Influence of site and stand factors on Hymenoscyphus fraxineus‐induced basal lesions

Hymenoscyphus fraxineus is an invasive fungus in Europe and causes a severe decline affecting ash, which began in the late 1990s. One of the symptoms associated with the disease is lesions in the outer bark of the collar area. However, the aetiology of these basal lesions, and in particular the relative roles of H. fraxineus and Armillaria species, is still controversial; moreover, little is known about the influence of environmental factors on the disease epidemiology. This study therefore surveyed 42 plots located in northeastern France, in an area affected by ash decline since 2008, in order to determine which environmental factors condition the severity of lesions associated with H. fraxineus on ash collar. The spatial pattern that is a consequence of the invasive spread of the disease was taken into account in the analysis, using a spatial hierarchical Bayesian model fitted by integrated nested laplace approximation (INLA). Results show that while basal lesions are tightly associated with H. fraxineus, their severity is influenced by the Armillaria species present in the plot. Sites with vegetation indicating moist conditions, or more humid topographical positions, were associated with more developed basal lesions.     

4种常用杀菌剂对江苏省番茄枯萎病菌的毒力

采用菌丝生长速率法测定了4种杀菌剂对36株番茄枯萎病菌(Fusarium oxysporum)的毒力。结果表明,不同杀菌剂对番茄枯萎病菌的毒力水平有显著差异,25%氰烯菌酯悬浮剂和50%多菌灵可湿性粉剂对菌落生长的抑制毒力最强,EC50分别为1.65μg/mL和2.91μg/mL;3%中生菌素可湿性粉剂的毒力次之,EC50为12.56μg/mL;75%百菌清可湿性粉剂的毒力最小。不同地区的番茄枯萎病菌对4种杀菌剂的敏感性存在明显的差异,铜山地区的菌株除了对多菌灵、氰烯菌酯有较高的敏感性外,对其他2种杀菌剂都呈不同程度耐药性;沭阳地区的菌株对4种杀菌剂的敏感性均很强;姜堰地区的菌株对百菌清有较弱的敏感性,对其他3种杀菌剂的敏感性均较强。本研究为化学防治番茄枯萎病、科学合理用药提供参考依据。     

猕猴桃溃疡病菌在中国的适生性分析

通过分析猕猴桃溃疡病菌在中国的适生性,为科学制定有效的检疫监管措施,防范其入侵和扩散,确保猕猴桃产业健康发展提供理论依据。本研究根据前人研究结果,采用模糊数学综合评判的原理和方法,定量分析猕猴桃细菌性溃疡病菌(Pseudomonas syringae pv.actinidiae)在我国各个地区的适生性。猕猴桃溃疡病菌在我国最适宜的省份主要分布在四川、云南、贵州、福建、安徽、湖南、湖北、河南、江西、陕西、浙江、重庆、西藏。鉴于该病具有发生发展迅速,危害性强,防治难度大等特点,应当加强猕猴桃种苗等繁殖材料的检疫,加强对果园的管理和病害监测,积极采取有效的防治措施并加强抗病育种方面的研究。     

河北省甘薯镰孢菌腐烂与溃疡病的病原鉴定

为明确河北省甘薯镰孢菌腐烂与溃疡病的症状特点和病原种类,在不同种植区采集储藏期和育秧期病样,描述其症状特征;对病原菌进行分离纯化,采用柯赫氏法则回接验证,依据病原菌的形态特征和基因序列确定病原菌种类。结果表明,在储藏期甘薯发病可导致薯块表面腐烂的占总病薯的59.09%,端部腐烂的占40.91%;薯块带有褐色轮纹病斑的占61.36%,病斑没有轮纹或者轮纹不明显的占38.64%;发病初期薯块内部病斑浅、黑褐色的占27.27%,发病后期薯块内部形成空腔、布满白色菌丝的占72.73%;病斑带有苦味的占59.09%,病斑没有苦味或苦味不明显的占40.91%;在育秧田发病导致薯秧溃疡,表现为主茎基部呈点片发生黑色或者褐色病斑,部分有开裂。分离的病原菌能够同时侵染薯块和薯秧;病原菌单瓶梗产孢,大型分生孢子稍弯,两端钝圆,多数3~7个分隔,顶细胞钝圆,基细胞足跟较明显。其rDNA-ITS、EF-1α、β-tubulin基因序列与茄镰孢菌Fusarium solani的同源性分别为97%、99%和98%。初步确定甘薯镰孢菌腐烂与溃疡病的病原菌为茄镰孢菌F.solani。     

Effect of defoliation by livestock on stem canker caused by Leptosphaeria maculans in Brassica napus

