versão impressa ISSN 0100-5405
Summa phytopathol. vol.37 no.2 Botucatu abr./jun. 2011
Lesões foliares e queda de folhas em Eugenia spp. causadas por Cylindrocladium spathiphylli e C. candelabrum no Brasil
Luiz Sebastião PoltronieriI; Rafael Ferreira AlfenasII; Jaqueline Rosemeire VerzignassiIII,*; Acelino Couto AlfenasII; Ruth Linda BenchimolI; Tathianne Pastana de Sousa PoltronieriI
IEmbrapa Amazônia Oriental, Tv. Enéas Pinheiro, S/N, CEP 66095-100, Belém, PA
IIDepartamento de Fitopatologia, Universidade Federal de Viçosa, CEP 36570-000, Viçosa, MG
IIIEmbrapa Gado de Corte, Rodovia BR 262, km 4, Caixa Postal 154, CEP 79002-970, Campo Grande, MS
Relata-se a incidência de mancha, queima foliar e desfolha, causadas respectivamente por Cylindrocladium candelabrum (Calonectria scoparia) em Eugenia stipitata Mc Vaugh (araçá-boi) e C. spathiphylli (Calonectria spathiphylli) em Eugenia patrisii Vahl (ubaia-da-amazônia), no Estado do Pará, Brasil. Em ambos os hospedeiros, a doença caracteriza-se por lesões necróticas de diferentes dimensões e formas, coloração marrom escura, contendo uma massa branca brilhante de esporulação típica de Cylindrocladium, facilmente observada sob microscópio estereoscópico ou com o auxílio de uma lente de bolso de 10 20 x de aumento. Sob condições favoráveis à infecção, as plantas podem sofrer intensa queda prematura de folhas. Embora, o maior número de conídios germinados e o maior crescimento micelial foram obtidos a 25ºC para ambas as espécies, C. candelabrum foi mais sensível às variações de temperatura (10, 20, 30 e 40 ºC) que C. spathiphylli. Este é o primeiro relato de C. candelabrum em Eugenia stipitata e C. spathiphylli em Eugenia patrisii no Brasil.
Palavras-chave adicionais: lesões foliares, Myrtaceae.
Leaf blight and defoliation of Eugenia stipitata Mc Vaugh and Eugenia patrisii Vahl, caused respectively by Cylindrocladium candelabrum (Calonectria scoparia) and C. spathiphylli (Calonectria spathiphylli) are reported in the state of Pará, Brazil. On both host species, the disease is characterized by dark brown lesions of different sizes and shapes. A whitish bright sporulation, resembling Cylindrocladium is observed on the necrotic lesions by using a stereomycroscope or a pocket lense (10-20 X). Under favorable conditions and depending on the level of infection, intense premature tree defoliation may also be found.Although the conidial germination and mycelial growth were higher at 25ºC for both species, C. candelabrum was more sensitive to the variation of temperature (10, 20, 30 and 40 ºC) than C. spathiphylli. This is the first report of C. candelabrum and C. spathiphylli on Eugenia stipitata (araçá-boi) and on Eugenia patrisii (ubaia-da-amazônia), respectively in Brazil.
Keywords: foliar lesions, Myrtaceae.
Plants of Eugenia stipitata Mc Vangh (araçá-boi) and Eugenia patrisii Vahl showing leaf blight and defoliation were found in the Experimental field of Emb 0 x 4,5-5,0 µm and globose vesicle typical of Cylindrocladium spathiphylli Schoult., El-Gholl & Alfieri (Calonectria spathiphylli El-Gholl, J.Y. Uchida, Alfenas, T.S. Schub., Alfieri & A. R. Chase) (Figure 2), sensu Crous (3).
Inoculations to confirm the pathogenicity of both fungi were made by placing inoculum plugs (5 mm diameter) on the adaxial portion of the leaf limb of the respective plant species. After inoculation the plants were maintained in a moist chamber for 48 h and then transferred to a green house. Three days later typical symptoms of the disease were observed and re-isolations of the fungi to PDA confirmed their pathogenicity on the respective host species. This is the first report of C. candelabrum on E. stipitata and C. spathiphylli on Eugenia patrisii in Brazil, although C. scoparium Morgan and C. gracile (Bugn.) Boesew. were already found causing fruit and root decay in araçá-boi in Pará State and in Federal District, respectively (4, 5). The two fungal species reported here have an ample geographic distribution and a wide host range (3).
Conidial germination and the mycelial growth of both fungi were evaluated at 5, 15, 20, 25, 30 and 35ºC in the dark. For germination, 25 µl of a 1x104 conidia.mL-1 suspension were added into three cavities of a sterile glass slide. Each treatment contained three replicates, in a completely randomized design. After 4h of incubation in the dark, germination was interrupted by addition lacto phenol-cotton blue and the percentage of germination was estimated by scoring 600 randomly chosen conidia per treatment, under a optical mycroscope (200 X). Conidia presenting differentiated germ tubes, independently on their size were considered germinated. Germination of C. candelabrum and C. spathiphylli conidia varied significantly with the temperature of incubation, but it was higher at 25°C for both species (Figure 3). However, C. candelabrum was more sensitive to temperature variation than C. spathiphylli (Figure 3). On the other hand, based on the regression equation, the estimated optimum temperature for conidial germination was of 23°C for C. candelabrum and 28°C for C. spathiphylli.
For the mycelium growth one culture disk (4 mm diameter) of each fungus was transferred separately to each 125 mL Erlenmeyer flask, containing 50 mL of a semi-synthetic liquid growth media (1), following incubation at the same temperatures tested for spore germination. Five replicates in a completely randomized experimental design were employed. At 10 days of incubation the mycelial mat was filtered in a Buchner funil containing a Whatman no. 1 filter paper. After removal of the water excess by pressing the mycelial mat in germ test filter paper, the fresh weight was determined. The highest mycelial growth of both species was at 25°C. Based on the regression equation (Figure 4), the estimated optimum temperature was 20°C for C. candelabrum and 23°C for C. spathiphylli. As for conidial germination, C. candelabrum was also more sensitive to the temperature variation than C. spathiphylli. Generally, the effect of temperature on mycelial growth for both fungi studied in the present work was similar to that found for C. ilicicola isolated from eucalyptus (2). This findings may have important implications on the occurrence of these fungi according to the temperature oscillation around the year and may explain the wide geographical distribution of C. candelabrum in less warm southeaster regions in Brazil.
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Data de chegada: 21/12/2009.
Aceito para publicação em: 06/11/2010.