The effects of Trichoderma on preventing cucumber fusarium wilt and regulating cucumber physiology

In our previous studies, we identified 3 Trichoderma strains with anti-Fusarium oxysporum activity, including T. asperellum 525, T. harzianum 610, and T. pseudokoningii 886. Here, we evaluated the effects of these 3 Trichoderma strains on preventing cucumber fusarium wilt through pot culture and greenhouse culture experiments. All 3 Trichoderma strains demonstrated higher control effects toward cucumber fusarium wilt than previous studies, with efficacies over 78%. Additionally, inoculation with the 3 Trichoderma strains significantly promoted the quality and yield of cucumbers. Among the 3 strains, Trichoderma 866 was the most effective, with disease control efficacy of 78.64% and a cucumber yield increase of 33%. Furthermore, seedlings inoculated with Trichoderma exhibited significantly increased measures of plant height, stem diameter, leaf area, aboveground fresh weight, underground fresh weight, chlorophyll content, and nitric nitrogen content, as well as the activities of several stress-resistance enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and ascorbate oxidase (AAO). In addition, the plants inoculated with Trichoderma showed decreased cell membrane permeability and malondialdehyde (MDA) content in the leaves. Together, our results suggest that T. asperellum 525, T. harzianum 610, and T. pseudokoningii 886 inoculations inhibit F. oxysporum infection, stimulate the metabolism in cucumbers, and enhance the activities of stress-resistance enzymes, which consequently promote the growth of cucumber plants, prevent cucumber fusarium wilt, and improve the yield and quality of cucumbers. T. harzianum is a commonly used biocontrol fungus, while few studies have focused on T. asperellum or T. koningense. In this study, strains of T. asperellum and T. pseudokoningii showed excellent plant disease prevention and growth promoting effects on cucumber, indicating that they also have great potential as biocontrol fungi.     

Soil application of Trichoderma asperellum GDFS1009 granules promotes growth and resistance to Fusarium graminearum in maize

Of diseases affecting maize (Zea mays), Fusarium graminearum is one of the most common pathogenic fungi that cause stalk rot. In the present study, the Trichoderma asperellum GDFS1009 strain was shown to be an effective biocontrol agent against stalk rot. In a confrontation culture test, Trichoderma strain displayed an approximately 60% inhibition rate on the mycelial growth of F. graminearum. In pot trials, the application of 2 g/pot of T. asperellum GDFS1009 granules had the best control effect on stalk rot at the seedling stage (up to 53.7%), while the average plant height and fresh weight were also significantly improved. Additionally when fertilizer was added at 8 g/pot, the application of 3 g/pot of Trichoderma granules had the best control effect on maize stalk rot (40.95%). In field trials, when inoculating F. graminearum alone, the disease index for inoculating was 62.45, but only 31.43 after treatment with T. asperellum GDFS1009 granules, suggesting a control efficiency of 49.67%. Furthermore, in a naturally F. graminearum-infected field, Trichoderma granules, when applied for 3 consecutive years, showed significant control of stalk rot and increased yields.     

Screening of antagonistic Trichoderma strains and their application for controlling stalk rot in maize

Maize is one of the major crops in China, but maize stalk rot occurs nationwide and has become one of the major challenges in maize production in China. In order to find an environment-friendly and feasible technology to control this disease, a Trichoderma-based biocontrol agent was selected. Forty-eight strains with various inhibition activities to Fusarium graminearum, and Fusarium verticillioides were tested. A group of Trichoderma strains(DLY31, SG3403, DLY1303 and GDFS1009) were found to provide an inhibition rate to pathogen growth in vitro of over 70%. These strains also prevented pathogen infection over 65% and promoted the maize seedling growth for the main root in vivo by over 50%. Due to its advantage in antifungal activity against pathogens and promotion activity to maize, Trichoderma asperellum GDSF1009 was selected as the most promising strain of the biocontrol agent in the Trichoderma spectrum. Pot experiments showed that the Trichoderma agent at 2–3 g/pot could achieve the best control of seedling stalk rot and promotion of maize seedling growth. In the field experiments, 8–10 g/hole was able to achieve over 65% control to stalk rot, and yield increased by 2–11%. In the case of natural morbidity, the control efficiency ranged from 27.23 to 48.84%, and the rate of yield increase reached 11.70%, with a dosage of Trichoderma granules at 75 kg ha~(-1). Based on these results, we concluded that the Trichoderma agent is a promising biocontrol approach to stalk rot in maize.     

