The effectiveness of the biocontrol product Actinovate® at enhancing tomato plant growth and yield, and reducing the presence of fungal pathogens was studied in greenhouse and field conditions. In the greenhouse, no differences were found among seed germination or plant survival rates, seedling heights, dry root weights, and dry shoot weights of tomato seedlings grown from seeds drenched with Actinovate® or Rootshield®. The effects of one initial Actinovate® seed drench at sowing, repeated applications through the drip irrigation throughout the season, or repeated applications through the drip irrigation plus foliar applications throughout the season at reducing plant infection by fungal plant pathogens, and increasing yield and quality for tomato plants (Solanum lycopersicum) were investigated in Los Alamos, CA, on a sandy loam soil. No significant differences in plant height were found among the four treatments. Marketable fruit weight was greater in the drip plus foliar treatment than in the Actinovate® seed drench treatment. The foliar plus drip treatment resulted in the greatest amount of powdery mildew present, although the disease pressure was low. No significant differences were found among the four treatments in the presence of Verticillium wilt or Sclerotinia.

The hemlock woolly adelgid (HWA), Adelges tsugae Annand, (Hemiptera: Adelgidae) is an invasive species in the eastern United States and Canada. This scale-like insect feeds on the xylem ray parenchyma cells of eastern hemlock, Tsuga canadensis (L.) Carrière, (Pinales: Pinaceae) and Carolina hemlock, Tsuga caroliniana Englem., resulting in multiple physical and physiological symptoms, all of which commonly leads to tree mortality within 4 to 10 years. Currently, HWA has spread throughout most of the eastern hemlock range and all of the range of Carolina hemlock and threatens the forest ecosystems they serve. In its introduced range, there are no natural enemies specialized to feed on HWA and suppress HWA populations below damaging levels. In the urban environment and at some public locations, the use of chemicals, such as imidacloprid, have been used to temporarily protect hemlocks, however; this does not provide a permanent solution. In the 1990's a classical biological control program for HWA was created with the goal to suppress HWA populations below damaging levels to reduce tree mortality, and to reduce the negative effects associated with the loss of either hemlock species. Presently, four predators have become the main focus of this program: Laricobius nigrinus Fender, Laricobius osakensis Shiyake and Montgomery (Coleoptera: Derodontidae), Leucotaraxis argenticollis (Zetterstedt), and Leucotaraxis piniperda (Malloch) (Diptera: Chamaemyiidae). Throughout the eastern US, La. nigrinus has established populations and expanded its distribution beyond where it has been released. Although it has successfully established and continues to spread, its effect on eastern hemlock health has been unknown. A 1-year study, carried out in 2021, revealed that La. nigrinus predation on the sistens generation not only reduced the sistens generation, but also had a similar net photosynthetic rate to the negative control on 1-2 year old shoot growth. In addition, significantly more shoots were produced for treatment branches with the highest La. nigrinus density. This also led to a significantly reduced aestivating sistens density compared to the no predator treatment. However, predation was insufficient to reduce HWA populations below the suggested damaging threshold of eastern hemlock (< 4 HWA/cm), suggesting that additional predators would be needed. Recently, the western strain of Le. argenticollis had been released in the eastern US. However, its phenology in the eastern US was unknown. A 2-year study, from 2021-2023, revealed that Le. argenticollis eggs and larvae were present when both generations of HWA adults with eggs and HWA nymphs were present. In addition, Le. argenticollis was capable of completing development in NY and VA, showing promise that this species could establish populations in the eastern US. Timing the adult fly releases into cages at the time when sistens were producing eggs resulted in Le. argenticollis phenology to synchronize well with HWA phenology at both locations, thus providing additional support for its release in the eastern US. Another 2-year study conducted in 2021-2022, at five locations (MD, NC, PA, TN, and VA), sought to determine how the predation of La. nigrinus and Le. piniperda, alone and together, would impact the sistens and progrediens generations, as well as how their predation would affect the aestivating sistens density and new shoot growth production. From this study, La. osakensis was found as the dominant Laricobius species present at the TN site, and similarly to La. nigrinus, reduced intact ovisac density in. This provided a small preview in La. osakensis capabilities and how this predator may be impacting HWA populations at locations where it has established. In order to assess Le. piniperda's impact on the progrediens generation, mesh cages were applied to treatment branches at each site. The study found that Le. piniperda could reproduce at all field sites and that the percentage of disturbed progrediens was significantly higher for treatments with Le. piniperda present at all field sites, except at PA in 2022. However, the affect of both of these predators on the aestivating sistens density and eastern hemlock