Igor Poletto

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.

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.

Culture Medium, Light Regime and Temperature Affect the Development of Sirosporium diffusum

Sirosporium diffusum is the causal agent of the brown leaf spot disease on pecan trees that seriously damages the foliage of adult plants and seedlings. This fungal species is difficult to grow satisfactorily in a culture medium. Therefore, the aim of this study was to evaluate the effects of different physical conditions on the development of S. diffusum . In the first assay, eight culture media and five light regimes were combined, while in the second, the three treatments that promoted highest sporulation were combined with three temperatures. The trials were conducted in a two-factorial arrangement in a fully randomized design with six replicates. V8, V8CaCO 3, and CA media under a 24-h photoperiod produced the highest respective sporulations: 29 × 10 4 , 35 × 10 4 , and 41 × 10 4 conidia ml -1 . The best temperature for sporulation was 20±1 °C for all culture media, especially V8CaCO 3 and CA. The best artificial conditions for obtaining good mycelial growth and sporulation consisted of a photoperiod of 24 h, temperature of 20±1 °C and V8CaCO 3 or CA culture medium.

FUNGOS ASSOCIADOS ÀS FLORES E FRUTOS DA NOGUEIRA-PECÃ (Carya illinoinensis)

O presente trabalho teve como objetivo identificar e determinar a incidencia os fungos associados ao sistema reprodutivo, flores e sementes, de nogueira-peca, bem como testar a eficiencia da assepsia em sementes. Este conhecimento e de suma importância para uma boa realizacao das praticas culturais e conservacao dos frutos. Para analise, foram coletadas flores e amendoas em pomares de Santa Maria e de Anta Gorda – (RS), durante os meses de setembro de 2010 a julho de 2011. O material foi analisado atraves de testes de sanidade pelo metodo de papel filtro, comparando a incidencia fungica presente nas flores dos dois locais, e nas amendoas comparando a eficiencia da assepsia. Observou-se alta incidencia de Alternaria sp. nas flores femininas coletadas em Santa Maria e Anta Gorda e em flores masculinas de Anta Gorda. Incidencia elevada de Fusarium sp. e Penicillium sp. foi observada em flores femininas e masculinas de ambas procedencias. Cladosporium sp. esteve presente em flores femininas de Santa Maria e flores masculinas de Anta Gorda. Nas sementes (amendoas) os fungos que ocorreram associados foram: Ceplalosporium sp., Colletotrichum sp., Fusarium sp., Penicillium sp. e Verticillium sp., sendo que nao houve reducao estatisticamente significativa de sua incidencia com a realizacao da assepsia das sementes, exceto para Ceplalosporium sp. Fungos potencialmente patogenicos, tais como Fusarium sp., Pestalotiopsis sp., Alternaria sp., Cladosporium sp. e Colletotrichum sp., foram identificados tanto em flores quanto em frutos de nogueira-peca representando riscos as mudas no caso de sua transmissao via semente.

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.