Biological preparations with different mechanisms of action for protecting potato against fungal diseases

Mycological analysis throughout the vegetation period of potato (Solanum tuberosum) made it possible to study in detail the structure of the micromycete community, to determine typical dominant (frequency, more than 60%), typical common (frequency, 30 to 60%), typical rare (frequency, 10 to 30%), and casual (frequency, less than 10%) species and to estimate changes in the microorganism community caused by plant protection preparations with different mechanisms of action. It was shown that, as a result of occurrence of resistant forms, synthetic preparations against fungal pathogens of potato (such as TMTD, Ridomil gold MC, and Cupricol) were only slightly more effective than biological preparations (Trichodermin and AgroChit), with the former considerably changing the natural saprophytic mycological community. An increase in the soil pool of Trichoderma harzianum as a result of application of a biological preparation based on this antagonistic fungus correlated with its effectiveness against the soil pathogen Fusarium sp., which causes root rot. A chitosan-based elicitor preparation more effectively suppressed the development of early (Alternaria sp. and Macrosporium sp.) and late (Phytophthora sp.) blighting of leaves and had a weaker effect on soil microflora.     

Variation in antibiosis ability, against potato pathogens, of bacterial communities recovered from the endo- and exoroots of potato crops produced under conventional versus minimum tillage systems

The culturable component of bacterial communities found in the endoroot and associated exoroot (root zone soil) was examined in potatoes (Solanum tuberosum L.) grown under either conventional or minimum tillage systems. Bacterial species--abundance relationships were determined and in vitro antibiosis ability investigated to discover whether tillage practice or bacteria source (endo- or exoroot) influenced bacterial community structure and functional versatility. Antibiosis abilities against Phytophthora erythroseptica Pethyb. (causal agent of pink rot of potatoes), Streptomyces scabies (Thaxt.) Waksm. and Henrici) (causal agent of potato common scab), and Fusarium oxysporum Schlecht. Emend. Snyder and Hansen (causal agent of fusarium potato wilt) were selected as indicators of functional versatility. Bacterial community species richness and diversity indices were significantly greater (P = 0.001) in the exoroot than in the endoroot. While both endo- and exoroot communities possessed antibiosis ability against the phytopathogens tested, a significantly greater proportion (P = 0.0001) of the endoroot population demonstrated antibiosis ability than its exoroot counterpart against P. erythroseptica and F. oxysporum. Tillage regime had no significant influence on species-abundance relationships in the endo- or exoroot but did influence the relative antibiosis ability of bacteria in in vitro challenges against S. scabies, where bacteria sourced from minimum tillage systems were more likely to have antibiosis ability (P = 0.0151). We postulate that the difference in the frequency of isolates with antibiosis ability among endoroot versus exoroot populations points to the adaptation of endophytic bacterial communities that favour plant host defence against pathogens that attack the host systemically.     

Gari as culture medium for moulds

No significant differences (P<0.05 occurred in the frequency of isolation from soil of four common moulds – Rhizopus stolonifer, Monilia sitophila, Aspergillus niger and Penicillium sp., on malt extract agar (MEA) and gelled gari (carbohydrate gel). Growth of the moulds on slide microcultures of potato dextrose agar (PDA) and gari showed typical diagnostic features of the organisms, which were often clearer on gari. It is concluded that gari, which is much cheaper and far more readily available in Nigeria than MEA or PDA, is an effective alternative to the two standard mycological media.     

The effect of anthropogenic arsenic contamination on the earthworm microbiome

Earthworms are globally distributed and perform essential roles for soil health and microbial structure. We have investigated the effect of an anthropogenic contamination gradient on the bacterial community of the keystone ecological species Lumbricus rubellus through utilizing 16S rRNA pyrosequencing for the first time to establish the microbiome of the host and surrounding soil. The earthworm‐associated microbiome differs from the surrounding environment which appears to be a result of both filtering and stimulation likely linked to the altered environment associated with the gut micro‐habitat (neutral pH, anoxia and increased carbon substrates). We identified a core earthworm community comprising Proteobacteria (～50%) and Actinobacteria (～30%), with lower abundances of Bacteroidetes (～6%) and Acidobacteria (～3%). In addition to the known earthworm symbiont (Verminephrobacter sp.), we identified a potential host‐associated Gammaproteobacteria species (Serratia sp.) that was absent from soil yet observed in most earthworms. Although a distinct bacterial community defines these earthworms, clear family‐ and species‐level modification were observed along an arsenic and iron contamination gradient. Several taxa observed in uncontaminated control microbiomes are suppressed by metal/metalloid field exposure, including eradication of the hereto ubiquitously associated Verminephrobacter symbiont, which raises implications to its functional role in the earthworm microbiome.     

