Genetic variation, real-time PCR, metabolites and mycotoxins ofFusarium avenaceum and related species

In this paper the latest studies dealing with genetic variation and mycotoxins ofF. avenaceum and related species are reviewed and compared to the data from chromatographic image analyses. Forty-three European strains ofFusarium avenaceum and related species were classified by chromatographic image analysis on full chromatographic matrices. The results were in most cases in agreement with those from morphological and molecular analyses and supported the separation betweenF. avenaceum, F. arthrosporioides andF. tricinctum and betweenF. avenaceum groups I and II. The mycotoxin profiles of the FinnishF. avenaceum, F. arthrosporioides andF tricinctum strains were very similar to each other. Moniliformin and enniatins were the main mycotoxins produced. A fluorogenic TaqMan PCR assay (qPCR) was used for the detection ofF. avenaceum/ F. arthrosporioides DNA in Finnish barley and wheat. The qPCR results obtained from grain samples were compared to mycotoxin levels. A correlation was found betweenF. avenaceum/F. arthrosporioides DNA and moniliformin (MON) and enniatin (ENNs) levels in barley. A correlation was also found between the combinedF. avenaceum/F. arthrosporioides/F. tricinctum contamination and MON and ENNs levels in barley in 2002, but not in 2003. This was probably due to the higher MON and ENNs levels in 2002 than in 2003. It was possible to use the DNA levels ofF. avenaceum/F. arthrosporioides to distinguish between most barley samples containing high amounts of MON and ENNs from those containing low levels of the mycotoxins. Presented at the EU-USA Bilateral Workshop on Toxigenic Fungi & Mycotoxins, New Orleans, USA, July 5–7, 2005 Financial support: Grants from the National Technology Agency of Finland (No. 40168/03) and the Academy of Finland (No. 52104); travel grants from NorFA and the European Commission to the Laboratory of Dr. Ulf Thrane     

Root rot of onion caused byPythium irregulare andPythium coloratum

Pythium irregulare andPythium coloratum were isolated consistently from roots of onion plants exhibiting root rot and associated foliar symptoms in fields located in Organe County, NY.P. coloratum predominated following extremely wet weather in 1984 and 1986, whileP. irregulare was prevalent following moderately wet weather in 1985. Both species produced root rot symptoms similar to field symptoms when 12 week old onion plants (cv Downing Yellow Globe) were inoculated and incubated in a growth chamber at 14°C for 10 days. This is the first report ofP. irregulare andP. coloratum as causes of root rot of onion.     

Effects of Commercial and Indigenous Microorganisms on Fusarium Wilt Development in Chickpea

The purpose of this research was to determine whetherBacillus subtilis,nonpathogenicFusarium oxysporum,and/orTrichoderma harzianum,applied alone or in combination to chickpea (Cicer arietinumL.) cultivars ‘ICCV 4’ and ‘PV 61’ differing in their levels of resistance to Fusarium wilt, could effectively suppress disease caused by the highly virulent race 5 ofFusarium oxysporumf. sp.ciceris.Seeds of both cultivars were sown in soil amended with the three microbial antagonists, alone or in combination, and 7 days later seedlings were transplanted into soil infested with the pathogen. All three antagonistic microorganisms effectively colonized the roots of both chickpea cultivars, whether alone or in combination, and significantly suppressed Fusarium wilt development. In comparison with the control, the incubation period for the disease was delayed on average about 3 days and the final disease severity index and standardized area under the disease progress curve were reduced significantly between 14 and 33% and 16 and 42%, respectively, by all three microbial antagonists. Final disease incidence only was reduced byB. subtilis(18–25%) or nonpathogenicF. oxysporum(18%). The extent of disease suppression was higher and more consistent in ‘PV 61’ than in ‘ICCV 4’ whether colonized byB. subtilis,nonpathogenicF. oxysporum,orT. harzianum.The combination ofB. subtilis+T. harzianumwas effective in suppressing Fusarium wilt development but it did not differ significantly from treatments with either of these antagonists alone. In contrast, the combination ofB. subtilis+ nonpathogenicF. oxysporumtreatment was not effective but either antagonist alone significantly reduced disease development.     

