Resumo

ALICE, Chávez¹  e  KOHLI², Mohan. Alternative hosts of Magnaporthe grisea of wheat in Paraguay. Investig. Agrar. [online]. 2015, vol.17, n.1, pp.54-59. ISSN 2305-0683.  https://doi.org/10.18004/investig.agrar.2015.junio.54-59.

The first epidemic of wheat blast disease caused by Magnaporthe grisea (T.T. Hebert) M.E. Barr (anamorfo Pyricularia grisea Sacc.), was reported in 2002, causing more than 70% of production losses in seeded fields in the first half of April in Paraguay. This fungus attacks a wide number of hosts, including wheat and rice, as well as large number of other grass species and local weeds. So far, there is no knowledge on alternative host species to wheat blast fungus or their contribution to inoculum load for wheat in Paraguay. Therefore, the objective of this study was to identify alternative host species of Magnaporthe grisea present in the Capitán Miranda Research Center, Itapúa, and in the Yhovy Experimental Station, Canindeyú, during 2013 and 2014 crop cycle. Weed samples of showing characteristic blast disease symptoms were collected from both locations. These samples were kept in the humid chamber and later the fungus was transferred to Potato Dextrose Agar, PDA, culture medium and incubated for five days at 25ºC in the Phytopathology laboratory at Hernando Bertoni Research Center, Caacupé. Afterwards, the fungal identification was done by observation under stereoscope and microscope. From the 21 weed species collected in the field, the fungus was observed on Bromus catharticus, Chloris gayana, Cyperus diffusus, Digitaria horizontalis and Lolium multiflorum. Pathogenicity tests conducted with isolates collected from Bromus catharticus, Digitaria horizontalis and Lolium multiflorum confirmed their potential to infect wheat

Palavras-chave : Magnaporthe grisea,; wheat,; alternative host species.

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