health was inconclusive. In addition, the percentage of new shoot growth was highly variable among treatments at all field sites, and there was no treatment effect on the mean length of new shoot growth produced at all field sites. The results of this study suggests that in order to fully understand the affects of these predators on HWA populations and on hemlock tree health, longer term studies should be conducted. However, this study does provide some insight on the capabilities of these predators in the short term and supports the continued release and redistribution of these predators. / Doctor of Philosophy / The hemlock woolly adelgid (HWA), is an invasive species in the eastern United States and in Canada. This small scale-like insect was introduced likely on nursery stock material from southern Japan and was first discovered in the eastern US in 1951 in Richmond, Virginia. Two generations of HWA occur each year known as the sistens and progrediens; both reproduce without males. This insect feeds on eastern hemlock and Carolina hemlock, and since its discovery has spread through most of their range. While this insect feeds, it weakens the tree, eventually causing tree death. In eastern North America, eastern hemlock is one of the major tree species in the forest and provides a unique habitat for various mammals, birds, fish, and invertebrate species. To protect this habitat, multiple management strategies have been developed. The two main management strategies that are in use are the use of pesticides and the release of predators of HWA. Pesticides have been useful in the urban environment and in parks and forests, but they only last for a short time and can lead to negative affects to the environment. Since the 1990's, the release of insect predators originally found in the native range of HWA, has occurred with the goal of predator establishment, to lower HWA populations, and to lower hemlock tree death in the eastern US. Four small insect predators have been the main focus of this program: Laricobius nigrinus, Laricobius osakensis, Leucotaraxis argenticollis, and Leucotaraxis piniperda. So far La. nigrinus and La. osakensis have populations at multiple locations throughout the eastern US, and a low number of sites have been recently found for Le. argenticollis and Le. piniperda. Past studies have indicated that La. nigrinus has a significant impact to the sistens generation of HWA, but its affect to eastern hemlock health has been unclear. A 1-yr study conducted in VA in 2021, released La. nigrinus adults into mesh cages, with two different population sizes of beetles, to determine if La. nigrinus predation on HWA populations lead to an indirect effect on eastern hemlock health at the branch level. Results confirmed that La. nigrinus had a significant impact to the sistens generation of HWA. Photosynthesis of branches with La. nigrinus, in June, was similar to the photosynthesis of the negative control branches, which started with a lower number of sistens present on the branch at the beginning of the study. Suggesting that branches with La. nigrinus may be healthier compared to branches without La. nigrinus. Laricobius nigrinus predation also significantly reduced the number of aestivating sistens on new shoot growth, but not below damaging levels (< 4 HWA/cm). This suggested that additional predators may be needed to target the progrediens generation of HWA so that HWA populations do not return to damaging levels after La. nigrinus predation. To learn more about the potential for Le. argenticollis to survive and reproduce in the eastern US, a 2-yr study was conducted in 2021 – 2023, to determine when different life stages of Le. argenticollis could occur in NY and VA. Results revealed that Le. argenticollis was able to reproduce in the mesh cages and complete its life cycle. In addition, Le. argenticollis eggs and larvae were present at the time when HWA adults were producing eggs and when HWA nymphs were present for both generations of HWA. These results provide insight on Le. argenticollis life cycle and shows that Le. argenticollis has a good chance in surviving throughout the eastern US. A 2-yr study at five locations in the eastern US (MD, NC, PA, TN, and VA), tried to combine two predators, La. nigrinus and Le. piniperda, to determine if their combined impact would be sufficient to reduce HWA populations and affect eastern hemlock tree health. Three assessments were conducted each year to determine the impacts of La. nigrinus and Le. piniperda on HWA populations and on eastern hemlock shoot growth production as a representation of tree health. Results confirmed that La. nigrinus significantly reduced the sistens generation at all locations, except at TN. At the TN site, La. osakensis was found to be the main predator of the sistens generation and had a similar affect on the sistens generation as La. nigrinus. Leucotaraxis piniperda was able to reproduce at all locations and also had a significant affect on progrediens ovisacs at four of the locations in 2021 (MD, NC, PA, and VA) and at three of the locations in 2022 (MD, NC, and VA). However, the results on the number of aestivating sistens on new shoot growth and eastern hemlock health were inconclusive. Therefore, it is unclear as to how the presence of both of these predators' affect eastern hemlock health. A long term study may be needed in order to understand the relationship between these predators and their indirect affect to eastern hemlock health.

