Control of black foot disease in grapevine nurseries

Black foot disease of grapevines is a decline and dieback disease caused by a soilborne pathogen complex including Cylindrocarpon liriodendri , C. macrodidymum , Campylocarpon fasciculare and Campyl. pseudofasciculare . These pathogens cause primary infections of roots and basal ends of grafted cuttings in nursery soils. Thirteen fungicides were screened in vitro for mycelial inhibition of these pathogens. Prochloraz manganese chloride, benomyl, flusilazole and imazalil were the most effective fungicides tested, and were subsequently included in semi-commercial field trials. Basal ends of grafted cuttings were dipped in various chemical and biological treatments prior to planting in open-rooted nurseries. Black foot pathogens were not isolated from grafted cuttings prior to planting. Additional treatments involved soil amendments with Trichoderma formulations and hot water treatment of dormant nursery grapevines. Field trials were evaluated after eight months. Isolations from uprooted plants revealed low levels of black foot pathogens in the roots of untreated control plants, and significantly higher levels in basal ends of rootstocks. The incidence of black foot pathogens, as well as that of Petri disease pathogens, was not significantly and/or consistently reduced by the majority of chemical or biological treatments. However, these pathogens were not isolated from uprooted plants that were subjected to hot water treatment. It is therefore recommended that hot water treatment of dormant nursery plants be included in an integrated strategy for the proactive management of these diseases in grapevine nurseries.     

柱孢属(Cylindrocarpon)真菌和参类锈腐病的研究历史与现状

柱孢属（Cylindrocarpon）真菌是引致人参和西洋参锈腐病的重要病原菌。根据国内外相关献和目前生产现状，综述了引起参类锈腐病的柱孢属真菌的分布与危害、形态与分类、致病性和寄主范围、病原生物学特性、发病规律及防治等方面的研究历史与现状、并对该属真菌今后的研究方向进行了讨论和展望。     

两种有机硫熏蒸剂处理连作土壤对三七根腐病复合症的防治效果

测试了有机硫熏蒸剂大扫灭(Dazomet)对三七(Panax notoginsengWall.)根围几种主要病原生物:线虫、细菌和真菌的最低灭生浓度(MBC值)分别为≥7.8、≥31.2和≥125μg/mL。4种主要病原真菌:立枯病丝核菌(Rhizoctoni solani)、根腐病菌毁坏柱孢霉(Cylindrocarpon destructant)、镰孢霉(Fusariumspp.)和黑斑病交链孢(Alternaria tenus)的MBC值分别为≥31.2、≥62.5、≥125和≥125μg/mL。钾-威百(K-Vapam)对线虫、细菌和病原真菌的灭生活性与Dazomet相当。连作三七田播种前和移苗前用98%大扫灭粉粒剂20~40 g/m2和35%钾-威百液剂30~50 mL/m2进行耕作层土壤熏蒸处理,对三七出苗和成苗率无显著影响;杂草和线虫发生量比对照分别减少90%~95%。播前处理比对照苗病发生率降低45.0%~82.5%,移苗前处理苗病发生率降低35.0%~50.0%。适当充足的土壤含水量、适时彻底的土壤毒气排除对提高药效和避免残毒对后茬药害至关重要。     

柱孢属一新种

本文报道油桐枯枝病菌——油桐丛赤壳(Nectria aleuritidia Chen et Zhang)的无性时期,属半知菌亚门,丝孢纲、丛梗孢目、丛梗孢科、柱孢属的一新种,命名为油桐柱孢(Cylindrocarpon aleuritum sp.nov.)     

Involvement of Cylindrocarpon destructans in root death of Pinus sylvestris seedlings: Pathogenic behaviour and predisposing factors

The common rhizospheric fungus Cylindrocarpon destructans was investigated in relation to its role in root death of Pinus sylvestris in Nordic nurseries and plantations. Laboratory methods were developed for studying similar root problems as well as the early effects of phytotoxicity and fungal infection. Seedlings grown under standardized optimal conditions were exposed to controlled stress (known to occur in nurseries), with or without C. destructans in the rhizosphere. Low light conditions, anaerobic root environment, and fungicide treatment were each found to predispose pine seedlings to invasion by the pathogen. The pathogen was very sensitive to competition as well as antagonism on the root, and fungicide‐induced inhibition of antagonists such as Trichoderma spp. also increased the severity of attack by the pathogen. To compete successfully, the pathogen would have to invade and dominate weakened roots prior to the arrival of saprophytes. Toxic metabolites produced by the pathogen weakened or killed nearby root tissues, and pathogen metabolites seemed to prevent saprophytes from taking hold in the infected roots. Such heavily infected, dead roots may act as inoculum sources allowing the pathogen to invade adjacent living roots, even healthy ones. Dead roots left in nursery soil after earlier harvests may act as reservoirs of inoculum for long periods and pose a threat to new plants.     

