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During August 2003, guava fruit (Psidium guajava L.) cv. Red Dominicana from Cojedes state in Venezuela showed circular, purple-to-brown lesions (0.5 to 1.0 cm) that spread over all surfaces and became black and shrunken on severely affected fruit. Symptomatic tissues were plated aseptically on potato dextrose agar (PDA). Colonies that were initially gray and turned black with age were consistently isolated. The fungus was characterized by dense, submerged, brown-to-black mycelium with septate hyphae. Ascocarps were perithecial, abundant, granulose, subglobose to cylindric obpyriform, solitary or aggregated, mostly unilocular with prominent long necks; ascocarp walls were stromatic, composed of several layers of cells, thick walled, and deeply pigmented on the outside. Asci were subclavate to cylindrical, stipitate, 44 to 84 × 7 to 9 μm, and eight-spored; asci walls were thick and bitunicate. Ascospores were unicellular, hyaline, guttulate, fusiform ellipsoid, widest in the mid-region with rounded ends and gelatinous plugs, and 12 to 17 × 4.5 μm. Conidiomata were pycnidial, intermixed among ascocarps, variable in shape, dark brown, solitary or aggregated, ostiolate, and with long necks up to 1 mm. Pycnidial walls were pseudoparenchymatic, multicellular, and composed of many layers of brown compressed cells. Conidiogenous cells were hyaline, subglobose to cylindrical, and smooth, and holoblastic. Conidia were hyaline, unicellular, obovate, 6 to 12 (7.5) × 5 to 8 μm, slightly truncate at the bases, rounded at apices, guttulate, and provided a gelatinous envelope and apical appendage. Appendages were hyaline, tubular, smooth, and 3.0 to 4.5 × 0.5 μm. The fungus is homothallic because single ascospores and single conidia developed ascigerous states. The ascigerous state was identified as Guignardia psidii (1) and the anamorph as Phyllosticta psidiicola (1,2). Pathogenicity tests were conducted on detached fruits inoculated with monosporic cultures. Pathogenesis and symptom development only occurred when a mixture of mycelium, ascospores, and conidia was used as inoculum. The fungus was reisolated from symptomatic fruit tissues. To our knowledge, this is the first report of Guignardia psidii, an ascigerous state of Phyllosticta psidiicola from guava fruits in Venezuela. References: (1) B. A. Ullasa and R. D. Rawal. Curr. Sci. 53:435, 1984. (2) H. A. van der Aa. Page 95 in: No. 5, Stud. Mycol., 1973.

A survey conducted in SP state in 2005 and another in 2007 found that black spot (Guignardia psidii) incidence on guava reached 58 %. The aim of this study was to investigate the effects of temperature and wetness duration on the development of black spot symptoms in detached guava naturally infected under controlled conditions. Guava fruit cv. Kumagai from a production field with a history of occurrence of the disease were subjected to different temperatures (10, 15, 20, 25, 30 and 35 °C) with wetness periods of 6 and 24 h. Analyses of variance and nonlinear regression were employed to evaluate the combined effects of temperature and wetness duration on the disease incidence, the final disease severity, the rate of disease progression and incubation period. Black spot symptoms were observed at all temperatures, except at 10 and 35 °C. The first symptoms of black spot in guavas were observed 2 days after incubation at 25 and 30 °C with wetness duration of 6 h. All variables reached their maximum values close to 30 °C, regardless of wetness duration. This temperature combined with 24 h of wetness duration resulted in black spot incidence of 100 %, disease severity of 3.02 cm, progress rate of 6.9 mm/day and incubation period of 6 days, 10 days after incubation. The postharvest storage of fruits at 10 °C and other control methods based on low or high temperature can delay the black spot incidence on ‘Kumagai’ guavas and prolong the fruit shelf life.

