玉米褐斑病药剂防治效果评价

选用7种杀菌剂,研究了拌种和喷雾2种方法对玉米褐斑病的防治效果。结果表明:利用7种供试药剂进行种子包衣,对玉米出苗率和生长发育影响不大,但对褐斑病防治效果较佳;而在玉米5~6叶期2次喷雾,对玉米褐斑病具有较好的防治效果,并且防治效果可持续到乳熟后期。世高和粉锈宁药剂对褐斑病的防治效果较好,平均防效分别达96.79%和93.1%。     

海南芒果蒂腐病可可球二孢抗药性及遗传多样性分析

探索海南芒果蒂腐可可球二孢(Botryodiplodia theobromae)的抗药性、培养特性及遗传多样性的关系。以区分剂量法检测30个菌株对10种杀菌剂的敏感性,采用RAPD技术对菌株的遗传多样性进行分析。研究表明,芒果可可球二孢菌株对多菌灵、甲基硫菌灵、醚菌酯、嘧菌酯、吡唑醚菌酯、苯醚甲环唑和咪鲜胺锰盐7种杀菌剂产生了抗药性,抗性菌株比率(MR和HR)分别为66.67%、70.00%、90.00%、76.67%、53.33%、20.00%和16.67%。供试菌株的培养特性存在明显差异。应用6个随机引物对共扩增出64条带,DNA多态率高达90.6%,遗传距离在0.58~0.86,芒果蒂腐病菌遗传分化较大。在遗传距离为0.65时,可分为两个群,群Ⅰ分成3个类群,共有26个菌株,群Ⅱ分成2个类群。聚合类型与菌株的抗药性表现一致。菌株的致死温度与聚合类型、抗药性有一定的关联。     

Characterization of sensitivity of grove and packing house isolates of Penicillium digitatum to pyrimethanil

In most northeast Argentinean citrus packing houses, postharvest fungicide treatments are based on the use of thiabendazole and imazalil. However, these fungicides have been used in a manner highly conducive to the selection and proliferation of resistant biotypes of Penicillium digitatum, the main fruit decay fungus in the area. Recently, a new fungicide, pyrimethanil (PYR), was introduced to control molds. Aims of this study were to determine the baseline sensitivities for PYR against isolates of P. digitatum considering its use in the region is not yet widespread and to evaluate the control of the fungus in vivo. One hundred and nine (109) P. digitatum isolates were collected from diseased fruit within citrus groves (43 isolates) and packing houses (66 isolates). EC₅₀ was determined for each isolate by measuring colony diameters on different agar dilutions of the fungicide. The mean EC₅₀ value of the green mold isolates collected from the groves was 0.14 ± 0.03 mg L⁻¹ while the mean EC₅₀ of those collected from packing houses was 0.13 ± 0.05 mg L⁻¹. No resistant isolates were found in the field where the fungicide is not used, while one isolate originated from a packing house showed an EC₅₀ of 3.40 mg L⁻¹, 26-fold higher than the mean level. This isolate was collected from lemons stored in cool rooms of a packing house where PYR had not been used. Fruit decay by sensitive isolates was reduced approximately 80% by PYR applied at 500–600 mg L⁻¹ by immersion for 60 s at room temperature to inoculated oranges and mandarins. In contrast, the resistant isolate was not controlled by PYR applied at 1000 mg L⁻¹. Thus, the introduction of PYR applied into packing houses should be done carefully and control strategies should be implemented in order to minimize the development of resistant isolates.     

Integration of biocontrol yeast and thiabendazole protects stored apples from fungicide sensitive and resistant isolates of Botrytis cinerea

Three selected biocontrol yeasts, known for their elevated antagonistic activity against several fungal pathogens, were tested in vitro for compatibility with common fungicides. The antagonists were resistant to several fungicides, but they were inhibited by triazoles and dithiocarbamates. The yeast isolate LS28 (Cryptococcus laurentii), which tolerated in vitro high rates of benzimidazoles, was tested, alone or in combination with a low dose (10% of the full label rate) of thiabendazole, against grey mould on stored apples. Wounded fruit were inoculated with thiabendazole resistant and sensitive isolates of Botrytis cinerea, applied separately or as a mixture. A more effective and prolonged control of fungal decay was always exerted by the biocontrol yeast applied together with thiabendazole at a low dose. This treatment provided synergistic effects and was markedly better than treatments applied separately, whereas the fungicide applied alone at the highest label dose was ineffective in the presence of the isolate of B. cinerea resistant to thiabendazole. The biocontrol yeast applied alone provided significant protection of apples stored for up to 12 days at 20 °C (from 39 to 81% less decay than untreated control), whereas the fungicide alone at low or high dose was always ineffective in the presence of the B. cinerea isolate resistant to benzimidazoles. The integrated treatment was highly effective and durable showing high reduction of decay (from 66 to 92%) even after 18 days of storage. This study suggests that the integration of a biocontrol agent with a low rate of fungicide may be a useful alternative strategy to manage both sensitive and resistant isolates of fungal pathogens efficiently and to reduce risks involved with extensive use of synthetic chemicals.     

