Genetic variability and virulence among Verticillium albo-atrum isolates from hop

Verticillium wilt, caused by Verticillium albo-atrum or V. dahliae, is an important disease of many worldwide crop species. In Europe, V. albo-atrum isolates infecting hop express different levels of virulence, inducing mild or lethal disease syndromes, and it is therefore an attractive model for studying the virulence of this pathogen. In this work, eleven amplified fragment length polymorphism (AFLP) primer combinations were used to analyze genetic variability among 55 V. albo-atrum hop isolates from four European hop growing regions, as well as isolates from other hosts and V. dahliae isolates. Cluster analysis divided V. albo-atrum and V. dahliae isolates into two well-separated groups. Within the V. dahliae cluster, isolates were separated without host specific grouping, although no host adapted isolates were included. In V. albo-atrum, the alfalfa isolates were distinct from isolates of other hosts, where a high association with virulence was observed in hop and tomato isolates. All lethal hop isolates were genetically different from mild hop isolates. The lethal hop isolates from England and Slovenia expressed the same virulence phenotype, although they showed a different AFLP pattern. The mild hop isolates formed two subgroups, to which isolates clustered irrespective of geographical location. These data suggest multiple origins of V. albo-atrum hop isolates, and the possible appearance of new virulent isolates in the future in other hop growing regions.     

Risikofolgeabschätzung für den Einsatz mikrobieller Antagonisten: Gibt es Effekte auf Nichtzielorganismen?

Biological control of phytopathogenic fungi using antagonistic microorganisms is an environmentally friendly alternative in plant protection. However, possible non-target effects of the applied antagonists on ecologically important soil-microbes need to be considered. Therefore, the aim of this study was to analyse the effect of biological control agents (BCAs) on non-target microbes in the field. Whereas the bacterial BCAs Serratia plymuthica HRO-C48 and Streptomyces sp. HRO-71 were applied to control the pathogen Verticillium dahliae on strawberry and potato, the bacterial strains Pseudomonas trivialis 3Re2-7, P. fluorescens L13-6-12, S. plymuthica 3Re4-18 and the fungal antagonists Trichoderma reesei G1/8 and T. viride G3/2 were introduced to control Rhizoctonia solani on lettuce and potato. As the analysed BCAs belong to different microbial groups like grampositive (HRO-71) and gramnegative (HRO-C48, L13-6-12, 3Re2-7, 3Re4-18) bacteria or the ascomycota (G1/8, G3/2) and originated from different micro-habitats like the rhizosphere or the endorhiza, general conclusion could be drawn from our results. After BCA treatment we did not observe any long-term effect on the plant-associated microbes in any tested pathosystem. Therefore, no sustainable risks could be seen for the indigenous micro-organisms. Our new findings may help to improve the development as well as the registration procedures of future microbial plant protection products.     

Influence of drought and season on compartmentalization of black locust (<Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> L.) inoculated with <Emphasis Type="Italic">Armillaria mellea</Emphasis>

Olive plantations and tree nurseries are economically and ecologically important agricultural sectors. However, Verticillium wilt, caused by Verticillium dahliae Kleb., is a serious problem in olive-growing regions and in tree nurseries worldwide. In this review we describe common and differentiating aspects of Verticillium wilts in some of the main economically woody hosts. The establishment of new planting sites on infested soils, the use of infected plant material and the spread of highly virulent pathogen isolates are the main reasons of increasing problems with Verticillium wilt in tree cultivation. Therefore, protocols for quick and efficient screening of new planting sites as well as planting material for V. dahliae prior to cultivation is an important measure to control Verticillium wilt disease. Furthermore, screening for resistant genotypes that can be included in breeding programs to increase resistance to Verticillium wilt is an important strategy for future disease control. Collectively, these strategies are essential tools in an integrated disease management strategy to control Verticillium wilt in tree plantations and nurseries.     

