First Report of Colletotrichum fructicola Causing Anthracnosis on Glycine max in Brazil.

Brazil is the largest producer of soybean [Glycine max (L.) Merrill], cultivated in diverse environments and systems. This scenario can contribute to emergence of new diseases or increase the severity of secondary diseases. In March 2023, elliptical to circular, brownish lesions, 5.2-6.1 cm length and 1.1-1.5 cm width, with salmon-colored masses of conidia in the center of the lesions, were observed on the stems of soybean cultivar 'CZ 16B17 IPRO', in the municipality of Campos Novos, Santa Catarina, Brazil (27º25'19''S and 51º14'14''05W). The presence of 210-355 µm length and 210-232 µm width acervuli was rare, with arrows larger than the mass of conidia (Figure S1). Fragments of the infected tissues were cut, disinfected and placed in Petri dishes containing Potato Dextrose Agar (PDA) or V8-agar medium and maintained at 23 ± 2ºC and a photoperiod of 12 h dark-light cycle. After 13 days, the development of grayish-white colonies was observed on both culture media, with the formation of a mass of septate hyaline, oblong, cylindrical conidia, 13.3-15.3 µm length and 2.9-3.5 µm width, with obtuse ends. One pure monosporic isolate was selected, isolate CF1. The presence of sexual structures was observed on PDA after 13 days and in V8 after 15-20 days. Perithecia were dark brown and globose, either immersed in the culture medium or on the surface between the mycelia. Inside of perithecia, unitunicate, clavate, and cymbiform asci, 39.1-61.0 µm length and 9.6-11.7 µm width were observed, containing eight spindle-shaped and slightly curved ascospores with rounded tips 13.8-18.3 µm length and 3.0-4.2 µm width (Figure S1). Pathogenicity tests were performed on young soybean plants at V1 phenological growth stage in four repetitions. PDA disks, 7mm in diameter, with growth mycelium were placed on stems while using uninfected PDA disks as a control. Plants were incubated in a chamber at 25 ± 2°C and 90% relative humidity. Anthracnose lesions were observed only on the stems of the inoculated plants. The same pattern of symptoms was observed on the stems, and the fungus were reisolated on PDA. The colony and morphological characteristics were identical to the previously isolated fungus. For molecular characterization, the growth mycelia were collected, macerated in liquid nitrogen, and DNA was extracted using the method Doyle and Doyle (1990) with CTAB. End-point PCR was performed using the GoTaq® Flexi DNA Polymerase (Promega, USA) and the primers, ITS-1F/ITS-4, T1/Bt2b, CL1C/CL2C, GDF/GDR, and SODglo2-F/SODglo2-R (Weir et al. 2012) for the amplification of internal transcribed spacer (ITS), ß-tubulin (TUB2), calmodulin (CAL), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and superoxide dismutase (SOD), respectively. Amplified fragments were sequenced and compared with the available sequences in the Genbank (www.ncbi.nlm.nih.gov/genbank/). The sequences of all five-genes (Accession numbers OR883777, OR891749, OR891750, OR891751 and OR891752, respectively) of the isolate CF1 characterized in this study showed 99% nucleotide identities whith the stand isolate ICMP 18581 of Colletotrichum fructicola. A phylogenetic tree was constructed in MEGA X (Kumar et al. 2021), containing the amplified and concatenated sequences and representative species from the Colletotrichum gloeosporioides complex. The isolate grouped only with C. fructicola clade, confirming the identity of the fungus (Figure S2). To our knowledge, this is the first study reporting the infection of C. fructicola in soybeans in Brazil, which has already been reported in China (Xu et al. 2023).

Performance of 'Gala Select' and 'Fuji Suprema' grafted on Geneva series rootstocks under fallow land and replanting conditions in southern Brazil.

Background: Rootstocks less vigorous are among the most crucial management techniques to modernize fruit cultivation. Replanting with fallow land has become necessary due to a lack of land to establish new orchards. Objective: The aim of this study is to determine the effect of various rootstocks of the American Geneva® series on the yield performance of the apple (Malus domestica Borkh) cultivars 'Gala Select' and 'Fuji Suprema' under replanting conditions in southern Brazil. Methods: After two years of fallow land, the experiments were initiated in 2017 and conducted during the 2018, 2019, 2020, and 2021 growing seasons in Painel and Caxias do Sul municipalities at the Santa Catarina and the Rio Grande do Sul State, respectively. The 'Gala Select' and 'Fuji Suprema' were grafted onto the G.202, G.814, G.210, and G.213 Geneva series rootstocks in a tall spindle training system using a randomized complete block design with four replicates. Principal component analysis (PCA) was used to assess the interrelationship among the variable's vigor, productivity, and fruit quality. Results: The PCA result showed significant differences in vigor, productivity, and fruit quality when the G.210 and G.213 and G.814 and G.213 Geneva series rootstocks were used in combination with Gala Select and Fuji Suprema cultivars, respectively. The PCA analysis clustered all cultivar/rootstock combinations into two groups, based on their vigor and productivity and the yield performance and fruit quality data, that differed significantly among combinations and regions. The 'Gala Select'/G.202 and 'Fuji Suprema'/G.213 combinations were less vigorous than the 'Gala Select'/G.210 and 'Fuji Suprema'/G.814 combinations. However, 'Gala Select'/G.210 (semi-dwarfing) and G.213 (dwarfing) are the combinations with high yield performance, productive efficiency and fruit quality, being more reliable to the producer, and less vigorous, resulting in lower labor costs under replating conditions, with two years of fallow land, from 2018 until 2021 growing seasons.

First report of Leek yellow stripe virus, Onion yellow dwarf virus, and the putative allium polerovirus A in elephant garlic (Allium ampeloprasum) in Brazil.