哈茨木霉菌HNA12在防控玉米黄曲霉毒素污染中的应用

为从源头控制真菌毒素污染,本实验开展了玉米黄曲霉毒素污染拮抗微生物高通量筛选及生物防治研究。从江苏、山东、山西和河南等主产区的健康玉米籽粒内分离到1 055株木霉菌,其中,10株木霉菌拮抗带宽超过8 mm,抑制率为36.5%~90.0%。活体实验发现,7株木霉对黄曲霉菌有较强的抑制作用,抑制率为44.2%~87.0%,对黄曲霉毒素污染的抑毒率为40.5%~85.0%。试验菌株中,HNA12、T40-3和T85-5对黄曲霉菌的防治效果最高,分别达到87.0%、68.8%和64.5%,HNA12、T21-1和T40-3抑毒率最强,分别达到85.0%、75.2%和68.5%。田间试验显示,菌株HNA12的促生率及抑毒率最高,分别达到10.5%及90.5%,生防潜力巨大。经形态学及分子生物学分析,菌株HNA12被鉴定为哈茨木霉。拮抗机制实验证明,菌株HNA12发酵产物及其蛋白提取物对黄曲霉菌生长有较强的抑制能力,可以作为微生物制剂开发应用。     

Identification of Antifungal Substance (Iturin A2) Produced by Bacillus subtilis B47 and Its Effect on Southern Corn Leaf Blight

Bacillus subtilis B47 is an endophytic bacterium of tomato, and produces substance that strongly inhibits the growth of Bipolaris maydis, the pathogen of southern corn leaf blight (SCLB), as well as several other phytopathogenic fungi. The antifungal substance was purified from the broth culture of the bacterium using acid precipitation, methanol extraction, and three-step chromatography. Based on FT-IR spectrometry, amino acid composition, and MALDI-TOF-MS/MS CID analyses, the antifungal substance was identified as iturin A₂, a cyclic lipopeptide antibiotic. To evaluate the efficacy of iturin A₂ for control of SCLB, partially purified iturin A₂ (75%, w/v) was applied under different conditions. At the concentration of 300 mg kg^-1, iturin A₂ showed efficacy ranging from 100 to 53.1% under in vitro, in plot and in field conditions. This efficacy was higher than or similar to that of the fungicide chlorothalonil. When the concentration of iturin A₂ was increased to 500 mg kg^-1, the control efficacy was enhanced to 64.2% in field, which was significantly higher than that of chlorothalonil. These results indicate that iturin A₂ has potential for SCLB control and could be a substitute to synthetic fungicides. To our knowledge, this is the first report on using partially purified iturin A for control of SCLB under field conditions.     

Bacterial extracts and bioformulates as a promising control of fruit body rot and root rot in avocado cv. Hass

At least 20–40% of annual losses of avocado crops are caused by pathogenic fungi. The chemical treatments of these diseases are inefficient, cause environmental pollution and are increasingly restricted by international laws. This work aimed to assess the biocontrol capacity of a bacterial extract to protect avocado fruits and plants from pathogen infections. Extracts from the bacterial isolate Serratia sp. ARP5.1 were obtained from liquid fermentations in a biorreactor. A body rot postharvest infection model with Colletotrichum gloeosporioides on fruits was developed. Moreover, packaging conditions were simulated using the bacterial extract and the commercial fungicide prochloraz as a positive control. Additionally, seedlings infections with Phytophthora cinnamomi were performed on two types of avocado(West Indian race and cv. Hass). The Area Under Disease Progress Curve(AUDPC) was recorded using the bacterial extract and a commercial product with fosetyl-aluminium as treatments. The bacterial extract significantly reduced infections by C. gloeosporioides on injured avocado fruits at 31.1 μg mL–1. Intact fruits were also protected against body rot infections at the same concentration and showed no significant differences with the commercial fungicide. On the other hand, AUDPC in the seedlings was significantly reduced with the extract treatment at 3 μg mL–1 compared to the control. However, a possible phytotoxicity effect of the extract was evidenced in the seedlings and confirmed by pathogen recovery and tests on Raphanus sativus seedlings. Finally, formulations of the extracts(emulsion and emulsifiable concentrate) were prepared, and bioactive stability was assessed for 8 wk. The emulsion formulates demonstrated very stable bioactivity against P. cinnamomi. The extract and the emulsion formulate showed promising results for the control of avocado pathogens. New bioproducts based on this type of active principles could be developed for the benefit of avocado industry.     