A chalcone synthase controls the verticillium disease resistance response in both <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> and cotton

Verticillium wilt is a devastating disease caused by the soil-borne fungus Verticillium dahliae that causes severe wilt symptoms in more than 400 plant species, including economically important cotton. However, the molecular mechanism of plant resistance to Verticillium remains unclear. In this study, we identified an Arabidopsis mutant, vsad1 (verticillium sensitive and anthocyanin deficient 1), which showed more serious disease symptoms such as discoloration and chlorosis than wild-type Arabidopsis. vsad1 is a previously identified allele of the transparent testa 4 gene (tt4), which encodes chalcone synthase (CHS), a key enzyme involved in the biosynthesis of flavonoids. Our results showed that VSAD1 expression was induced in response to Verticillium dahliae infection. Overexpression of VSAD1 partially recovered the anthocyanin accumulation phenotype of the vsad1–1 mutant. The concentration of V. dahliae increased and ROS accumulation decreased in the vsad1 mutant after infection with V. dahliae. Knockdown of the homologous gene GhCHS in cotton plants increased their susceptibility to V. dahliae infection. Thus, we conclude that VSAD1 is involved in the regulation of plant resistance to Verticillium wilt.     

Wilt diseases in Gerbera

In The netherlands, the glasshouse area used for cultivation of gerbera as a cutflower was strongly restricted in the past since dying off of the plants generally occurred and constituted a great risk for growers.In most casesPhytophthora cryptogea appeared to be the cause of the disease and this fungus is probably responsible for the main difficulties in this crop since the introduction. Besides foot rot, caused byP. cryptogea, Verticillium albo-atrum andV. dahlinae cause a wilt disease of gerbera. Newly developed cultural methods prevent heavy losses, resulting in a strong expansion of the culture.Samenvatting Schade door bodemschimmels heeft lange tijd een sterke uitbreiding van de gerberateelt in Nederland verhinderd. Hierin is verandering gekomen doordat een goede bedrijfshygiëne en verbeterde cultuurmaatregelen (grondontsmetting, grondverwarming, drainage) het risico voor de kweker aanzienlijk hebben verminderd.De oorzaak van de belangrijkste ziekte in Nederland, het zogenaamde voetrot, is de schimmelPhytophthora cryptogea. Er zijn verschillende argumenten die er voor pleiten dat deze vanaf de invoering van de teelt in Nederland verantwoordesijk is geweest voor de grootste moeilijkheden op de bedrijven. Daarnaast kunnenVerticillium albo-atrum enV. dahliae optreden als oorzaak van verwelkingsziekte.Stationed at the Proefstation voor de Bloemisterij in Nederland, Aalsmeer.     

Accumulation of phytoalexins in susceptible and resistant near-isogenic lines of tomato infected with Verticillium albo-atrum or Fusarium oxysporum f.sp. lycopersici

The time course of accumulation of two phytoalexins, the terpenoid rishitin and the polyacetylene cis-tetradeca-6-ene-1,3-diyne-5,8-diol, was determined in near-isogenic susceptible and resistant tomato lines inoculated with either Verticillium albo-atrum or Fusarium oxysporum f.sp. lycopersici.Cultivars containing the Ve gene for verticillium wilt resistance accumulated phytoalexins at a rate similar to that in susceptible plants following stem inoculation with V. albo-atrum. Higher amounts of phytoalexins were isolated from susceptible than from resistant plants at 11 days after inoculation. Inoculum concentrations of 10⁵, 10⁶, 10⁷ and 10⁸ conidia ml⁻¹ had no differential effect on phytoalexin accumulation at 3 days after inoculation. Also, no differences were observed between fungal growth in susceptible and resistant cultivars during that period.A cultivar containing the I-1 gene for fusarium wilt resistance contained more rishitin than did susceptible plants at 2 and 3 days after inoculation with 10⁷ conidia of F. oxysporum f.sp. lycopersici ml⁻¹, but at 7 and 11 days after inoculation more rishitin had accumulated in the susceptible plants.No difference was observed between the rate of accumulation of phytoalexin in stem segments from resistant and susceptible plants inoculated by vacuum-infiltration.To estimate the concentration of phytoalexins in the xylem fluid, sap was expressed from vascular tissue and amounts of phytoalexins were determined in the sap and in the expressed tissue. Less than 5% of the phytoalexins present in stem segments was recovered from the sap, indicating that their concentration in the xylem fluid may be relatively low.The role of phytoalexins in resistance to verticillium and fusarium wilt is discussed.     

