TIRIRICA (Cyperus rotundus): FONTE DE INÓCULO DE Pyricularia grisea AGENTE CAUSAL DA BRUSONE

Abstract

The Tiririca (Cyperus rotundus) is a common perennial weed native to Africa, present in tropical and subtropical regions including Asia, the Americas and Australia. It is a difficult species to control due to its extensive root system. Herbicides of natural origin such as plants, bacteria or fungi are less toxic and environmentally persistent strategies for weed control. The objective of this work was to record and describe the symptomatology and etiology of Pyricularia grisea incident on nutsedge leaves. Leaves were collected in January 2023 and analyzed under a stereoscopic microscope. Symptoms were recorded with the naked eye under a stereomicroscope. Using lactophenol (cotton blue dye), semi-permanent slides (direct collection and histological section) were prepared for microscopic recording. The morphology and morphometry of macro and microscopic structures were performed for identification and comparison with the description by Klabauf et al. (2014). Symptoms: brown leaf spot, spherical to subspherical, from two to 15 mm in diameter, without the presence of halos, with concentric rings in the necrotic tissue, and amphigenous stroma, present on the leaves of basseiro, with an approximate severity of 1-8%. Signs: conidiophores from stromal tissue originating from one to two conidiophores, truncated, irregular and at apex, healed, geniculate, indistinctly multiseptate 78.0-(59.0)-32.8 x 7.0-(3.5 )-1.4 μm; Conidia hyaline, acicular, straight or slightly curved, truncated, subacute and with a pointed base, indistinctly multiseptate 36.2-(21.7) -14.1 x 6.1-(3.6) -2.2 m. This is the first record of the occurrence of P. grisea incident on nutsedge leaves in the municipality of Urutaí (GO).