Five elephant garlic plants (Allium ampeloprasum L.) showing leaf symptoms of chlorotic streaks and mosaic (Figure 1A and B) were collected, in September 2021, in an experimental area in municipality of Rio do Sul (27°11'07"S, 49°39'39"W), State of Santa Catarina, Brazil. Total RNA was extracted using TRIzol® reagent (Invitrogen, USA), according to the manufacturer's instructions to investigate viral infection. The RNA from all five plants were pooled into a single sample for cDNA library construction with the TruSeq Stranded Total RNA with Ribo-Zero Plant (Illumina) kit, which was then sequenced on the Illumina HiSeq2500 platform (Proteimax Biotechnology LTDA). After high throughput sequencing (HTS), 49 million raw reads (each 151nt) were generated. They were trimmed with the BBduk tool and de novo assembled with the Tadpole assembler tool (Geneious Software version 2022). A total of 28,345 contigs were generated and searched against the NCBI virus genome database using BLASTn and BLASTx, with positive results for two potyviruses, leek yellow stripe virus (LYSV), onion yellow dwarf virus (OYDV), and the putative polerovirus allium polerovirus A (APVA). The trimmed reads were mapped with the BBmap tool (Bushell 2014), using reference sequences for LYSV (NC_004011), OYDV (NC_005029), and APVA isolate Won (MH898527). A total of 806,060 reads were mapped, resulting in the nearly complete genome of LYSV (isolate RDS22-2, 10,268 bp, ON565071), which shared the highest (89.41%) nucleotide (nt) identity with LYSV isolate MG (KP258216). The nearly complete genome of OYDV (isolate RDS22-1, 10,519 bp, ON565070) was assembled using 311,467 reads, being 90.21% nt identical to OYDV isolate G-118 (KF632714). The APVA genome (isolate RDS22-3, 4,367 bp, ON565072, Figure 1C) was assembled from 116,303 reads and it shared the highest (90.73%) nt identity with APVA isolate Won. Subsequently, each sample was RT-PCR screened separately for potyviruses and poleroviruses, using the generic primer pairs NIb2F/NIb3R (Zheng et al., 2010) and Pol-G-F/Pol-G-R (Knierim et al., 2010), respectively. Amplified DNA fragments with approximately 350 bp and 1000 bp were obtained for potyviruses and poleroviruses, respectively, and were sent for Sanger sequencing (ACTGene, Alvorada, Brazil). The Sanger derived partial sequences shared 98 to 100% nt identities with corresponding HTS-derived sequences. The most common virus was LYSV, which was found in three of the five tested samples, whereas OYDV and APVA were only found in one sample each. The plants were also screened with specific primers for each virus, and none of the samples revealed mixed infections. Elephant garlic is primarily utilized for industrial garlic production in several countries, and it is now being researched in Brazil for the same purpose. It can be observed from this study that elephant garlic is susceptible to two of the most common viruses in garlic (LYSV and OYDV), which must be considered in the future while developing resistant varieties or in using thermotherapy and shoot tip/meristem culture to recover virus-free cultivars. LYSV and OYDV have already been described in Brazil infecting Allium sativum (Kitajima 2020). The only complete APVA sequence available is from China (Isolate Won), but no further characterization of the virus has been performed and published. The occurrence of this virus in Brazil highlights the importance of further research to obtain a more robust virus characterization.

A novel tenuivirus infecting wheat in Brazil.

Since 1948, pale yellow wheat spike have been reported in southern Brazil. This symptom was associated with tenuiviruses due to the observation of cytoplasmic inclusions constituted by a mass of filamentous particles (7-10 nm in diameter) with indeterminate length, identical to those found in "leaf dip" preparations. Such symptoms are still seen in wheat crops; however, there is a lack of information regarding this pathosystem. Decades after the first report, the first sequences of wheat white spike virus were characterized. Wheat plants with symptoms such as pale yellowing, chlorotic streaks, and leaf mosaic were collected in Paraná State, Southern Brazil. High-throughput sequencing was used to determine the nearly complete nucleotide sequence of the viral genome. The genome is composed of five RNAs with a total size of 18,129 nucleotides, with eight open reading frames (ORFs). The virus identified in this study can be included in a new species in the family Phenuiviridae, genus Tenuivirus, and we have tentatively named this virus "wheat white spike virus".

Geneva® Series Rootstocks for Apple Trees Under Extreme Replanting Conditions in Southern Brazil.

Geneva® rootstocks in Brazil are known to be efficient in controlling vigor, and are precocious and resistant to diseases. The objective of this study was to evaluate the performance of apple tree cultivars grafted on the Geneva® rootstocks in severe replant disease areas, by planting 60 days after the eradication. The experiments were implemented in 2017, in São Joaquim and Vacaria. The Gala Select and Fuji Suprema cultivars were grafted onto 'G.202', 'G.814', 'G.210', and 'G.213' rootstocks in the Tall Spindle training system. In 2018/2019, total thinning was carried out to promote plant growth. In São Joaquim, partial thinning was carried out in 2019/2020 harvest of 'Gala Select'. The rootstocks were divided into two groups based on vigor, for both areas and cultivars. 'G.202' and 'G.213' were 40% less vigorous than 'G.210' and 'G.814'. For 'Gala Select', the extreme non-fallow condition mainly affected the vigor and productivity of 'G.213' in both areas. At the end of two harvests, 'G.213' was 17% less productive than 'G.210', contrary to what is observed in areas where the fallow period is respected. However, 'G.213' confirmed a greater yield efficiency, which was 27% higher than 'G.210'. This suggests that a perspective of forecasting production for the third crop is higher for 'G.213' than for 'G.210'. In the case of 'Fuji Suprema', the G.210 rootstock was the most productive in both areas. In São Joaquim, 'G.202' matched 'G.210' in productivity and efficiency as it sprouts better in colder regions. Considering the fruit quality, 'G.213' anticipated the maturation with fruits of larger size and higher total soluble solids (TSS) in both areas and cultivars, making it possible to anticipate the harvest. It was concluded that the non-fallow condition does not alter the relative differences in vigor and fruit quality among the rootstocks. However, notwithstanding the overall replant tolerance of these rootstocks, it does reduce productivity by mainly affecting less vigorous rootstocks that need about three crops to overcome the allelopathic effects of the soil and start growing normally. The G.210 semi-dwarfing rootstock is an alternative for the immediate conversion of apple orchards of Gala Select and Fuji Suprema cultivars in southern Brazil.

First report of Podosphaera macularis causing hop (Humulus lupulus) powdery mildew in Brazil.

The hop (Humulus lupulus L.) is a dioecious perennial climbing plant grown commercially worldwide. Wild hops are widely distributed throughout the Northern Hemisphere, Europe, Asia, and North America (Neve, 1991). In the Southern Hemisphere, some of the leading hop-producing countries include South Africa, Australia, and New Zealand. Brazil began hop production less than 5 years ago. In January 2019, amphigenous white powdery circular fungal colonies were observed on the leaves and stems of hop plants (cultivar Chinook) within a 900m2 hop garden in Lages municipality, Santa Catarina State, southern Brazil. The incidence of the disease was present on almost 100 per cent of "Chinook" cultivar plants and diseased foliage was collected to identify the pathogen and used to inoculate healthy plants. Hop powdery mildew lesions with hyaline and septate mycelium with chains of unicellular conidia (n =100) hyaline, barrel-shaped, mean of length/width ± standard deviation 25-27 × 13-18 µm ± 0.980, with fibrosin bodies, and conidiophores erect with cylindrical foot cells, were visible within 10 days. The causal agent was identified as Podosphaera macularis (Wallr.:Fr.) Lind (synonym S. humuli (DC.) Burrill) on the basis of conidial shape, size and host range (Royle 1978; Braun 1987; Mahaffee et al., 2009), complemented with the present molecular analysis. Chasmothecia have not been observed in the field to date. A conidial suspension of 200 ml at concentration of 1.4 x 105 was mixed with 5ul of Tween® 20 for the pathogenicity assay. Ten plants of 9-month-old of hop "Chinook" cultivar, were inoculated with 5 ml of the conidial suspension using a manual spray. The control plot was only sprayed with water. The inoculated plants were maintained at 22ºC ± 1ºC with a 12-hour photoperiod and 65% relative humidity. White mycelia were visible first on the adaxial leaf surfaces of the inoculated younger leaves after 10 days and the disease severity reached between 2 to 5%. No symptoms were observed at the control plot. P. macularis infected most aerial plant tissues of the inoculated plants and caused approximately 50% of cones losses. P. macularis conidia were collected from the infected leaf tissue with a sterile soft camel-hair brush and DNA was extracted using a Wizard Genomic DNA extraction kit. The primers ITS1/ITS4 (White et al., 1990) were used to amplified and sequenced a fragment of the ITS region. PCR products were subjected to Sanger Sequencing to confirm sample species. The resulting 522-bp sequence was deposited into GenBank (accession n°. MN630490). BLASTn showed a 99.81% sequence identity with the CT1 isolate of P. macularis from H. lupulus (MH687414). The presence and identification of P. macularis in hop production regions is a new challenge to growers in Brazil. Research related to the knowledge of the disease cycle, epidemiology, and control strategies for the integrated management should be conducted, as there are no registered fungicides for powdery mildew on hop in Brazil. To our knowledge, this is the first report of P. macularis in Brazil, as well as in South America. References Braun, U. (1987) A Monograph of the Erysiphales (Powdery Mildews). J. Cramer, Berlin, German Democratic Republic. p 113. Mahaffee, W. F., Pethybridge, S.J., Gent, D.H (2009) Compendium of hop diseases and pests. The American Phytopathological Society Press, Saint Paul, Minnesota. Neve R. A (1991). Hops. Chapman and Hall: London. Royle, D. J (1978). Powdery mildew of the hop. Pages 381-409 in: The Powdery Mildews. D. M. Spencer, ed. Academic Press, New York. White, T. J., Bruns, T., Lee, S., and Taylor, J. (1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. pp. 315-322 in: PCR Protocols: A Guide to Methods and Applications. M. Innis, D. Gelfand, J. Sninsky, and T. White, eds. Academic Press, San Diego.

