Disease caused by Neofusicoccum parvum in pruning wounds of grapevine shoots and its control by Trichoderma spp. and Xenorhabdus szentirmaii.

Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular colonization and/or production of toxins. We report herein the inhibitory effects of Trichoderma spp. isolates and the antifungal effects of cell-free supernatants (CFS) from Xenorhabdus and Photorhabdus bacteria against N. parvum in agar plates. We also evaluated the effects of the most effective fungi and bacteria against the pathogen in pruning wounds of vine shoots. All isolates of Trichoderma exhibited antifungal activity ranging between 82 and 97.5% at 14 days of post-treatment. All Xenorhabdus and Photorhabdus CFS at 10 and 33% concentrations inhibited mycelial growth with X. szentirmaii PAM 11 and PAM 25 causing the highest inhibition (>74%). In the shoot experiments, T. asperellum IB 01/13 and T. asperellum Quality®, X. szentirmaii PAM 11 (undiluted growth culture and CFS) suppressed the fungus by ≥ 93%. Our study highlights the potential of Trichoderma and X. szentirmaii PAM 11 for use as biofungicides in the management of N. parvum in grapevines. Further studies should be conducted to develop formulations of Trichoderma and Xenorhabdus that enhance stability in shelf-life and increase the efficacy of N. parvum control in grapevines under field conditions.

Effect of satellite-emitted frequency sequences on Phakopsora pachyrhizi control, on soybean nutrition and yield

The obstacles in Phakopsora pachyrhizi management result especially from susceptible soybean genotypes and resistant fungal strains. The objective of the current study was to evaluate the applicability of the emission of extremely low and specific frequencies by Effatha technology in the soybean Asian rust control, nutrition, and its impact on yield. The in-vivo test followed the detached leaves method, with six treatments: frequencies 1 and 2 individually and in association; the conventional chemical treatment (fungicide azoxystrobin + benzovindiflupyr); and witnesses in presence and absence of the fungus. Frequency 1 relates to inhibition of the enzyme succinate dehydrogenase and 2 to ubiquinone oxidase. In the field, frequencies 1 and 2 associated (with the same fungicidal action of the in-vivo study); nutritional frequency; application of azoxystrobin + benzovindiflupyr + mancozeb, and control without application were evaluated. In vivo, the fungicide provided 85% control of the disease symptoms, against 65% of frequencies 1 and 2 in association, which showed a higher efficiency compared to the isolated frequencies. In the field, the rate of increase of symptoms were reduced by all treatments compared to the control. At the end of the soybean cycle, the conventional fungicide resulted in 33% severity against 56% of frequencies 1 and 2 associated, and 69.2% of the control. The emission of the frequency for increased nutrient efficiency stood out positively on yield in relation to all the other ones. The conventional application provided the highest weight of 1,000 grains, possibly a direct reflection of the better control of the disease.

New treatments to disinfect vine cuttings with Phaeomoniella chlamydospora and the reason for the control

Petri disease is a problem for vineyard caused mainly by the fungus Phaeomoniella chlamydospora. Contaminated seedlings are source of inoculum for the disease. Treatment to disinfect vine rootstock cuttings for seedling production is hot water treatment (HWT) by 50 °C for 30 min, but the efficiency is contested. To improve its efficacy, the study aimed to assess the combination of the following methods and the reason for the control: i) exposition of the fungus to five different temperatures in HWT bath for 30 min; ii and iii) exposition of the fungus and also plants infected with P. chlamydospora to different disinfection treatments (biofumigation = soil + cabbage at 40 °C; temperatures of 40 and 23 °C, all in microcosm), in different periods (7, 14 and 21 days), with and without additional HWT (51 °C for 30 min). The results showed that HWT with high temperatures (55­70 °C) for 30 min inactivated the fungus. Biofumigation technique at 40 °C and the temperature solely of 40 °C applied for up to 21 days and combined with HWT (51 °C for 30 min) inhibited mycelial growth and inactivated the fungus in vine plant tissues without compromising the rooting.

Genome-Wide Association Study Reveals Genomic Regions Associated with Fusarium Wilt Resistance in Common Bean.

