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Venezuela, Spain

Inflorescence smut of Panicum maximum Jacq. is caused by the fungus Tilletia ayresii, which disables the production of seeds to form galls on the ovaries of the spicules. The aim of this study was to establish a method to quantify the production of inoculum of T. ayresii in inflorescences of P. maximum. Spicules affected were collected, which were determined length, total weight, empty weight and weight of the inoculum content. To quantify the total in oculum (IT) standardizes a methodology for using a McMaster counting chamber differential fungal structures (fs) providing the IT: teliospores (TE), sterile cells (EC) and conidia (CO). The data were subjected to statistical tests to assess normality and significance. The results show an average length of 4.2 mm by spicules affected, with a total weight and inoculums weight of 26 and 8.9 mg, respectively, as found high correlation (r = 0.97/P<0.0001) between the size and weight of spicules affected. There was high production of reproductive structures of the fungus T. ayresii and quantified loads of 9.2x104, 2.9x106 and 11.4x106 mg.ef-1 inoculum with a percentage distribution in 2.52; 11.37 and 86.11% respectively for TE, CE and CO, totaling 20.9x107 ef-1.spicule affected. In conclusion, T. ayresii has a high capacity to produce viable inoculum for future infestations, consisting mostly of conidia, which are considered the primary source of infestation and warty teliospores that form the dormant inoculum in the soil. Source

Borges J.A.,Instituto Nacional Of Investigaciones Agricolas | Camacaro O.,Fundacion CIEPE | Dominguez L.,Fundacion CIEPE | Graterol A.,Fundacion CIEPE
Revista de la Facultad de Agronomia

The fern P. aquilinum is considered one of the five most important weeds in the world and their presence are considered as a predisposing factor for the occurrence of Bovine Enzootic Haematuria in farms of high zones. This research was based on determining the chemical composition (proximal and mineral) of the fern P. aquilinum subs. Arachnoideum present in grazing areas in Bolivar municipality, Yaracuy state, as a contribution to enable new research-oriented routing management of this global problem. For this, samples were collected fronds (2 kg c/u), stratified by phenology in regrowth, young and adult frond, which were subjected to drying and subsequent proximate and mineral analysis. The results indicate that in this species, the crude protein and fat are higher in regrowth (21.4 and 2.03%, respectively) and decrease as the plant changes its stage, while crude fiber and total carbohydrates were higher in adult plants (23.4 and 67.9%, respectively). The average energy levels were 3.3 Mcal.kg-1 DM in all stages. Nitrogen content (2.5%), phosphorus (0.3%), magnesium (0.1%), copper (10.5 mg.kg-1) and zinc (10.4 mg.kg-1) is negatively associated (r = -0.96) with the increase of the dry matter. These results disclose the physicochemical characteristics of P. aquilinum subs. Arachnoideum, allowing the inference that the same consumption by cattle is related to poor quality forage supply and there in the fields where it is located. Source

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