Evaluation of Olive Cultivars for Resistance to Verticillium dahliae

Resistance of 23 important olive cultivars to Verticillium dahliae has been evaluated in four experiments under controlled conditions. Nine-month-old nursery olive plants were inoculated with a cotton non-defoliating (ND) (V4) or a cotton defoliating (D) (V117) isolate of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves. The percentage of plants killed and of those which recovered from the disease were used as additional parameters for including a particular cultivar into a defined category. Most of the evaluated cultivars were susceptible, although at different levels, to both isolates of V. dahliae. All cultivars were more susceptible to the D pathotype than to the ND one. A group of 11 cultivars, including several important Spanish cultivars, were susceptible or extremely susceptible to both pathotypes of V. dahliae. A second group showed differences of resistance depending on the pathotype used. They were susceptible or extremely susceptible to the D pathotype but resistant or moderately susceptible to the ND one. Finally, 'Frantoio', 'Oblonga' and 'Empeltre' were moderately susceptible to the D isolate of V. dahliae and resistant to the ND one. The resistance of 'Empeltre' was evident by the plant ability to recover from infection with either isolates. 'Empeltre' is considered to be a valuable cultivar for inclusion in breeding programmes for resistance to Verticillium wilt.     

北疆棉花黄萎病发病率调查及土壤中黄萎病菌微菌核数量与种群类型分析

为了解北疆棉花黄萎病的发生情况及发病与土壤中黄萎病菌微菌核数量的关系和病原菌种群类型, 2021年对北疆石河子?奎屯?博乐等8市(县)棉田棉花黄萎病发病率?土壤中黄萎病菌的微菌核数量?菌株种群类型进行了抽样调查?结果表明, 北疆未发生棉花黄萎病的棉田占49.2%, 0%<发病率<5.0%的棉田占32.7%, 发病率≥5.0%的棉田占18%?与2013年?2015年相比, 2021年无病田率分别增加17.7和12.7百分点, 发病率≥5%的棉田分别减少15.7和21.6百分点?从棉田黄萎病发病率与土壤中微菌核数量的关系来看, 整体上北疆棉田棉花黄萎病发病率与微菌核数量相关性不显著(r=0.119 1); 分区域看, 石河子-沙湾片区?奎屯-乌苏片区?精河-博乐片区棉田黄萎病发病率与微菌核数量的相关系数分别为0.033 2?0.007 6?0.062 3, 均无显著相关性; 而呼图壁-玛纳斯片区棉田黄萎病发病率与微菌核数量的相关系数为0.635 7, 呈中度正相关?土壤中的黄萎病菌菌株以菌核型为主, 占57.9%, 菌丝型占23.2%, 中间型占18.9%?用特异性引物进行PCR检测表明, 土壤中黄萎病菌落叶型菌株占97.6%, 占绝对优势?本研究将为北疆棉区棉花黄萎病的综合防控提供理论依据?     

桃树黄萎病在我国首次发生报道

在甘肃省农业科学院林果所2010年建植的桃园内,自2011年以来,每年6-8月都陆续出现枯死的桃树;严重年份桃树病株率达20%。经病原菌分离培养、形态观察和致病性测定,确认桃树枯死是由大丽轮枝菌(Verticillium dahliae)侵染所致。这是桃树黄萎病在我国的首次发生报道。     

黄芪黄萎病病原菌鉴定

甘肃素有"千年药乡""天然药库"等美称,全省有中药材资源2 540种,大宗药材30多种,黄荏(Astragalus menbranaceus Bge.)作为"十大陇药"之一,黄(红)芪种植面积达2.8万hm2,占全国的40％.黄芪补脾益气,具有生血摄血,增强免疫功能、保肝、利尿、抗衰老、抗应激、降压的功能.随着我省黄芪...     

嫁接茄子根系分泌物对黄萎病菌的化感作用

研究了不同砧木、不同浓度嫁接茄子根系分泌物对茄子黄萎病菌（Verticillium dahliae）孢子萌发和菌丝生长的影响。结果表明,与自根茄相比,所有参试的嫁接茄根系分泌物都不同程度抑制了黄萎病菌孢子萌发和菌丝生长;并且随着根系分泌物浓度的增加,抑制作用增强。     

大丽轮枝菌在茄田土壤中的分布及抽样方法

对茄子黄萎病在田间的空间分布及取样方法进行了研究,并探讨了田间土壤带菌量的准确测定方法。研究结果表明:用分布型指数法测定茄田土壤中微菌核的空间分布型,当菌核数量在8-63 ～39-93 个/g 干土范围内,为聚集分布。当茄田发病率小于75 % 时,病株在田间均属聚集分布;发病率大于75 % 时呈均匀分布。土壤中微菌核的调查方法以棋盘式为最适宜。     