人参锈腐病菌拮抗放线菌JY36发酵条件研究

对人参锈腐病拮抗放线菌JY36的发酵条件进行研究,确定了其最佳培养基组成及培养条件。单因素试验和正交试验结果表明,最佳斜面固体培养基为3号培养基,最佳种子培养基为4号培养基,最佳发酵培养基为6号培养基。最适发酵时间为120 h,最适发酵培养温度为30℃,最适初始pH值为7。     

哈茨木霉菌Tri41对人参锈腐病菌的抑制作用

我国是人参的生产和销售大国,近年来农药残留问题严重影响我国人参出口,研究生物菌剂代替化学菌剂防治人参病害已成为人参安全生产的主要环节。试验研究了哈茨木霉菌Tri41(Trichoderma harzianum Tri41)对人参锈腐菌(Cylindrocarpon destructans)的抑制作用。结果表明:哈茨木霉菌Tri41对锈腐菌的抑制作用受温度影响,25℃条件下,菌株Tri41对人参锈腐菌的抑制率高达80.1%,20℃条件下抑制率降低9.7%;菌株Tri41的挥发性代谢物和难挥发代谢物对人参锈腐菌的抑制率分别为57.3%和48.0%;菌株Tri41发酵液对锈腐菌菌丝生长和孢子萌发均有一定的抑制作用。初步明确了哈茨木霉菌Tri41对人参锈腐菌的拮抗机理以竞争和抗生作用为主。     

Occurrence and etiology of death of young olive trees in southern Spain

New plantations of olive tree in southern Spain are being severely affected by wilt or dieback and death, which has been locally called Drying Syndrome. To determine the etiology of this problem, a study was carried out in samples of affected young trees collected during a seven year period (1989–1995), and in two field surveys in 1994–95 and 1996. Besides some insect damage and agronomic problems, the Drying Syndrome was associated with Verticillium wilt, winter frost and root rot fungi. Although Drying Syndrome can be distinguished from Verticillium wilt, the latter was included in this study, since, frequently, Verticillium wilt symptoms were unspecific and Verticillium dahliae could not be always isolated in the diagnostic work that preceded this study. Early winter frost caused a vascular necrosis and wilt of the young olive trees. This unusual and severe damage was related with the lack of frost hardiness due to warm temperatures during the previous autumn. Root rot fungi were very frequent in the samples of diseased olive trees of field or nursery origin, and they were the main cause of Drying Syndrome in the second field survey, when a heavy rainfall level occurred during winter. Pathogenicity tests showed that five fungal species (Cylindrocarpon destructans, Phytophthora megasperma, P. palmivora, Pythium irregulare and Sclerotium rolfsii) were pathogenic to olive trees and reproduced symptoms of Drying syndrome in rooted cuttings of cultivar Picual. Other fungal species associated with root rot of olive trees in the field or in the nurseries, including Fusarium acuminatum, F. eumartii, F. oxysporum, F. solani, Macrophomina phaseolina and Rhizoctonia solani, were weakly or not pathogenic. Pathogenicity of P. megasperma, P. palmivora and P. irregulare depended on soil water content, since isolates tested caused extensive root rot and sudden plant death only when the soil was continuously waterlogged. The high frequency of P. megasperma in waterlogged field soils and its pathogenicity dependence on soil water content suggest that this pathogen may play an important role in the well known sensitivity of young olive trees to root asphyxiation.     

人参锈腐病拮抗细菌的筛选鉴定

为获取对毁灭柱孢菌(Cylindrocarpon destructans(Zinss.)Scholtan)防治效果优良的菌株,从人参根际土壤中分离到113株细菌,采用平板对峙法筛选出13株拮抗性良好的拮抗细菌,生长速率法对经过滤和灭菌的菌株发酵液进行抑菌谱测定,采用盆栽试验研究其对人参锈腐病的防治效果及其人参植株促生效果。SZ-2菌悬液对毁灭柱孢菌的抑制率达88.80%,同时具有广谱抑菌能力。盆栽试验结果表明,菌株SZ-2对人参锈腐病的防治效果为68.50%;其对人参植株具有一定促生作用,经其处理后的人参平均植株高度、整株鲜质量、整株干质量、根长、根鲜质量和根干质量均有不同程度的增加,其中整株干质量、根干质量和根长增长量高达79.39%、131.51%和86.90%;与对照组相比具有显著差异(P0.05)。经形态学、生理生化特征、16SrDNA及gyrB基因测序等分析,确定菌株SZ-2为甲基营养型芽孢杆菌(Bacillus methylotrophicus),在GenBank中序列登录号为KC511107。     

三七连作田根腐病复合症综合治理措施与效果

以土壤熏蒸剂、枯草芽孢杆菌、选择性杀菌剂复配剂处理种苗和根围土壤为主要方法,对连作田三七根腐病复合症进行了综合治理试验。结果表明:(1)大扫灭(98%含量,30~40 g/m2剂量)、钾-威百(35%含量,40~60 g/m2剂量)和氰氨化钙(60~90 g/m2剂量)对三七连茬病土进行熏蒸处理后,真菌、杂草、细菌和线虫灭生效果达90%~99%,1年生与2年生三七成苗率显著提高,生长季前期3个月内根腐病复合症发病率明显降低,其中大扫灭灭生效果突出。(2)土壤熏蒸后,用G3菌剂(枯草芽孢杆菌)与单杀菌剂农利灵、噻菌灵和扑海因组合播前拌种和移苗前沾根处理,其中以菌剂与农利灵组合最好,噻菌灵和扑海因组合次之。枯草芽孢杆菌G3菌剂(2×1010/cfu/g用量3 kg/100 m2)单独施用,在田间温度低于15℃条件下无明显防效。(3)熏蒸 G3 化学杀菌剂复配剂1或2播种前拌种和移栽前沾根处理组合试验防效最好。