A comparative evaluation of post-infection efficacy of mefenoxam and potassium phosphite with protectant efficacy of azoxystrobin and potassium phosphite for controlling leather rot of strawberry caused by Phytophthora cactorum

Leather rot, caused by Phytophthora cactorum, is one of the most important fruit-rotting diseases of strawberry worldwide. Efficacy of mefenoxam and potassium phosphite against leather rot, when applied in a post-infection fungicide program, made in response to rain events was evaluated over 3 years of testing. Post-infection treatments of potassium phosphite and mefenoxam were compared with calendar-based treatments of azoxystrobin or potassium phosphite sprayed weekly, starting at late bloom (fruit set). In order to obtain high-risk conditions for infection (splash dispersal of the pathogen and subsequent infection periods), plots were flooded until standing water was observed between the rows. Post-infection applications were made within 36 h after the initiation of a flooding event. Leather rot incidence in the untreated controls ranged from 15 to 66% over the 3 years. All fungicide treatments had significantly (P < 0.001) less leather rot incidence than in the untreated control. There were no significant differences in leather rot incidence between the different fungicide treatments. Percent control (the percentage reduction in incidence relative to the check) was as high as 100% with all fungicide treatments. Mefenoxam and potassium phosphite post-infection (after flooding) provided control equal to that obtained with a calendar-based spray program, but with from 1 to 3 fewer fungicide applications.     

35%多菌灵·嘧菌酯水悬浮剂配方研究

为了研究35%多菌灵·嘧菌酯水悬浮剂更合理的配方,采用湿法超微粉碎法和正交优化试验法,对分散剂、乳化剂、增稠剂、防冻剂等进行了筛选,结果表明：多菌灵30.0%,嘧菌酯5.0%,亚甲基双萘磺酸钠2.0%,农乳600# 4.0%,蓖麻油聚氧乙烯醚3.0%,黄原胶0.1%,乙二醇2.0%,正辛醇0.5%,水补足100%,该组分及配比情况下,该产品悬浮率在98%以上,热贮[（54±2）℃,14天]分解率小于3%,产品各项指标符合悬浮剂的要求,产品用量为1500 g/hm2时对草莓白粉病的防效为92.76%。配制的35%多菌灵·嘧菌酯产品指标符合要求,对草莓白粉病有很好的防效。     

嘧菌酯与烯酰吗啉对葡萄霜霉病菌的毒力测定

化学药剂长期连续使用会使葡萄霜霉病菌对部分药剂产生抗药性。通过采用离体叶盘法,测定嘧菌酯和烯酰吗啉及两者的混用对葡萄霜霉病菌的毒力作用。结果表明,95%嘧菌酯、98%烯酰吗啉及两者的5 个配比（1:1、1:2、2:1、1:4、4:1）对葡萄霜霉病菌的EC50 值分别为7.9003、1.7656、1.454、1.685、1.0117、1.9688、3.2009 μg/mL。其中嘧菌酯:烯酰吗啉为2:1 时对葡萄霜霉病菌生长的抑制作用较强,可以用于防治葡萄霜霉病的田间试验。     

30%苯醚甲环唑·嘧菌酯悬浮剂在香蕉和土壤中的残留分析方法研究

建立GC-NPD测定苯醚甲环唑和嘧菌酯在香蕉和土壤中残留的分析方法。样品经乙腈提取,弗罗里硅土小柱净化,洗脱液为正己烷∶丙酮=9∶1。结果表明:该方法可以同时检测出香蕉和土壤中两种物质的含量,两种物质在0.05～2μg/mL的范围内有良好的线性关系,苯醚甲环唑和嘧菌酯的线性相关系数分别为0.997 3和0.999 4。在香蕉果、肉和土中的最低检测浓度皆为0.05 mg/kg,最小检出量为0.05 ng,在不同样品中的平均回收率分别为85.4%～107.4%和93.4%～106.3%,相对标准偏差分别为1.67%～7.80%和1.40%～5.84%。     

Efficacy of azoxystrobin for the control of cucumber downy mildew (Pseudoperonospora cubensis) and fungicide residue analysis

During a five-year trial (2007–2011), the efficacy of azoxystrobin (Quadris, 250 g a.i. L⁻¹, Syngenta) in two doses (187.5 g a.i. ha⁻¹ and 250 g a.i. ha⁻¹) and chlorothalonil (Bravo 720-SC, 720 g a.i. L⁻¹, Syngenta) at a rate of 1.44 kg a.i. ha⁻¹ was tested for the control of cucumber downy mildew (CDM). Cultivars that were susceptible or resistant to CDM (Regal and Haros, respectively) were tested for their response to fungicide applications. Differences in both disease severity and yield of the cultivars among resistance levels and fungicide treatments were observed. A highly significant and negative correlation was obtained between AUDPC and yield. Higher yields can be achieved by planting more resistant cultivars in combination with lower doses of fungicides. This is an indication that CDM contributes significantly to yield losses in cucumber production in Serbia. While monitoring the degradation of azoxystrobin residues, a decrease in residue levels to 1.0 mg kg⁻¹ below the maximum residue level (MRL) was observed at the end of the pre-harvest interval (PHI).     