Symptom expression of the tomato wilt fungiverticillium andfusarium as affected by the presence of tobacco mosaic virus

The severity of Verticillium wilt symptoms increased 20-30 days earlier in the season in tomato plants in the presence of Tobacco Mosaic Virus than in plants infected with fungus alone. There were no differences in symptom intensity between tomato plants infected withFusarium alone and with aFusarium-TMV combination. The increase of fungus infectivity in aVerticillium-TM’V combination treatment is suggested to be a synergistic effect.     

Enkele waarnemingen over het opreden van de verwelkingsiekte bij luzerne in Zeeland in 1957

Summary Some observations have been made on lucerne wilt disease during the growing season in 1957, and in experimental inoculation tests in a glasshouse in 1958. In the province of Zeeland the disease does harm to the crop and prevents many farmers from keeping their crops longer than two years.In a survey data have been collected on soil type, preceding crops, green manuring and manuring with stable dung, pH, structure and weeds. No correlations between these factors and the degree of attack by the disease could be proved, except that on heavy soils the disease was less severe than on lighter soils (as a mean of all observations).Development of the disease is facilitated by damage caused by mechanical equipment to the crop. Damage to the crown of the plants should be avoided as much as possible. The disease is distributed extensively after frequent mowing. On attacked leaves left behind on the mowed stalks, and on decayed leaves dropped to the soil, masses of spores ofVerticillium albo-atrum are produced, which form a potential source of infection in a weakened crop.It seems that the disease is more air-borne than soil-borne, since one year old crops are seldom attacked.From attacked lucerne plants in the field the following fungi have been isolated:Verticillium albo-atrum Reinke & Berth.,Gliocladium roseum Bain andFusarium avenaceum (Fr.) Sacc. (table 1).Isolations have been made from 50 different species of weeds, out of which the following fungi were obtained:Verticillium albo-atrum Reinke & Berth. fromCapsella bursa-pastoris Med. andPlantago major L.,V. dahliae Kleb. fromPrunella vulgaris L.,Capsella bursa-pastoris Med. andThlaspi arvense L., andV. lecanii (Zimm.) Viegas fromPlantago major L.In inoculation experiments with all these isolates, in roots, stalks and on cut plants of lucerne, onlyV. albo-atrum, both from lucerne and weeds, andV. lecanii proved to be able to cause wilting of leaves and stalks. WithGliocladium, Fusarium andVerticillium dahliae no such symptoms could be obtained. The results were the same whatever method of inoculation was used.     

棉花内生真菌CEF-373菌株对棉花黄萎病的防效及其作用机理

为明确棉花内生真菌CEF-373菌株对棉花黄萎病的防效及其作用机理,利用圆盘滤膜法和平板对扣培养法测定菌株CEF-373对大丽轮枝菌Verticillium dahliae菌丝生长的抑制作用,测定其对棉花黄萎病的温室和田间防效,并通过活性氧含量及防御基因表达情况来分析其作用机理。结果表明,菌株CEF-373的挥发性代谢产物和非挥发性代谢产物对大丽轮枝菌菌丝的生长均有显著抑制作用,抑制率最高分别可达37.75%和100.00%。用1×107CFU/mL的菌株CEF-373分生孢子悬浮液灌根后,对棉花黄萎病的温室防效可达71.12%,用质量比为3%的菌株CEF-373固体菌剂拌土栽培后,对棉花黄萎病的温室防效可达62.74%,防治作用显著。菌株CEF-373的发酵液滴灌和微生物肥料处理40 d后,对棉花黄萎病的田间防效达到最大,分别为36.23%和27.71%,而在后期有所降低。菌株CEF-373可以诱导棉花叶片中细胞活性氧的爆发;且菌株CEF-373成功激活了苯丙氨酸解氨酶、过氧化物酶、多酚氧化酶、几丁质酶和病程相关蛋白基因PR10的表达,对大丽轮枝菌的侵染具有抵御作用。表明棉花内生真菌CEF-373菌株通过抑制大丽轮枝菌生长以及诱导寄主系统抗病性来有效防治棉花黄萎病,具有较好的生物防治应用前景。     

Involvement of two different types of Verticillium dahliae in lettuce wilt in Ibaraki Prefecture, Japan

Although wilt diseases of various plants by Verticillium dahliae occur worldwide, Verticillium wilt of lettuce is relatively new and rare. In 2009, this disease appeared suddenly in commercial fields in Ibaraki Prefecture, Japan. To investigate the cause of the disease, we characterized each lettuce isolate for pathogenicity, mating types, and genetic characteristics and found two types of V. dahliae. A population that included at least two types of V. dahliae was the putative infection source of the disease. Effective management systems against V. dahliae isolates of different races and having different host ranges are necessary.     