Increasing use efficiency of boron fertilisers by rescheduling the time and methods of application for crops in India

Boron-deficiency is prevalent in light-textured acidic soil regions receiving high precipitation. Crop use efficiency of fertiliser B is also low under such B-leaching environments. For high leaching regimes, we hypothesised that the optimal timing and method of B application would vary with the crop sensitivity to B-deficiency and periods of peak demand for B. The aim of the present experiment was to vary the timing and method of B application to increase use efficiency on typical B-deficient Entisols. Mustard (Brassica campestris L.), wheat (Triticum aestivum L.) and potato (Solanum tuberosum L.) were the test crops. There were seven treatment combinations of B, applied either to soil or as foliar sprays at different doses and growth stages of the crops. Biomass and yield related characters of the crops at harvest, B concentration in plants and its uptake increased with B application being highest in mustard, followed by potato and wheat. Foliar application, in general had higher economic benefits than soil application. Split application of B either to soil (as basal and 25 days after sowing) or foliar sprays (at 25 and 40 and 25 and 45 days after sowing for mustard and potato, respectively) had an edge over a single application. For wheat, a single late application of B (at 45 or 60 days after sowing through soil or foliar spray, respectively) was more effective than the early or split application in increasing yields. Better use efficiency of B can thus be achieved if it is applied late for wheat but in splits over a longer period for mustard and potato with higher economic benefits.     

Fungal community diversity and soil health in intensive potato cropping systems of the east Po valley, northern Italy

An ecological approach was used to investigate the relationship between diversity of soil fungal communities and soil‐borne pathogen inoculum in a potato growing area of northern Italy affected by yield decline. The study was performed in 14 sites with the same tillage management practices: 10 named ‘potato sites’, that for many years had been intensely cultivated with potatoes, and 4 named ‘rotation sites’, subject to a 4‐year rotation without potatoes or any recurrent crop for many years. Fungal communities were recorded using conventional (soil fungi by plate count and endophytic fungi as infection frequency on pot‐grown potato plant roots in soil samples) and molecular approaches [Basidiomycetes and Ascomycetes with specific and denaturing gradient gel electrophoresis (DGGE) analysis]. Diversity of fungal communities in potato sites was significantly lower than that in rotation sites. In addition, fungal communities in rotation sites showed lower Berger–Parker dominance than those in the potato sites, suggesting that rotation sites had a higher diversity as well as a better fungal community balance than potato sites. The ANalysis Of SIMilarity test of soil fungi and root endophytic fungi revealed that the two cropping systems differed significantly for species composition. Root endophytic fungal communities showed a greater ability to colonise potato roots in soil samples from potato sites than those from rotation sites. Moreover, the majority of endophytic root fungal community species in potato sites belonged to the potato root rot complex and storage disease (Colletotrichum coccodes, Fusarium solani and Fusarium oxysporum), while those in rotation sites were mainly ubiquitous or saprobic fungi. Soil rDNA analyses showed that Ascomycetes were much more frequent than Basidiomycetes in all the soils examined. DGGE analysis, with the Ascomycete‐specific primer (ITS1F/ITS4A), did not reveal distinctions between the communities found at the potato and rotation sites, although the same analysis showed differences between the communities of Basidiomycetes (specific primer ITS1F/ITS4B). These findings showed that recurrent potato cropping affected diversity and composition of soil fungal communities and induced a shift in specialisation of the endophytic fungi towards potato.     

