莱阳地区梨锈病防治适期研究

在山东莱阳地区,梨锈病菌冬孢子角自梨花现蕾期开始陆续成熟,成熟的冬孢子角遇1.5 mm/d以上的降雨,萌发产生担孢子。经2～3次降雨后,冬孢全部萌发,以后不再产生担孢子。梨树初花后35 d内对锈病最敏感,即为防治期。若该期内降雨量大于1.5 mm/次、叶面结露时间长于7 h/次,担孢子即可侵染。其侵染量与梨园周围越冬菌原的数量、降雨持续时间和品种抗病性等因子有关。田间试验表明:担孢子侵染后至病斑显症前(约7 d)是内吸性杀菌剂防治的有效时期。病斑显症后只有少数杀菌剂能抑制病斑扩展,20.67%氟硅唑乳油、10%苯醚甲环唑水分散粒剂和15%三唑酮可湿性粉剂3种药剂在病原菌侵入前喷施能有效地抑制担孢子侵染,持效期约7 d;担孢子侵染后喷药能有效抑制病斑显症,因此,要特别关注梨树初花时第1次降雨后梨锈病的防治。     

苹果锈病防治药剂筛选及施药适期研究

为了筛选防治苹果锈病的有效杀菌剂,明确其最适施药时期,通过先接种后施药和先施药后接种的方法,测试了8种药剂对苹果锈病的内吸治疗效果和7种药剂的保护效果.结果表明,8种内吸治疗剂中,氟硅唑、戊唑醇、苯醚甲环唑3种药剂对苹果锈病的治疗效果为100％;嘧霉胺和吡唑醚菌酯两种药剂的治疗效果分别为81.58％和74.52％;多抗霉素、嘧菌环胺和甲基硫菌灵3种药剂对苹果锈病没有治疗作用.7种保护剂中,代森锰锌、百菌清、吡唑醚菌酯和氟硅唑在接种前12 d内施药,保护效果皆为100％;异菌脲和甲基硫菌灵的保护效果分别为90.58％和90.21％;多抗霉素没有保护作用.上述结果表明,三唑类药剂是防治苹果锈病有效的内吸治疗剂,在病菌侵染后的5d内使用效果较为理想.代森锰锌、百菌清、吡唑醚菌酯等是防治苹果锈病的有效保护剂,持效期可达7～10 d.     

不同药剂及施药技术对玉米南方锈病的防效研究

近年来, 由多堆柄锈菌Puccinia polysora Underw.引起的玉米南方锈病在黄淮海玉米产区发生频率高、危害重。为明确玉米南方锈病的最佳防治时期, 不同杀菌剂种类、施用剂量及防治次数对玉米南方锈病的防治效果, 在大田条件下, 以丙硫菌唑为供试杀菌剂, 探讨了在玉米不同生育期防治及防治次数对玉米南方锈病的防效及对玉米产量的影响, 同时研究了丙环唑、戊唑醇、氟环唑和丙硫菌唑4种杀菌剂不同使用剂量对玉米南方锈病的防效及对玉米产量的影响。结果表明, 分别在玉米大喇叭口期、抽雄初期、吐丝期和灌浆期防治, 以抽雄初期的防效最好(58.47%), 挽回产量损失率最高(108.05%)。施药两次对玉米南方锈病的防治效果显著优于施药一次的防治效果。丙环唑、戊唑醇、氟环唑和丙硫菌唑4种杀菌剂对玉米南方锈病均有一定的防控效果, 施药后14 d的防效均在85%以上, 施药后28 d的防效呈明显下降趋势。4种杀菌剂防治玉米南方锈病, 防效以氟环唑(1 350 mL/hm2)和丙硫菌唑(1 350 mL/hm2)最好, 施药后14 d的防效分别为95.68%和95.57%;施药后28 d的防效分别为55.39%和60.27%。4种杀菌剂不同使用剂量的挽回产量损失率均在70%以上。从防治效果及挽回产量损失率等方面综合考虑, 防治该病的最佳施药期为玉米抽雄初期, 4种供试药剂均可在大田防治中推广应用。     