Control of <Emphasis Type="Italic">Verticillium dahliae</Emphasis> at a strawberry nursery by paddy-upland rotation

Effects of crop rotation between rice paddy fields and strawberry nurseries on the control of Verticillium wilt of strawberry were studied. For detecting Verticillium dahliae, the causal agent of Verticillium wilt, in soil, eggplant was used as an indicator plant. We were thus able to detect as low as 1 microsclerotium/g dry soil. In field surveys of Chiba and Hokkaido from 2000 to 2003, V. dahliae was detected in 9 of 10 upland fields but in none of 21 paddy-upland fields. In Hokkaido during 2000–2007, strawberry mother plants were planted, and plantlets were produced in upland and paddy-upland fields to assess V. dahliae infestation. Verticillium wilt of strawberry had never occurred in 72 tested paddy-upland fields, compared to 13.2–73.9% of plantlets infected with V. dahliae in upland fields. In a pot experiment in a greenhouse, two flooding treatments or two paddy rice cultivations suppressed Verticillium wilt symptoms on eggplant. In field experiments, one paddy rice cultivation in Chiba and two in Hokkaido prevented development of Verticillium wilt symptoms on eggplant. Verticillium wilt of strawberry was controlled completely with one paddy rice cultivation in infested fields in Chiba. In these field experiments, the number of microsclerotia of V. dahliae decreased under the flooding conditions for paddy rice cultivation. Based on the reduction in microsclerotia, a crop rotation system with paddy rice for 3 years (three times), green manure for 1 year, and strawberry nursery for 1 year was designed for Hokkaido.     

Symptom development, pathogen isolation and Real-Time QPCR quantification as factors for evaluating the resistance of olive cultivars to Verticillium pathotypes

Verticillium wilt is the most serious olive disease in the Mediterranean countries and worldwide. The most effective control strategy is the use of resistant cultivars. However, limited information is available about the level and source of resistance in most of the olive cultivars and there are no published data using microsclerotia, the resting structures of Verticillium dahliae, as the infective inoculum. In the present study, we correlated symptomatology and the presence of the fungus along with the DNA relative amount (molecules μl⁻¹) of a defoliating (D) and a non-defoliating (ND) V. dahliae strain in the susceptible cv. Amfissis and the tolerant cvs Kalamon and Koroneiki, as quantified by the Real-Time QPCR technology. The viability of the pathogen in the plant tissues was confirmed by isolating the fungus on PDA plates, while symptom assessment proved the correlation between the DNA relative amount of V. dahliae in plant tissues and cultivar susceptibility. It was further demonstrated that the D and ND strains were present at a significantly higher level in cv. Amfissis than in cvs Kalamon and Koroneiki. It was finally observed that the relative amount of the pathogen in roots was lower than in stems and shoots and declined in plant tissues over time. These data constitute a valuable contribution in evaluating resistance of olive cultivars or olive root-stocks to V. dahliae pathotypes.     

Asexual fungus <Emphasis Type="Italic">Verticillium dahliae</Emphasis> is potentially heterothallic

Verticillium dahliae, a soilborne plant pathogen, causes wilt disease in many important crops. We reported previously that the mating type gene MAT1-2-1 is spread to isolates of this asexual fungus. However, we did not determine whether V. dahliae is homothallic or heterothallic because the opposite mating type gene, MAT1-1-1, had not been identified. In the present study, we identified the MAT1-1-1 gene from an isolate lacking MAT1-2-1 and the mating type idiomorphs of V. dahliae. Each isolate we tested contained either the MAT1-1 or MAT1-2 idiomorph, indicating that the asexual fungus V. dahliae is potentially heterothallic.     