Fusarium wilt (Fusarium oxysporum f. sp. phaseoli, Fop) is one of the main fungal soil diseases in common bean. The aim of the present study was to identify genomic regions associated with Fop resistance through genome-wide association studies (GWAS) in a Mesoamerican Diversity Panel (MDP) and to identify potential common bean sources of Fop's resistance. The MDP was genotyped with BARCBean6K_3BeadChip and evaluated for Fop resistance with two different monosporic strains using the root-dip method. Disease severity rating (DSR) and the area under the disease progress curve (AUDPC), at 21 days after inoculation (DAI), were used for GWAS performed with FarmCPU model. The p-value of each SNP was determined by resampling method and Bonferroni test. For UFV01 strain, two significant single nucleotide polymorphisms (SNPs) were mapped on the Pv05 and Pv11 for AUDPC, and the same SNP (ss715648096) on Pv11 was associated with AUDPC and DSR. Another SNP, mapped on Pv03, showed significance for DSR. Regarding IAC18001 strain, significant SNPs on Pv03, Pv04, Pv05, Pv07 and on Pv01, Pv05, and Pv10 were observed. Putative candidate genes related to nucleotide-binding sites and carboxy-terminal leucine-rich repeats were identified. The markers may be important future tools for genomic selection to Fop disease resistance in beans.

A protocol for selection of Trichoderma spp. to protect grapevine pruning wounds against Lasiodiplodia theobromae.

There is no standardized protocol to select Trichoderma against trunk disease pathogens in grapevine. This study describes a protocol to select Trichoderma isolates for protecting the pruning wounds of grapevine against Lasiodiplodia theobromae. Thus, four assays were performed: (1) in vitro antagonism of Trichoderma isolates, molecularly identified, to control L. theobromae; (2) in vitro effect of grapevine fungicides on the conidia of the antagonists; (3) capability of Trichoderma to survive and endophytically penetrate in grapevine canes; and (4) efficiency of Trichoderma and fungicides to protect the pruning wounds of grapevine shoots against L. theobromae. T. asperelloides (02/03), T. koningiopsis (09/02), and T. asperellum (01/13) were the best antagonists for L. theobromae. The conidia of the three isolates were affected only by tebuconazole, with the first two fungi being the most tolerant to the fungicides. The Trichoderma isolates survived on the cane tip for 15 days, but only T. asperelloides (02/03) penetrated endophytically 4 cm in the cane and showed preventive and curative capability to control L. theobromae, with similar efficiency as that of the fungicides in both the periods tested post inoculation. These four assays are suggested to select Trichoderma against L. theobromae or other trunk disease pathogens.

Culture media to detect and criteria to evaluate and report the activity of extracellular enzymes produced by phytopathogenic fungi / Meios de cultura para detectar e critérios para avaliar e divulgar atividade de enzimas extracelulares produzidas por fungos fitopatogênicos

Extracellular enzymes are involved in the fungal pathogenesis in plants. Currently, culture media, data analyses, and data report related to extracellular enzymes produced in vitro conditions are different and therefore, lack standardization. This work aimed to compare the culture media cited on the literature (normal) with the potato-dextrose-agar (PDA) medium combined with a specific compound to produce extracellular enzymes through three soilborne phytopathogenic fungi (F. solani f. sp. passiflorae, S. rolfsii, and R. solani AG-4 HGI), as well as to analyze and report enzyme data based on five different criteria. The assay was randomized, with three factors (culture media, isolates, and enzymes) and six repetitions. The studied enzymes were amylase (AM), carboxymethylcellulase (CMCase), lipase (LP), laccase (LC), catalase (CT), and gelatinase (GT). The normal media detected more enzymes and was more precise compared to the PDA medium plus specific compound. The criteria that calculated the area of the circular crown of AM, CMCase, LP, and LC and measured the intensity (0 = absence, up to 4 = intense) of CT and GT adopting note scale were the best to evaluate and report the results of the enzymes. We suggest the normal media culture to study enzyme production, as well as the criteria mentioned to assess and report the data related to enzyme activities.(AU)