植物病害生物防治概述

使用化学杀菌剂是控制植物病害的有效方法,但化学杀菌剂存在污染环境、破坏生态平衡、药物残留等问题,因此,植物病害的生物防治越来越受到重视。简要介绍了植物病害生物防治的概念、作用机制,概述了生防细菌、生防真菌、生防放线菌的种类以及开发利用情况,并且介绍了植物内生菌在生物防治上的开发应用;探讨了利用生防微生物进行植物病害生物防治中存在的问题,并提出了相应的解决途径。     

拮抗木霉菌对玉米弯孢叶斑病的诱导抗性作用

本文在温室和田间条件下研究了木霉菌株H6、D9、C40、SH2303包衣种子诱导玉米抗弯孢叶斑病的效果。研究结果发现,在温室条件下H6、C40、D9、SH2303包衣种子长出的幼苗对于弯孢叶斑病的防效分别为20．69％、53．77％、72．74％、37．52％。田间试验表明：H6可诱导玉米对弯孢叶斑病的防效可达到50％470％。防御酶系测定结果表明,不同菌株包衣种子后PAL、POD酶活性显著增加,SOD酶活性均无明显变化趋势。因此,木霉诱导寄主抗性效应与寄主PAI。、POD活性增加有关,但与SOD活性没有明显相关性。本研究表明：利用木霉菌剂处理玉米种子可系统诱导玉米幼苗产生对叶斑病的抗性,为深入研究木霉菌诱导玉米系统抗性机制提供了线索。     

三唑酮防治小麦雪霉叶枯病的研究

三唑酮100μg/mL可完全抑制小麦雪霉叶枯病菌分生孢子萌发,25μg/mL即可引起90％芽管畸变。离体叶碟法和盆栽幼苗法测定表明,三唑酮有较强的保护作用和治疗作用。田间药效试验确认该剂能有效地控制成株叶斑和叶枯。在小麦条锈病流行区,可用三唑酮常规喷雾,兼治该两种病害。田间用药量应不低于10～15g/亩。     

Resistance of barley root rot pathogens to chemical and biological fungicides

The species composition of root rot pathogens of the genera Fusarium and Bipolaris is studied. The heterogeneity of strains of the phytopathogens within the same species with respect to sensitivity to chemical fungicides and to strains of the genus Trichoderma depending on the species of antagonist and fungicide dose is established. To maintain the numbers of phytopathogens at a minimum threshold of harmfulness, it is expedient to use integrated protection, a combination of biological and chemical methods.     

哈茨木霉T2-16突变体库的构建及突变株表型分析

为了优化高效拮抗生防菌哈茨木霉T2-16的EMS诱变条件,构建哈茨木霉T2-16突变体库,为哈茨木霉功能基因组研究奠定材料基础,以哈茨木霉T2-16为试验材料,采用单因素试验以0～0.6 mol·L^-1 EMS溶液分别处理不同浓度孢子0～6 h,明确适于哈茨木霉诱变的EMS最佳浓度、处理时间和孢子浓度。以最适参数诱变处理野生型菌株,进行生长势、拮抗能力和生防效果比较。结果显示,0.4 mol·L^-1 EMS溶液处理浓度为10⁶ ·mL^-1的孢子4 h,其致死率接近70%,诱变效果最佳。经生长势、拮抗能力和生防效果比较发现,生长势呈正向突变占有率达46.20%,其中,16株突变菌株拮抗作用明显增强,T42和T62的生防效果分别高出野生型菌株31.64%和27.91%,为研究哈茨木霉与生防相关的功能基因打下基础。     

不同木霉菌株对黄瓜枯萎病菌的拮抗作用

比较不同木霉菌株对黄瓜枯萎病菌的竞争作用、重寄生作用、抗生作用和防病作用的差异,筛选出高效菌株,为利用木霉菌防治土传病害提供理论依据。通过与致病菌对峙培养,研究竞争作用。结果表明:供试木霉菌能限制黄瓜枯萎病菌的菌丝扩展,哈茨木霉(Trichoderma harzianum)TH菌株竞争作用最强,菌丝扩展抑制率为67.70%。试验发现木霉菌株能够通过紧贴、缠绕、穿透等方式寄生于黄瓜枯萎病菌的菌丝上,最后引起菌丝断裂,细胞内容物外泄。通过无菌滤膜过滤获得的不同木霉菌代谢产物抗生作用明显,TH菌株代谢产物的抑菌圈直径达到3.9cm,对黄瓜枯萎病菌的菌丝生长和孢子萌发的抑制率分别为57.19%和68.35%。盆栽试验结果显示,育苗时施加木霉菌株不同程度控制苗期黄瓜枯萎病的发生,TH菌株防病作用最强,防效为64.34%,绿色木霉(Trichoderma viride)TV菌株促进黄瓜生长作用最强,地上部分和地下部分鲜质量分别增加42.81%和86.92%。     