大丽轮枝菌在茄田土壤中的分布及抽样方法

对茄子黄萎病在田间的空间分布及取样方法进行了研究,并探讨了田间土壤带菌量的准确测定方法。研究结果表明:用分布型指数法测定茄田土壤中微菌核的空间分布型,当菌核数量在8-63 ～39-93 个/g 干土范围内,为聚集分布。当茄田发病率小于75 % 时,病株在田间均属聚集分布;发病率大于75 % 时呈均匀分布。土壤中微菌核的调查方法以棋盘式为最适宜。     

Highly infested soils undermine the use of resistant olive rootstocks as a control method of verticillium wilt

Verticillium wilt of olive (VWO) is probably the most devastating fungal disease for olive trees worldwide, and currently the main cultivars are susceptible or moderately susceptible to this disease. The evaluation of resistant cultivars as rootstocks to control the disease has scarcely been explored, and mainly in short-term studies under controlled conditions, which usually do not correspond with field evaluations. The main objective of this study was to assess the responses to VWO of different scion × rootstock combinations of the olive cultivars Picual, Arbequina, Changlot Real, and Frantoio in a long-term field experiment with a soil highly infested with the defoliating pathotype of Verticillium dahliae. The results showed that grafting the susceptible cultivar Picual onto resistant rootstocks delayed the onset of the disease symptoms; however, after 4 years, it was observed that all combinations that contain Picual (a) were extensively colonized by V. dahliae; (b) developed severe symptoms of the disease; and (c) had plant mortality similar to Picual growing on its own roots. This result highlights the importance of long-term field experiments to evaluate VWO and shows that grafting susceptible olive cultivars onto resistant ones does not provide a durable control of VWO under high inoculum potential, as V. dahliae is able to progress through the resistant rootstock and then extensively colonize and kill the susceptible scion. However, the high inoculum potential observed in this study does not allow us to consider the evaluated resistant cultivars as completely ineffective under lower inoculum densities.     

Application to soil of disinfectants through irrigation reduces Verticillium dahliae in the soil and verticillium wilt of olive

The application of disinfectants through drip irrigation could be a feasible practice against verticillium wilt (Verticillium dahliae) of olive. OX-VIRIN (activated peroxide) and OX-AGUA AL25 (quaternary ammonium compounds) are two disinfectants that have shown efficacy against V. dahliae in irrigation water and potential for reducing the disease in young olive plants. In this work, various post-planting application strategies incorporating OX-VIRIN (once a month, or twice a month on alternate or successive weeks) or OX-AGUA AL25 (once a month, or twice a month on alternate weeks) were assessed for their effect on V. dahliae in soil, disease in olive trees, and olive yield, in a 2-year pot-experiment under natural environmental conditions. The disinfectants were injected via metering pumps into a drip irrigation system that irrigated olive trees planted in V. dahliae-inoculated soil. All the application strategies significantly reduced the total inoculum density in soil compared to controls with no disinfectants and noninoculated soil. The microsclerotia density was also significantly reduced in disinfested soils by 73.6–86.8%, depending on the strategy. The symptoms and infection incidence were always lower in treatments subjected to disinfestation. The treatment with OX-AGUA AL25 applied twice a month on alternate weeks most reduced the symptoms (by 53.0%) and colonization index (by 70.8%) with respect to untreated water control. This soil disinfestation also significantly strengthened the symptom remission. Tree growth and production were negatively affected by soil inoculation (reduced by 45.6% and 88.7%, respectively), but not so by disinfectants, which even relieved the reduction in inoculated soils, especially when OX-AGUA AL25 was applied.     

新疆棉花黄萎病的发生现状及其病原菌的分子鉴定与ISSR分析

为掌握新疆主要植棉区棉花黄萎病的发生现状及其病原菌大丽轮枝菌Verticillium dahliae的落叶型菌系分布以及遗传变异情况,于2015年对26个新疆主要植棉区棉花黄萎病的发生情况进行了随机调查,统计新疆大丽轮枝菌的培养性状,利用大丽轮枝菌落叶型特异引物D1/D2、INTD2F/INTD2R与非落叶型特异性引物ND1/ND2、INTNDF/INTNDR对新疆大丽轮枝菌菌系进行互补鉴定,并对部分菌系的遗传变异进行简单序列重复区间(inter simple sequence repeat,ISSR)分析。结果表明:2015年新疆棉花黄萎病发病田比例为54.0%,其中病情指数在10.0以上的发病田与2013年持平,而病情指数在20.0以上的严重发病田比例为10.8%,比2013年增加3.8个百分点;新疆大丽轮枝菌的培养性状以菌核型为主,比例为70.1%,菌丝型与中间型比例分别为13.4%和16.5%;新疆大丽轮枝菌落叶型菌系比例为53.2%,26株菌株的来源地全部检出落叶型菌系;聚类分析结果显示,当遗传相似系数为0.66时,新疆大丽轮枝菌落叶型与非落叶型菌系聚为2个谱系,菌系地理来源、培养性状与大丽轮枝菌的遗传分化无明显相关性。     