武汉市郊梨锈病流行学调查

2003年4～6月武汉市东西湖区荷包湖农场、辛安渡农场、走马岭农场、东山农场梨锈病流行,致使4个农场共1400hm^2梨绝收。通过对梨锈病的症状、病原形态特征观察和田间调查,初步摸清该病的发生特点和流行规律,进一步明确梨锈病流行与转主寄主桧柏的密切相关;提出在5km以内不栽转主寄主桧柏,并对梨树进行喷药保护等防治措施。     

12种杀菌剂对杜梨苗梨火疫病的预防与治疗效果测定

梨火疫病是苹果、梨等蔷薇科仁果类植物上一种重要的细菌性病害。为了筛选出有效防治梨火疫病的药剂,本研究采用预防和治疗的方式评价了12种药剂和其中5种药剂3种浓度对盆栽杜梨苗梨火疫病的预防和治疗效果,测定了其中4种药剂对梨火疫病的预防持效期和不同潜伏期的治疗效果。结果表明:预防和治疗效果都高于60%的药剂有6种,其中效果最好的是40%春雷·噻唑锌SC,喷施1 000倍液后2 d的预防效果和接菌后2 d的治疗效果分别达到95.63%和80.55%;不同药剂使用浓度对防效影响较大,5种药剂中只有40%春雷·噻唑锌SC在3种浓度下预防和治疗效果都达到70%以上;4种药剂中40%春雷·噻唑锌SC持效期最长,喷施1 000倍液21 d后预防效果仍能达到51.94%,在病害不同潜伏期的治疗效果最好,接菌后6 d治疗效果仍可达到62.31%。本研究结果为后续田间试验示范和大面积推广应用提供了技术支撑。     

绿化树种的选择须考虑植保后果，防重于治——从武汉市梨树锈病流行说起

梨树锈病在我国南北果园均普遍发生，常造成早期大量落叶，严重影响果树生长和产量。梨树锈病是一种转主寄生病害，仅在果树附近种植桧柏类树木较多的城镇郊区发生较重。防治梨锈病的根本方法是在梨园5km范围以内不种桧柏树，彻底切断病害的侵染循环。各地采用这一措施都收到很好效果。近期中国工程院院士、中国农业大学教授曾士迈先生多次接到湖北等地果农来访、来电，反映梨锈病在当地发生危害严重，咨询防治方法。为此曾先生特为本刊写了“绿化树种的选择须考虑植保后果，防重于治一从武汉市梨树锈病流行说起”。本刊全文发表如下，以引起各地领导及果农们对梨锈病的重视，确保果树丰产丰收。     

鲜食玉米南方锈病发生动态及药剂防控

田间条件下采用目测法调查了由多堆柄锈菌(Puccinia polysora Underw.)引起的南方锈病在广州鲜食玉米产区的发生动态,并测试了锈病对鲜食玉米产量的影响及几种药剂对南方锈病的防治效果。结果表明,南方锈病在鲜食玉米生产期间持续危害,7月份和11月份发生最严重,发病率近100%。锈病危害直接造成鲜食玉米果穗净重降低,重度危害(危害严重度50%)比轻度危害(危害严重度30%)折合每667m2产量减少47.6kg。化学药剂对南方锈病具有抑制作用,其中125g/L氟环唑SC和250g/L吡唑醚菌酯EC的防治效果最好,处理后锈病危害严重度比对照分别降低63.04%和57.21%,可挽回产量损失8%以上。     

6种药剂对玉米南方锈病田间防效评价

玉米南方锈病是豫南玉米生产上毁灭性的病害,近年来发生频繁,危害严重,缺乏药剂防治是该病害严重的主要原因之一。为明确表态杀菌剂对玉米南方锈病的防治效果,笔者选用戊唑醇,己唑醇,丙环唑,苯甲·丙环唑,醚菌酯,吡唑醚菌酯等6中不同杀菌剂对玉米南方锈病进行田间药效试验,结果表明6种杀菌剂对南方玉米锈病具有良好的控制作用,防治效果达到75%以上,增产效果显著,并对玉米生产安全,可以在大田生产中推广应用。     

康乃馨锈病病原鉴定及药剂筛选

通过鉴定发现引起甘肃省康乃馨锈病的病原为石竹单胞柄锈菌(Uromyces dianthi Niessl.);分别采用孢子萌发法和田间喷雾法、灌根法对防治康乃馨锈病的药剂进行了室内筛选和田间药效试验.结果表明,12.5％烯唑醇可湿性粉剂、25％嘧菌酯悬浮剂等7种药剂对康乃馨锈病夏孢子的萌发抑制率均超过50％;对筛选出的7种药剂进一步进行田间药效试验,发现采用喷雾法时12.5％烯唑醇可湿性粉剂、25％嘧菌酯悬浮剂和10％苯醚甲环唑水分散粒剂三种药剂的防效高于其他几种药剂,分别达70.2％、68.3％和65.0％,而灌根法对康乃馨锈病的防效并不理想,最高防效仅为8.1％.     