我国植物病害生物防治综述

植物病害生物防治是利用有益微生物和微生物代谢产物对农作物病害进行有效防治的技术与方法,该文介绍了我国生防与化防的不同和积极意义,概况归类说明了生物防治因子的种类;结合有害生物防治原理和应用现状,评述了生物防治的有效防治,其生防机制在防病机制上的应用和探索。     

Integrated pest management programme for cereal blast fungus Magnaporthe oryzae

Magnaporthe oryzae, the causal agent of blast diseases, is a destructive filamentous fungus that infects many plants including most economically important food crops, rice, wheat, pearl millet and finger millet. Magnaporthe oryzae has numerous pathotypes because of its high host-specificity in the field. The Oryza pathotype (MoO) of M. oryzae is the most devastating pathogen of rice, causing 10–30% yield loss in the world. On the other hand, the Triticum pathotype (MoT) causes blast disease in wheat, which is now a serious threat to wheat production in some South American countries, Bangladesh and Zambia. Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties, control of rice and wheat blast diseases is difficult. Therefore, an integrated management programme should be adopted to control these two diseases in the field. Here, we introduced and summarized the classification, geographical distribution, host range, disease symptoms, biology and ecology, economic impact, and integrated pest management (IPM) programme of both rice and wheat blast diseases.     

Machine vision smart sprayer for spot-application of agrochemical in wild blueberry fields

An essential part of the wild blueberry cropping system is the proper management of agrochemical inputs including herbicides, fungicides and insecticides. A machine vision system was developed and mounted on the rear sprayer boom 0.18 m in front of the sprayer nozzles capable of targeting the agrochemical application on an as-needed basis. The three-point hitch mounted sprayer featured 27 nozzles over a 13.7 m boom width and a storage tank capacity of 1135 l. Nine digital color cameras continually take images in real-time while computer software processes the images in 0.15 s to determine the target locations where the nozzles open and spray at speeds up to 1.77 m s^?1. Two wild blueberry fields in central Nova Scotia were selected for smart sprayer performance testing with spot-application (SA) of agrochemical as compared to control and uniform application techniques. Chateau^® herbicide was applied in a field with an infestation of hair cap moss. Spray droplet comparison showed moss patches were properly targeted using the smart sprayer. SA provided the same coverage performance as compared to uniform on the moss targets with herbicide application savings of 78.5% using the smart sprayer. Harvestable yield results were similar for all application tracks. TruPhos Magnesium and ZincMax foliar fertilizers were tank mixed with Bravo^® and Proline^® fungicides and applied to compare the difference of SA, control and uniform application. Results showed SA of foliar fertilizer and fungicide led to less premature leaf drop and increased the blueberry stem height, number of branches, stem diameter and fruit buds. SA of foliar fertilizer and fungicide also increased the percent of healthy wild blueberry plants by 57.8% and the harvestable yield by 137.8%. Fungicide application savings using the smart sprayer for SA were 11.6%.     

微生物酶及其在植物病害生物防治中的作用

介绍了生防菌产生的细胞壁降解酶,如几丁质酶、葡聚糖酶和蛋白酶及其生防作用机制,不同细胞壁降解酶之间以及与抗生素等次生代谢产物之间的协同抑菌作用,以及细胞壁降解酶在植物病害生防中的潜在应用。     

三七根际耐皂苷木霉菌的分离鉴定及其拮抗促生活性评价

为筛选出三七根际具有拮抗促生活性的耐皂苷木霉菌,通过收集一年生健康三七根际土壤进行木霉菌株的分离,并测定三七根系分泌物对木霉菌孢子萌发的影响以及皂苷对木霉菌菌丝生长的抑制效果,筛选获得耐皂苷的菌株,进一步对其分类鉴定后进行拮抗根腐病病原菌活性测定以及盆栽促生效果、根际定殖能力及其对连作障碍缓解效果的评价。结果表明:试验共分离到6株木霉菌株,其中2株对三七根系分泌物敏感性较低,经过形态学特征和ITS序列比对鉴定为绿色木霉(Trichoderma viride)T3和渐绿木霉(T. viridescens)T20。T3和T20菌株对三七主要根腐病病原菌恶疫霉菌(Phytophthora cactorum)、毁灭柱孢菌(Cylindrocarpon destructans)、茄腐镰刀菌(Fusarium solani)、尖孢镰刀菌(F. oxysporum)和雪腐镰刀菌(Monographella cucumerina)均具有较强的拮抗效果,对恶疫霉菌抑制率分别可达到61.76%和70.59%;T3和T20菌株能促进三七植株的生长,将其接种于三七连作土中,在接种20 d后能够在根际较好的定殖,增加三七植株的存苗率,降低根腐病发病率。该研究结果为缓解三七连作障碍提供了重要的生防菌资源。     