Yes

Les bactéries du sol produisant des antifongiques comme le 2,4-diacétylphloroglucinol(DAPG) protègent les racines des plantes vis-à-vis des champignons phytopathogènes. Néanmoins, les conditions de fonctionnement de ces populations bactériennes dans le sol restent très mal connues. Dans certains sols, dits résistants aux maladies, ces bactéries phytoprotectrices sont présentes à des effectifs importants et leur activité est suffisante pour protéger la plante malgré la présence du pathogène. L'objectif de cette thèse a été de comprendre la relation entre la résistance des sols à la maladie de la pourriture noire des racines de tabac, et la fonction de synthèse du DAPG chez les bactéries du genre Pseudomonas. Dans la situation de référence de Morens (Suisse), les sols résistants diffèrent des sols sensibles par la présence de vermiculite, argile capable de relarguer du fer. On sait que la présence de vermiculite améliore la phytoprotection assurée par les Pseudomonas producteurs de DAPG, mais les mécanismes moléculaires sous-jacents restent inconnus. Dans un premier temps, la quantification de ces bactéries par une nouvelle méthode de PCR quantitative développée ici, a confirmé que leurs effectifs sont élevés dans les sols résistants, mais aussi dans les sols sensibles, suggérant que la résistance puise plutôt dépendre d'une plus forte expression de la fonction de synthèse du DAPG. Dans un second temps, l'étude de l'expression des gènes de synthèse du DAPG en système de sol artificiel, à l'aide de la souche rapportrice P. protegens phlA-gfp, a montré que la présence de vermiculite dans le sol se traduit par une plus forte biodisponibilité du fer pour les Pseudomonas, induisant une plus forte expression des gènes de synthèse du DAPG et la protection du tabac. En conclusion, la résistance des sols de Morens à la maladie de la pourriture noire des racines est conditionnée par plusieurs facteurs abiotiques et biotiques, dont la biodisponibilité du fer qui régule l'expression des gènes de synthèse du DAPG chez Pseudomonas / Soil bacteria producing antimicrobial compounds like 2,4-diacetylphloroglucinol (DAPG) protect plants from soil-borne phytopathogens. Nevertheless, the functioning of these bacterial populations in the soil is largely unknown. In certain soils, termed disease- suppressive soils, these bacteria are present at high numbers and their activity is sufficient to assure effective plant protection in the presence of the pathogen. The aim of this thesis was to understand the relation between soil suppressiveness towards black root rot of tobacco, and the 2,4-diacetylphloroglucinol synthesis ability of certain Pseudomonas. In Morens region (Switzerland), suppressive soils differ from conducive soil by the presence of vermiculite, an iron-releasing clay. It is known that DAPG-producing Pseudomonas provide better plant protection in the presence of vermiculite, but the molecular basis of this interaction is still unknown. First, the quantification of these bacteria, through a new real-time PCR method developed here, confirmed that high numbers of DAPG-producing Pseudomonas occur in suppressive soils, as well as in conducive ones, raising the possibility that suppressiveness depends rather on a higher expression of DAPG synthetic genes. Second, expression studies of DAPG synthetic genes using a P. protegens ph/A- gfp reporter strain and artificial soil systems, confirmed that the presence of vermiculite in the soil can translate into higher iron bioavailability for Pseudomonas, triggering higher expression of DAPG synthetic genes and effective plant protection. In conclusion, black root rot suppressiveness of Morens soils is determined by several abiotic and biotic factors, among which iron bioavailability regulating the expression of DAPG synthetic genes in plant-protecting Pseudomonas