Brassica napus (canola, oilseed rape), an important break crop for cereals across the Australian wheat belt, is being rapidly adopted as a dual‐purpose (forage and grain) crop in mixed farming systems. Stem canker caused by the fungus Leptosphaeria maculans is the most important disease of B. napus in Australia. The primary source of inoculum is airborne ascospores released during autumn/winter which coincides with the grazing of dual‐purpose crops. Field experiments were defoliated by sheep to determine the effect of grazing on blackleg stem canker severity at plant maturity in B. napus cultivars differing in their resistance level and grazed at different times. One cultivar was sown on different dates to investigate the impact of grazing at the same time, but at different growth stages. Defoliation by mowing was compared to defoliation by livestock. Similar amounts of dry matter remained after defoliation by machinery (0·66 t ha^?1) or livestock (0·52 t ha^?1). However, stem canker severity was higher in the grazed (40% of crown cross‐section diseased) compared with the mown (25%) treatment, which was higher than the ungrazed control (9%). Stem canker severity generally increased with grazing, but the increase was eliminated or reduced in cultivars with good resistance. Grazing during vegetative plant growth minimized the increase in stem canker severity compared with grazing during reproductive growth. Currently, cultivars with good L. maculans resistance are recommended in high disease situations. To avoid excessive yield loss in dual‐purpose B. napus crops due to L. maculans it is recommended that such cultivars are grown even in low‐moderate disease situations.     

The significance of guttation in the secondary spread of Clavibacter michiganensis subsp. michiganensis in tomato greenhouses

Bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), can spread in commercial tomato greenhouses causing epidemics. Results of greenhouse experiments with Cmm‐contaminated tools demonstrated disease spread for only a limited distance (<4 plants) from infected plants. However, touching symptomless infected plants bearing guttation droplets prior to touching nearby plants spread the pathogen over longer distances within rows (>22 plants). The pathogen was exuded in large numbers in the guttation fluid of infected plants; its presence in the guttation fluid was not influenced by the inoculation procedures, leaf age or the volume of the guttation droplets. Population size of Cmm and the incidence of leaflets with epiphytic bacteria were significantly higher in plants placed in a guttation‐induction chamber than in those kept in a growth chamber with high humidity, suggesting exudation through guttation contributed to the formation of epiphytic populations on leaflets. This new knowledge may provide a simple and environmentally friendly means for decreasing the spread of the disease by avoiding contact with plants during periods when they bear guttation droplets.     

怀集县柑桔溃疡病的发生现状与防控对策

介绍怀集县柑桔溃疡病的发生现状,分析其发生原因及对当地柑桔产业的影响,并提出相应的防控对策,以为当地柑桔溃疡病的防治提供参考。     

Retrospective study on 30 horses with chronic proliferative pododermatitis (canker)

The medical records of 30 horses (18 Warmbloods, 7 draught horses, 3 other breeds and 2 of unknown origin) with chronic proliferative pododermatitis (canker) were reviewed and long‐term outcome was obtained by telephone questionnaire. In 28/30 cases, the owner was the first to discover the problem. The disease was initially recognised as canker in only 5/28 cases, whereas in 10/28 cases a treatment for thrush had been continued for several months before referral. There was a similar prevalence in the fore (41) and hind (44) hooves; 13/30 horses had 4 hooves affected. Treatment consisted of surgical debridement and hoof care. Duration of hospitalisation was significantly decreased in horses receiving oral prednisolone for 3 weeks compared to those without this additional systemic treatment (mean ± s.d. 24 ± 5 days, n = 7 vs. 40 ± 19 days, n = 19, respectively). Long‐term follow‐up ranged from 3 months to 6 years (36 ± 22 months) and was available for 24 horses. No recurrence was reported in 10 horses. In 14 horses problems recurred within the first year, and 6 had been subjected to euthanasia for this reason specifically, whereas the others were managed by regular trimming. There was no significant association between recurrence and the number of affected hooves or the use of any systemic treatment. Horses with delayed referral because of preceding treatments had significantly more chance to develop recurrence, highlighting the need for prompt diagnosis and subsequent treatment.     

杨树对溃疡病区域抗性试验研究

在陕西关中的杨陵及陕北的榆林两地建立试验地，对不同产地苗木进行带菌诱发试验和区域性栽植，研究了北京杨、陕林４号杨、毛白杨、６９杨和新疆杨等杨树在不同区域性气候中的生长状况和对杨树溃疡病的抗性变化。研究结果表明，苗木来源不同，其带菌量不同，栽植后发病率也就不同；造林地区溃疡病菌存在量不同，即使苗木带菌量相同，其造林后发病率亦不同；不同树种在同一环境条件下发病情况不同，同一树种在不同环境条件下感病程度也不相同，为选择适生的杨树品种造林提供了理论依据     

柑桔溃疡病菌噬菌体XCP#-1检验技术研究

 本文首次报道了根据噬菌体XCP#-1的特性以及寄主溃疡病细菌吸附和噬菌体增殖的原理，采用双层琼脂法测定游离噬菌体的数量变化来检测柑桔溃疡病无症材料。经过四川省12个县、市80个送检柑桔标样的噬菌体吸附或增殖检验，证实它是一种特异性强、灵敏度高、快速准确的先进检测技术。