柑桔贮藏病害发生动态和化学防腐保鲜技术的研究

作者1983～1995年间研究了浙江自然状态下柑桔贮藏病害的发生动态。结果显示,以采后侵染为主的病害发病率占59.79±22.40％;采前采后均可侵染,但以采前侵染为主的病害发病率占40.21±22.40％。后一类病害为害加剧是浙江柑桔贮藏病害发生的新动态,从国内外16种药剂中筛选出抑霉唑(Imazalil)、扑霉灵(Prochloraz)、百可得(Bellkute)等新型柑桔防腐保鲜剂,大量用于生产,解决了柑桔青、绿霉病菌对苯并咪唑类药剂的抗药性问题,经济和社会效益显著。研究了抑霉唑对柑桔青、绿霉病菌的敏感基线,在国内外首次报道大幅度降低使用浓度(仅原来的1/2～1/4)仍有良好效果,并率先在浙江桔区大量使用。     

Infection Behavior of Venturia nashicola, the Cause of Scab on Asian Pears

ABSTRACT The infection of Japanese pear by Venturia nashicola, the cause of scab on Asian pears (Japanese pear, Pyrus pylifolia var. culta; Chinese pear, P. ussuriensis), was examined using light and electron microscopy to determine the mechanism of resistance in pears. Early stages of infection were similar on the susceptible cv. Kosui, the resistant cv. Kinchaku, and the nonhost European pear (P. communis) cv. Flemish Beauty. V. nashicola penetrated only the cuticle layer on pear leaves and formed subcuticular hyphae on all three cultivars. Hyphae were localized in the pectin layer of pear leaves and never penetrated into the cytoplasm of epidermal cells. This restriction of fungal growth suggested that pectinases released by infection hyphae or subcuticular hyphae may be important in infection. Subcuticular hyphae were modified ultrastructurally in the pectin layer of resistant pear cultivars accompanied by fungal cell death. In contrast, fungal cells appeared intact in susceptible pear cultivars, suggesting the existence of resistance mechanisms.     

梨叶叶龄与梨黑星病菌侵染发病的关系

田间试验结果表明，鸭梨叶片在生长发育期抗病性差，易感染黑星病；发育成熟后，抗病性逐渐增强。自然条件下，受叶片抗病性和孢子着落量的综合影响，鸭梨成熟叶片很少感染黑星病。鸭梨叶片从展叶到发育成熟，在梨树生长发育前期（盛花期后60d内）约需40d，后期（盛花期60d后）约需30d。正处在生长发育期的鸭梨叶片受侵染，潜育期为18－25d，发病后，病斑大，产孢期短；成熟叶片受侵染，潜育期多在40d以上，发病后，病斑小，产孢期长。梨树生长前期梨黑星病的流行主要由于大部分叶片正处在生长发育期抗病性较差；后期果实发病则主要源于成熟叶片内长期潜育和长期产孢的黑星病菌。     

冬型中国梨木虱在梨树不同部位的产卵特点

昆虫母代产卵部位的选择特点直接影响到子代的生存适应性,但已有研究对冬型中国梨木虱产卵部位选择特点尚未明确。本研究调查了冬型中国梨木虱随时间变化在梨树花芽、叶芽、枝条基部、花柄、幼叶上产卵特点的变化。结果表明,冬型梨木虱产卵期约45 d,以枝条基部刻痕处着卵量最大,显著高于其他部位。冬型梨木虱产卵部位的选择随梨树的物候变化而变化:萌芽前,优先选择枝条顶芽,其次在腋芽和枝条基部刻痕处产卵;花期和展叶期,花芽、叶芽、枝条基部刻痕处着卵量下降,主要于花柄和幼叶部位产卵;冬型梨木虱产卵部位的选择顺序依次为花芽、叶芽、枝条基部、花柄、幼叶。本研究明确了冬型梨木虱在梨树不同部位产卵的变化特点,研究结果可用于指导梨木虱防控。     