Expanding global populations, unequal food distribution and disease pressure suggest food poverty is increasing. Consequently, much attention is focussed on alternative natural methods in which to increase agricultural yield. Previously, it was observed that Trichoderma hamatum strain GD12 and its respective N-acetyl-β-D-Glucosamine mutant ∆Thnag:hph promoted plant biomass and fitness that, as a result, may provide a credible natural alternative to synthetic fertilisers. However, on a molecular level, the manner in which this is achieved has not been fully elucidated. In this thesis, I report the biofertiliser effect of GD12 and mutant ∆Thnag::hph once applied to autoclaved peat microcosms as sole applications. Furthermore, I demonstrate the biocontrol ability of GD12 when co-inoculated with Sclerotinia sclerotiorum or Rhizoctonia solani and reveal, that once mycelium co-inoculation has occurred, GD12 increase plant biomass and provide protection; whilst ∆Thnag::hph does not. Consequently, I challenged the biocontrol effects of Trichoderma metabolite extract where I validate that both Trichoderma wild type GD12 and mutant ∆Thnag::hph are incapable of suppressing pathogen growth. Subsequently, I characterised the up-regulated signatures associated with GD12 and ∆Thnag::hph using LC-MS techniques where unique compounds were discovered from each strain of Trichoderma. In conclusion, I provide evidence that N-acetyl-β-D-Glucosamine mutation bring about metabolomic changes that affect the fungal secretome which, in turn, alters plant phenotype, fitness and germination. Furthermore, I have shown that these effects are species specific and depend upon pathogen, plant and fungal properties. However, further investigations are needed to fully elucidate the compound(s) responsible for biocontrol and biofertilisation; especially plant-specific effects that take place as a consequence of fungal activity.

Volatile organic compounds (VOCs) are organic chemicals typically characterized as having low molecular weight, low solubility in water, and high vapor pressure. Consequently, they readily evaporate from liquid to the gaseous phase at standard temperature and pressure. VOCs are produced by many microorganisms as a result of both uninduced and induced metabolic pathways. Volatile-based microbial inhibition in environments such as soil is well founded, with numerous antimicrobial VOCs and formulations having been identified. Inhibitory VOCs are of particular interest as microbial control agents, as low concentrations of gaseous VOCs have been observed to elicit significant antimicrobial effects. It is believed that this contact-independent antagonism may present unique advantages over traditional microbial control methods, particularly where contact-dependent treatment methods are either impractical or inconvenient. This method may be of particular benefit for managing infections where disease may become pervasive in the population, such as with white-nose syndrome (WNS) among bats. A list of potential antifungal compounds and formulations was compiled by referencing the scientific literature. Screening of compounds and formulations was conducted through toxicity analyses and antimicrobial susceptibility testing for the in vitro ability of VOCs and formulations to inhibit growth of select pathogenic fungi. A dispersal system was developed that entailed electrical circuit and software engineering as well as quantitative analysis to validate consistent and accurate dispersal of potential treatment compounds and formulations. Successful completion of these goals culminated in exposure trials involving live bats to determine any significant toxicological effects. Ex and in situ treatment trials were conducted to determine efficacy of promoting the reduction of disease severity and increasing survivorship of infected bat populations. The identification of volatile-based inhibitory compounds, in conjunction with a novel method for accurate and automated delivery, could prove a promising treatment and prophylactic in combatting microbial pathogenesis and contamination.