盐城滨海滩涂湿地典型植物群落土壤微生物组成与结构特征

土壤微生物是生态系统维持正常结构与功能的重要组成部分,为探究盐城滩涂典型湿地土壤微生物群落结构特征,以江苏盐城滩涂互花米草、藨草、盐地碱蓬、芦苇及淤泥质光滩5种典型群落为对象,采用16S rRNA高通量测序技术分析0—10 cm(表层)、10—30 cm(中层)、30—60 cm(深层)土壤微生物多样性及群落结构。结果表明：(1)几种植物群落间,土壤微生物群落结构差异较大,主要体现在细菌群落结构的差异性,古菌群落结构差异相对较小。光滩与植物群落间,在土壤细菌种类及相对丰度上差异相对较大,互花米草群落与本土植物群落间,在微生物群落的细菌种类组成上存在较大差异;藨草群落土壤表层微生物群落结构与互花米草群落相似,深层与盐地碱蓬、芦苇群落相似。(2)同一群落不同层次土壤微生物群落结构相似,差异小于不同群落间土壤微生物群落的结构差异性;不同群落对应层次间,表深层土壤中五种群落土壤微生物多样性存在显著差异,中层土壤中五种群落微生物多样性差异不显著。总体上,植物群落类型对土壤微生物群落结构的影响大于土壤深度;与本土植物群落相比,互花米草群落土壤主要优势门微生物种类差异较小,但部分优势门微生物相对丰度...     

Effect of a preparation from Chaetomium fungi on the growth of phytopathogenic fungi

We studied the fungicidal activity of a biological preparation from the fungi of the genus Chaetomium against soil phytopathogenic fungi Rhizoctonia solani and Fusarium oxysporum. The inhibitory effect of the preparation under study depended on its concentration, duration of storage, and growth characteristics of pure cultures of the phytopathogens. The highest (98.8%) inhibitory activity was observed on day 3 of the interaction with Rhizoctonia solani. After a 2-year storage, this preparation was capable of inhibiting the growth of the phytopathogens only at high doses. The preparation precluded the development of bare patch and increased the productivity of potato plants. The preparation may serve as an alternative to chemical fungicides for plant protection.     

The first investigation of the diversity of bacteria associated with <Emphasis Type="Italic">Leptinotarsa decemlineata</Emphasis> (Coleoptera: Chrysomelidae)

Colorado potato beetle, Leptinotarsa decemlineata (Say), is a devastating pest of potatoes in North America and Europe. L. decemlineata has developed resistance to insecticides used for its control. In this study, in order to find a more effective potential biological control agent against L. decemlineata, we investigated its microbiota and tested their insecticidal effects. According to morphological, physiological and biochemical tests as well as 16S rDNA sequences, microbiota was identified as Leclercia adecarboxylata (Ld1), Acinetobacter sp. (Ld2), Acinetobacter sp. (Ld3), Pseudomonas putida (Ld4), Acinetobacter sp. (Ld5) and Acinetobacter haemolyticus (Ld6). The insecticidal activities of isolates at 1.8×10⁹ bacteria/mL dose within five days were 100%, 100%, 35%, 100%, 47% and 100%, respectively, against the L. decemlineata larvae. The results indicate that Leclercia adecarboxylata (Ld1) and Pseudomonas putida (Ld4) isolates may be valuable potential biological control agents for biological control of L. decemlineata.     

Methylobacterium-Induced Endophyte Community Changes Correspond with Protection of Plants against Pathogen Attack

Plant inoculation with endophytic bacteria that normally live inside the plant without harming the host is a highly promising approach for biological disease control. The mechanism of resistance induction by beneficial bacteria is poorly understood, because pathways are only partly known and systemic responses are typically not seen. The innate endophytic community structures change in response to external factors such as inoculation, and bacterial endophytes can exhibit direct or indirect antagonism towards pathogens. Earlier we showed that resistance induction by an endophytic Methylobacterium sp. in potato towards Pectobacterium atrosepticum was dependent on the density of the inoculum, whereas the bacterium itself had no antagonistic activity. To elucidate the role of innate endophyte communities in plant responses, we studied community changes in both in vitro and greenhouse experiments using various combinations of plants, endophyte inoculants, and pathogens. Induction of resistance was studied in several potato (Solanum tuberosum L.) cultivars by Methylobacterium sp. IMBG290 against the pathogens P. atrosepticum, Phytophthora infestans and Pseudomonas syringae pv. tomato DC3000, and in pine (Pinus sylvestris L.) by M. extorquens DSM13060 against Gremmeniella abietina. The capacities of the inoculated endophytic Methylobacterium spp. strains to induce resistance were dependent on the plant cultivar, pathogen, and on the density of Methylobacterium spp. inoculum. Composition of the endophyte community changed in response to inoculation in shoot tissues and correlated with resistance or susceptibility to the disease. Our results demonstrate that endophytic Methylobacterium spp. strains have varying effects on plant disease resistance, which can be modulated through the endophyte community of the host.     