As enzimas extracelulares estão envolvidas na patogênese de fungos em plantas. Atualmente, não há uma padronização de meios de cultura, formas de analisar e divulgar os dados de enzimas extracelulares produzidas em condições in vitro. Assim, o presente trabalho objetivou comparar os meios de cultura específicos relatados na literatura (normal) com o meio de batata-dextrose-ágar mais adição do substrato específico para produção de enzimas extracelulares por três diferentes fungos fitopatogênicos habitantes de solo (Fusarium solani f. sp. passiflorae, Sclerotium rolfsii e Rhizoctonia solani AG-4 HGI), bem como avaliar os dados das enzimas por cinco critérios diferentes. O delineamento experimental adotado foi o inteiramente ao acaso, em esquema de três fatores (meios, isolados e enzimas), com seis repetições. As enzimas investigadas foram amilase, carboximetilcelulase, lipase, lacase, catalase e gelatinase. Os meios normais detectaram mais enzimas, e essa detecção foi mais precisa em comparação com os meios de batata-dextrose-ágar mais o substrato específico. Os critérios que calcularam a área da coroa circular para as enzimas amilase, carboximetilcelulase, lipase e lacase e adotaram a escala de notas para medir a intensidade (0=ausência até 4=intensa) de catalase e gelatinase foram os melhores para avaliar e divulgar os resultados das enzimas. Assim, sugere-se padronizar os meios normais para estudos de produção de enzimas, bem como os critérios citados para avaliar e divulgar os dados das atividades das referidas enzimas.(AU)

Colonization of vines by Petri disease fungi, susceptibility of rootstocks to Phaeomoniella chlamydospora and their disinfection / Colonização de videiras pelos fungos da doença de Petri, suscetibilidade de porta-enxertos ao fungo Phaeomoniella chlamydospora e sua desinfecção

Petri disease is complex, attacks young vine plants and it is difficult to be controlled. The fungus Phaeomoniella chlamydospora (Phc) has been identified as the main causative agent of this disease. This study aimed to evaluate the prevalent colonization of the Petri disease fungi in different portions of vine plants; to assess the susceptibility of grapevine rootstocks to the fungus P. chlamydospora; to assess the effect of solarization and biofumigation, followed by hot-water treatment (HWT), on the disinfection of cuttings of the rootstock IAC 766 infected with P. chlamydospora, and assess the effect of solarization and biofumigation, followed by HWT, on the rooting of cuttings of the rootstock IAC 766. For the prevalent colonization test, the fungus species detected and identified in 'Niagara Rosada' grafted on two rootstocks different were Phc and Phialemoniopsis ocularis. This is the first report of P. ocularis in a young vineyard in Brazil. Both fungi, in particular Phc, colonized only the plant's basal part, drawing attention to the rootstock as target for control measures. Measurement of the dark streaks in the vascular system revealed that Golia was the least susceptible rootstock, and IAC 572 was the most susceptible to Phc. Moreover, biofumigation or temperature of 37°C applied for 7 and 14 days, both followed by HWT, suppressed Phc in cuttings of the rootstock IAC 766 without hampering their rooting. Meanwhile, new studies are needed to validate the efficiency of these disinfection techniques.(AU)

A doença de Petri é complexa, ataca plantas jovens de videira e é difícil de ser controlada. O fungo Phaeomoniella chlamydospora é o principal agente causal dessa doença. Os objetivos deste estudo foram: avaliar o local prevalente dos fungos da doença de Petri, em diferentes partes de plantas de videira; avaliar a suscetibilidade de porta-enxertos de videira para o fungo P. ­chlamydospora; avaliar o efeito da solarização e da biofumigação seguido de tratamento com água quente sobre a desinfecção de estacas do porta-enxerto IAC 766 infectadas com o fungo P. ­chlamydospora; avaliar o efeito da solarização e da biofumigação seguido de tratamento com água quente sobre o enraizamento de estacas do porta-enxerto IAC 766. Para o teste de colonização, as espécies de fungos detectadas e identificadas em Niagara Rosada enxertada em dois porta-enxertos diferentes foram P. ­chlamydospora e Phialemoniopsis ocularis. Este é o primeiro relato de P. ocularis em parrerais jovens de videira no Brasil. Ambos os fungos, em particular P. chlamydospora, colonizaram somente a parte basal das plantas, destacando-se os porta-enxertos como foco para medidas de controle. Medidas das estrias escuras no sistema vascular revelaram que Golia foi o porta-enxerto menos suscetível, e o IAC 572 foi o mais suscetíveis para P. chlamydospora. Além disso, a biofumigação ou a temperatura de 37ºC aplicadas por 7 e 14 dias seguidas de tratamento com água quente eliminaram P. ­chlamydospora em estacas do porta-enxerto IAC 766 sem afetar o enraizamento. No entanto, novos estudos são necessários ainda para validar a eficiência dessas técnicas de desinfecção.(AU)