砧用瓠瓜抗枯萎病相关性及杂种优势分析

枯萎病是一种严重危害瓜类蔬菜生产的土传病害,嫁接栽培是防治瓜类枯萎病的有效方法。该文研究了砧用瓠瓜种质幼苗生长指标与抗病性的相关性,并对抗病杂种优势进行了分析。结果表明:(1)砧用瓠瓜种质H041对西瓜枯萎病表现高抗(HR),对瓠瓜枯萎病表现抗病(R),种质H01、H05和杂交组合H01×H041、H041×H05、H05×H041对两种枯萎病均表现抗病(R)。(2)砧用瓠瓜幼苗接种西瓜枯萎病菌后,病情指数与下胚轴粗度呈显著负相关;接种瓠瓜枯萎病菌后,总根长、根系表面积与病情指数呈极显著负相关,表明砧用瓠瓜对枯萎病的抗病性与根系生长具有相关性,可以根据根系生长情况快速评价砧用瓠瓜对瓠瓜枯萎病的抗性表现。(3)分析砧用瓠瓜杂交组合的抗病性杂种优势显示,供试杂交组合H05×H041对西瓜枯萎病具备超中亲优势;杂交组合H01×H041和H02×H041对瓠瓜枯萎病抗性具有负向杂种优势。综合研究结果发现,种质H01、H041、H05兼抗西瓜枯萎病和瓠瓜枯萎病,且配制出的杂交组合表现抗性杂种优势,可作为选育抗两种枯萎病的砧木或栽培品种的抗源亲本,其中H041可作为优势骨干亲本。     

Seasonal variation of growth and development of the roots of five second year conifer species in the nursery

Every other week over their second growing season, stem height, collar diameter, shoot and root dry masses, number of lateral roots and length of the tap root were measured on nursery grown seedlings ofAbies balsamea L. Mill.,Pinus banksiana Lamb.,Pinus resinosa Ait.,Picea mariana Mill. BSP andPicea glauca Moench Voss. Root elongation, branching and mycorrhizal development were also recorded.Given species showed distinct seasonal growth patterns. The rate and timing of maximum root growth (mg/dry weight/week) differed markedly between species.Except for the increase in height ofPinus banksiana, root and shoot growth were not negatively correlated.The results are discussed in relation to the performance of tree seedlings in the nursery.     

Induction of pathogenesis-related proteins during biocontrol of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> with <Emphasis Type="Italic">Pseudomonas aureofaciens</Emphasis> in soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L. Merr.) plants

To investigate the biocontrol effectiveness of the antibiotic producing bacterium, Pseudomonas aureofaciens 63–28 against the phytopathogen Rhizoctonia solani AG-4 on Petri plates and in soybean roots, growth response and induction of PR-proteins were estimated after inoculation with P. aureofaciens 63–28 (P), with R. solani AG-4 (R), or with P. aureofaciens 63–28 + R. solani AG-4 (P + R). P. aureofaciens 63–28 showed strong antifungal activity against R. solani AG-4 pathogens in Petri plates. Treatment with P. aureofaciens 63–28 alone increased the emergence rate, shoot fresh weight, shoot dry weight and root fresh weight at 7 days after inoculation, when compared to R. solani AG-4; P + R treatment showed similar effects. Peroxidase (POD) and β-1,3-glucanase activity of P. aureofaciens 63–28 treated roots increased by 41.1 and 49.9%, respectively, compared to control roots. POD was 26% greater in P + R treated roots than R. solani treated roots. Two POD isozymes (59 and 27 kDa) were strongly induced in P + R treated roots. The apparent molecular weight of chitinase from treated roots, as determined through SDS-PAGE separation and comparison with standards, was about 29 kDa. Five β-1,3-glucanase isozymes (80, 70, 50, 46 and 19 kDa) were observed in all treatments. These results suggest that inoculation of soybean plants with P. aureofaciens 63–28 elevates plant growth inhibition by R. solani AG-4 and activates PR-proteins, potentially through induction of systemic resistance mechanisms.     

Effects of irrigation frequency on germination and on root and shoot yields ofAcacia species

Summary Maximum germination response and root + shoot yields of Acacias were obtained at daily irrigation. Any deviation from daily irrigation resulted in variations of performance (germination and growth yield) between the six Acacia species studied. Species of relatively dry habitse.g. A. nubica andA. seyal were more sensitive to water supply compared with those of relatively wet habitatse.g. A. nilotica andA. albida. This was reflected at the establishment phase by the greater production of root + shoot yields of species of drier zones than by those of wetter ones. It is concluded that variations in water supply may account for species adaptation and distribution in semi-arid zones.     