The demand for locally sourced hops from Northeastern microbreweries began the recent resurgence in local hop production. The farming community has increased acreage and improved the quality of hops grown and processed in the Northeast region over the past five years. There was a sharp increase in the number of Northeast hop producers from six in 2009 to over 175 in 2014. Hop growers in the Northeast are new to the crop and have limited experience with pest identification and management. This dissertation encompasses three research projects that were conducted over the 2012-2014 growing seasons. These projects were the first critical steps taken to develop arthropod integrated pest management (IPM) tactics for Northeastern hop growers. First, the arthropod community in seven Vermont hop yards was evaluated. The objectives of Chapter 2 are to 1) present current hop pest biology and management strategies, 2) report the phenology of arthropod pests observed over three growing seasons, 3) report abundance and peak date for each pest, and 4) document natural enemy abundance in Vermont hop yards. The survey indicates that in cool, wet seasons hop aphid (Phorodon humuli Schrank) is expected to be a pest of concern. Two-spotted spider mite (Tetranychus urticae Koch) is expected to be a pest of concern in hot, dry conditions. Potato leafhopper (Empoasca fabae Harris) is an unpredictable pest of special concern for first year hop plants. When hop aphid or potato leafhopper are sprayed for with broad-spectrum insecticide, two-spotted spider mite secondary outbreak can be expected. Second, the abundance of major arthropod pests and their natural enemy groups were evaluated under drive row flowering cover crop treatments. The objectives of this study were to 1) measure the effect of cover crops on natural enemy group abundance, 2) measure the effect of cover crops on the three major Northeastern hop pests, and 3) measure the effect of cover crop presence on hop yield and quality. Natural enemy groups and pests were positively correlated yet cover crop treatments had no significant effect on natural enemy abundance. Red clover cover crop treatments served as a trap crop for potato leafhopper. No significant difference in hop yield or quality was observed between flowering cover crop treatments. Finally, potato leafhopper is a documented but understudied regional pest of hops. The objectives of this study were to 1) measure the physiological response of eight hop cultivars to adult potato leafhopper feeding and 2) measure hop leaf recovery from potato leafhopper injury. Gas exchange (net photosynthesis and transpiration) and chlorophyll content were measured to quantify injury by adult potato leafhopper to first year hop leaves in field and greenhouse studies. Cultivars did not vary significantly in their physiological response to potato leafhopper feeding. Injury significantly reduced gas exchange measures in the field (P < 0.05) and greenhouse (P < 0.05) and when leafhoppers were removed, gas exchange was restored.

Compost can suppress soilborne plant pathogens that cause significant damage on globally important food crops. However, reports of plant pathogen suppression are inconsistent likely because there are no established standards for feedstock material, application rate, and maturity age upon application. Excellent results can be achieved in greenhouse trials, but field applications are much less reliable. Disease suppression occurs through the activity of biocontrol organisms (direct antagonism), and general microbial competition. Biocontrol species are hypothesized to colonize the pile during the curing phase, but single species may not be as important as microbial consortia. Substrate composition during maturation may give rise to a suppressive microbial community. More research is needed to understand the relationships between feedstock, maturity, and production process on compost microbial ecology. The thesis had two main objectives: 1) identify biological indicators in compost that could (a) characterize maturity, process, and feedstock, and (b) predict disease suppression against R. solani, and 2) identify bacterial and fungal community composition and/or structure that is associated with suppression of soilborne disease. Rhizoctonia solani is a facultative saprophytic fungus and soilborne plant pathogen that attacks many globally important food crops and turfgrass. Prior research suggests that managing carbon quality and compost maturity will alter relative competition between biological control microbes and the R. solani pathogen. The pathogen is responsible for economic losses to organic vegetable production in Vermont and there are no available methods to manage the disease that meet organic certification. R. solani on radish was chosen as a model system given its global importance, competitiveness affected by carbon quality, and lack of disease management options for organic production. Compost samples were most abundant in the bacterial phyla Proteobacteria and Bacteroidetes, and known biocontrol species were not detected in abundance. Compost samples did not differ significantly in fungal community composition, suggesting a dominance effect from the native soil fungal community. Overall, anaerobic digestate and vermicompost were most suppressive against R. solani. Thermophilic composts were not very suppressive overall, though a specially made hardwood bark compost was comparable to the suppressiveness of vermicompost application. Ecoenzyme analysis was able to integrate information on environmental substrate composition, microbial nutrient acquisition, and microbial community metabolism, offering the best view of current ecological conditions in compost. Ecoenzyme analysis showed that the most suppressive composts, anaerobic digestate and vermicompost, were most nutrient limited. All compost samples were severely nitrogen (N) limited, and anaerobic digestate and vermicompost were severely limited in both N and phosphorus (P). The additional P limitation may support non-pathogenic species to outcompete R. solani. The key to disease suppression may lie in matching up the ecology of the plant pathogen with the ecology of biocontrol, which may be engineered in compost.

