Denise Ester Ceconi

Primeira ocorrência de Pythium sp. e Rhizoctonia sp. causando podridão-de-raízes em ervais no Rio Grande do Sul.

In 2004, some plantations of Ilex paraguariensis A. St.-Hil. In Taquari Valley, state of Rio Grande do Sul, started presenting growth stagnation, yellowing, leaf drop and necrosis in the root system, typical symptoms of root rot. Roots samples were collected in farms of two cities and sent for analysis at the Plant Disease Laboratory at the Department of Plant Protection/CCR/UFSM. The presence of Rhizoctonia and Pythium was diagnosed and these were pathogenic when inoculated in plants of erva-mate . This is the first observation of these two fungi causing root rot in erva-mate plantations in the state of Rio Grande do Sul, Brasil.

Historical gene flow within and among populations of Luehea divaricata in the Brazilian Pampa

Within and among population gene flow is a central aspect of the evolutionary history of ecosystems and essential for the potential for adaptive evolution of populations. We employed nuclear microsatellite markers to assess inter- and intra-population gene flow in five natural populations of Luehea divaricata growing in the Pampa biome, in southern Brazil. This species occurs in practically all secondary forests of the Pampa and has recognized ecological significance for these formations. The genetic structuring of the studied populations suggests limited gene dispersal among forest fragments, despite a homogeneous level of migration among populations. Notwithstanding the gene flow among populations, significant SGS is still found in some fragments. Significant spatial genetic structure within population was also found likely as result of limited seed and/or pollen dispersal. The scattered distribution of the populations and their relatively high density seem to limit pollen dispersal. Also seed dispersal by wind is not efficient due to large distances among forest formations. As conservationist actions towards preserving the genetic resources of L. divaricata and the Brazilian Pampa, we suggest the protection of the existing forest formations and the maintenance of the natural expansion of the forests over the grasslands in the biome.

Germination and development of pecan cultivar seedlings by seed stratification

The objective of this work was to evaluate the effect of seed stratification on germination rate, germination speed, and initial development of seedlings of six pecan ( Carya illinoinensis ) cultivars under subtropical climatic conditions in southern Brazil. For stratification, the seeds were placed in boxes with moist sand, in a cold chamber at 4°C, for 90 days. In the fourteenth week after sowing, the emergence speed index, total emergence, plant height, stem diameter, and number of leaves were evaluated. Seed stratification significantly improves the germination potential and morphological traits of the evaluated cultivars.

INFLUÊNCIA DA INOCULAÇÃO DE Fusarium spp. E NÍVEIS DE SOMBREAMENTO NO CRESCIMENTO E DESENVOLVIMENTO DA ERVA-MATE

The “erva-mate” ( Ilex paraguariensis A. St.-Hill) is a species broadly cultivated in southern Brazil and neighboring countries, whose leaves and fine branches, prepared according to the appropriate method, make the “mate” or “chimarrao”, the most popular tea consumed in Brazil and exported around the world. With an increasing planted area, mainly in the last decade, phytosanitary problems caused by pests and disease have increased in this crop and root-rot is becoming one of the main problems. The disease is caused by Fusarium spp. and it causes serious damage to the roots, in the most serious cases, leading to the death of the plant. The “erva-mate” is a species that inhabits the forest underwood, and cultivation in a homogeneous way to full sun can be a stressful factor for the species causing less growth and development and, also, more susceptibility to root-rot. Therefore, experiments were conducted in the Forest Nursery area belonging to Forest Sciences Department of the Federal University Santa Maria with the objective of confirming these assumptions. The experiment was conducted in a factorial design (2 x 5), composed by Fusarium spp. inoculation and by shading levels. It was verified that plants submitted to lower shading levels or full sun had less development and were more susceptible to the disease. The plants inoculated with Fusarium spp. had less development in comparison with non-inoculated plants, mainly at the lower shading levels.