Production of trichothecene mycotoxins byFusarium graminearum andFusarium culmorum on barley and wheat

Wheat cultivars (Stoa, MN87150, SuMai-3, YMI-6, Wheaton) and barley cultivars (Robust, Excel, Chevron, M69) were inoculated in the field with isolates ofFusarium graminearum andF. culmorum. The diseased (Fusarium head blight) kernels were analyzed for deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON) and nivalenol (NIV).F. culmorum produced all three trichothecenes on all cultivars tested whereasF. graminearum only produced DON and 15-ADON. There was no well defined correlation between DON production in the host and resistance although the data tended to favor SuMai-3 as having definitive resistance to bothF. graminearum andF. culmorum.Minnesota Agricultural Experiment Station, Paper No. 20 279.     

木贼镰孢基因功能注释及比较基因组学分析

为挖掘木贼镰孢(Fusarium equiseti (Corda) Sacc.)的产毒基因及明确其进化关系,通过BLAST软件与GO、KEGG、COG、E职NOG、CAZy等14个数据库结合的方法对其全基因组进行功能注释并挖掘产毒基因,进行系统进化分析及运用色谱技术研究产毒基因的分泌规律;以麦根腐平脐蠕孢、燕麦镰孢、尖...     

The response of seedlings of two dipterocarp species to nutrient additions and ectomycorrhizal infection

An experiment was conducted to investigate the effect of ectomycorrhizal infection on growth and nutrient uptake, especially of P and K of dipterocarp seedlings.Hopea helferi (Dyer) Blanco andHopea odorata Roxb. seedlings were grown in a sandy loam soil given a basal dressing. Nutrient treatments were unamended soil (NIL), amended soil with the addition of P and K (F), amended soil without P but with K (-P), amended soil without K but with P (-K), amended soil without P or K addition (-PK). Seedlings grown in the amended soil treatments showed foliar symptoms suggestive of calcium deficiency. Ectomycorrhizal infection appeared to improve shoot Ca concentration and relieved the foliar symptoms. Ectomycorrhizal infection inH. odorata plants increased shoot P concentration and increased shoot and total dry weight to the same or greater extent than those of uninfected plants growing on P amended soil.H. helferi showed a positive response to ectomycorrhizal infection in shoot, root and total dry weight in all nutrient treatments but no response to the nutrient treatments themselves.     

Response of root and sediment phosphatase activity to increased nutrients and salinity

Wetlands of northern Belize, distributed along a salinity gradient, are strongly phosphorus limited and dominated largely by three species of emergent macrophytes: Eleocharis cellulosa, Cladium jamaicense, and Typha domingensis. We assessed changes in root and sediment phosphatase activities of each species to simultaneous changes of nutrients (N, P) and salinity in a mesocosm experiment. Phosphorus and nitrogen treatment effects on both root and sediment phosphatase were highly significant for all the species, while salinity significantly affected root phosphatase activity in Cladium only. All species showed a significant negative correlation between root phosphatase activity and increasing tissue P content until a threshold of 0.2% P, 0.15% P and 0.12% P in Eleocharis, Cladium and Typha, respectively. There was also a significant negative correlation between soil available P and root and sediment phosphatases in all species. Activity of root phosphatases of Eleocharis and Typha were positively correlated with root tissue N. Both root and sediment phosphatases of all three species were positively correlated with soil available N. The strongest (positive) correlation was found between phoshatase activites and N/P ratios. The results confirmed that these systems are P-limited and that extracellular phosphatases respond to P enrichment by decreasing their activities. Expression of root phosphatase activity by dry root weight, sediment volume, or whole plant biomass gave very different relative results across nutrient treatments and species, suggesting that root phosphatase activities need to be interpreted in a wider context that considers root density.     