嘧菌酯处理对哈密瓜采后抗病性的影响

[目的]研究嘧菌酯(AZX)处理对哈密瓜采后病害的影响,为控制哈密瓜采后腐烂提供技术参考.[方法]以哈密瓜西州蜜26号为试验材料,经50、150、250、300 mg/L嘧菌酯(AZX)溶液浸泡3min,自然晾干后贮藏于常温条件下,研究嘧菌酯处理对哈密瓜采后抗病性的机理.[结果]250 mg/L嘧菌酯(AZX)处理能有效抑制哈密瓜采后腐烂率、呼吸强度、乙烯释放量上升,且明显提高了贮藏后期木质素含量、过氧化氢酶( CAT)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、β-1,3-葡聚糖酶(GHU)等抗病性酶活性,显著抑制了几丁质(GHT)酶活性降低.[结论]嘧菌酯(AZX)处理提高了哈密瓜采后抗病性,可能与激活果实体内的相关防御酶活性有关.     

复凝聚法制备嘧菌酯微囊剂工艺研究

[目的]提高农药的有效利用率、减轻其毒性和药害、降低环境污染。[方法]在L9(34)正交试验中,以包封率为判断指标,研究药胶质量比、搅拌速度、固化时间对嘧菌酯微囊包封率的影响。[结果]药胶质量比、搅拌速度、固化时间对嘧菌酯微囊包封率的影响依次为:药胶比>搅拌速度>固化时间。根据包封率确定的最佳工艺条件为:药胶比1.0∶10.0,搅拌速度100 r/min,固化时间30 min。经验证,由此工艺制得的嘧菌酯微囊的包封率可达70%。[结论]用该法制备农药微囊能改善药物的物理特性,提高农药的有效利用率。     

嘧菌酯和腐霉利混配对番茄灰霉病菌的毒力及田间防效

采用菌丝生长速率法测定嘧菌酯和腐霉利混配对番茄灰霉病菌的抑制作用,并测定混配制剂对灰霉病菌的田间药效。结果表明,嘧菌酯和腐霉利按质量比1.00∶2.00、1.00∶3.00、1.00∶3.75和1.00∶5.00四个比例混配后对番茄灰霉病菌的共毒系数CTC分别为140.06、148.42、167.90和126.69,均大于120,表现增效作用。田间药效试验结果表明,30%嘧菌酯·腐霉利悬浮剂每hm2施药量1 012.5~1 125.0 m L,防治效果达到76%以上,具有较好地防治效果,并且对作物无药害,适合在生产上推广应用。     

嘧菌酯在西瓜和土壤中的消解动态和残留分析

为评价嘧菌酯在西瓜上使用的安全性,于2012、2013年在济南、杭州两地采用田间试验和气相分析方法研究了嘧菌酯在西瓜及土壤中的消解动态和最终残留。结果表明:嘧菌酯在西瓜和土壤中的降解行为均符合一级降解动力学方程,其降解半衰期分别为2.2~4.7、10.0~13.7 d。嘧菌酯在西瓜和土壤中的最终残留质量分数均小于最低检出限0.01 mg/kg,低于嘧菌酯在西瓜上的最高残留限量(MRL)1.0 mg/kg。     

阿米西达控制杧果果实采后病害的技术

进行了阿米西达控制杧果采后病害的研究。结果表明:在测试的3种药剂中,阿米西达对杧果炭疽病病菌(Colletotrichum gloeosporioides) 的菌丝体生长、产孢及孢子萌发均有明显的抑制作用,而对杧果蒂腐病菌(Botrydiplodiatheobromae) 菌丝体生长的抑制效果较施保功差;采后用100~200μgmL的阿米西达控制杧果贮运期间炭疽病的发生具有较好的效果,而在此质量浓度时,对杧果蒂腐病和酸腐病的防效则不稳定;阿米西达结合热处理防治杧果炭疽病的效果更好。