Soil solarization for the control of verticillium wilt of greenhouse tomato

Verticillium dahliae, the causal agent of Verticillium wilt of tomato, causes serious damage to crops grown in unheated greenhouses. To control this disease, growers are obliged to employ strong soil disinfestants. The possibility of controllingV. dahliae by using soil solarization during the months of June — August was examined. The soil was covered with transparent polyethylene sheets for 10 weeks. The pathogen could not be isolated from the solarized soil, whereas the inoculum level in the nonsolarized soil remained high (1379–1806 propagules/g soil). The yield from the solarized soil was increased by 112.4% in comparison with the control, and no infected plants were observed. The percentage of infected roots was very low (0.3–0.4%) in relation to the nonsolarized soil (66.7–67.1%). From these results it was concluded that solarization can effectively control Verticillium wilt of greenhouse-grown tomato under the summer conditions in Crete.     

Effect of altering the steric hindrance of the nitrogen atom in 2,5-bis(pyridin-n-yl)-1,3,4 thiadiazole isomers on their ability to elicit tomato defense responses against Verticillium wilt and crown gall diseases

Three isomers of the ligand 2,5-bis(pyridinyl)-1,3,4-thiadiazole, with the N atom of pyridine group in position 2, 3 or 4, named respectively, L2, L3 and L4 were compared for their use as plant defense activators. They were examined for their ability to protect tomato plants from Verticillium dahliae and Agrobacterium tumefaciens in the greenhouse, to induce reactive oxygen species and to activate plant defenses, including antioxidant enzymes. The three ligand isomers exhibited in vitro only slight inhibition of radial growth of V. dahliae, while no significant inhibition was observed for phytopathogenic bacteria. In the greenhouse, the three ligand isomers statistically reduced the severity of Verticillium wilt and crown gall on tomato plants, and the isomers L3 and L4 were the most efficient to control Verticillium wilt. This superiority was reflected in their differential ability to activate H₂O₂ accumulation, antioxidant enzymes including catalase and ascorbate peroxidase and other defense-related enzymes such as guaiacol peroxidase and polyphenol oxidase. These results demonstrated that the presence of the N atom within the two pyridinyl groups in the position 3 or 4 highly enhanced the activity of plant defense and antioxidant responses as well as their ability to reduce the severity of symptoms caused by V. dahliae on tomato.     

Distribution of Verticillium dahliae through watering systems in widely irrigated olive growing areas in Andalucia (southern Spain)

Verticillium dahliae Kleb. causes Verticillium wilts in many herbaceous and woody species. Many hosts of the pathogen are commonly cultivated in Andalucía (southern Spain), particularly major crops such as cotton, vegetables, almond, peach and, particularly, olive, in which the fungus causes Verticillium wilt of olive. Infective structures of the pathogen (microsclerotia), produced in the late phases of the infection cycle in senescent tissues of the infected plants, can be spread over short or long distances by a number of dispersal methods. Irrigation water is one of the factors implicated in this spread of V. dahliae. Indeed, increasing irrigation dosages in crops or an inadequate irrigation schedule have been identified as cultural practices favouring Verticillium wilt onset and severity in olive and other hosts. Most of the cultivated areas in the Guadalquivir Valley of Andalucía are irrigated by pumping stations using modern infrastructures that supply water to thousands of hectares of farm land, which are usually associated with irrigation communities. This study demonstrates that the pathogen survives in the sediment and particles suspended in water used for irrigation in different facilities of an irrigation community, that were involved in distributing water (main canal and reception tank of a investigated pumping station, irrigation pools and sand from filters). Thus microsclerotia moves from the pumping station to individual plots (olive and cotton cultivated farm) as viable microsclerotia, free or embedded in soil particles and plant debris, suspended in the irrigation water, or deposited in the sludge in piping systems or water storage ponds. We have detected amounts of inoculum in the solid pellet samples in these facilities that ranged from 2.7 to 6.7 microsclerotia per gram. Besides this, water from drippers in cultivated plots released into the soil a variable amount of infective propagules of the pathogen over time that accounted for 3.75 microsclerotia/m³ in some of the recording times. Therefore, irrigation water becomes an important source of inoculum that is very effectively involved in medium and long-distance spread of the pathogen.     

