Susceptibility of several Japanese plum cultivars to pests and diseases in a newly established organic orchard

The susceptibility of 14 Japanese plum cultivars to an aphid pest and three fungal diseases was analysed during 2007 and 2008 in two experimental orchards, one in organic and the other in conventional management. There was a significantly higher incidence of green peach aphids [Myzus persicae (Sulzer)] for most of the cultivars in the organically managed treatment. ‘Fortune’, ‘Primetime’, ‘Larry Ann’ and ‘Sapphire’ were the cultivars most affected, and ‘Souvenir’ suffered the lowest attack in both treatments. Shot hole disease (Wilsonomyces carpophilus) affected both orchards at low levels, and only two cultivars, ‘Santa Rosa’ and ‘Larry Ann’, suffered a moderate attack. Powdery mildew (Sphaerotheca pannosa) incidence was significantly higher in the conventionally managed orchard and only the ‘Red Beaut’ cultivar was affected. Rust disease (Tranzschelia spp.) incidence was significantly higher in the organic treatment. The cultivars in which the rust disease appeared earliest and reached the highest levels were ‘Showtime’, ‘Santa Rosa’, ‘Friar’, and ‘Larry Ann’. An intense rust infestation in leaves provoked a premature defoliation in the organic plot, indicating that proper control of this disease is important to maintain tree vigour and yield.     

小麦秆锈菌新致病小种21C3CTR致病谱分析

用从国内１６个小麦主产省收集的１１２个小麦主栽品种及抗源，分析测定秆锈菌新致病小种２１Ｃ３ＣＴＲ的致病谱，并与国内另７个致病小种２１Ｃ３ＣＫＨ，２１Ｃ３ＣＫＲ，３４ＭＫＧ，３４ＭＫＨ，３４Ｃ２ＭＫＲ，３４Ｃ２ＭＦＧ和３４Ｃ２ＭＦＲ的致病谱进行比较。２１Ｃ３ＣＴＲ的致病谱为４３．８％，另７个致病小种的致病谱则分别为４４．６％，４８．３％，５２．７％，５２．７％，５６．３％，４５．５％，６６．８％。２１Ｃ３ＣＴＲ的致病谱除比２１Ｃ３ＣＫＨ高外，比另６个致病小种都低，与３４Ｃ２ＭＦＲ的差异已达极显著水平。说明２１Ｃ３ＣＴＲ（Ｓｒｌｌ毒力）的出现引起抗病性丧失尚不十分严重。其原因是尽管２１Ｃ３ＣＴＲ对Ｓｒｌｌ有毒力，但对国内生产品种及抗源出现频率最高的抗秆锈病基因Ｓｒ５不具有毒力，制约了其致病谱。通过测定还明确了来自不同省份的小麦品种抗秆锈病水平存在极显著差异，具体阐明了各省小麦品种的抗性水平。建议今后秆锈病测报重点应放在品种抗性差的地区。     

黄柏锈病的初步研究

本文以荥经县川黄柏种植基地为主要观测点，对黄柏叶锈病发生情况进行了调查。病害发生程度与海拔高度相关性不明显，而与林龄密切相关，1a生的发病明显重于3a生。黄柏锈病病原菌夏孢子的超微结构研究显示，夏孢子表面有一个呈塔状的疣状结构，其疣的高度为1.8μm～3．0μm。     

STUDY ON SPECIES DIVERSITY OF RUST FUNGUS IN FIVE FOREST TYPES

INTRODUCTIoNSSPCCiesdiversityistheoneofthreekcysubjcctS(Theglobalweatherchange,speiesdiversltyandsustainedecologysystem)inccologicalandenvironmentalscienceinrecenttenyears.Williams(I943)firstputfonvardsPecicsdiversitywhenhestUdiedtherelationbctx`centhcabundanccandinsectspecicsofLcl,i`mptcra.In6()'s~7()'s-ccologicaIscicn-tistshadgotagreatofachicvementsonsPCcicsdlt'crslti'stud\.Sinccl98()-s.somcscientistsstartcdtostud}'sPCcicsdivcrsityinCl1ina.Thcy'havcgotsolnercsultsol1artl1roPOdcom…     

Specialization of crown rust (Puccinia coronata Corda) on clones of Italian ryegrass (Lolium multiflorum Lam.)