Near-complete genome sequence and seed transmission evaluation of Physalis rugose mosaic virus from southern Brazil / Sequência do genoma completo e avaliação da transmissão por sementes do Physalis rugose mosaic virus no sul do Brasil

ABSTRACT: Physalis rugose mosaic virus (PhyRMV) causes severe damage to Physalis peruviana L., affecting vegetative parameters, fruit quantity and quality. The aim of this study was to perform a molecular characterization of PhyRMV associated with P. peruviana from commercial fields in the municipality of Lages, Santa Catarina State, Southern Brazil, and to evaluate its transmission by seeds. Plants displaying mosaic, dwarfism, and leaf malformation symptoms were collected from P. peruviana. Double-stranded RNA was extracted and submitted to cDNA library synthesis and high-throughput sequencing (HTS). For the virus transmission assay, seeds from PhyRMV-infected plants were used, and viral infection in seedlings was verified using symptomatic and molecular diagnosis. PhyRMV RNA has 4162 nucleotides (nts) and a genomic organization similar to that of other sobemoviruses and shares 97% nt identity with the previously characterized PhyRMV Piracicaba isolate. Results indicated the unlikely transmission of PhyRMV by physalis seeds.

RESUMO: Physalis rugose mosaic virus (PhyRMV) causa danos severos em Physalis peruviana L., afetando características vegetativas, a quantidade e qualidade de frutos. Os objetivos desse estudo consistem na caracterização molecular do PhyRMV associado a P. peruviana coletada em campos de produção em Lages, Santa Catarina, Brasil; e avaliar a transmissão do vírus por sementes. Plantas apresentando sintomas de mosaico, deformação e nanismo foram coletadas de P. peruviana. Amostras foliares dessas plantas foram utilizadas para extração de RNA de fita dupla, síntese de biblioteca de cDNA e sequenciamento de alto rendimento. No experimento de transmissão, sementes obtidas de plantas infectadas por PhyRMV foram utilizadas, e a infecção viral nas plântulas foi avaliada por inspeção visual de sintomas e diagnóstico molecular. O RNA viral apresentou 4162 nucleotideos (nts), a organização genômica foi similar à de outros sobemovírus e apresentou 97% de identidade de nucleotídeos com o isolado de Piracicaba de PhyRMV previamente caracterizado. Os resultados obtidos sugerem que é improvável a transmissão de PhyRMV por sementes de physalis.

Prohexadione-calcium on downy mildew and botrytis bunch rot epidemiology, and yield and technological and phenolic parameters of the Merlot vine cultivar in the highland region of southern Brazil / Efeitos da prohexadiona de cálcio na epidemiologia do mildio e podridão de botrytis e no desempenho vitícola da cultivar de videira Merlot em região de altitude do sul do Brasil

ABSTRACT: Prohexadione-calcium (ProCa) is a gibberellin biosynthesis inhibitor and the objective of this study was to evaluate the effect of ProCa on the downy mildew (DM) and Botrytis bunch rot (BBR) epidemiology, and the yield and technological and phenolic parameters of grape Merlot cultivar. Experiments were carried out in a commercial vineyard in São Joaquim Municipality/SC, Southern Brazil, during the 2017-2018 and 2018-2019 growing seasons. ProCa was applied at four doses and three phenological stages: A) 0 g ha−1 (control); B) 1000 g ha−1 (inflorescence fully developed); C) 500 + 500 g ha−1 (inflorescence fully developeted and full flowering); D) 500 + 500 + 500 g ha−1 (inflorescence fully developed, full flowering, and berries pea-sized). DM and BBR incidence and severity were quantified weekly from the first symptom appearance until harvest, and their epidemiology was compared according to: a) the beginning of symptom appearance; b) the time to reach the maximum disease incidence and severity; c) the maximum value of disease incidence and severity; d) the area under the disease progress curve. In general, there were significant differences in the ProCa doses for all epidemiologic parameters of DM and BBR compared with the control plot; however, there was no significant difference among the ProCa doses. The principal epidemiological variables that differentiated the effect of ProCa on the DM and BBR control were the Smax and AUSDPC. Some yield and technological and phenolic parameters were negatively affected by different doses of ProCa, but it was still a good option for DM and BBR control in highland region of southern Brazil during the 2017-2018 and 2018-2019 growing seasons.

RESUMO: A prohexadiona-cálcio (ProCa) é um inibidor da biossíntese de giberelina e o objetivo desse estudo foi avaliar o efeito do ProCa na epidemiologia do míldio da videira (MV) e da podridão de Botrytis (PB) e no desempenho vitícola da cultivar de videira Merlot. Experimentos foram realizados em um vinhedo comercial no município de São Joaquim/SC, Sul do Brasil, durante as safras 2017-2018 e 2018-2019. A ProCa foi aplicada em quatro doses e três estágios fenológicos: A) 0 g ha-1 (controle); B) 1000 g ha-1 (inflorescência totalmente desenvolvida); C) 500 + 500 g ha-1 (inflorescência totalmente desenvolvida e floração completa); D) 500 + 500 + 500 g ha-1 (inflorescência totalmente desenvolvida, floração completa e baga tipo ervilha). A incidência e severidade de MV e PB foram quantificadas semanalmente a partir do aparecimento dos primeiros sintomas até a colheita e a epidemiologia das doenças foram comparadas de acordo com: a) o início do aparecimento dos sintomas; b) tempo para atingir a máxima incidência e severidade da doença; c) valor máximo da incidência e severidade da doença; d) área abaixo da curva de progresso da doença. Em geral, houve diferenças significativas na dose de ProCa para todos os parâmetros epidemiológicos de MV e PB em comparação com o controle; no entanto, não houve diferença significativa entre as doses de ProCa. As principais variáveis ​​epidemiológicas que diferenciaram o efeito da ProCa no controle do MV e PB foram o Smax e o AUSDPC. Algumas variáveis vitícolas da cultivar Merlot foram afetados negativamente por diferentes doses de ProCa, mas ainda foi uma boa opção o uso da ProCa para o controle do MV e PB em região de altitude do sul do Brasil durante as safras 2017-2018 e 2018-2019.