山东棉花黄萎菌致病力分化的研究

选用山东省有代表性的棉黄萎菌１６个菌株（系）各配制成一定浓度的孢子悬浮液，于棉苗２～３叶期蘸根接种，观察发病的反应型。结果表明：各菌株致病力强弱差异明显，可分为致病力强的Ⅰ型（即与落叶型相似）、致病力中等的Ⅱ型和致病力弱的Ⅲ型，并发现山东省有落叶型菌系存在。     

Variability and selection of verticillium wilt resistant genotypes in cultivated olive and in the Olea genus

Developing verticillium wilt resistant genotypes is currently a major objective in olive breeding. In this study, 6017 genotypes derived from 48 crosses obtained by open pollination and crosses between olive cultivars, wild olive genotypes and other Olea species and Olea europaea subspecies were individually evaluated for verticillium wilt resistance. More than 800 genotypes were identified as resistant to the disease based on the absence of symptoms. High genetic variability and wide segregation in resistance were observed. The inheritance of resistance was studied, and the best parents and crosses to breed resistant genotypes were identified. According to the results, verticillium wilt resistance in olive appears to be a quantitative trait. The results obtained by comparing the level of resistance between different crosses as well as by estimating heritability suggest that it is possible to breed for verticillium wilt resistance in olive.     

野生抗病茄植株腐解物对茄子黄萎病的调控研究

以4种野生抗病茄为试材,通过生长速率法和悬滴法测试了其根、茎、叶腐解物的乙醇提取液对茄子黄萎病菌菌丝生长和分生孢子萌发的室内抑制作用,并对室内抑菌效果较好的处理进行了盆栽防病试验。供试腐解物提取液对茄子黄萎病菌均具有一定抑制作用。其中,叶对菌丝生长的抑制率最高(>30%),抑制作用顺序为刚果茄>托鲁巴姆>CRP(刺茄)>赤茄,对孢子萌发的抑制效果较好的是刚果茄叶>CRP叶>刚果茄茎>赤茄叶>托鲁巴姆叶(>77%)。盆栽试验表明,除赤茄叶片腐解物外,其他3种野生茄叶片腐解物对茄子黄萎病均具有治疗效果;4种野生茄叶片腐解物对茄子黄萎病的预防效果均较好。     

应用聚合酶链式反应鉴定新疆棉花落叶型黄萎病菌

用一对棉花落叶型黄萎病菌的特异性引物D1和D2进行PCR扩增,对于落叶型黄萎病菌,该对引物可特异性地扩增产生一段550bp的产物,而非落叶型黄萎病菌则不能被扩增.供试的35个新疆黄萎菌系中,有3个菌系扩增出550bp大小的落叶型黄萎病菌特异性片段,表明目前新疆已存在落叶型黄萎病菌,用此技术可快速、准确地检疫和鉴定落叶型黄萎病菌.     

Integrated control of verticillium wilt of olive with cryptonol in combination with a solar chamber and fertilizer

A study was conducted during 2 years to determine the effects of three different control measures on the development of Verticillium wilt on olive trees cv. ‘Nabali’ at Al-Hallabat, Jordan. The causal agent of the wilt wasVerticillium dahliae Kleb. Treating diseased trees with Cryptonol (8-hydroxyquinoline sulfate) in a soil drench, or covering trees with a solar chamber for 15 days, was effective in suppressing disease development. The fertilizer treatment (NPK, 15:15:30) decreased disease severity and percent infection. All decreases are in comparison with the untreated control, and as recorded during the active phase of the pathogen. The treatments did not differ significantly from each other, and disease incidence in treated trees remained lower than in the control throughout the examined period.     

Evaluation of organic amendments from agro‐industry waste for the control of verticillium wilt of olive

Biological control of plant diseases using soil amendments such as animal manure and composted materials can minimize organic waste and has been proposed as an effective strategy in crop protection. In this study, 35 organic amendments (OAs) and 16 compost mixtures were evaluated against Verticillium dahliae by assessing both the antagonistic effect on the mycelial growth of two representative isolates of V. dahliae and the effect on the reduction of microsclerotia viability of the pathogen in naturally infested soil. Eleven OAs and five compost mixtures showed a consistent inhibition effect in in vitro sensitivity tests, with solid olive‐oil waste compost one of the most effective. Therefore, a bioassay with olive plants was conducted to evaluate the suppressive effect against V. dahliae of these selected OAs and compost mixtures. Significant reduction in the severity of the symptoms of V. dahliae indicates the potential use of grape marc compost (100% disease severity reduction) and solid olive‐oil waste, combined with other OAs. Microorganism mixtures and dairy waste OAs had a potential suppressive effect when they were combined with compost, showing a 73% and 63% disease severity reduction, respectively. A mixture of agro‐industrial waste with other biological control agents is a promising strategy against verticillium wilt of olive. To the authors' knowledge, this is the first report on the effectiveness of compost extracts (compost teas) on the inhibition of natural microsclerotia of V. dahliae, and also on verticillium wilt suppression in olive with solid olive‐oil waste.     

