Genotypic and phenotypic variation among 16 isolates of Ramularia areola of Gossypium hirsutum collected from five different geographical regions of Brazil was studied through virulence spectrum on three cultivars in the glasshouse and through ERIC-and REP-PCR and ITS1-5.8S-ITS2 rDNA analysis. Difference in virulence spectrum and molecular analysis of some isolates was observed. ERIC-and REP-PCR showed similar results and revealed a high level of diversity among the isolates. A unique profile for both ERIC and REP was obtained for most isolates. On the other hand, the ITS rDNA analysis did not show different PCR-RFLP patterns. While some isolates differed among each other considering genotypic and phenotypic reactions, no clear cut evidence was found about the existence of genetic lineages of R. areola in Brazil. Identification of genetic variability among the R. areola isolates originated from different geographic regions would permit screening of Brazilian germplasm and achieve sources with a wide spectrum of resistance. This is the first report of the genotypic and phenotypic variability among the R. areola isolates originated from five cotton growing regions of Brazil.

A newly emerged disease, the Pyricularia blast caused by Pyricularia grisea, is commonly observed on wheat and black oats, since its discovery in 1985. Within a few years the disease spread to other species of Gramineae, but white oat cultivars remained resistant and were the only ones among cultivated cereals resistant to this disease. In 2012, one commercial field of white oat cultivar IAC 7 was found severely attacked by Pyricularia blast in Assis, in the state of São Paulo. The objective of the present investigation was to find out whether other white oat cultivars are also susceptible to the new P. grisea isolate from cv. IAC 7 and to determine the pathogenic variability, if any, among P. grisea isolates from black oats. Thirty-three white oat cultivars, along with some cultivars of black oat, barley, wheat, triticale, and rye were evaluated against the IAC 7 isolate. Results of disease severity analysis indicated that four white oat cultivars were resistant, seven were moderately resistant and the remaining were susceptible or highly susceptible. Five wheat cultivars were also resistant. Pathogenic variation among P. grisea isolates from black oats was observed.

There is a lack of information about the level of resistance of cotton genotypes to a wider range of Ramularia areola isolates occurring across the cotton growing areas of Brazil. For this purpose, firstly it is necessary to know the existence or not of genotypic and phenotypic variability among the R. areola isolates from different geographical origins. The objective of the present investigation was to verify the existence of phenotypic variability among 23 R. areola isolates collected from six cotton growing states of Brazil. Two resistant genotypes, FMT 02102996 and CNPA BA 2003-2059, and the susceptible genotype FMT 701 were individually inoculated with 23 R. areola isolates under glasshouse conditions and the severity of infection was evaluated 30 days after inoculation. Genotypes CNPA BA 2003-2059 and FMT 02102996 were susceptible to three isolates and resistant to the rest of the isolates. Genotype FMT 701 was susceptible to all the isolates except the isolates 22.3 and 42.7. Results indicate the existence of variability among R. areola isolates and that the three genotypes are useful in distinguishing phenotypic variability within isolates of this pathogen.

The theoretical E‐curve for the laminar flow of non‐Newtonian fluids in circular tubes may not be accurate for real tubular systems with diffusion, mechanical vibration, wall roughness, pipe fittings, curves, coils, or corrugated walls. Deviations from the idealized laminar flow reactor (LFR) cannot be well represented using the axial dispersion or the tanks‐in‐series models of residence time distribution (RTD). In this work, four RTD models derived from non‐ideal velocity profiles in segregated tube flow are proposed. They were used to represent the RTD of three tubular systems working with Newtonian and pseudoplastic fluids. Other RTD models were considered for comparison. The proposed models provided good adjustments, and it was possible to determine the active volumes. It is expected that these models can be useful for the analysis of LFR or for the evaluation of continuous thermal processing of viscous foods.

In recent years, Corynespora leaf blight is on the increase in cotton and has become an important disease in the State of Mato Grosso, Brazil. It attacks several plant species including soybean. It is not yet known whether the same strain of this pathogen attacks both the crops. The objectives of the present investigation were to verify the genotypic and phenotypic variation between the isolates attacking cotton and soybean and to verify the sources of resistance in cotton. Differential response of 23 cotton genotypes was studied under glasshouse conditions using mixture of two randomly selected isolates of C. cassiicola of cotton in equal proportion. Genotypic variation among three cotton and two soybean isolates was studied using ERIC/REP-PCR and rDNA molecular techniques. With one exception, all the cotton genotypes tested so far were susceptible to C. cassiicola isolates of both cotton and soybean. Similarly, results of both molecular techniques indicated that the C. cassiicola isolates attacking cotton and soybean belong to the same strain of the pathogen in Brazil. Since Corynespora blight is a newly immerging disease of cotton and soybean in Brazil, integration of crop rotation and the sanitary practices are suggested to manage the disease.