Aspectos epidemiológicos da podridão-de-raízes da erva-mate (Ilex paraguariensis)

The root-rot of erva-mate, caused for Fusariumspp., Rhizoctoniasp. and Pythium sp., is the main disease of the culture and causes serious damages in nurseries and forest stands. However, few studies exist regarding to the epidemiology of this disease. Thus, the present work studied and described the main epidemic aspects related to erva-mate root-rot in nurseries and forest stands. For that, nurseries and forest stands were chosen for studies in Vale do Taquari, RS state, where flowers, fruits, seeds, plantlets, seedlings and soil were collected for laboratory analyses. It was observed that the pathogens can enter in the patho-system through the flowers, because 80% of them presented contamination of Fusarium sp. and 15% of Rhizoctonia sp. Moreover, the obtaining method and stratification of the seeds, used in the nurseries, contribute to the increase of contamination, reaching 100% of the seeds in the moment of sowing. It was also observed that contaminated seedlings may be symptomless and, after transplanting in the field, contaminate pathogen free areas. Pathogenicity tests with some isolates showed their capacity of causing the disease.

Epidemiological aspects of root-rot of 'erva-mate' (Ilex paraguariensis)

The root-rot of erva-mate, caused for Fusarium spp., Rhizoctonia sp. and Pythium sp., is the main disease of the culture and causes serious damages in nurseries and forest stands. However, few studies exist regarding to the epidemiology of this disease. Thus, the present work studied and described the main epidemic aspects related to erva-mate root-rot in nurseries and forest stands. For that, nurseries and forest stands were chosen for studies in Vale do Taquari, RS state, where flowers, fruits, seeds, plantlets, seedlings and soil were collected for laboratory analyses. It was observed that the pathogens can enter in the patho-system through the flowers, because 80% of them presented contamination of Fusarium sp. and 15% of Rhizoctonia sp. Moreover, the obtaining method and stratification of the seeds, used in the nurseries, contribute to the increase of contamination, reaching 100% of the seeds in the moment of sowing. It was also observed that contaminated seedlings may be symptomless and, after transplanting in the field, contaminate pathogen free areas. Pathogenicity tests with some isolates showed their capacity of causing the disease.

Influência da aplicação de NPK e calcário sobre o crescimento da erva- mate, severidade da podridão-de-raízes e população fúngica do solo

The present work evaluated the influence of the application of NPK and liming doses in the soil, on the growth of Erva-mate, the severity of rot-root and the fungi population of the soil. To do so, an experiment was installed at the green house, in the Forest Nursery of UFSM, using an experimental design completely randomized factorial 4x3x4 (Factor F: Fusarium spp. inoculation; Factor C: soil limestone; Factor A: NPK doses) , totaling 48 treatments. The seedlings were cultivated in vases containing 2 kg of soil, classified as ‘Red-Yellow Argisoil’ (clay soil). At the end of the experiment was measured the stem diameter, height of the aerial part, leaves number, aerial dry biomass, root dry biomass and total dry biomass of the seedlings. Also, the soil was collected, from each treatment, for the chemical analysis and the counting of the fungi population. It was observed that the association among application of NPK and liming in the soil hampered the development of Erva-mate seedlings. The analysis of some variables suggests that the limestone absence provided greater resistance of seedlings to the attack of Fusarium spp. or the severity of Fusarium spp. was reduced in lower pH. The fungi population of the soil presented varied behavior depending on the applied treatments.

Inoculação de Fusarium oxysporum e Fusarium solani e níveis de sombreamento na erva-mate: influência na severidade da podridão-de-raízes

Ilex paraguariensis A. St.-Hill is a broadly cultivated species in the South of Brazil. With the increasing planted area, mainly in the last decade, fitosanitary problems caused by pest and diseases have increased in this crop, and the root-rot is becomin g one of the main problems. Among the pathogens, Fusarium oxysporum Schlecht. and Fusarium solani (Mart.) Sacc are the main ones. These fungi provoke severe damages resulting in the destruction of the root system and, in the most serious cases, they ca use the death of the plant. It is suspected that the incide nce and severity of disease are influenced by culti vation of Ilex paraguariensis in different levels of shading or full sun. Theref ore, experiments were conducted in the Forest Nursery area belonging to Forest Sciences De partment/CCR/UFSM with the objective of confirming this assumption. The experiment was conducted in a factorial design (2 x 5), composed by Fusarium oxysporum and Fusarium solani inoculation and by shading levels. It was verified that the plants submitted to lower shading levels or full sun had their predi sposed to the disease.