Effect of arbuscular mycorrhiza on inter- and intraspecific competition of two grassland species

We were interested in the role of arbuscular mycorrhiza (AM) in the competition between plants of different sizes. A pot experiment of factorial design was established, in which AM root colonization and competition were used as treatments. Five-week-old Prunella vulgaris seedlings were chosen as target plants (i.e. plants whose response to competition was studied) and the following (13 replicates of each) were used as neighbours: (1) a large, 10-week-old P. vulgaris, (2) two P. vulgaris seedlings, and (3) a large, 10-week-old Fragaria vesca. In the experiment where small neighbours were grown together with small target plants, competition did not reduce target plant weight significantly, compared to the other two treatments. The competitive effects of large neighbours were significant, regardless of species (both older neighbours reduced the weights of target plants similarly), but there was a clear difference between intra- and interspecific competition when plants were mycorrhizal. In intraspecific competition with a large neighbour, the target plant shoot weight was reduced 24% when inoculated with AM. Thus, AM amplified rather than balanced intraspecific competition. In interspecific competition with old F. vesca, the shoot weights of target plants were 22% greater when inoculated with AM than when non-mycorrhizal. The results showed that, for given soil condition, AM might increase species diversity by increasing competitive intraspecific suppression and decreasing the interspecific suppression of small plants by larger neighbours.     

Role of salicylic acid in systemic resistance induced by Pseudomonas fluorescens against Fusarium oxysporum f. sp. ciceri in chickpea

Selected isolates of Pseudomonas fluorescens (Pf1-94, Pf4-92, Pf12-94, Pf151-94 and Pf179-94) and chemical resistance inducers (salicylic acid, acetylsalicylic acid, DL-norvaline, indole-3-carbinol and lichenan) were examined for growth promotion and induced systemic resistance against Fusarium wilt of chickpea. A marked increase in shoot and root length was observed in P. fluorescens treated plants. The isolates of P. fluorescens systemically induced resistance against Fusarium wilt of chickpea caused by Fusarium. oxysporum f.sp. ciceri (FocRs1), and significantly (P = 0.05) reduced the wilt disease by 26-50% as compared to control. Varied degree of protection against Fusarium wilt was recorded with chemical inducers. The reduction in disease was more pronounced when chemical inducers were applied with P. fluorescens. Among chemical inducers, SA showed the highest protection of chickpea seedlings against wilting. Fifty two- to 64% reduction of wilting was observed in soil treated with isolate Pf4-92 along with chemical inducers. A significant (P = 0.05; r = -0.946) negative correlation was observed in concentration of salicylic acid and mycelial growth of FocRs1 and at a concentration of 2000 microg ml(-1) mycelial growth was completely arrested. Exogenously supplied SA also stimulated systemic resistance against wilt and reduced the disease severity by 23% and 43% in the plants treated with 40 and 80 microg ml(-1) of SA through root application. All the isolates of P. fluorescens produced SA in synthetic medium and in root tissues. HPLC analysis indicated that Pf4-92 produced comparatively more SA than the other isolates. 1700 to 2000 nanog SA g(-1) fresh root was detected from the application site of root after one day of bacterization whereas, the amount of SA at distant site ranged between 400-500 nanog. After three days of bacterization the SA level decreased and was found more or less equal at both the detection sites.     

Chemical,physical and biological control of carrot seedling diseases

In naturally infested soil containingPythium ultimum, P. acanthicum andPhytophthora megasperma, onlyP. ultimum was associated with root rot and damped-off seedlings. Damping-off was promoted by low soil temperatures and by flooding. Seedling stands were markedly reduced when seed was pre-incubated in soil at 12°C but not at 25°C or 35°C. Dusting carrot seed with metalaxyl significantly increased seedling stands in the field at rates from 1.5–6 g kg⁻¹ seed and in both flooded and unflooded, naturally infested soil at 3.15 g kg⁻¹. In greenhouse experiments using artifically infested soil,P. ultimum andP. paroecandrum caused damping-off of carrot seedlings andRhizoctonia solani reduced root and shoot weights.R. solani caused damping-off in nutrient-enriched soil.P. acanthicum andP. megasperma were not pathogenic to seedlings, although both fungi colonized roots. Soil populations of allPythium spp., particularlyP. ultimum, increased during growth of seedlings and population growth ofP. megasperma was promoted by periodic flooding. Infestation of soil withP. acanthicum did not reduce damping-off of carrot seedlings byP. ultimum orP. paroecandrum, but significantly increased root and shoot weights and decreased root colonization byR. solani P. acanthicum has potential as a biocontrol agent againstR. solani.     

