The forest species are frequent targets of diseases. In this context, the plant-parasitic algae comprise a separate group in this process, including the algae genus Cephaleuros, which attacks mahogany cultivars. The objective of this work was to accomplish the molecular and morphological characterization of the causal agent of algae spots occurring in Brazilian mahogany (Swietenia macrophylla). Somatic and reproductive algae structures contained in lesions on the leaves had the DNA extracted and amplified by primers 18SHf and 18SLr of the rRNA nuclear gene 18S. Then, the amplicons were purified and sequenced. The algae structures too were characterized under light microscope. In addition, a total of 12 injured leaves located in the lower third of each attacked tree were randomly extracted for lesion characterization according to its size and number. After algae structures measurements, sporangiophores and sporangia had 260.2 x 12.9 μm and 25 x 18.8 μm. These measurements, combined with the molecular identification, indicated that the algae found in Brazilian mahogany leaves is C. virescens. Attacked leaves showed an average of 33 lesions, 60% of which were smaller than 2 mm in diameter, which shows great capacity of the pathogen to reach different parts of the foliar limb. These measurements, combined with molecular identification, confirmed the algae found in Brazilian mahogany leaves to be C. virescens.

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The aim of this study was to evaluate four strains of Trichoderma spp. (T. harzianum IBLF 006 WP, T. harzianum IBLF 006 SC, T. harzianum ESALQ 1306 and T. asperellum URM 5911) for seedling growth promotion in laboratory and head lettuce yield in field conditions. The experiment was carried out in a completely randomized design with four treatments (strains): IBLF 006 WP, IBLF 006 SC, ESALQ 1306 and URM 5911 and a non-inoculated (without Trichoderma) control. Each treatment consisted of 200 seeds, arranged in four replicates. Lettuce seeds cv. Astra were treated with 2 mL Trichoderma suspension (2.5 x 108 conidia mL-1 per each 100 g seeds) and submitted to growth assay in laboratory up to 7 days after sowing. For field experiment, we opened furrows, which were manually sprayed with 5 x 107 conidia mL-1. Afterwards, seedlings were transplanted (4 to 6 leaves of head lettuce cv. Mauren) and harvested 40 days later. Each treatment consisted of four replicates (1.2 x 1.2 m, 16 plants per plot) arranged in randomized blocks. In both experiments, a control without Trichoderma application was included, and we evaluated shoot length, root and total length, shoot, root and total fresh mass and shoot, root and total dry mass, shoot mass ratio, root mass ratio and shoot/root ratio. The germination (%) was evaluated by laboratory tests, whereas in field experiment, height, stem diameter, head diameter, number of leaves and yield were evaluated. The T. harzianum strain ESALQ 1306 provided the best head lettuce growth rate in laboratory test, which was confirmed in field experiment, in which the productivity (50.2 t ha-1) was superior when compared to the other strains (41.38 to 44.23 t ha-1) and the control (30.18 t ha-1).

O potencial de uso de Trichoderma para o controle biológico de patógenos em sementes, assim como no controle de doenças do feijoeiro em condições de campo, tem sido constatado. Além de possuir diferentes mecanismos de controle, tais como antibiose, competição e hiperparasitismo, o fungo Trichoderma possui habilidade para colonizar a rizosfera e as radículas das plântulas, podendo também atuar na promoção do crescimento inicial do feijoeiro. Esta revisão tem por finalidade levantar as recentes pesquisas realizadas no Brasil, acerca deste fungo como agente de biocontrole de Cladosporium sp., um importante patógeno de sementes e de Sclerotinia sclerotiorum, causador do mofo branco, abordando também seu efeito promotor sobre o crescimento do feijoeiro.

Objetivou-se com esta revisão realizar um levantamento sobre a cercosporiose do quiabeiro, enfocando os aspectos mais relevantes para a doença no Brasil: características micromorfológicas do patógeno, sintomatologia, epidemiologia e controle da doença. Resumidamente, P. abelmoschi e Cercospora (C. hibiscina e C. malayensis) podem ser diferenciados baseando-se nas características dos conidióforos, enquanto C. malayensis e C. hibiscina são diferenciados pelo comprimento dos conidióforos e conídios. No Brasil, a cercosporiose está frequentemente associada às espécies C. malayensis e C. hibiscina, em que C. malayensis é uma espécie menos agressiva, causando manchas foliares escuras e arredondadas e, por outro lado, C. hibiscina é mais agressiva, causando manchas foliares escuras, irregulares e maiores que a anterior. O controle da cercosporiose na cultura do quiabeiro é baseado em práticas culturais e controle químico, pois não existe o controle varietal.