Transmission of Microdochium albescens from seeds to seedlings in the pre-germinated cultivation system of irrigated rice / Transmissão de Microdochium albescens de sementes para plântulas de arroz irrigado no sistema de cultivo pré-germinado

ABSTRACT: The fungus Microdochium albescens is one of the main pathogens associated with irrigated rice seeds in southern Brazil. The objective of the present study was to quantify the transmission of M. albescens from naturally infected seeds to the crown, coleoptile, and first true leaf of the seedlings of six cultivars growing in pre-germinated cultivation system of irrigated rice. Seeding was carried out on a water-saturated substrate, using four untreated seed lots for each of the six cultivars. At 14 days after sowing, the crown, coleoptile, and first true leaf of the seedlings were carefully highlighted, and the samples were disinfected and plated onto potato-sucrose-agar culture medium. M. albescens was transmitted asymptomatically to crown, coleoptile, and first true leaf, at rates of 39.3%, 25.8%, and 5.4%, respectively (these values represent the average incidence of the six cultivars). This is the first report that proves that M. albescens is transmitted from infected seeds to irrigated rice seedlings in a pre-germinated seed system.

RESUMO: O fungo Microdochium albescens é um dos principais patógenos associados às sementes de arroz irrigado no sul do Brasil. O objetivo do presente estudo foi quantificar a transmissão de M. albescens de sementes naturalmente infectadas para a coroa, coleóptilo e primeira folha verdadeira das plântulas de seis cultivares semeadas em sistema de cultivo pré-germinado de arroz irrigado. A semeadura foi realizada em substrato saturado com água, utilizando quatro lotes de sementes não tratadas para cada uma das seis cultivares. Aos 14 dias após a semeadura, a coroa, o coleóptilo e a primeira folha verdadeira das plântulas foram cuidadosamente dissecados, desinfestados e plaqueados em meio de cultura batata-sacarose-ágar. M. abescens foi transmitido de forma assintomática para coroa, coleóptilo e primeira folha verdadeira, nas taxas de 39,3%, 25,8% e 5,4%, respectivamente (estes valores representam a incidência média das seis cultivares). Este é o primeiro relato de M. albescens transmitido de sementes infectadas para plântulas de arroz irrigado em sistema de semente pré-germinada.

Molecular and biological characterization of a putative new sobemovirus infecting Physalis peruviana.

Physalis peruviana is a perennial solanaceous plant that has recently been established as a commercial crop in Brazil. This work reports the near-complete genome sequence, particle morphology, and plant host responses to a putative new sobemovirus, named "physalis rugose mosaic virus". The virus, characterized by isometric particles of ca. 30 nm in diameter, causes foliar symptoms of mosaic, malformation and blistering, accompanied by stunting. The near-complete genome sequence comprises 4175 nucleotides and contains five open reading frames that are similar to those of other sobemoviruses. In addition to P. peruviana, the new virus systemically infected Capsicum annuum, Nicotiana tabacum and Solanum lycopersicum by mechanical inoculation. Thus, this virus may cause disease in these crops in the field.

European apple canker: morphophysiological variability and pathogenicity in isolates of Neonectria ditissima in southern Brazil / Cancro europeu da macieira: variabilidade morfofisiológicas e patogenicidade de isolados de Neonectria ditissima no sul do Brasil

ABSTRACT: European apple canker (EC) is caused by Neonectria ditissima, a pathogen officially registered as a quarantine pest in 2012. Thirty-five isolates of N. ditissima of different geographical regions of southern Brazil from apple branches showing symptoms of EC were identified by the specific pair primers Ch1 and Ch2 and analyzed concerning the virulence on Gala apple cultivar and morphophysiological characteristics. The disease symptoms were characterized and the isolates compared based on average mycelium growth (AMG), mycelium growth index (MGI), colony color, conidia type, dimensions and growth on potato dextrose agar (PDA), malt agar (AM), and synthetic SNAY (SN) culture media. Nineteen isolates showed the greatest AMG on PDA, forming three growth groups of 35.56 (GI), 52.71 (GII), and 62.67mm (GIII). Seven isolates showed MGI greater than 4.0mm diameter on PDA compared with that on AM and SN. The highest conidia production was on SN, and the predominant colony color in all media was white to beige with central pigmentation of brown and borders colored in shades of beige. There were significant differences among the average dimensions of micro- and macroconidia on PDA, AM, and SN. The pathogenicity was confirmed for all isolates despite of different morphophysiological characteristics. There was no correlation among isolates morphophysiological variability, virulence, and geographical origin.

RESUMO: O cancro europeu (CE) da macieira é causado pelo fungo Neonectria ditissima e foi oficialmente registrado como praga quarentenária em 2012. Foram avaliados 35 isolados de N. ditissima provenientes de ramos de macieira com sintomas típicos de CE de diferentes regiões do sul do Brasil. Os isolados foram identificados pelos primers específicos Ch1 e Ch2 e analisados quanto as características morfofisiológicas e virulência na cultivar de macieira Gala. Os sintomas foram caracterizados e os isolados comparados com base no crescimento micelial médio (CMM), índice de crescimento micelial (ICM), coloração das colônias e tipos, dimensões e produção de conídios em meios de cultura batata-dextrose-ágar (BDA), malte-ágar (MA) e meio sintético SNAY (SS). Dezenove isolados tiveram os maiores CMM sobre BDA, formando três grupos de crescimento de 35.56 (GI), 52.71 (GII) e 62.67mm (GIII). Sete isolados tiveram ICM maior de 4mm de diâmetro sobre BDA quando comparados com os meios MA e SS. A maior produção de conídios ocorreu sobre o meio SS e a coloração predominante foi de branco-à-bege com pigmentação central marrom e bordas de colônia em tons de bege. Foram observadas diferenças significativas nas dimensões médias dos micro- e macroconídios sobre os meios de culturas BDA, MA e SS. Todos os isolados foram patogênicos na cultivar de macieira gala, independentemente das diferenças morfofisiológicas. Não foram observadas correlações entre a variabilidade morfofisiológicas, virulência e origem geográfica dos isolados.

