木霉在植物病害生物防治中的应用及作用机制

木霉是植物病害生物防治中应用和研究非常广泛的一类生防真菌。本文阐述了木霉在多种植物病害防治上的应用及防治效果,并概括了木霉在生防过程中对植物病原物的生防机制,包括竞争、重寄生、抗生作用等,以及木霉与植物互作中对植物促生和诱导植物抗性的机制。目前,世界上含木霉的商品化制剂已超过250种,在不同国家地区都取得了良好的防治效果,更多的优秀生防木霉菌株也在通过野生菌株筛选或遗传改良等方式开发。木霉生物防治及机制研究对推广生物防治和减少化学农药有重要意义。     

我国农林园艺作物土传病害发生和防治现状及对策分析

土传病害正日趋成为限制我国农林业生产可持续发展的重要因素。本文简要分析了我国农林植物土传病害加重的原因,概述了我国农林植物土传病害的发生状况,总结了土传病害发生和为害的特点,总结分析了现有各类土传病害防治措施的优点和弊端,提出了今后研究中应予加强的课题和技术。     

土壤熏蒸与水肥菌/药一体化技术联用防控设施番茄病害

为了减少设施番茄生产中农药化肥的使用,集成了土壤熏蒸及水肥菌/药一体化技术,并在湖北十堰开展了设施番茄病害的综合防控试验示范。试验设置3个处理,分别为CK(不做土壤熏蒸+水肥药常规化管理)、T1(土壤熏蒸+水肥药常规化管理)、T2(土壤熏蒸+水肥药一体化管理)。田间试验结果表明:采用土壤熏蒸可使番茄的根结线虫病降低70.7%~75.0%,灰霉病、早疫病和青枯病的综合发病率降低33.0%~63.7%,产量增加25.0%左右;土壤熏蒸结合水肥菌/药一体化技术可使番茄的根结线虫病降低 82.7%~85.1%,灰霉病、早疫病和青枯病的综合发病率降低70.2%~74.0%,产量增加35.9%~41.0%。相对于常规管理措施,采用水肥菌/药一体化技术可以节约灌溉用水18.8%、节约用肥33.3%、节约用药21.3%。上述结果表明:土壤熏蒸消毒结合使用水肥菌/药一体化产品和技术,可以节水、节肥、节药,显著降低设施番茄各类病害的发生,提高番茄产量,实现节本增效。     

设施番茄连作障碍土壤修复及其对青枯病害的防治效果

连作障碍的土壤修复是世界性难题。本研究利用土壤微生态修复剂结合青枯病植物疫苗菌剂来改良土壤和预防青枯病发生。在连作7年的番茄地,设3种处理,处理1为添加量60 t/hm²的土壤微生态修复剂和植物疫苗100倍稀释液,处理2为添加量30 t/hm²的土壤微生态修复剂和植物疫苗100倍稀释液,CK为不添加土壤微生态修复剂和植物疫苗,研究不同处理对连作番茄土壤养分、土壤酶活性、植株生长特性及病害防效的影响。结果表明,土壤微生态修复剂2种不同添加量处理的番茄土壤有机质、全氮、全磷和交换性钙含量均显著高于对照,而全钾含量显著低于对照;两种不同添加量处理的番茄土壤过氧化氢酶、脲酶、蔗糖酶和酸性磷酸酶活性均显著高于对照,添加量为30 t/hm²处理的土壤各酶活性（酸性磷酸酶除外）大于添加量为60 t/hm²处理的土壤;添加30 t/hm²处理的单果重量（113.82 g）显著高于添加量60 t/hm²处理（104.07 g）和对照处理（104.99 g）（P<0.05）,其对番茄青枯病防效达91.87%,大于添加量为60 t/hm²处理的防效（55.34%）。     

Studies on the interaction between the biocontrol agent,Serratia plymuthica A30, and blackleg‐causing Dickeya sp. (biovar 3) in potato (Solanum tuberosum)