In vitro suppression of fungi caused by combinations of apparently non-antagonistic soil bacteria

We hypothesized that apparently non-antagonistic soil bacteria may contribute to suppression of fungi during competitive interactions with other bacteria. Four soil bacteria (Brevundimonas sp., Luteibacter sp., Pedobacter sp. and Pseudomonas sp.) that exhibited little or no visible antifungal activity on different agar media were prescribed. Single and mixed strains of these species were tested for antagonism on a nutrient-poor agar medium against the plant pathogenic fungi Fusarium culmorum and Rhizoctonia solani and the saprotrophic fungus Trichoderma harzianum. Single bacterial strains caused little to moderate growth reduction of fungi (quantified as ergosterol), most probably due to nutrient withdrawal from the media. Growth reduction of fungi by the bacterial mixture was much stronger than that by the single strains. This appeared to be mostly due to competitive interactions between the Pseudomonas and Pedobacter strains. We argue that cohabitation of these strains triggered antibiotic production via interspecific interactions and that the growth reduction of fungi was a side-effect caused by the sensitivity of the fungi to bacterial secondary metabolites. Induction of gliding behavior in the Pedobacter strain by other strains was also observed. Our results indicate that apparently non-antagonistic soil bacteria may be important contributors to soil suppressiveness and fungistasis when in a community context.     

黄土丘陵区坡面整地和植被耦合下的土壤水分特征

水分是干旱半干旱地区植被恢复的主要环境制约因子。在黄土高原小流域,合理整地能够有效截留降雨补给土壤水,进而促进植被恢复。选择地处甘肃定西的半干旱黄土小流域为研究区,基于野外实测数据,分析不同植被和整地方式(柠条水平阶、山杏水平沟、侧柏反坡台,油松反坡台)综合影响下的土壤水分特征。采用最优分割法将不同整地方式土壤水分垂直层次划分为活跃层,次活跃层和相对稳定层。结果表明:生长季不同整地方式土壤水分的变化与降水量的变化密切相关,不同月份以及不同深度各整地方式土壤水分之间差异显著(P0.05)。根据土壤水分垂直变化特征,山杏水平沟水分活跃层与次活跃层为0—80cm,其深度范围均大于其他3种整地方式,而柠条水平阶土壤水分均在30 cm以下较为稳定,其深度范围均小于其他3种整地方式。不同整地方式土壤水分含量具体表现为:山杏水平沟侧柏反坡台柠条水平阶油松反坡台。     

吉林乾安大布苏晚更新世动物群

描述比较了在吉林省乾安县大布苏泡子新发现的鬣狗科化石Crocutaultima。依据到目前为止所发现的 6目 1 2科 1 8属 1 9种脊椎动物化石组合 ,结合含化石地层的孢粉分析和1 4 C测年数据推测 ,大布苏一带在晚更新世晚期曾经以草原景观为主 ,兼有森林及荒漠 ,而且经历了从干凉草地向较潮湿凉爽的疏林或森林草原 ,直至干凉半荒漠草原环境变迁的历程。     

Legacy Effects of Oil Road Reclamation on Soil Biology and Plant Community Composition

Following the unprecedented oil drilling presently occurring in western North Dakota, thousands of kilometers of oil roads must be reclaimed to an acceptable post‐extraction condition. This study assessed the soil biological and plant communities of nine decommissioned oil roads reclaimed during three periods between 1983 and 2002 in the Little Missouri National Grasslands of western North Dakota. We hypothesized that time‐since‐reclamation would positively affect soil biological and plant communities and, consequently, success of reclamation at older sites. To assess this hypothesis, we measured soil enzyme activity, soil microbial community composition, plant community composition, and soil physical and chemical properties along a gradient extending from road‐center to adjacent native prairie for the nine roads. Time‐since‐reclamation did not affect soil and plant properties measured, indicating that older reclamations are not more similar to native prairie than reclamations occurring more recently. A strong gradient between samples from road‐center and native prairie was identified with univariate and ordination analyses, indicating that soil and plant communities of reclaimed oil roads do not resemble those of the surrounding prairie. Soil organic matter (SOM) was identified as the most significantly affected soil property, being 30% lower on reclaimed roads than prairie. The relationship between SOM, microbial community, and plant community suggests that incorporating additional SOM could hasten reclamation as a result of improving the physical environment for plants and providing a labile carbon and energy source for the soil microbial community which, in turn, will enhance the nutrient and physical conditions for plant growth.     