La lutte biologique est souvent présentée comme une méthode de lutte contre les ravageurs respectueuse de l'environnement, même si la lutte par acclimatation (introduction d'une espèce exotique) peut être à l'origine d'invasion biologique. La coccinelle asiatique Harmonia axyridis Pallas (Coleoptera : Coccinellidae) a été utilisée comme agent de lutte biologique introduit en Amérique et en Europe pour lutter contre les pucerons. Actuellement, cette espèce est considérée comme envahissante, et a des impacts négatifs sur l'environnement. L'objectif principal de cette thèse est d'améliorer notre connaissance des processus évolutifs pouvant accompagner l'élevage en captivité, ainsi que ceux qui sont liés aux invasions biologiques. J'ai pour cela utilisé une approche expérimentale au travers d'études permettant de caractériser les différences de traits d'histoire de vie entre les trois compartiments populationnels d'H. axyridis (populations natives, envahissantes et de lutte biologique). Les résultats obtenus montrent que les changements évolutifs les plus importants concernent le compartiment de lutte biologique par rapport aux compartiments sauvages (natifs et envahissants). Ce compartiment a subi des changements phénotypiques remarquables en réponse aux conditions d'élevage en laboratoire. Les changements évolutifs les plus spectaculaires concernent différents traits liés à la reproduction. Par exemple, les femelles de lutte biologique se reproduisent plus tôt, ont une fécondité journalière plus élevée, ainsi qu'une longévité et une durée de vie reproductive plus courte. Nous avons également mis en évidence des changements évolutifs entre des populations sauvages natives et envahissantes. Les adaptations aux conditions d'élevage peuvent parfois être désavantageuses dans l'environnement naturel. Par exemple, la résistance au froid et aux pathogènes est moins importante que celle des populations sauvages. Nos résultats montrent aussi que, même si la souche de lutte biologique européenne est incapable de s'implanter dans la nature, l'hybridation avec les populations envahissantes américaines pourrait avoir jouer un rôle positif au cours de l'invasion en Europe. / Biological control is generally considered as an environmentally low-impact solution for pest control. However, the use of foreign control agents may ultimately lead to undesired biological invasions. The Asian harlequin ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae) was originally used as a biological control agent of aphids in North America and Europe. This species is now considered as invasive, and can have harmful effects on the environment. The main objective of this thesis is to better understand the impact of mass rearing on life-history traits, with a focus on traits that may be associated with invasion success. To do so, experimental approaches were carried out to monitor changes in life-history traits for three types of populations (biocontrol, native or invasive). The corresponding results indicate that the most important evolutionary changes occur in the biocontrol populations (by contrast with the invasive and native populations). Mass rearing appears to induce significant phenotypic changes in the biocontrol populations, with the most spectacular changes being related to reproductive life-history traits. For instance, biocontrol females reproduce significantly earlier, have a higher daily fecundity, but also exhibit lower life expectancy and lower reproductive lifespan. We also evidence other differences between the native and invasive populations. Cold tolerance and pathogen resistance are also lower in biocontrol populations than in wild populations. Altogether, our findings indicate that adaptations to mass rearing conditions may affect the fitness of H. axyridis populations in natural environments. This suggests that, even if the European biocontrol strain is unable to successfully colonize a natural environment, it may nonetheless impact the invasion dynamics of the species in Europe thanks to the admixture with the invasive American population