以覆膜增温为主的综合技术对玉米丝黑穗病控制的初步研究

2005~2006年,在玉米丝黑穗病发生较为严重的山西省寿阳县,开展了以覆盖农膜为主,结合抗病品种和杀菌剂处理对玉米丝黑穗病控制效果以及玉米生长和产量影响的初步研究。结果显示,2005年和2006年,覆膜使玉米丝黑穗病的平均发病率分别从15.5%和8.9%降低到6.3%和6.5%,防治效果分别达59.4%和27.0%;使玉米产量分别提高746.2kg/hm²和1410.0kg/hm²。选种抗丝黑穗病品种能显著降低丝黑穗病的发病率。晋单34号在2005年和2006年较宽诚1号和张玉1号丝黑穗病的发病率分别从17.3%和9.5%降低到4.5%和6.0%。本研究所选用的杀菌剂15%三唑酮、CAM和黑虫双全均未显著降低丝黑穗病的发病率。     

中草药源杀菌剂的研究进展

对中草药源杀菌剂的资源情况、活性成分及其作用机理的研究进行了概述,并阐述了中草药源杀菌剂研究存在的问题与展望.     

葡萄黑痘病无公害防治药剂筛选及控害技术研究

选取咪酰胺EC、福星EC等6种对葡萄黑痘病有效的常用杀菌剂品种进行田间试验。结果表明福星EC、苯醚甲环唑WG、咪酰胺EC等3种药剂对预防和控制黑痘病的发生有较好的效果,其中福星EC、苯醚甲环唑WG效果好且对人体无毒副作用,可推荐使用;另外4种药剂可在控害过程中作为轮换药剂,与其他农药搭配使用,以延缓病原菌抗药性的产生。同时针对病害发生特点对其综合防控技术进行了研究集成。     

9种杀菌剂对苹果炭疽病菌的毒力比较

采用菌丝生长速率法测定了9种杀菌剂对苹果炭疽病菌的抑制活性。结果表明,苹果炭疽病菌对三唑类杀菌剂戊唑醇、己唑醇、氟硅唑、苯醚甲环唑、腈菌唑的敏感性依次下降,EC50值均在2.2μg/ml以下,EC90值均低于21μg/ml;甲基硫菌灵对苹果炭疽病菌毒力EC50值为1.9008μg/ml,与腈菌唑毒力相当;而福美锌、醚菌酯和代森联抑制病菌生长的毒力显著低于三唑类杀菌剂。     

Reduced efficacy of rovral and botran to control Sclerotinia minor in lettuce production in the Salinas Valley may be related to accelerated fungicide degradation in soil

Accelerated soil degradation with repeated application was suggested to be responsible for the lack of efficacy of commercial fungicides to control lettuce drop caused by Sclerotinia minor in the Salinas Valley in California. In 2000, a study was initiated in a field artificially infested with S. minor to evaluate the efficacy and degradation potential of four selected fungicides (i.e., Rovral, Botran, Switch, and Endura). Crisphead lettuce was direct-seeded twice a year (spring and fall season) from 2000 to 2002. Fungicides were applied at recommended label rates twice during each season. Disease incidence was evaluated in fungicide treatments and nontreated control plots weekly starting immediately after thinning until harvest, and areas under the disease progress curves (AUDPC) were compared between treatments from 2000 to 2002. Soil samples (0–15 cm) were collected at regular intervals during the spring and fall 2002 lettuce seasons, and analyzed for residual fungicide concentration. Disease progress and final disease incidence were significantly affected by the fungicide treatment, season, year and interactions among these factors (p < 0.05). At the end of the three year experiment, up to 18 and 50% of the lettuce was infected by S. minor for the spring and fall seasons, respectively. Fungicide efficacy to control lettuce drop was highest for Endura, followed by Switch and Botran, and lowest for Rovral. Relative persistence in soils was lowest for Rovral and Botran, followed by Switch and Endura. In 2002, residual soil fungicide concentrations were 11% for Rovral and Switch, 23% for Botran, and 88% for Endura relative to their initial concentrations. Results of this study provide first evidence suggesting that reduced efficacy of lettuce drop control from Rovral and Botran in the Salinas Valley may be related to an accelerated degradation of these fungicides due to repeated application. However, insufficient fungicide persistence due to inherent properties of this sandy loam soil or the chemical structure of these fungicides can not be excluded. Both hypotheses deserve further investigation.     

Influence of fungicide spray schedules on the sensitivity of Cercospora beticola to the sterol demethylation-inhibiting fungicide flutriafol

A field experiment was conducted over a three-year period (1997–1999) to study the efficacy of several fungicide spray-schedules and their effects on the sensitivity of Cercospora beticola populations to the DMI fungicide flutriafol. Spray applications of flutriafol, either alone at the recommended dose, or at a reduced dose in mixtures with maneb, or in alternation with tank mixed fentin-acetate and maneb, were included in the spray programs. Applications of flutriafol at the recommended dose showed a significantly greater control efficacy in comparison with the other treatments, while applications of flutriafol alternated with tank mixed fentin-acetate and maneb showed lower efficacy in comparison with the remaining flutriafol treatments. Fungal populations from plots continuously treated with flutriafol, either alone at the full dose or at reduced dose with maneb, had lower sensitivity to flutriafol in comparison with populations from plots treated alternatively with flutriafol and tank mixed fentin-acetate and maneb. Repeated applications of flutriafol, at full or reduced doses, favoured the selection of highly resistant strains. Since applications of flutriafol in alternation with tank mixed fentin-acetate and maneb do not maintain a high level of disease control, the only available anti-resistance strategy would be the restriction of the number of flutriafol treatments, by applying them only when environmental conditions are favourable for disease development and by using alternative fungicides during the rest of the growing season.