Search

In recent years, worldwide scientific efforts towards controlling maize late wilt disease (LWD) have focused on eco-friendly approaches that minimize the environmental impact and health risks. This disease is considered to be the most severe threat to maize fields in Israel and Egypt, and a major growth restraint in India, Spain, and Portugal. Today's most commonly used method for LWD control involving resistant maize genotypes is under constant risk from aggressive pathogen lines. Thus, this study's objectives were to evaluate the effect of crop rotation and avoiding tillage on restraining the disease. Such an agrotechnical approach will support the continuity of soil mycorrhiza networks, which antagonize the disease's causal agent, Magnaporthiopsis maydis. The method gained positive results in previous studies, but many knowledge gaps still need to be addressed. To this end, a dual-season study was conducted using the LWD hyper-susceptible maize hybrid, Megaton cv. The trials were performed in a greenhouse and in the field over full dual-growth seasons (wheat or clover as the winter crop followed by maize as the summer crop). In the greenhouse under LWD stress, the results clearly demonstrate the beneficial effect of maize crop rotation with clover and wheat on plant weight (1.4-fold), height (1.1–1.2-fold) and cob yield (1.8–2.4-fold), especially in the no-till soil. The clover-maize growth sequence excels in reducing disease impact (1.7-fold) and pathogen spread in the host tissues (3-fold). Even though the wheat-maize crop cycle was less effective, it still had better results than the commercial mycorrhizal preparation treatment and the uncultivated non-infected soil. The results were slightly different in the field. The clover-maize rotation also achieved the best growth promotion and disease restraint results (2.6-fold increase in healthy plants), but the maize rotation with wheat showed only minor efficiency. Interestingly, pre-cultivating the soil with clover had better results in no-till soil in both experiments. In contrast, the same procedure with wheat had a better impact when tillage was applied. It may be concluded that crop rotation and soil cultivation can be essential in reducing LWD, but other factors may affect this approach's benefits in commercial field growth. [ABSTRACT FROM AUTHOR]

Abstract: The occurrence of OTA in fresh and packed wheat and in maize bread and the evaluation of the exposure degree through their consumption in two Portuguese populations from Porto and Coimbra, during the winter of 2007, were studied. One hundred and sixty eight bread samples, 61 maize and 107 wheat, were analysed by liquid chromatography–fluorescence detection (LC–FD). The results showed that 84% of samples were contaminated, with a maximum level of 3.85ng/g (above the EU maximum limit, 3ng/g). Fresh wheat bread presented higher levels than packed wheat bread. Moreover, the traditional maize bread, in either city, was consistently more contaminated than wheat bread, 0.25 vs 0.19ng/g, and 0.48 vs 0.34ng/g for Porto and Coimbra, respectively. Avintes maize bread showed the highest mean contamination and maximum levels. The higher estimated daily intake of OTA from both types of bread in the population of Coimbra compared to Porto reflects the higher average contamination of bread in the first city. [Copyright &y& Elsevier]

A total of 307-samples of plant crops (both home-grown and imported) marketed in Portugal, including maize and maize-based products (132), wheat and wheat-based products (82), barley (25), soybean (53), sunflower (8) and alfalfa (7), were analyzed for the co-occurrence of the Fusarium toxins, zearalenone (ZEA) and deoxynivalenol (DON). Analysis for ZEA and DON was carried out by HPLC, with fluorescence and UV detection, respectively. Of the 307 samples, ZEA and DON co-occurred in 46 samples (co-occurrence of 15?); 84 samples were DON-positive and 171 were ZEA-positive. The mean ZEA and DON concentrations were 0.17 and 0.07 mg kg-1, respectively. The highest levels found in the samples were 0.93 mg kg-1 for ZEA and 17.9 mg kg-1 for DON. One DON-positive and 13 ZEA-positive samples had contamination levels above the EU maximum legal limit. [ABSTRACT FROM AUTHOR]