The guava fruit is very as high perishable due to its intense metabolism and the occurrence of postharvest diseases. Due to the lack conservation technologies for this fruit, this study aimed to evaluate the effect of alternative products [potassium phosphite, calcium chloride, cassava starch edible coat, 1-methylcyclopropene (1-MCP), ethanol followed by dichloro s. triazinatriona sodium (ethanol+chlorine)] and hot water treatments, singly or in combination, in black spot control and the physic-chemical characteristics of ‘Pedro Sato’ guavas. The treatments were evaluated in naturally infected guavas at three maturity stages and stored at 22-25ºC and 80-85% RH for 8 days. The treatment association of ethanol+chlorine and cassava starch reduced the incidence of black spot in three maturity stages of guavas, allowing the increase of fruit’s shelf life, with a delay of two to four days in the onset of black spot symptoms. The maintenance of the physical and chemical quality characteristics of guavas with association of treatments were evidenced by the delay in skin color change, and a smaller decrease in firmness. Correlation occurred between the black spot incidence and the skin color parameter, ie, fruits harvested at later maturity stages presented higher incidence of the disease. The greater efficiency of ethanol+chlorine/starch association in the control of black spot was directly related to the ripening delay in fruits, evidenced by the skin color and firmness attributes., A goiaba apresenta elevada perecibilidade decorrente do seu intenso metabolismo e da ocorrência de patologias no período pós-colheita. Em virturde da carência de tecnologias de conservação de goiabas, objetivou-se avaliar o efeito de produtos alternativos [fosfito de potássio, cloreto de cálcio, fécula de mandioca, 1-metilciclopropeno (1-MCP), etanol seguido de dicloro s. triazinatriona sódica dihidratada (etanol+cloro)] e de hidrotermia, isoladamente e em associação, no controle da pinta preta e nas características físico-químicas de goiabas ‘Pedro Sato’. Os tratamentos foram avaliados em goiabas infectadas em condições de campo, em três estádios de maturação, armazenadas a 22-25ºC e 80-85% de UR, por 8 dias. A associação de tratamento etanol+cloro/fécula de mandioca reduziu a incidência de pinta preta nos três estádios de maturação de goiabas, permitindo um maior período de conservação dos frutos, com um atraso de dois a quatro dias no aparecimento dos sintomas da doença. A manutenção da qualidade físico-química das goiabas com as associações de tratamentos foi evidenciada pelo atraso na mudança de coloração da casca e menor redução na firmeza da polpa. Observou-se correlação entre os parâmetros incidência de pinta preta e cor da casca, ou seja, frutos colhidos em estádios mais avançados de maturação apresentaram maior incidência da doença. A maior eficiência da associação etanol+cloro/fécula no controle da pinta preta relacionou-se diretamente com o atraso no amadurecimemento dos frutos, evidenciado pelos atributos cor da casca e firmeza da polpa.

As doenças pós-colheita representam sério obstáculo à cultura da goiaba, uma vez que comprometem a qualidade e a quantidade dos frutos para comercialização. Neste estudo, foram identificadas e quantificadas injúrias mecânicas decorrentes dos processos de colheita e transporte das goiabas. Além disso, avaliou-se a incidência de doenças pós-colheita e pragas em goiabas da cultivar 'Pedro Sato' comercializadas na CEASA-Bauru e em goiabas das cultivares 'Pedro Sato' e 'Paluma' de pomares do Centro-Oeste paulista. Os frutos de goiaba amostrados em quatro etapas da colheita (colheita com luva, sacola do colhedor, contentor e barracão) e na CEASA foram armazenados durante nove dias a 25 ºC. A incidência de injúrias foi avaliada visualmente a cada três dias. A ocorrência de frutos com podridões foi superior na goiaba 'Pedro Sato' (92,0% a 96,6%) comparada a 'Paluma' (77,1%) no fim do armazenamento. A antracnose foi a principal doença nas duas cultivares, seguida pela pinta-preta. A incidência de injúrias mecânicas foi crescente no decorrer das etapas de colheita, entretanto, não influenciaram no aparecimento das podridões. Elevada infestação de moscas-das-frutas foi constatada na goiaba 'Paluma'. Postharvest diseases represent a serious drawback to guava crop, once they reduce quality and quantity of fruits for marketing. This study identified and quantified mechanical injuries resulting from the processes of harvesting and transporting of guavas and the incidence of postharvest diseases and pests in 'Pedro Sato' guava commercialized at CEASA/Bauru and in 'Pedro Sato' and 'Paluma' guavas cultivated in the Midwest Region of the State of São Paulo. Guava fruit collected at four harvest stages (harvest with gloves, harvest bag, tractor trailer and packing table) and at a wholesale market (CEASA) were stored for nine days at 25 ºC. The incidence of damages was visually evaluated every three days. The occurrence of rot fruit was higher in Pedro Sato cultivar (92.0% to 96.6%) than in 'Paluma' (77.1%) at the end of storage period. Anthracnose was the main disease in the two cultivars, followed for the black spot. The incidence of mechanical injuries increased along the harvest stages; however, it was not related to the occurrence of rots. High infestation of fruit fly in 'Paluma' guava was also verified.