Compatibilidade fenotípica entre cultivares de pereiras europeias eporta-enxertos de marmeleiro / Phenotypic compatibility among european pear cultivars and quince rootstocks

A cultura da pereira (Pyrus communisL.) possui grande potencial de expansão no sul do Brasil devido às condições climáticas e de solo. A carência de informações a respeito da(s) melhor(es) combinação(ões) de cultivares 'copa de pereiras europeias' e porta-enxertos de marmeleiro em relação à compatibilidade de enxertia é um dos fatores que tem limitado o cultivo de pera no país. A utilização de porta-enxertos de marmeleiros apresentam as vantagens de redução do vigor e rápida entrada em produção, porém, quando enxertados com algumas cultivares de 'pereira europeia', pode acarretar incompatibilidade de enxertia. O trabalho foi realizado com o objetivo de avaliar fenotipicamente a compatibilidade morfológica entre cultivares 'copa de pereiras europeias' e porta-enxertos de marmeleiro através das variáveis de crescimento das plantas, como o incremento de diâmetro (mm) do tronco da cultivar e do porta-enxerto; diferença de diâmetro entre a cultivar e o porta-enxerto; incompatibilidade 'translocada'; incompatibilidade 'localizada'; e análise da conexão vascular no ponto de enxertia pela imersão em solução corante de Ácido Fuccínico 0,08%. Os experimentos foram conduzidos em pomares de pereiras europeias na região de Urupema, estado de Santa Catarina, durante os ciclos de cultivo 2011/12, 2012/13 e 2013/14. As combinações de cultivares de pereiras europeias e porta-enxertos avaliados foram a 'Abbè Fetel'/'Adams', 'Decana du Comice'/'Adams', 'Clapp's Favourite'/'EMA', 'Rocha'/'Adams', 'Packham´s Triumph'/'EMA' e 'Santa Maria'/'Adams'. A combinação 'Clapp´s Favourite'/'EMA' apresentou incompatibilidade do tipo 'localizada' pela descontinuidade vascular na região de união do enxerto, impedindo a passagem do corante. As combinações 'Rocha'/'Adams' e 'Abbè Fetel'/'Adams' não apresentaram incompatibilidade de enxertia. Nessas combinações, foram observadas união vascular contínua entre as cultivares e os porta-enxertos. As combinações ...

The pear (Pyrus communis L.) crop offers an expansive market opportunity in southern Brazil, because of amicable climatic and soil conditions. However, the lack of studies on compatibility of european pear cultivars and rootstocks is one of the limiting factors on the development of the pear crop in southern Brazil. The use of quinces as rootstocks has the advantages of vigor reduction and earlier bearing trees. However, some of these combinations can present some incompatibility graft. The objective of this study was to evaluate phenotypicaly the morphological compatibility among european pear cultivars and quince rootstocks. The evaluated variable were the section increment of cultivars and rootstocks trunk diameter at the graft union; the diameter difference between scion and cultivars and rootstocks; 'translocated' incompatibility; 'located' incompatibility; and the vascular connection of the graft union by immersion of the base of the plants (under the graft union) in a 0.08% Fuccinic acid solution. The experiments were conducted in an european pear orchards in the region of Urupema municipality, state of Santa Catarina, during the 2011/12, 2012/13 and 2013/14 growing seasons. The european pear cultivars and rootstocks evaluated were: 'Abbé Fetel'/'Adams', 'Decana du Comice'/'Adams', 'Clapp's Favourite'/'EMA', 'Rock'/'Adams', 'Packham's Triumph'/'EMA' and 'Santa Maria'/'Adams'. 'The Clapp´s Favourite'/'EMA' combination showed a `located incompatibility by descontinued vascular graft region, preventing the dye translocation. 'The Rocha'/'Adams' and 'Abbè Fetel'/'Adams' combinations did not present graft incompatibility, showing continued vascular union and no vascular disruption between cultivars and rootstocks. The 'Santa Maria'/'Adams', 'Decana du Comice'/'Adams' and 'Packham´s Triumph'/'EMA' combinations showed a good graft union region with clear and continued bark and wood bond lines. The 'Clapp´s Favourite'/'EMA' ...

Elaboration and validation of a diagrammatic scale to assess downy mildew severity in grapevine / Elaboração e validação de uma escala diagramática para quantificação da severidade do míldio da videira

The downy mildew, caused by Plasmopora viticola, is one of the most important grapevine (Vitis vinifera) diseases in Southern Brazil, causing defoliation and economic losses. The evaluation of disease severity is an important decision for adoption of strategies and tactics for disease control. Therefore, the objective of this work was to elaborate and to validate a diagrammatic scale to assess downy mildew severity in grapevine, respecting the limitations of visual acuity. The diagrammatic scale with seven levels of disease severity of 1, 3, 6, 12, 25, 50 and 75% was developed in two versions of black-and-white and color scale. The scales were tested and validated by eight raters with and without previous experience with grapevine downy mildew. The raters estimated the severity of 30 grapevine leaves with different downy mildew severity, with and without the use of the scales. Minimum, intermediate and maximum severity levels were collected according to Weber-Fechner's stimulus-response law. The accuracy and precision were analyzed by linear regression between the actual and the estimated severity. Actual severity was assessed with ASSESS(r) Program. The scales provided good levels of accuracy (means of 88%) and excellent levels of precision (means of 95%). The raters showed great precision and accuracy when used the diagrammatic scale. The color scale provided more precise and accurate estimates than the black-and-white scale. The scale proposed in this work presented appropriate applicability for downy mildew evaluation in grapevine.

O míldio da videira causado pelo fungo Plasmopora viticola é uma das doenças mais importantes da videira (Vitis vinifera) no sul do Brasil, causando desfolha e perdas econômicas. A avaliação da severidade de doenças é uma decisão importante na adoção de estratégias e táticas de controle. Assim, o objetivo deste trabalho foi elaborar e validar uma escala diagramática para a avaliação da severidade do míldio da videira, respeitando as limitações da acuidade visual. A escala diagramática com sete níveis de severidade: 1, 3, 6, 12, 25, 50 e 75%, foi desenvolvida em duas versões preto-e-branco e em cores. As escalas foram avaliadas e validadas por oito avaliadores com e sem experiência prévia com o míldio da videira. Os avaliadores estimaram a severidade em 30 folhas de videira com diferentes níveis de severidade da doença, com e sem experiência no uso da escala diagramática. Severidades mínimas, médias e máximas foram obtidas pela Lei do estímulo visual de Weber-Fechner. A acurácia e a precisão foram analisadas por meio de regressão linear, confrontando os valores de severidade reais com os estimados. A severidade real foi estimada pelo programa ASSESS(r). As escalas proporcionaram bons níveis de acurácia (média 88%) e excelentes níveis de precisão (média de 95%). Os avaliadores apresentaram grande precisão e acurácia com o uso da escala diagramática. A escala colorida proporcionou estimativa melhor de precisão e acurácia do que a escala preto-e-branco. A escala diagramática proposta apresenta apropriada aplicabilidade para a avaliação do míldio da videira.

Critical yield-point model to estimate damage caused by brown spot and powdery mildew in barley / Modelo do ponto crítico para estimar danos causados pela mancha-marrom e oídio em cevada

Barley (Hordeum vulgaris L.) is the second most important winter crop in Southern Brazil. The excessive rainfall in this region during the crop-growing season increases the frequency and intensity of foliar fungal diseases. The research aimed to determine the damage function equations (DFE) for the multiple pathosystem of barley brown spot and powdery mildew based on the relationship between grain yield and diseases intensity at different 'BRS Cauê' cultivar growth stages (GS) during 2009 and 2010 growing seasons in Southern Brazil. The experiments were arranged in a randomized complete block design with nine treatments and four replicates. The disease gradients were generated by strobilurins and triazols fungicides rates and number of applications on barley cv. Cauê. The fungicide applications and disease incidence and severity assessments were performed at the 22, 31, 39, 45 and 56 plant GS. The DFE were obtained by variance analysis and linear regression between grain yield and diseases intensity. Significant and negative DFE were obtained and the damage coefficients (DC) varied from 29.48 to 100.08 (2009) and from 36.08 to 113.57kg ha-1 (2010) for incidence, and from 219.5 to 6,276.6 (2009) and 102.3 to 5,292.5kg ha-1 (2010) for severity. The largest damage coefficients were obtained when diseases assessments were made on GS 22 and 31 on both growing seasons evaluated. DFE were used to calculate the economic damage threshold (EDT) as a criterion to indicate the fungicide application moment to control the diseases in cultivars similar to 'BRS Cauê' in Southern Brazil.

