Rice production experiences significant losses due to fungal diseases, particularly rice sheath blight caused by Rhizoctonia solani. Despite the intensive and continuous use of synthetic fungicides, diseases severity has not reduced and control has become increasingly challenging; therefore, the search for environmentally friendly and sustainable products has intensified. Here, we conducted a chemical characterization of Xylopia frutescens and using in silico analysis evaluated the interaction of their two major compounds with lectin protein site of R. solani. In vitro tests using increasing concentrations of essential oil against R. solani were performed. Subsequently, in four varieties of rice, five concentrations of X. frutescens essential oils were applied and evaluated the phytotoxicity effect as well the potential of Xylopia frutescens essential oil for controlling, both preventively and curatively, rice sheath blight. We further investigate the selectivity of this essential oil towards the non-target organism, Trichoderma asperellum. Our analysis revealed that trans-pinocarveol and myrtenal are the main compounds of X. frutescens essential oil and interact with the lectin of R. solani, supporting the antifungal properties of X. frutescens essential oil. In in vitro conditions, the highest tested concentrations of X. frutescens essential oil inhibited the pathogen’s sclerotia and mycelial growth. Under greenhouse conditions, the treatments caused low phytotoxicity and effectively reduced disease severity when applied, both preventively and curatively. Furthermore, the biocontrol agent T. asperellum exhibited tolerance to X. frutescens essential oil. Collectively, our findings demonstrate the potential of X. frutescens essential oil for the development of botanical fungicides capable of controlling R. solani without harming beneficial non-target organisms such as T. asperellum.

Cassava (Manihot esculenta Crantz) can be affected by several diseases, among which anthracnose stands out. Despite its importance, few studies have been conducted on aggressiveness and virulence in cassava-producing areas of northern Brazil. Isolates of three species of Colletotrichum (C. musicola, C. chrysophillum, and C. truncatum) were obtained from collections of diseased cassava plants previously collected in the states of Tocantins and Pará. Inoculation was performed on the leaves of nine cassava cultivars grown in pots. The inoculated plants were kept in a humid chamber for 48 hours at a temperature of 25°C and after two days, the first symptoms appeared on the leaves. All inoculated Colletotrichum species caused symptoms of anthracnose on the leaves. Although C. musicola was, in general, the most aggressive species, there was a significant difference in virulence between C. chrysophillum and C. truncatum. Among the studied cultivars, “Água morna” proved to be more resistant, showing the lowest values for both aggressiveness and virulence measures. The “Lagoão” cultivar was the most susceptible in both variables. Currently, there are no recommendations for the effective control of anthracnose in cassava; however, the results obtained in the present work confirmed the variation in aggressiveness and virulence of Colletotrichum species that infect cassava, as well as the existence of possible sources of resistance. These results provide important information in the management of anthracnose and in the implementation of a genetic improvement program aimed at the development of cultivars resistant to anthracnose in commercial tropical areas.

Rice is a major global cereal crop, which is mostly produced through irrigation systems. Fungal diseases are a threat to its production, with one of the most devastating being sheath blight, which is caused by Rhizoctonia solani. Since very few studies were conducted on the temporal dynamics of this disease in controlled irrigated rice conditions, this research was meant to determine the resistance of 18 genotypes of irrigated rice to sheath blight. The experiment was in a greenhouse on a completely randomized four-replication design. The area under the Disease Progress Curve (AUDPC) was used to assess resistance, and temporal disease progress was modeled. These genotypes showed the highest level of resistance, as indicated by the lowest AUDPC values: AB171292, AB171294, and AB171275. AB171292 was the most resistant of these, with a maximum disease severity of 9.25%. BRS Catiana, BRS A702 CL, AB171266, and AB171267 were the most susceptible genotypes, causing 75% plant death severity. The Gompertz model was most appropriate to describe the temporal disease progression of the susceptible genotypes, which follows the rapid epidemic, whereas the resistant genotypes followed the Monomolecular model, which marked the slow and restricted increase of the disease. Also, genotypes AB171307 and AB171294 possessed the highest fresh mass, which is indicative of their tolerance. The current research has determined resistant genotypes that are promising to be used in breeding programs and has also explained the epidemiology of sheath blight to manage the disease better.

Rice (Oryza sativa L.) is a staple crop of global importance, but its productivity is often constrained by diseases and weeds, which lead to significant reductions in rice yield and quality. The technology of Clearfield enables the effective use of imidazolinone herbicides in rice with a resistant genotype. Nonetheless, besides the presence of weeds, diseases like the sheath blight, which is caused by the Rhizoctonia solani, are another limitation to irrigated rice farming. Clearfield genotypes have not been extensively studied for their resistance to sheath blight, and this disease has been on the rise in recent years, especially in the State of Tocantins, Brazil. The objective of this study was to determine the resistance of herbicide-resistant genotypes of irrigated rice to sheath blight at floodplain conditions in southern Tocantins. This was tested in 2019/20 and 2020/21 with a randomized block design (4 replications) in naturally infested commercial fields where sheath blight has previously occurred. The treatments consisted of advanced breeding lines and commercial cultivars. The temporal dynamics of sheath blight in the two years were best represented by the monomolecular model. Genotypes AB191132-RH and AB191122-RH exhibited the lowest disease severity and area under the disease progress curve (AUDPC) values without compromising yield, indicating partial resistance to sheath blight. Disease severity and yield loss were also minimized by the preventive use of fungicides. These results indicate that resistant Clearfield(r) rice genotypes and fungicide management are promising methods of sheath blight control in irrigated rice systems as integrated approaches.

O açaí (Euterpe oleracea) é uma planta natural do Brasil da região Amazônica, norte do país, e apresenta grande importância pelo seu valor econômico da polpa a nível nacional e internacional. Dentre os problemas nas etapas de coleta, transporte e armazenamento de sementes de açaí, há contaminação por agentes fúngicos, os quais influenciam negativamente na qualidade das sementes. Desta maneira, o presente estudo teve como objetivo avaliar o potencial antifúngico de óleos essenciais no controle de doenças nas plantas e no tratamento de sementes de açaí. Foi desenvolvido no Laboratório de Fitopatologia, na Universidade Federal do Tocantins, Campus de Gurupi. Os frutos foram coletados no município da Lagoa da Confusão, Tocantins. Os ensaios de sanidade, germinação e transmissibilidade foram realizados com e sem desinfestação e com e sem polpa. No ensaio de patogenicidade, inoculou-se fungos em plantas sadias. Os resultados demonstraram a incidência de fungos patogênicos em sementes, que no ensaio de transmissibilidade foram o Fusarium sp, Colletotrichum sp. e Lasiodiplodia sp. O óleo essencial de M. splendens apresentou um potencial no tratamento de sementes de açaí com polpa, diminuindo a incidência dos gêneros fúngicos Lasiodiplodia sp., Alternaria sp., Curvularia sp. e Colletotrichum sp. Diante disso, o óleo essencial de M. splendens foi promissor como biocontrole de incidência de fungos no tratamento de sementes de açaí.