.结果表明,火龙果溃疡病的病原菌为新暗色柱节孢Neoscytalidium dimidiatum (Penz.) Crous & Slippers.碳氮源对病原菌菌丝生长和产孢量的影响差异明显,菌丝生长和产孢的最佳碳源为蔗糖,菌丝生长最佳氮源为酵母膏,产孢最佳氮源为甘氨酸.温度、pH对病原菌菌丝生长、产孢和孢子萌发的影响差异显著,菌丝生长、产孢、孢子萌发的最佳温度均为30℃;菌丝生长最佳pH为8,产孢和孢子萌发最佳pH为7.光照对病原菌菌丝生长和产孢有抑制作用,对孢子萌发没有明显影响.相对湿度高有利于孢子萌发,高于98％时,萌发率达100％.     

16 种杀菌剂对火龙果褐腐病菌抑菌持效期及田间防效试验

【目的】筛选对火龙果褐腐病菌(Neoscytalidium dimidiatum)抑菌持效期长且田间防治效果好的杀菌剂,为火龙果生产上最具毁灭性的褐腐病防治提供科学依据。【方法】采用琼脂扩散法,通过测量和观察抑菌圈大小及消失时间测定16种杀菌剂抑制病菌生长的持效期,对其中抑菌效果好或持效期长的杀菌剂开展田间药效试验与防效比较。【结果】咯菌腈、丙环唑、丙硫菌唑、戊唑醇、氟硅唑、异菌脲等6种杀菌剂对病菌的抑菌持效期长,培养15 d后抑菌圈尚未消失;咪鲜胺、苯醚甲环唑、腈菌唑等3种杀菌剂对病菌的抑菌持效期较长;多菌灵、噻菌灵、嘧菌酯等3种杀菌剂初期对病菌的抑菌持效期较短;丙森锌、春雷霉素、百菌清、氟环唑等4种杀菌剂的抑菌持效期极短。田间药效试验显示,戊唑醇、异菌脲、氟硅唑、丙硫菌唑、丙环唑等5种杀菌剂对火龙果嫩茎具有良好的防治效果;除丙环唑在500 mg/kg施药浓度下对火龙果嫩茎生长产生抑制作用外,其余4种杀菌剂对火龙果生长安全。【结论】生产上优先推荐使用具有内吸活性的戊唑醇、异菌脲、氟硅唑、丙硫菌唑、丙环唑等药剂防治火龙果褐腐病,轮换用药;在病情压力较大的果园,施药浓度可以适当加大。     

火龙果溃疡病研究进展

火龙果溃疡病是火龙果生产上的重要病害之一, 对我国火龙果产业构成严重威胁?目前, 我国对火龙果溃疡病及其抗病育种的研究基础非常薄弱?本文介绍了火龙果溃疡病发病症状?病原学研究?流行规律以及防治措施等方面的研究进展, 为溃疡病的发生机制研究?病害防治及抗性品种选育提供参考?