Seedling establishment ofPolygonum cuspidatum andPolygonum weyrichii var.alpinum at high altitudes of Mt Fuji

Seedling establishment ofPolygonum cuspidatum (Seib. et Zucc.) andPolygonum weyrichii (F. Schmit) var.alpinum (Maxim.), dominant early-successional species in a volcanic gravel area on Mt Fuji, Japan, was compared for current-year seedlings at 2500 m a.s.l. The rate of survival in the first winter after germination at 2500 m was 2% and 24% forP. cuspidatum andP. weyrichii seedlings, respectively, and correlated with the upper distribution limit of each (2500–2600 m forP. cuspidatum; 3200–3300 m forP. weyrichii). The critical size for survival was 12 mg dry weight for overwintering current-year seedlings of both species. At 2500 m, the percentage of seedlings that attained the critical size for survival at the end of the first growing season was 19% and 85% forP. cuspidatum andP. weyrichii, respectively. Growth curves indicated that the larger-seeded characteristic ofP. weyrichii contributed to larger end-of-season size and resulted in higher rate of seedling survival at 2500 m, compared with smaller-seededP. cuspidatum. Current-year seedlings ofP. weyrichii, at least up to 3250 m, attained the first year annual growth critical for overwintering and therefore for successful seedling establishment, due to the large-seeded characteristic. At the top (3770 m) beyond the upper distribution limit ofP. weyrichii, most seedlings raised artificially failed to attain the critical size for survival in the first growing period due to the reduced growing period. Failure of seedling establishment would thus appear to restrict the distribution of the species at altitudes higher than 3300 m.     

Interaction between the root-lesion nematode Pratylenchus vulnus and the mycorrhizal association of Glomus intraradices and Santa Lucia 64 cherry rootstock

The effects of the interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus intraradices on growth and nutrition of Santa Lucia 64 cherry rootstock was studied under microplot conditions during one growing season. Fresh top weight, and stem diameter of mycorrhizal plants and high P treatments with and without P. vulnus were significantly higher than those of non-mycorrhizal plants. The lowest shoot length and fresh root weights were recorded in nematode inoculated plants in low P soil. Mycorrhizal infection did not affect the number of nematodes per gram of root in plants infected with P. vulnus. In the presence of the nematode, internal spore production by G. intraradices was significantly reduced. No nutrient deficiencies were detected through foliar analysis, although low levels of Ca, Mn and Fe were detected in nematode treatments. Mycorrhizal plants achieved the highest values for N, P, S, Fe, and Zn, whereas high P treatments increased absorption of Ca and Mn. Early mycorrhizal infection of Santa Lucia 64 cherry rootstock by G. intraradices confers increased growth capacity in the presence of P. vulnus.     

Antagonistic interactions between fungal pathogens and phylloplane fungi of guava

Dominant phylloplane fungi of guava (Psidium guajava L.) were screened for their antagonistic activities against the two pathogens,Colletotrichum gloeosporioides andPestalotia psidii, bothin vitro andin vivo. Culture filtrates ofAspergillus niger, Fusarium oxysporum andPenicillium citrinum caused more than 50% growth inhibition ofC. gloeosporioides. Filtrates ofCephalosporium roseo-griseum andF. oxysporum were most effective in reducing the growth ofP. psidii. Volatiles produced from the cultures ofA. niger, F. oxysporum, P. citrinum andP. oxalicum inhibited the growth ofC. gloeosporioides, whereas volatiles fromC. roseo-griseum, F. oxysporum andTrichoderma harzianum inhibited the growth ofP. psidii. The inhibitory effect of volatiles decreased with increase in incubation time. In general, the maximum effect of volatiles was noticed after 48 h incubation. Different grades of colony interactions in dual cultures were recognised between the two pathogens and the phylloplane fungi examined. Maximum inhibition ofC. gloeosporioides was caused byAureobasidium pullulans, Cladosporium cladosporioides, epicoccum purpurascens, F. oxysporum andMyrothecium roridum, whereasAspergillus terreus, C. roseo-griseum andP. oxalicum significantly reduced the growth ofP. psidii. Application of a spore suspension of each test fungus inhibited lesion development of guava leaves caused by the test pathogensin vitro. Inhibition was more pronounced when the spore concentration was increased.A. pullulans, C. cladosporioides, E. purpurascens, F. oxysporum, andT. harzianum were found to be strongly antagonistic toC. gloeosporioides. A. niger, A. terreus, C. roseo-grisem andT. harzianum were strongly antagonistic toP. psidii.     