Interactions between Serratia plymuthica A30 and a blackleg‐causing biovar 3 Dickeya sp. were examined. In a potato slice assay, S. plymuthica A30 inhibited tissue maceration caused by Dickeya sp. IPO2222 when co‐inoculated at a density at least 10 times greater than that of the pathogen. In glasshouse experiments, population dynamics of the antagonist and of the pathogen in planta were studied by dilution plating and confocal laser scanning microscopy (CLSM) using fluorescent protein‐tagged strains. Pathogen‐free minitubers were vacuum‐infiltrated with DsRed‐tagged Dickeya sp. IPO2222 and superficially treated during planting with a water suspension containing GFP‐tagged S. plymuthica A30. A30 reduced the blackleg incidence from 55% to 0%. Both the pathogen and the antagonist colonized the seed potato tubers internally within 1 day post‐inoculation (dpi). Between 1 and 7 dpi, the population of A30 in tubers increased from 10¹ to c. 10³ CFU g^?1 and subsequently remained stable until the end of the experiment (28 dpi). Populations of A30 in stems and roots increased from c. 10² to c. 10⁴ CFU g^?1 between 7 and 28 dpi. Dilution plating and CLSM studies showed that A30 decreased the density of Dickeya sp. populations in plants. Dilution plating combined with microscopy allowed the enumeration of strain A30 and its visualization in the vascular tissues of stem and roots and in the pith of roots, as well as its adherence to and colonization of the root surface. The implications of these finding for the use of S. plymuthica A30 as a biocontrol agent are discussed.     

Rate, placement and timing of aldicarb applications to control Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in oranges

BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a cosmopolitan insect pest of citrus and vectors the bacterium Candidatus Liberibacter asiaticus, a suspected causal organism of citrus greening or ‘huanglongbing’ disease. Aldicarb 150 g kg^?1 GR (Temik^® 15 G) was evaluated at three rates, two placements and three timings for ACP control in orange trees. RESULTS: Application of aldicarb at 5.6, 2.8 and 1.4 kg AI ha^?1 in March 2006 reduced adults by 58–66%, 45–46% and 25–37% respectively compared with untreated controls in two separate trials. No difference was observed in placement (one versus two sides of the tree) or tree size (8 years old versus 12 years old). Application at 5.6 kg ha^?1 in January 2007 reduced adults by 86% and shoot infestation by 77% in spring, and was generally better than the November and especially February applications. Even more striking results were evident on adults caged on treated plants for 25 days in March. Spiders and ladybeetles were equally abundant in treated and untreated trees. CONCLUSION: Aldicarb application at 5.6 kg ha^?1 to the bed side of mature citrus trees 2–3 months before spring growth can suppress ACP through spring without a direct effect on principal psyllid natural enemies. Copyright © 2008 Society of Chemical Industry     

Botrytis cinerea in greenhouse vegetables: chemical,cultural, physiological and biological controls and their integration

Botrytis cinerea is an ubiquitous pathogen which causes severe losses in many fruit, vegetable and ornamental crops. The pathogen infects leaves, stems, flowers and fruits. The complexity of diseases caused by B. cinerea in greenhouses makes this pathogen one of the most important diseases of vegetable crops in greenhouse in many countries. In general, epidemics occur in cool and humid conditions, which favour infection and may also predispose the host to become susceptible. High relative humidity in the greenhouse and free moisture on plant surfaces are considered the most important environmental factors which influence infection by B. cinerea. In this review we specify the factors affecting the development of diseases incited by B. cinerea and discuss different approaches for its suppression. Chemical and non-chemical controls are outlined and their integration is discussed. Finally, achievements, gaps in knowledge, and future needs are indicated. The most common means for disease management is by application of chemical fungicides. Both spraying of fungicides and application of fungicides directly to sporulating wounds is practiced. However, high activity of several fungicides is being lost, at least in part, due to the development of resistance. As fungicides still remain an important tool for control of epidemics caused by B. cinerea, it is important to monitor populations of the pathogen for their resistance towards potential fungicides. Cultural measures can be a powerful means to suppress plant diseases in greenhouses where the value of crops is high and the farmers make considerable efforts during long cropping seasons. Such measures are usually aimed at altering the microclimate in the canopy and around susceptible plant organs, prevention of inoculum entrance into the greenhouse and its build up, and, rendering the host plants less susceptible to diseases. Calcium loading of plant tissues and alteration of nitrogen fertilization reduce susceptibility to Botrytis. Cultivars resistant to B. cinerea are not available. Another alternative methods to control B. cinerea is by means of biological control agents. At least one preparation is already available in the market and in many cases it was as effective as the conventional fungicides. A decision support system was recently developed for integration of chemical and biological controls. Adaquate suppression of B. cinerea diseases in greenhouse crops is an attainable goal. In our opinion this goal can be reached by considering the ecology of the pathosystem in its broader sense and by integration of all possible control measures. This implies optimization of plant nutrition, microlimate and control (cultural, biological, physiological and, if necessary, chemical) measures. Moreover, Botrytis management must be incorporated in a more holistic system that is compatible with insect control, crop production systems and profitability of the crop.