A cevada (Hordeum vulgaris L.) é a segunda mais importante cultura de inverno no Sul do Brasil. Nessa região, o excesso de chuvas durante a estação de crescimento da cultura favorece o aumento na frequência e intensidade de doenças foliares. O trabalho objetivou determinar as equações de função de dano (EFD) para o patossistema múltiplo mancha-marrom e oídio da cevada pela relação entre rendimento de grãos e intensidade foliar das doenças em diferentes estádios fenológicos da cultivar de cevada 'BRS Cauê', nas safras 2009 e 2010 no sul do Brasil. O delineamento foi em blocos casualizados com nove tratamentos e quatro repetições. Os tratamentos foram constituídos de diferentes doses e número de aplicações dos fungicidas triazóis e estrobilurinas para gerar os gradientes de intensidade das doenças. As aplicações de fungicidas e as avaliações da incidência e severidade foliar foram realizadas nos estádios fenológicos (EF) 22, 31, 39, 45 e 56. As equações foram obtidas pela análise de variância e regressão linear entre rendimento de grãos e intensidade das doenças. As EFD foram significativas e negativas e os coeficientes de danos variaram de 29,48 a 100,08kg ha-1 (2009) e 36,08 a 113,57kg ha-1 ( 2010) para a incidência e de 219,5 a 6.276,6kg ha-1 ( 2009) e 102,3 a 5.292,5kg ha-1 (2010). Os maiores coeficientes de dano foram obtidos nos estádios EF 22 e 31em ambas as safras. As EFD foram usadas para calcular o limiar de dano econômico, que é um critério que indica o correto momento de aplicação de fungicidas para o controle das doenças em cultivares similares a 'BRS Cauê' no sul do Brasil.

Cultivares e portaenxertos sobre o vigor de plantas de pereira europeias / Cultivars and rootstocks on plants vigor of European pear

A cultura da pereira (Pyrus communis) possui grande potencial de expansão no sul do Brasil devido às condições climáticas e solo. A carência de informações a respeito da(s) melhor(es) combinação(ões) de cultivares copa de pereira europeia e portaenxertos, quanto ao aspecto vegetativo e potencial produtivo, tem limitado o cultivo. O objetivo do trabalho foi avaliar a influência de cultivares copa de pereira europeia e portaenxertos de marmeleiro (Cydonia oblonga) sobre o vigor e variáveis de plantas. Os experimentos foram conduzidos em pomares comerciais da cidade de Fraiburgo, Estado de Santa Catarina, durante os ciclos de cultivo 2008/09, 09/10 e 10/11. As cultivares avaliadas foram 'Packham's Triumph', 'Santa Maria', 'Rocha' e 'Abbè Fetel' e os portaenxertos de marmeleiro EMC e Adams. O espaçamento de plantio foi de 0,3m entre plantas e 4m entre linhas. As variáveis analisadas foram: a. incremento de altura de plantas (m); b. incremento de volume de copa (m³); c. incremento de diâmetro do tronco da cv. 'copa' (mm); d. incremento de diâmetro do tronco do portaenxerto (mm); e. diferença de diâmetro do tronco entre a cultivar copa e o portaenxerto (mm); f. índice de fertilidade (no de gemas cm-1); g. massa fresca média total acumulada do material vegetativo das três podas de inverno (kg); h. diferença cumulativa entre a massa fresca e a massa seca dos ramos podados (kg). As diferentes combinações de cultivares e portaenxertos interferiram nas diferentes variáveis analisadas. As combinações Abbè Fetel e Rocha sobre marmelo Adams, foram significativamente mais vigorosas em termos de incremento de diâmetro do tronco da cultivar copa, incremento de altura de plantas, incremento de volume de copa e massa fresca média total acumulada do material vegetativo das podas de inverno dos três anos. A combinação Santa Maria sobre marmelo Adams apresentou vigor intermediário significativo de plantas de acordo com o incremento em volume de copa, diferença de diâmetro do tronco entre a cultivar copa e do portaenxerto, sendo mais indicada para uso comercial, devido ao maior equilíbrio proporcionado entre parte vegetativa e produtiva da planta, nas condições edafoclimáticas experimentais do Sul do Brasil.

The pear (Pyrus communis) culture offers a great expansive market opportunity in southern Brazil, according to climatic conditions and soil. However, there are still some barriers that prevent satisfactory economic production, such as lack of knowledge about the best combinations of cultivars and rootstocks. The objective of the study was to evaluate the influence of European pear cultivars and quince (Cydonia oblonga) rootstocks on the plants vigor variables. The experiments were carried out in commercials orchards in Fraiburgo Municipality, Santa Catarina state, during the crop season of 2008/09, 09/10 and 10/11. The cultivars evaluated were 'Packham's Triumph', 'Santa Maria', 'Rocha' and 'Abbè Fetel' and the quince rootstocks EMC and Adams. The cultivars and rootstocks combinations were conducted in a spacing of 0.3mx4m between plants and rows, respectively. The vigor variables evaluated were, a. plants height increment (m); b. canopy volume increment (m³); c. truck diameter increment of the cultivars canopy (mm); d. truck diameter increment of rootstocks (mm); e. difference between the trunk diameter of cultivars canopy and rootstock (mm); f. fertility index (buds cm-1); g. total cumulative average of fresh weight of pruned branches (kg); and h. cumulative difference between the fresh and dry weight of pruned branches (kg). All combinations evaluated affected the vegetative parameters of the European pear cultivars. The combinations Abbè Fetel and Rocha grafted on Adams quince rootstocks are significant more vigorous according to increment of cultivars canopy truck diameter, plant height increment, cultivars canopy volume increment and cumulative average weight of pruned branches, when compared with others combinations. The combination Santa Maria grafted on Adams quince rootstock showed significant intermediate vigor according to cultivar canopy volume increment, truck diameter of cultivar canopy and, truck diameter of rootstock. This combination presented a better proportion amongst the vigor variables and can be indicated for commercial production according to the experimental edafoclimatic conditions of southern Brazil.

Ethylene inhibitor aminoethoxyvinilglycine on glomerella leaf spot in apple cultivar 'Royal Gala' / Inibidor de etileno aminoetoxivinilglicina sobre a mancha foliar de 'Glomerella' na cultivar de macieira 'Royal Gala'

Aqueous solution of Aminoethoxyvinylglycine (AVG) has been commercialized in Brazil as ReTainTM C, 15 percent mainly as a potent inhibitor of ethylene biosynthesis by prevention of pre-harvest abscission and ripening of apple fruits. The effect of the product was evaluated during the 2007-08 and 2008-09 crop seasons in edafoclimatic conditions of Santa Catarina upland. Plants of 'Royal Gala' cultivar were sprayed with ReTainTM C, four weeks before the first commercial harvest at doses of 0; 62,5; 125, and 250mg a.i L-1. The incidence and severity were quantified weekly in 100 leaves distributed in four branches with 12 replications and assessed the area under the incidence -I and severity -S disease progress curve (AUIDPC and AUSDPC) of Glomerella leaf spot (GLS). The AUIDPC and AUSDPC were significantly higher after AVG application and although there was no significant difference between 125 and 250mg a.i L-1 doses in both 2007-08 and 2008-09 crop seasons. In general, the symptoms of GLS (e.g. chlorosis, necrosis) increased between the fourth and eighth week after application.

