Evidence of Resistance to QoI Fungicides in Contemporary Populations of Mycosphaerella fijiensis, M. musicola and M. thailandica from Banana Plantations in Southeastern Brazil

Yellow and black Sigatoka, caused by Mycosphaerella fijiensis and M. musicola, respectively, are the most important worldwide foliar diseases of bananas. Disease control is heavily dependent on intensive fungicide sprays, which increase selection pressure for fungicide resistance in pathogen populations. The primary objective of this study was to assess the level and spread of resistance to quinone-outside inhibitors (QoI—strobilurin) fungicides in populations of both pathogens sampled from banana fields under different fungicide spray regimes in Southeastern Brazil. Secondly, we aimed to investigate when QoI resistance was confirmed if this was associated with the target-site alteration G143A caused by a mutation in the mitochondrial encoded cytochrome b gene. QoI resistance was detected in fungicide treated banana fields, while no resistance was detected in the organic banana field. A total of 18.5% of the isolates sampled from the pathogens’ populations were resistant to QoI. The newly described M. thailandica was also found. It was the second most abundant Mycosphaerella species associated with Sigatoka-like leaf spot symptoms in the Ribeira Valley and the highest level of QoI resistance was found for this pathogen. The G143A cytochrome b alteration was associated with the resistance to the QoI fungicides azoxystrobin and trifloxystrobin in M. fijiensis, M. musicola and M. thailandica strains. In order to reduce resistance development and maintain the efficacy of QoI fungicides, anti-resistance management strategies based on integrated disease management practices should be implemented to control the Sigatoka disease complex

Nondairy ice cream based on fermented yam (Dioscorea sp.)

Abstract Background The demand for industrialized foods that contribute to health and well‐being has characterized the new generation of consumers. Yam (Dioscorea sp.) is a nutritious food; however, it is not used very much in industrial food processes. The objective of this study was to develop and to characterize a truly dairy‐free low‐fat ice cream prepared from unfermented and fermented with yam dough. Results The fermentation was conducted by Leuconostoc lactic CCMA 0415 remained viable (107 CFU/g) during 90 days of storage. The fermentation process reduced the starch concentration from 26.82% to 22.35% and the protein concentration from 4.68% to 3.99% and increased the concentration of some minerals (K, S, Cu, Mn, Zn, and Fe). The total phenolic contents for fermented and unfermented ice creams were 51 and 54 mg, respectively. The radical scavenging activity were 18% and 10% with the 1,1‐diphenyl‐2‐picrylhydrazyl method and 44% and 26% with the 2,2’‐azino‐bis (3 ethylbenzo‐thiazoline‐6‐sulfonic acid) method for the unfermented and fermented samples, respectively. The fermented and unfermented ice creams were both characterized as non‐Newtonian fluids exhibiting pseudoplastic behaviors. Conclusions These results indicated that yam is a suitable substitute for milk, thus making it an option to produce edible lactose‐free ice cream with low fat

Using <em>Trichoderma</em> to Manage Sclerotia-Producing Phytopathogenic Fungi

Sclerotia are resistance structures that allow several soil-borne plant pathogens to survive for extended periods of time. The white mold disease, caused by Sclerotinia sclerotiorum and the stem rot in Allium spp., caused by Stromatinia cepivora are examples of destructive pathogens in which sclerotia are the central survival structure in their life cycle. In this chapter, we explore the information on the use of Trichoderma to manage sclerotia-producing pathogens in Brazil. There are 34 registered commercial products registered in Brazil, and most of them are recommended to manage sclerotia-producing fungi. The mechanisms of action of Trichoderma against these pathogens involve mainly mycoparasitism. The number of species employed as active ingredients of these commercial products is very limited, although many other species have shown a high potential against these pathogens. The white mold pathogen in soybean was taken as an example of field management, where the technical recommendations are detailed. This management involves other practices in addition to the application of Trichoderma in an integrated manner, and they are essential to manage this disease in the field in Brazil

Evidence of Resistance to QoI Fungicides in Contemporary Populations of <i>Mycosphaerella fijiensis</i>, <i>M. musicola</i> and <i>M. thailandica</i> from Banana Plantations in Southeastern Brazil

Yellow and black Sigatoka, caused by Mycosphaerella fijiensis and M. musicola, respectively, are the most important worldwide foliar diseases of bananas. Disease control is heavily dependent on intensive fungicide sprays, which increase selection pressure for fungicide resistance in pathogen populations. The primary objective of this study was to assess the level and spread of resistance to quinone-outside inhibitors (QoI—strobilurin) fungicides in populations of both pathogens sampled from banana fields under different fungicide spray regimes in Southeastern Brazil. Secondly, we aimed to investigate when QoI resistance was confirmed if this was associated with the target-site alteration G143A caused by a mutation in the mitochondrial encoded cytochrome b gene. QoI resistance was detected in fungicide treated banana fields, while no resistance was detected in the organic banana field. A total of 18.5% of the isolates sampled from the pathogens’ populations were resistant to QoI. The newly described M. thailandica was also found. It was the second most abundant Mycosphaerella species associated with Sigatoka-like leaf spot symptoms in the Ribeira Valley and the highest level of QoI resistance was found for this pathogen. The G143A cytochrome b alteration was associated with the resistance to the QoI fungicides azoxystrobin and trifloxystrobin in M. fijiensis, M. musicola and M. thailandica strains. In order to reduce resistance development and maintain the efficacy of QoI fungicides, anti-resistance management strategies based on integrated disease management practices should be implemented to control the Sigatoka disease complex