Dual inoculation with Aspergillus fumigatus and Glomus mosseae enhances biomass production and nutrient uptake in wheat (Triticum aestivum L.) supplied with organic phosphorus as Na-phytate

In a pot experiment, wheat was grown for 50 days in two heat-sterilized low-phosphorus (P) soils supplied with organic P as Na-phytate. Seed inoculation with the phosphatase-producing fungus (PPF) Aspergillus fumigatus or soil inoculation with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae increased shoot and root dry weight and root length, phosphatase activity in the rhizosphere and shoot concentrations of P and to a lesser extent of K and Mg. As a rule, the greatest effects on those parameters were most in the combined inoculation treatment (PPF + VAM). Shoot concentrations of Cu and Zn were only enhanced by VAM, not by PPF. At harvest, depletion of organic P in the rhizosphere soil increased in the order of: sterilized soil < PPF < VAM < PPF + VAM which corresponded with the enhanced P concentrations in the plants. The results demonstrate that organic P in form of Na-Phytate is efficiently used by VAM and that use of organic P can be increased by simultaneous inoculation with phosphatase-producing fungi.     

Differential responses of three fungal species to environmental factors and their role in the mycorrhization of<Emphasis Type="Italic"> Pinus radiata</Emphasis> D. Don

Three ectomycorrhizal (ECM) isolates of Rhizopogon luteolus, R. roseolus and Scleroderma citrinum were found to differ markedly in their in vitro tolerance to adverse conditions limiting fungal growth, i.e. water availability, pH and heavy metal pollution. S. citrinum was the most sensitive, R. luteolus intermediate and R. roseolus the most tolerant species. Pinus radiata D. Don seedlings were inoculated in the laboratory and in a containerised seedling nursery with spore suspensions of the three ECM species. Colonisation percentage was considerably lower under nursery conditions, probably due to competition by native fungi. The effects of nursery ECM inoculation on seedling growth depended on the fungal species. Only R. roseolus-colonised plants showed a significantly higher shoot growth than non-mycorrhizal plants. All three fungi induced significantly higher root dry weights relative to control plants. Despite the low mycorrhizal colonisation, mycorrhization with all three species improved the physiological status of nursery-grown seedlings, e.g. enhanced root enzyme activity, shoot nutrient and pigment content, net photosynthesis rate and water use efficiency. Of the three fungal species, R. roseolus was the most effective; this species was also the most adaptable and showed the greatest range of tolerance to adverse environmental conditions in pure culture. It is, therefore, proposed as a promising fungal species for ECM inoculation of P. radiata in the nursery.     

绿色木霉TV41对尖孢镰刀菌FW0在西瓜植株空间分布和枯萎病防控效果的影响

【目的】为进一步探究盆栽试验条件下绿色木霉TV41 (Trichoderma viride TV41)对尖孢镰刀菌FW0 (Fusarium oxysporum FW0)在西瓜植株空间分布的影响以及对西瓜枯萎病的防控效果。【方法】通过定期检测不同处理西瓜根际/根表尖孢镰刀菌的数量、西瓜植株根内/茎内尖孢镰刀菌的数量以及植株侧根被侵染比例和尖孢镰刀菌在植株内的侵染进程,进行多次盆栽试验并统计发病率。【结果】当绿色木霉和尖孢镰刀菌接种量均为5×105孢子/g基质时,绿色木霉TV41在西瓜根际/根表的定殖数量明显高于尖孢镰刀菌FW0的数量,接种了绿色木霉TV41的处理,根际/根表尖孢镰刀菌的数量(103/g基质)显著低于仅接种FW0的对照(104/g基质);绿色木霉TV41不仅能够有效减缓尖孢镰刀菌在西瓜植株内的侵染进程,而且能够有效降低西瓜植株根内、茎内尖孢镰刀菌的数量。与对照(只接种FW0)相比,接种绿色木霉后西瓜枯萎病的发病率从66%降低到27%。【结论】绿色木霉TV41能够通过影响尖孢镰刀菌FW0在西瓜植株的空间分布,从而有效防控西瓜枯萎病的发生,防控效果达到60%。