Solução aquosa de Aminoetoxivinilglicina (AVG) tem sido comercializada no Brasil como ReTainTM C, 15 por cento, principalmente como um potente inibidor da biossíntese do etileno na prevenção da abscisão e maturação de frutos em macieira. O efeito do produto foi avaliado durante as safras 2007-08 e 2008-09 nas condições edafo-climáticas do planalto Catarinense. Plantas de maçãs 'Royal Gala' foram pulverizadas com o ReTainTM C, quatro semanas antes da primeira colheita comercial, nas concentrações de 0;62,5; 125 e 250mg i.a L-1. A incidência e a severidade foram quantificadas semanalmente em 100 folhas, distribuídas em quatro ramos por plantas, com 12 repetições e calculado a área abaixo da curva do progresso da incidência -I e severidade -S da doença (AACPID e AACPSD). A AACPID e AACPSD foram significativamente maiores após a aplicação do AVG e não houve diferença significativa entre as doses de 125 e 250mg i.a L-1 nos dois anos de cultivo avaliados. Em geral, os sintomas típicos de clorose e necrose da Mancha da Glomerella aumentaram entre a quarta e oitava semana após a aplicação.

ITS-rDNA phylogeny of Colletotrichum spp. causal agent of apple Glomerella leaf spot / Filogenia por ITS-rDNA de Colletotrichum spp., agente causal da mancha foliar da Gala em macieira

Several diseases have affected apple production, among them there is Glomerella leaf spot (GLS) caused by Colletotrichum spp. The first report of this disease in apple was in plants nearby citrus orchards in São Paulo State, Brazil. The origin of this disease is still not clear, and studies based on the molecular phylogeny could relate the organisms evolutionarily and characterize possible mechanisms of divergent evolution. The amplification of 5.8S-ITS (Internal Transcribed Spacer) of rDNA of 51 pathogenic Colletotrichum spp. isolates from apples, pineapple guava and citrus produced one fragment of approximately 600 bases pairs (bp) for all the isolates analyzed. The amplified fragments were cleaved with restriction enzymes, and fragments from 90 to 500bp were obtained. The sequencing of this region allowed the generation of a phylogenetic tree, regardless of their hosts, and 5 isolated groups were obtained. From the "in silico" comparison, it was possible to verify a variation from 93 to 100 percent of similarity between the sequences studied and the Genbank data base. The causal agent of GLS is nearly related (clustered) to isolates of pineapple guava and to the citrus isolates used as control.

A produção de maçã vem sendo comprometida pela ocorrência de muitas doenças, entre as quais se destaca a Mancha Foliar de Glomerella (MFG), causada por Colletotrichum spp. O primeiro relato dessa doença em maçã foi registrado em plantas próximas a pomares de citrus no Estado de São Paulo, Brasil. A origem da MFG ainda não está bem clara, e estudos baseados na filogenia permitirão relacionar o organismo evolutivamente, possibilitando caracterizar possíveis mecanismos divergentes de evolução. A amplificação da região 5.8S-ITS (espaçador interno transcrito) do rDNA de 51 isolados de Colletotrichum patogênicos em de maçã, goiabeira serrana e citrus produziu um fragmento de aproximadamente 600 pares de bases (pb) para todos os isolados analisados. Os fragmentos amplificados foram digeridos por enzimas de restrição, sendo obtidos fragmentos de 90 a 500pb. O sequenciamento dessa região permitiu a construção de uma árvore filogenética com a distribuição dos isolados em cinco grupos, independentemente de seus hospedeiros. A partir da comparação in silico, foi possível verificar uma variação de 93 a 100 por cento de similaridade entre as sequências estudadas e o banco de dados do GenBank. O agente causal da MFG está relacionado (agrupado) a isolados de goiabeira serrana e aos isolados padrões de citrus.

Dinâmica temporal da mancha foliar da 'Gala' em macieiras conduzidas sob os sistemas de produção convencional e orgânico / Temporal dynamic of 'Gala' leaf spot in apples under conventional and organic production systems

Este trabalho objetivou avaliar a dinâmica temporal da Mancha Foliar da 'Gala' em macieira nos sistemas convencional e orgânico de produção, em condições edafo-climáticas do Planalto Catarinense. A incidência e severidade foram quantificadas quinzenalmente, em 100 folhas, distribuídas em quatro ramos da cultivar 'Royal Gala' com 12 repetições, gerando 16 mapas em cada sistema de produção. A severidade foi avaliada de acordo com escala diagramática específica. Com os dados obtidos, foram plotadas curvas de progresso da doença, e as epidemias foram comparadas em relação à a) início do aparecimento dos sintomas (IAS); b) tempo para atingir a máxima incidência e severidade da doença (TAMID e TAMSD); c) valor máximo de incidência e severidade da doença (Imax e Smax); e d) área abaixo da curva de progresso da incidência e severidade da doença (AACPID e AACPSD). Os dados de incidência e severidade foram analisados por meio de análise de regressão linear simples, sendo ajustados para três modelos empíricos, Logístico, Monomolecular e Gompertz. A cultivar 'Royal Gala' foi suscetível ao Colletotrichum sp., e as maiores intensidades de doença foram registradas no sistema de produção orgânico. O modelo mais apropriado para descrever o progresso da doença foi o Logístico e, por meio do uso da incidência, não foram detectadas diferenças significativas entre os sistemas de produção, porém a taxa de progresso da severidade da doença foi significativamente maior no sistema de produção orgânico do que no convencional.

This study aimed to evaluate the temporal dynamic of 'Gala' leaf spot under conventional and organic systems of production in edafoclimatic conditions of Santa Catarina plateau. The incidence and severity were quantified biweekly in 100 leaves distributed in four branches of the "Royal Gala" cultivar with 12 replications, generating 16 maps for each system of production. The disease severity was evaluated in accordance with the specific diagrammatic scale. Curves of disease progress were made and the epidemics compared according to: a) the beginning of symptoms appearance (BSA); b) the time to reach the maximum disease intensity and severity (TRMDI and TRMDS); c) the maximum value of disease intensity and severity (Imax and Smax); and d) area under the incidence and severity disease progress curve (AUIPCI and AUSDPC). The incidence and severity data were analyzed by linear regression, adjusted for three empirical models, Logistic, Monomolecular and Gompertz. The 'Royal Gala' cultivar was susceptible to Colletotrichum spp. and the highest disease intensity was observed in the organic than in conventional system of production. The Logistic epidemiological model was the most appropriate to describe the disease progress curve and, there is no significant difference between systems when used only incidence value. The severity progress rate (r) was significantly higher in the organic than in the conventional system of production.