一种新的棉花黄萎病快速接种技术及其在病原菌致病力和寄主抗病性鉴定上的应用

 棉花品种抗黄萎病鉴定一般在田间病圃中进行,其结果受病圃中病原菌分布均匀程度、气象等因素影响极大,往往导致鉴定结果不准确。为了使鉴定方法简单、科学、可靠,我们在温室条件下比较了3种苗期接种棉花黄萎病的方法,即切根蘸孢子法(接种浓度为10⁶分生孢子/mL);菌培养物土壤接种法(0.5%、1%、2%,w/w);微菌核土壤接种法(10³个微菌核/g土)。结果表明,切根蘸孢子法导致棉苗发病均匀、严重、迅速,播种35~45 d后即可得到均匀一致的发病结果。而其它2种接种方法在播种75 d后才得到相对稳定的发病结果。同时,研究还表明接种浓度为10⁴分生孢子/mL所导致的黄萎病显著比10⁵或10⁶的轻。利用切根蘸孢子法在室内鉴定12个棉花品种或品系的抗黄萎病能力,证明该方法是抗黄萎病快速鉴定的有效方法。此外,该鉴定方法还可快速鉴定黄萎病菌不同菌株的致病性,并可应用于作物对其它土传病害的抗病性鉴定上。     

Morphophysiological response of young olive trees to verticillium wilt under different surface drip irrigation regimes

The effects of irrigation on verticillium wilt in olive, in terms of morphological, biomass and physiological parameters were evaluated on pot‐grown trees maintained in the field for 3 years. Plants inoculated and noninoculated with Verticillium dahliae were irrigated to high and low range of soil water content (HR and LR) at daily (DF; about 2 days/event), weekly (WF) and daily‐weekly (DWF) drip‐irrigation frequency. Morphological parameters, relative biomass and biomass water‐use efficiency were higher at LR than at HR (with few exceptions) and at DF than at other frequencies in noninoculated and inoculated plants, but the fungus reduced those parameters by 17.0–38.5%. Lower root weight ratio, relative biomass and shoot length as area originated at HR in noninoculated plants, could be favourable to the accumulation of root infections and the amount of fungus per tissue length in inoculated plants because higher infection was known at HR. Moreover, higher aerial biomass and length promoted by irrigation at DF could prevent the more severe expression of symptoms, which occurred at WF and DWF in the presence of Verticillium. Negative correlations were found between indicated parameters and disease. Lower water stress (S_Ψ), and higher stomatal conductance (g_s) and net photosynthesis at DF in noninoculated plants could limit the disease by improving water status, as S_Ψ was increased by the fungus only at WF and DWF, and g_s and disease were negatively correlated. LR‐DF treatment minimized the disease and kept the growth, water‐use efficiency and physiological parameters in inoculated plants to levels close to noninoculated plants.     

Assessment of the effect of surface drip irrigation on Verticillium dahliae propagules differing in persistence in soil and on verticillium wilt of olive

For efficient integrated management of verticillium wilt in olive (VWO), it is important to establish whether irrigation treatments (with Verticillium dahliae‐free water) that mitigate the disease in V. dahliae‐infested soil, also reduce the levels of more and less persistent propagules of the pathogen in the soil. Effects of irrigation on VWO and V. dahliae propagules were evaluated under natural environmental conditions. Potted plants were irrigated (pathogen‐free water) to two ranges of soil water content (RWC; high and low) at three surface drip‐irrigation frequencies (daily, weekly, and daily during some periods and otherwise weekly). VWO and total inoculum density (ID), density of less persistent micropropagules (MpD) and more persistent sclerotia in wet soil (S_wD), and sclerotia density for air‐dried soil (S_dD) were monitored. A logistic model (multiple sigmoid) of disease incidence revealed the lowest parameter values in treatments irrigated daily. Daily frequency of irrigation showed significantly lower disease incidence (39.2%) and disease intensity index (43.9%) and MpD (88.0%) values as areas compared with other frequencies, regardless of the RWC. High RWC significantly reduced (70.8–84.9%) ID, S_wD and S_dD as areas, but significantly increased (18.0%) the incidence of infected plants (IIP), regardless of the irrigation frequency. The disease incidence was not correlated with temperature. Daily irrigation to low RWC mitigated the VWO and the IIP, kept soil to the lowest MpD and resulted in the lowest S_dD level at the end of the trial. Results suggested that less persistent propagules could have played a part in the disease development.