内生球毛壳属真菌CEF-082对棉花黄萎病的控制作用

 内生真菌在生物防治上具有很大的应用潜力,本研究旨在明确棉花内生真菌球毛壳菌(Chaetomium globosum)CEF-082对黄萎病菌(Verticillium dahliae)的拮抗作用及对黄萎病(Verticillium wilt)的防治效果。采用圆盘滤膜法、凹玻片法等测定CEF-082对棉花黄萎病菌的抑制效果;温室采用滤液接种法和基质接种法测定其对棉花黄萎病的防治效果;并采用实时定量PCR检测棉株内防御基因的表达及黄萎病菌的含量。结果表明,CEF-082的非挥发性代谢物对棉花黄萎病菌菌落生长的抑制率为100%,对分生孢子产量的抑制率为70.5%,试验浓度范围内对分生孢子萌发没有明显抑制作用;棉苗预接种CEF-082培养滤液或将CEF-082的玉米沙粒培养物接入基质中再种植棉花,对黄萎病的防治效果分别为62.37%和66.88%;这两种处理对棉花的生长发育没有副作用,且后者对出苗有促进作用;荧光定量PCR结果表明,CEF-082代谢产物显著提高了棉花防御基因苯丙氨酸解氨酶基因(pal)、过氧化物酶基因(pod)和多酚氧化酶基因(ppo)以及β-1,3-glucanase基因的表达量,抑制了黄萎病菌在棉株体内的繁殖。棉花内生真菌CEF-082可以有效地防治棉花黄萎病,其作用机理主要有抗生作用和诱导抗性,在棉花黄萎病防治上具有较好的应用前景。     

A new aggressive strain of Verticillium albo-atrum in Verticillium resistant cultivars of tomato in the Netherlands

In 1991 serious losses caused byVerticillium wilt were found on two holdings in the Westland glasshouse district in the Netherlands in which theVerticillium resistant tomato cultivars Calypso and Criterium were grown in soilless systems. Isolates from diseased plants were identified asVerticillium albo-atrum.In inoculation experimentsVerticillium resistant tomato cultivars were seriously affected by the new isolates but not by a control isolate. Moneydor, a susceptible cultivar without the Ve gene, was the most seriously diseased by all isolates. The isolates from theVerticillium resistant tomato cultivars were less virulent on the susceptible cultivar than the control isolate.     

Mating type gene MAT1-2-1 is common among Japanese isolates of Verticillium dahliae

Mating type genes of Verticillium dahliae, a wilt pathogen affecting many plant species, were identified to examine sexual recombination between Japanese pathotypes. We amplified a DNA sequence encoding high mobility group (HMG) box from V. dahliae using PCR. A cloned genomic DNA fragment included a sequence homologous to MAT1-2-1 gene. Despite that sequence's presence in all V. dahliae isolates we used, MAT1-1-1 (an opposite mating type gene) was never amplified. We concluded that V. dahliae is potentially heterothallic. Furthermore, sexual bias practically obviates sexual recombination between Japanese pathotypes. This report describes, for the first time, a mating type gene of phytopathogenic Verticillium.     

棉秆生物炭对大丽轮枝菌生长及毒素作用的影响

棉花黄萎病难以防治的根源在于大丽轮枝菌Verticillium dahliae Kleb在土壤中形成的微菌核能抵抗不良环境,并在土壤中长期存活,将棉秆加工成生物炭施入棉田,可克服棉秆直接还田的缺点,从源头上防止黄萎病菌进入土壤。为探索棉秆生物炭还田对棉花黄萎病原菌的影响机理,采用液态摇床培养及平皿固态培养法研究生物炭对大丽轮枝菌菌丝生长及微菌核萌发的影响;通过平皿内棉花和甜瓜种子发芽试验研究生物炭对大丽轮枝菌毒素的减毒作用。结果表明:液态培养条件下,棉秆生物炭对大丽轮枝菌菌丝生长抑制作用不明显,在固态培养下对菌丝体生长有一定促进作用;生物炭能减慢微菌核的萌发速率,但对最终萌发率无影响;液态培养中加入棉秆生物碳对大丽轮枝菌毒素有较强的减毒作用。在摇床培养中期,加入2.0 g·L-1生物炭处理与对照棉种在培养12天时的发芽率分别为53.3%与33.3%(P0.05);前期、中期及后期加入0.5 g·L-1生物炭处理的棉花幼苗总长度分别为对照的4.9、2.1倍及3.2倍;加入棉秆生物碳处理甜瓜种子发芽率、胚根长度、胚轴长度及总苗长较对照均有不同程度增加。表明棉杆生物炭对棉花黄萎病菌大丽轮枝菌菌丝生长、微菌核萌发的抑制作用较弱,对大丽轮枝菌毒素危害有较强的减毒作用。