Summary Cultures of crown rust (Puccinia coronata Corda) from a mixed uredospore population obtained from plants in 16 localities in England and Wales were multiplied on four of 10 initially resistant clones of Italian ryegrass (Lolium multiflorum Lam.). Only two of the four cultures were found to be most pathogenic on the clones on which they had been multiplied. One clone became very susceptible to its own culture but the other became only moderately susceptible. Clone/culture interactions occurred which were not obviously related to the clone of origin of the culture. Thus, there was considerable genetic diversity in the crop which would tend to limit the multiplication of new races. There was a strong correlation between visual score for susceptiblity and uredospore production, showing the value of visual scores for resistance breeding.     

Canopy openings may prevent fir broom rust (<Emphasis Type="Italic">Melampsorella caryophyllacearum</Emphasis>) infections

Melampsorella caryophyllacearum is a heteroecious fungus that produces disease on silver fir resulting in galls that depreciate the value of trees. Currently, little is known about its epidemiology. The purpose of this study was to identify those site or management factors associated with fir broom rust infection. A 29-plot systematic sampling was carried out throughout all silver fir forests in the Spanish Pyrenees. In every sampling plot, we examined each tree for the presence of M. caryophyllacearum galls or witch’s brooms. We differentiated their position as either on the main stem or on the branches of trees. We identified the most susceptible stands by relating a compendium of tree and stand variables with the presence and severity of symptoms. Disease symptoms were observed in 11.8% (95% CI: 5.8–17.9%) of trees. Fir broom rust-infected trees tended to be those of larger diameters. The rust infection was observed in 55.2% (95% CI: 35.7–73.6%) of the stands. We identified a wide range of severities with 5 of 29 stands having more than 30% of trees infected. Fir broom rust appeared to be a widespread disease, although we observed important differences in terms of severity. The presence and severity of the rust in stands was associated with understories composed of more shade tolerant plant species and with longer periods without thinnings. Canopy opening should be experimentally tested as a possible control method.     

Variation of virulence of white pine blister rust

According to the literature the following evidence suggests racial variation in white pine blister rust: changes over site in general level of resistance; interaction of needle spot color types with crosses of western white pine; neutralization of specific resistance reactions; bark reactions and normal cankers on the same tree.     

贵州顶坛花椒锈病的发生特点与防治试验

调查了贵州顶坛花椒锈病的发生特点,并进行了药剂防治试验,结果表明：在所选的药剂中,15％三唑酮可湿性粉剂防治效果较好,浓度为1000倍液时,两次的防效分别为48．9％和67．1％;浓度为1500倍液时,防效分别为46．3％和61．3％。     

胺苯吡菌酮和叶菌唑混配对5种花卉病菌的联合毒力研究

为寻求防治花卉病害的高效、低毒杀菌剂,采用室内毒力测定方法,以玫瑰锈病菌、文竹叶斑病菌、郁金香灰霉病菌、菊花褐斑病菌和茶花炭疽病菌为测试菌株,研究胺苯吡菌酮和叶菌唑混配对5种花卉病害的联合毒力作用。结果显示:当叶菌唑和胺苯吡菌酮的混配比例为5∶1时,对玫瑰锈病菌的共毒系数为188.16;混配比例为10∶1时,对文竹叶斑病菌的共毒系数为198.07;混配比例为1∶1时,对郁金香灰霉病菌的共毒系数为190.29,对菊花褐斑病菌的共毒系数为192.55;混配比例为3∶1时,对茶花炭疽病菌的共毒系数为200.04。表明胺苯吡菌酮和叶菌唑按适当比例混配对此5种花卉病原菌菌丝和孢子具有明显抑制作用。     

小舌紫菀锈病菌(Aecidium asterum)及其熏寄生菌( Tuberculina persicina)研究

小舌紫菀是具有开发利用价值的药用植物。紫菀春孢锈病菌(Aecidium asterum Schw.)引起小舌紫菀(Aster albescens)锈病,为国内锈菌寄主新记录。该病在四川省蜂桶寨国家自然保护区小舌紫菀生长地造成危害,病株率为100％,病叶率28％,引起叶片枯斑、脱落。小舌紫菀锈病菌的重寄生菌(Tuberculina persicinaSacc.)是小舌紫菀锈病菌上的自然重寄生菌。该重寄生菌寄生于小舌紫菀锈菌春孢子器开口处,阻碍春孢子的释放。本文报道了小舌紫菀锈病的症状特点、病原形态特征及小舌紫菀锈病菌的重寄生现象和重寄生菌的形态特征。