防治茉莉白绢病的药剂筛选研究

[目的]筛选防治茉莉白绢病菌的化学药剂和生防菌。[方法]采用生长速率法和抑菌圈法测定化学药剂和生防菌对茉莉白绢病菌的抑制作用,采用盆栽试验测试化学药剂和生防菌以及化学药剂和生防菌复配对茉莉白绢病的防治作用。[结果]测试的9种化学农药和6种生防菌中,25%戊唑醇可湿性粉剂和芽孢杆菌Bv22菌株对茉莉白绢病菌生长的抑制作用最强,其LC50分别为2690.96cfu/ml和200.05μg/L,且25%戊唑醇可湿性粉剂对芽孢杆菌Bv22菌株的生长无抑制作用。室内防治试验结果表明,25%戊唑醇可湿性粉剂100mg/L和芽孢杆菌Bv22菌株108cfu/ml以及25%戊唑醇可湿性粉剂200mg/L＋芽孢杆菌Bv22菌株107cfu/ml和25%戊唑醇可湿性粉剂400mg/L＋芽孢杆菌Bv22菌株106cfu/ml对茉莉白绢病的防治效果分别为84.44%、60.00%、96.67%和96.67%。[结论]化学药剂和生防菌复配对茉莉白绢病的有较好的防治作用。     

不同施肥与耕作对紫色土坡耕地土壤侵蚀及氮素流失的影响

【目的】研究重庆紫色土坡耕地“冬小麦-夏玉米”种植模式在不同施肥制度和耕作模式下由降雨而引发的水土流失特征及氮素流失规律,可为该区农业生产及生态环境保护提供科学依据。【方法】设置4种施肥制度（顺坡耕作对照、顺坡耕作农家肥和化肥配合施用、顺坡耕作单施化肥、顺坡耕作单施化肥增量）和2种耕作模式（顺坡耕作单施化肥、横坡垄作单施化肥）,采用野外径流小区长期（2008—2012）定位监测,研究施肥与耕作对坡面土壤侵蚀及氮素流失的影响。【结果】不同施肥制度和不同耕作模式间产流量、产沙量、氮素流失量差异均显著,不施肥处理产流量、产沙量及氮素流失量均最大,施肥、横坡垄作均能有效降低坡面产流产沙及氮素流失量。与相同施肥水平的顺坡耕作相比,横坡耕作分别减少产流量、产沙量、全氮流失量25.9%、20.5%和33.4%,与相同耕作方式的对照相比,农家肥和化肥配合施用可分别减少产流量、产沙量和全氮流失量35.7%、40.5%和41.2%。紫色土区年降雨量与年产流产沙量均呈幂函数关系（y=ax^b,a＞0,b＞0）,氮素流失量与径流量呈线性关系（y=ax+b,a>0）,但与降雨量相关性不显著,旱坡地氮素流失以总可消化养分（total digestible nutrients,TDN）为主,占全氮的62.1%。农家肥和化肥配合施用可以降低总可消化养分（TDN）和铵态氮（NH₄⁺-N）占全氮的比例。【结论】紫色土区不宜采取顺坡耕作和不施用任何肥料的土地管理方式。农家肥和化肥配合施用、横坡垄作是防治重庆紫色坡面水土流失及径流氮素流失的有效途径,径流中氮素流失以总可消化养分为主。     

速保利对小麦条锈病的防治效果

温室盆栽及田间小区试验结果表明,速保利(Diniconazole)对防治小麦条锈病有优异的保护作用和治疗作用。该剂叶面施用后保护活性持续50d以上,能有效地防止条锈菌侵染和降低反应型。潜育期施药能中断侵染,铲除叶内菌丝体,在显症或产孢后施药,能使已有病斑褐变枯死,有效地抑制再侵染。田间适期喷药有很高的防治效果和保产效果,用药量略低于三唑酮。