不同食料对苹果蠹蛾生长发育和繁殖的影响

在室内研究了红玉苹果、红元帅苹果、张掖2号苹果、沙果、苹果梨、早酥梨、杏对苹果蠹蛾［Cydia pomonella (L.)］生长发育和繁殖的影响。结果表明,不同食料对苹果蠹蛾幼虫和蛹的发育历期、存活率、蛹重、雌成虫寿命、雌成虫产卵量等有显著影响。幼虫取食沙果、早酥梨、红玉苹果最有利于其生长发育和繁殖;取食红元帅苹果和张掖2号苹果的影响居中;而取食杏和苹果梨对其生长发育和繁殖表现出明显的不利性,主要表现为幼虫死亡率增加,幼虫期延长,蛹期延长,蛹重减轻,雌成虫寿命缩短,单雌产卵量降低。     

Bait twig method for soil detection of <Emphasis Type="Italic">Rosellinia necatrix</Emphasis>, causal agent of white root rot of Japanese pear and apple,at an early stage of tree infection

Mulberry twigs were inserted into the soil as bait to detect Rosellinia necatrix at an early stage of tree infection in the orchard. R. necatrix was frequently trapped on twigs near the trunk base at soil depths of 6–20 cm within 10–20 days in May–July, suggesting that the incubation period was dependent on soil temperature. Subsequently, we inserted twig in the soil around healthy-looking trees in naturally infested orchards. R. necatrix was trapped from 80.0% of Japanese pear and 75.0% of apple trees that later proved to be infected. This bait twig method facilitated quicker diagnosis of white root rot on Japanese pear and apple at early stages of infection and can be used to detect recurrence of the fungus after fungicide treatment.     

Detection of fungi producing infection-inhibiting metabolites against <Emphasis Type="Italic">Alternaria alternata</Emphasis> Japanese pear pathotype from fungi inhabiting internal tissues of Japanese pear shoots

Fungi inhabiting Japanese pear were isolated from internal tissues of cv. Nijisseiki, and culture filtrates (CFs) of 100 isolates were evaluated for their inhibitory activity against infection by Alternaria alternata Japanese pear pathotype. CFs of 11 isolates inhibited lesion formation on the pear by the pathogen. Among these isolates, CFs of five isolates inhibited spore germination. CFs of the six other isolates inhibited appressorial formation, infection hypha formation, AK-toxin production, or a combination of these actions. Analysis of sequence homology in the rDNA ITS1 regions of these isolates showed that most isolates had high homology with some fungal endophytes.     

梨叶片感染轮纹病菌后的生理变化

梨叶片被轮纹病菌感染后,多酚氧化酶(PPO)、过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)的活性均显著下降。但叶片内丙二醛(MDA)含量和超氧阴离子(O₂-)的产生速率上升;还原型谷胱甘肽(GSH)和抗坏血酸(ASA)含量降低。这些结果表明,梨叶片被轮纹病菌感染后,叶内活性氧消除系统被破坏,而叶内膜脂过氧化作用加强是最终导致梨叶片受害的原因。     

A dynamic model forecasting infection of pear leaves by conidia of <Emphasis Type="Italic">Venturia nashicola</Emphasis> and its evaluation in unsprayed orchards

A dynamic model, called VenInf, was developed to forecast infection of pear leaves by conidia of Venturia nashicola. By simulating conidial infection processes following a rain event, the model estimates % conidia that successfully infected leaves at the end of an infection period. The model is mainly derived from logistic models developed from recent laboratory and glasshouse experimental results on infection of pear seedlings to estimate the rates of infection and mortality. It simulates the conidial infection process at 5 min intervals using temperature, relative humidity (RH), surface wetness and rainfall as input. The model was evaluated against pear scab in four unsprayed orchards in China over a 4-year period. In all orchards, all significant disease increases were associated with infection periods predicted by the model. In one orchard, in 2004 the incidence of leaf infection remained very low (<3%) during the entire season despite the model forecasting several severe infection periods. Results of orchard evaluation suggest that the model is able to identify all important potential infection periods. Thus, further field studies should be carried out to determine whether and how the model can be used in practice to assist farmers in making decisions on fungicide applications.