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2017-09-26T21:37:04Z No. of bitstreams: 1 Disserta??o definitiva ILANA - revisada.pdf: 1964258 bytes, checksum: 73df2e7ec0b51bebe48619b3d272ec45 (MD5) / Made available in DSpace on 2017-09-26T21:37:04Z (GMT). No. of bitstreams: 1 Disserta??o definitiva ILANA - revisada.pdf: 1964258 bytes, checksum: 73df2e7ec0b51bebe48619b3d272ec45 (MD5) Previous issue date: 2017-03-27 / Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB / Pineapple is a tropical fruit of great commercial value, Brazil is the second largest producer of pineapple in the world. The most produced variety in the country is the ?Perola?, followed by Smooth Cayenne and, both have a high degree of sus-ceptibility to fusariosis or pineapple gum disease, caused by the fungus Fusarium guttiforme.Once installed, this disease can reduce pineapple yield by up to 80%. Lactic bacteria (BAL) have their metabolic characteristics and the potential to inhibit bacterial and fungal growth, as well as to neutralize toxins produced by F. guttiforme.This work aimed to determine by in vitro tests the inhibitory effect of lactic acid bacteria on the etiologic agent of fusariosis. Qualitative and quantitative microbial inhibition tests were performed, comparing strains of lactic acid bacteria and crude pineapple extract against F. guttiforme isolates. Determination of mycotoxins in the fungal extracts of these isolates. The inhibitory effect of Lactobacillus plantarum Abx3 and Lactobacillus paracasei subsp.paracasei Abx5.2 was observed for isolateson F. guttiforme, the same did not occur with crude pineapple extract, and mycotoxin production was not detected in extracts of fungal isolates. The preliminary results of this work point out that lactic bacteria present potential to be used as a biocontrol product on F. guttiforme. / O abacaxi ? uma fruta tropical de grande valor comercial, sendo o Brasil o se-gundo maior produtor no mundo. A variedade mais produzida no pa?s ? a P?rola, seguida pela Smooth Cayenne, ambas possuem alto grau de suscetibilidade ? fusa-riose ou gomose do abacaxi, causada pelo fungo Fusarium guttiforme. Esta doen?a, uma vez instalada, pode reduzir em at? 80% a produ??o dos cultivares. As bact?rias l?ticas (BAL), devido as suas caracter?sticas metab?licas possuem potencial de inibir o crescimento bacteriano e f?ngico, bem como neutralizar toxinas produzidas por algunsmicro-organismos. Este trabalho teve como objetivodeterminar atrav?s de tes-tes ?in vitro? o efeito inibit?rio de bact?rias l?cticas sobre o agente etiol?gico da fusa-riose do abacaxi.Foram realizados ensaios qualitativo e quantitativode inibi??o mi-crobiana, confrontando cepas de bact?rias l?ticas e extrato bruto do abacaxifrente aisolados de F.guttiforme. Determinarse h? micotoxina nos extratos f?ngicos destes isolados. Constatou-se efeito inibit?rio do Lactobacillus plantarum Abx3 e Lactobacillus paracaseisubsp.paracasei Abx5.2 sobre os isolados de F. guttiforme. O mesmo n?o aconteceu com o extrato bruto de abacaxi, e n?o foi detectada a produ??o de micotoxina nos extratos dos isolados f?ngicos. Os resultados preliminares deste trabalho apontamque as bact?rias l?ticas apresentam potencial de serem utilizadas em formula??es de produto de biocontrolede F. guttiforme.