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Pelotas, Brazil

A sowing tool denominated ERRS was developed, which, when coupled to the straw-cutting disks of no-till planters, reduces soil disturbance during crop sowing. To evaluate the effect of this tool on weed management, two experiments were carried-out at Cruz Alta-RS, Brazil. Soil exposure at corn row sowing, weed emergence density and site (row and inter-row) and the interaction of these characteristics with chemical weed control were determined. Both experiments were conducted in a split-plot design with five repetitions to test the factors weed control and tool used. The prototype evaluated kept the soil mulch almost intact when planting corn, with soil exposure in the field being reduced up to 78%, with consequent reduction in emergence of Bidens sp. (55%), Brachiaria plantaginea (up to 37%), Ipomoea sp. (50%) and Raphanus raphanistrum (26%). The species Bidens sp., B. plantaginea and R. raphanistrum germinated predominantly in the plant rows. This tendency was not so evident in the other weeds studied, mainly C. halicacabum and E. heterophylla. The use of the proposed equipment decreased soil exposure in the corn sowing rows, reducing the density of several weeds and improving the chemical weed control of the crop.

Mayer N.A.,BR 392 | Ueno B.,BR 392 | da Silva V.A.L.,Catholic University of Pelotas | Valgas R.A.,BR 392 | Silveira C.A.P.,BR 392
Revista Brasileira de Fruticultura | Year: 2015

The Peach Tree Short Life (PTSL) is a syndrome characterized by a tree collapse at end of dormancy and its causes involve several biotic and abiotic components. The objective of this research was to study if there was association between PTSL and soil fertility. Rhizosphere samples were collected for chemical analysis from two to eight-years-old symptomatic and asymptomatic trees (paired trees), at nine commercial peach orchards located in Pelotas and Canguçu, state of Rio Grande do Sul, Brazil, totaling 108 samples. According to the results, discriminate function for classifying trees into two categories (symptomatic or asymptomatic) did not provide satisfactory results because the misclassification rate exceeded 40%. The analysis of variance showed that there is no significant difference in soil fertility between two groups of trees sampled. Although soil fertility, in most orchards sampled, is below than recommended level for peach, the occurrence of PTSL was not associated with soil chemical properties. The present research suggests that other factors such as soil physical properties and the use of non-selected varietal mixtures of scion cultivars as rootstock, may be involved in PTSL. © 2015, Sociedade Brasileira de Fruticultura. All rights reserved.

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