Evaluation of contents of A and B group substances in biological preparations]

The study was aimed at determination of blood A and B group substances in biological preparations used in Poland. Twenty three series were investigated, namely: Di-Te-Per, Ty-Te, Ty, Te, against cholera, vaccine according to Delbet and Panodin. Also were tested: 65 series of imported preparations of immunoglobulin g (i.v.) such as Endobulin, Sandoglobulin, Gamma-Venin, Veinoglobuline and 5 local series such as Bioglobulin, as well as 9 series of preparation LNI (i.m.) Human Gamma Globulin. Presence of substance A was detected in tetanus and botulinum horse antitoxins in amount from 3.75 micrograms/ml to 30 micrograms/ml. Group substances A and B contained 6 series of LNI preparations-Veinoglobuline. Amount of substance A was detected as 3.75 micrograms/ml-7.5 micrograms/ml and of substance B as 2,5 micrograms/ml-5 micrograms/ml. Group substances A and B were not present in vaccines used according to vaccination calendar.     

土霉素暴露对小麦根际抗生素抗性细菌及土壤酶活性的影响

通过培养的方法研究了土霉素暴露和小麦根际抗性细菌的数量、种类、分布特征及土壤酶活性之间的剂量效应关系。结果表明,土霉素暴露下小麦根际单一抗生素抗性细菌数量和抗土霉素—链霉素双重抗性细菌数都明显增加,且与暴露剂量呈正效应关系;同时,土壤磷酸酶、脱氢酶活性下降,但与土霉素的剂量效应关系不明显。从土霉素暴露的土壤中分离到50株抗性细菌,经形态观察、RFLP分组和16S rDNA序列测定与分析,将它们聚集在Actinobacteria、Bacilli、Alphaproteobacteria、Gammaproteobacteria 和Sphingobacteria类群。其中放线菌最多（15株）,占抗性菌总数的30 %;其次是Bacillus属细菌（9株）和Pseudomonas属细菌（8株）,分别占18 %和16 %。同时,具有抗性的人类机会致病菌Pseudomonas、Sphingomonas和Stenotrophomonas属细菌在土霉素暴露的样品中均被分离到,分别占抗性菌株总数的16 %、8 %和4 %。值得注意的是,随着土霉素暴露剂量的增加,小麦根际优势促生菌Bacillus属细菌的抗性检出率逐步降低;但具有抗生素抗性的人类机会致病菌Pseudomonas、Sphingomonas和Stenotrophomonas属细菌的检出率却明显增加,提示可能会进一步增大其机会致病性。     

葡萄连作对土壤细菌和真菌种群的影响

分别采集种植葡萄30年的连作园和3年的新植园根围土、非根围土及葡萄园周边的空地土壤,采用PCR DGGE技术,研究葡萄连作对土壤细菌和真菌种群结构及多样性的影响,并对分离出的优势种扩增条带进行测序.结果表明：葡萄连作后土壤细菌和真菌的多样性增加,且根围土壤的微生物多样性高于非根围土壤.聚类分析显示：葡萄长期连作后根围与非根围土壤细菌和真菌的种群结构趋于一致,两者不同于空地土壤;而短期种植葡萄的根围土壤细菌和真菌的种群结构不同于非根围土壤和空地土壤.与新植园相比,连作园根围土壤中微生物种群结构发生较大变化,细菌中Flavobacterium sp.（DQ339585）和Bacillus sp.（AY039821）种群数量减少,Pedobacter sp.（AJ871084）种群数量增多;真菌中Omphalina farinolens（EF413029）出现,Pestalotiopsis sp.(DQ657877,DQ657875,DQ657871）、Phacidium lacerum（DQ470976）和Lecythophora decumbens（AF353597）种群数量减少,Pilidium acerinum voucher（AY48709）种群数量增多.其中Bacillus sp.、Flavobacterium sp.和Pestalotiopsis sp.对病原菌具有颉颃作用,连作园根围土中上述微生物种群数量的减少,不利于葡萄对病原菌的颉颃;Pilidium acerinum voucher数量的增加可能与葡萄连作后病害加重有关.     