Modelos de pontos críticos para relacionar o rendimento de grãos de aveia branca com a intensidade de doença no patossistema múltiplo ferrugem da folha: helmintosporiose / Critical-point models to relate white oat yield and disease intensity of the multiple pathosystem leaf rust: helminthosporium blight

A ferrugem da folha e a helmintosporiose são as principais doenças fúngicas foliares de aveia branca. Em cultivares suscetíveis, o controle químico não considera o limiar de dano econômico (LDE). O objetivo deste trabalho foi obter funções de dano, por modelos de ponto crítico, ao relacionar o dano pela ocorrência simultânea da ferrugem da folha e a helmintosporiose com o rendimento de grãos nas safras de 2006 e 2007, em Lages, Santa Catarina (SC). O gradiente da intensidade das doenças foi gerado por número de aplicações e doses de fungicidas nas cultivares 'UPFA 20' e 'UPFA 22'. Os ensaios consistiram de 10 tratamentos, distribuídos em blocos casualizados, com quatro repetições. As doenças foram avaliadas nos estádios de alongamento, emborrachamento e florescimento. Os modelos de ponto crítico foram obtidos por regressão linear entre rendimento de grãos e incidência (I) e severidade (S). Em 2006, funções significativas foram obtidas para 'UPFA 20' no emborrachamento (R=6.345-22,07I), enquanto para a 'UPFA 22' foi obtida no alongamento (R=5.726-17,96I; R=5.160-541,5S), emborrachamento (R=5.961-21,85I; R=5.433-966,8S) e florescimento (R=6.217-36,41I; R=5.539-1.185S). Em 2007, para 'UPFA 20', no alongamento (R=6.369-55,61I; R=4.965-2.911S), emborrachamento (R=6.620-40,91I; R=5.181-1.702S) e florescimento (R=6.129-32,34I; R=5.252-638,6S), e para 'UPFA 22', no alongamento (R=5.201-41,96I; R=4.977-657,8S), emborrachamento (R=5.329-60,51I; R=4.238-798,1S) e florescimento (R=5.604-32,83I; R=4.680-588,5S). A produção na cultivar 'UPFA 22' foi mais afetada pela ocorrência das doenças, e a intensidade das doenças no estádio de florescimento apresentou maior relação com o rendimento de grãos. As funções geradas permitem obter o coeficiente de dano para uso no cálculo do LDE em patossistema múltiplo ferrugem da folha e helmintosporiose.

The leaf rust and helminthosporium blight are the main foliar diseases of white oat. The chemical control in susceptible cultivars does not consider the economic damage threshold (EDT). The objective of this research was to obtain the damage functions by critical-point models to relate damage by simultaneous occurrence of white oat leaf rust and helminthosporium blight with yield grains during 2006/07 crop seasons in Lages, SC, Brazil. The gradient of diseases intensity was generated by number of applications and rates fungicides on cultivars 'UPFA 20' and 'UPFA 22'. The trials consisted by 10 treatments distributed in randomly blocks with four replications. Diseases evaluations were done in the elongation, booting and flowering stages. The critical-point models were obtained by linear regression between grain yield and leaf diseases incidence and severity. In 2006, significant function was obtained for 'UPFA 20' in booting stage (R=6.345-22.07I), with 'UPFA 22'. The significant functions were obtained in elongation (R=5.726-17.96I and R=5.160-541.5S), booting (R=5.961-21.85I; R=5.433-966.8S) and flowering stages (R=6.217-36.41I; R=5.539-1.185S). In 2007, the significant functions were obtained in all growth stages evaluated. To 'UPFA 20', the significant functions were in the elongation (R=6.369-55.61I; R=4.965-2.911S), booting (R=6.620-49.91I; R=5.181-1.702S) and flowering (R=6.129-32.34I; R=5.252-638.6S), while in the 'UPFA 22', were in the elongation (R=5.201-41.96I; R=4.977-657.8S), booting (R=5.329-60.51I; R=4.238-798.1S) and flowering (R=5.604-32.83I; R=4.680-588.5S). The 'UPFA 22' cultivar production was more affected by diseases occurrence and the diseases intensity in the flowering stage showed greater relation with the yield grain. The generated functions allowed obtaining the damage coefficient to use in the EDT in the multiple pathosystem leaf rust and helminthosporium.

Caracterização da diversidade genética entre acessos crioulos de feijão (Phaseolus vulgaris L.) coletados em Santa Catarina por marcadores RAPD / Characterization of the genetic diversity of landraces of common bean (Phaseolus vulgaris L.) collected in Santa Catarina State by RAPD markers

O conhecimento da diversidade genética, por meio da dissimilaridade entre os genótipos, permite a organização, a amostragem e a utilização eficiente do germoplasma em programas de melhoramento genético. O objetivo deste trabalho foi estimar a dissimilaridade entre acessos crioulos de feijão coletados no Estado de Santa Catarina, integrantes do banco ativo de germoplasma de feijão da UDESC e de três cultivares comerciais ("Pérola", "SCS 202-Guará" e "BRS Valente"), por meio de marcadores moleculares RAPD. Foram utilizados 21 iniciadores decâmeros que permitiram a visualização de 96 bandas, sendo que 41 (42,7 por cento) apresentaram polimorfismo entre os acessos estudados, resultando em bandas entre 650 e 2000pb. A dissimilaridade foi calculada utilizando-se o coeficiente de Sorensen-Dice e o agrupamento foi realizado pelo método UPGMA. Os acessos foram separados em dois grupos principais, com dissimilaridade relativamente alta, quando comparada com a dissimilaridade observada dentro de cada grupo. Os dois grupos formados indicam os centros de domesticação, Mesoamericano ou Andino, dos acessos analisados. A dissimilaridade entre as cultivares avaliadas ("SCS 202-Guará", "BRS Valente" e "Pérola") é baixa (0,15), se comparada com a dissimilaridade entre os demais acessos do banco de germoplasma (0,65). A menor dissimilaridade entre os acessos estudados (BAF63 e BAF04) foi de 0,02. A inexistência de acessos repetidos reforça a necessidade de novas coletas de germoplasma, o que resultará em um banco de germoplasma de feijão mais representativo da variabilidade genética remanescente em Santa Catarina.

The knowledge of the genetic diversity through the divergence among the genotypes allows the organization of the germplasm, sampling and efficient utilization in breeding programs. The objective of this study was to analyze the dissimilarity among germplasm collected in Santa Catarina State, stored in UDESC germplasm active bank of common bean, and of three cultivars ('Pérola', 'SCS 202-Guará' e 'BRS Valente'), using RAPD markers. 21 decamer-primers that allowed the visualization of 96 bands were used, and 41 (42.7 percent) presented polymorphism among the studied accesses, resulting in a band range of 650 to 2000pb. The dissimilarity was calculated using the Sorensen-Dice coefficient and the grouping analyses were derived from UPGMA. The accesses were separated in two main groups, with wide dissimilarity when compared with the divergence inside each group. These two groups indicate the possible center of domestication, Middle-American or Andean, of the accesses in this study. The dissimilarity among the cultivars evaluated ('SCS 202-Guará', 'BRS Valente' e 'Pérola') was small (0.15), if compared with the divergence among the accesses of the germplasm bank (0.65). The smaller dissimilarity among the studied accesses (BAF63 and BAF04) was 0.02. The results reinforce the need of new collection expeditions, which will increase the representation of the genetic variability of the remaining bean landraces in Santa Catarina State.