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).

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.

Distribution and phylogenetics of whiteflies and their endosymbiont relationships after the Mediterranean species invasion in Brazil.

The Bemisia tabaci is a polyphagous insect and a successful vector of plant viruses. B. tabaci is a species complex and in Brazil native species from the New World (NW) group, as well as the invasive species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) were reported. For better understanding the distribution of the different species four years after the Mediterranean species invasion in Brazil, whiteflies were collected from 237 locations throughout the country between the years of 2013 and 2017, species were identified and the facultative endosymbionts detected. The survey revealed that MEAM1 was the prevalent species found on major crops across Brazil. It is the only species present in North, Northwestern and Central Brazil and was associated with virus-infected plants. MED was found in five States from Southeast to South regions, infesting mainly ornamental plants and was not associated with virus-infected plants. The prevalent endosymbionts identified in MEAM1 were Hamiltonella and Rickettsia; and the mtCOI analysis revealed low genetic diversity for MEAM1. In contrast, several different endosymbionts were identified in MED including Hamiltonella, Rickettsia, Wolbachia and Arsenophonus; and two distinct genetic groups were found based on the mtCOI analysis. Monitoring the distribution of the whiteflies species in Brazil is essential for proper management of this pest.

Micropropagation of the new apple rootstock ‘G. 814’ / Micropropagação do novo porta-enxerto de macieira ‘G. 814’

ABSTRACT: International breeding programs launched new genetic material of apple rootstocks that in addition to precocity and great yield are resistant to major diseases and soil pests encountered in the largest apple producing regions in Brazil. Given this, there is a necessity for vegetative propagation of these materials for study and possible replacement of existing rootstocks. The objective was to adapt a micropropagation protocol for new apple rootstock ‘G. 814’. In the multiplication phase were evaluated BAP concentrations: 0; 0.5; 1; 2 and 4mg L-1 and in the rooting phase were evaluated IBA concentrations: 0; 0.25; 0.50; 1; 1.5 and 2.5mg L-1. These new results demonstrated that this new rootstock selection can be propagated with this tissue culture adapted protocol. For the successful in vitro propagation of apple rootstock ‘G. 814’ it is indicated the use of 1mg L-1 BAP at multiplication phase and 1.5mg L-1 IBA at rooting phase.

RESUMO: Programas de melhoramento internacional lançaram novos materiais genéticos de porta-enxertos de macieira que além de precoces e produtivos são resistentes as principais doenças e pragas de solo das maiores regiões produtoras de maçã no Brasil. Diante disto, existe a necessidade de propagação vegetativa destes materiais para estudos e possível substituição dos atuais porta-enxertos. O objetivo foi adaptar um protocolo de micropropagação para o novo porta-enxerto de macieira ‘G. 814’. Na fase de multiplicação dos explantes foram avaliadas concentrações de BAP: 0; 0.5; 1; 2 e 4mg L-1 e na de enraizamento concentrações de AIB: 0; 0.25; 0.50; 1; 1.5 e 2.5mg L-1. Esta seleção de porta-enxerto pode ser micropropagada com este protocolo adaptado. Para o sucesso na propagação in vitro do porta-enxerto de macieira ‘G. 814’ é indicado o uso de 1mg L-1 de BAP na fase de multiplicação e de 1.5mg L-1 de AIB na fase de enraizamento.

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.