Cultivable bacteria isolated from apple trees cultivated under different crop systems: Diversity and antagonistic activity against Colletotrichum gloeosporioides

This study evaluated the diversity of cultivable plant growth-promoting (PGP) bacteria associated with apple trees cultivated under different crop management systems and their antagonistic ability against Colletotrichum gloeosporioides. Samples of roots and rhizospheric soil from apple trees cultivated in organic and conventional orchards in southern Brazil were collected, together with soil samples from an area never used for agriculture (native field). Bacteria were identified at the genus level by PCR-RFLP and partial sequencing of the 16S rRNA, and were evaluated for some PGP abilities. The most abundant bacterial genera identified were Enterobacter (27.7%), Pseudomonas (18.7%), Burkholderia (13.7%), and Rahnella (12.3%). Sixty-nine isolates presented some antagonist activity against C. gloeosporioides. In a greenhouse experiment, five days after exposure to C. gloeosporioides, an average of 30% of the leaf area of plants inoculated with isolate 89 (identified as Burkholderia sp.) were infected, whereas 60 to 73% of the leaf area of untreated plants was affected by fungal attack. Our results allowed us to infer how anthropogenic activity is affecting the bacterial communities in soil associated with apple tree crop systems, and to obtain an isolate that was able to delay the emergence of an important disease for this culture.     

Verstärkung der antiphytoviralen Wirkung von 2,4-Dioxohexahydro-l,3,5-triazin durch Kombination mit Verbindungen mit Guanidinstruktur

Intensified antiphytoviral activity of 2,4-dioxohexahydro-l,3,5-triazine by combination with guanidines Combined application of the antiphytoviral compound 2,4-dioxohexahydro-l,3,5 triazine (DHT) and different guanidines (GDs) that were either unsubstituted or substituted only by low-molecular substituents reduced the concentration of potato virus χ (PVX) in leaves or Nicotiana tabacum L. cv. Samsun much more than application of either agent alone. In secondarily PVX-infected leaves, the activity of 2,4-dioxohexahydro- 1,3,5-triazine was increased by a larger number of GDs and to a greater degree than in inoculated ones. The activities of GDs against tobacco mosaic virus (TMV) in Nicotiana tabacum L. cv. Samsun as well as against brome grass mosaic virus (BRV) in Hordeum vulgare L. cv Vogelsanger Gold were only insignificantly increased by combination with DHT. On the other hand, in experiments with so-called identical potato eye cuttings, in which several eye cuttings were obtained from each potato tuber, one serving as a control and the others being treated with DHT, N-cyano guanidine or a combination of these substances, the number of cuttings with symptoms of potato leaf-roll virus (PLRV) could be much more greatly reduced by the combination than by the individual preparations. The number of cuttings with symptoms of potato virus Y and potato virus A was significantly reduced by treatment with the combined preparation, but not by treatment with DHT or N-cyano guanidine alone. Additional investigation with N-cyano-GD, and, beside this, with acetyl-GD and N N′ N triamino-GD indicated a close correlation between the diminution of numbers of potato eye cuttings with virus symptoms and the increase in tuber weight. The greater the reduction in the number of cuttings showing virus symptoms, the greater was the increase in tuber weight. These relationships were observed even in those cases where controls had been treated with ammonium nitrate solutions whose N contents equivalent to the N contents of the preparations. The observed effects of the preparations therefore are not attributable to N-fertilizing effects.     

Evaluation of Beauveria brongniartii and its Metabolite Oosporein Regarding Phytotoxicity on Seed Potatoes

The phytotoxic potential of Beauveria brongniartii and its main secondary metabolite oosporein were evaluated against seed potatoes ( Solanum tuberosum ) both in vitro and in situ . In a tray test, potatoes were inoculated using conidiospores and grown either in garden soil or in B. brongniartii -enriched soil. The only significant effect of the treatment was the fact that the weight of the roots was different compared with the controls. The weight of haulm and tubers was unaffected by the treatment with B. brongniartii . No oosporein was detected in the potatoes, although the density of B. brongniartii in the soil was forty times higher than recommended for the usage of this biological control agent (BCA). This indicates that oosporein does not enter the food chain via potato tubers. The effect of BCA on seed potatoes was also tested in situ . No B. brongniartii was detected in the potato field before the application of BCA. Three months after application, an average of 3 ×10 4 colony forming units per gram soil (dry weight) were recorded. Although Melolontha melolontha larvae damaged 60% of the potatoes, only 3% of the tissue samples were infected with B. brongniartii . The results obtained in this study suggest that B. brongniartii and its secondary metabolite oosporein pose no risks to potato plants, tubers, or to their consumers.