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Target spot, caused by Corynespora cassiicola, is an important leaf disease affecting cucumber plants, and alternative management studies are essential for the economic viability of this crop. Silicates were evaluated for the control of target spot and its pathogen, and the biochemical responses of plants were characterized. Preventive spraying was performed three times, at weekly intervals, with K2SiO3 + Cu and K2SiO3, at the concentrations 0, 28, 56, 84 and 112 mg L−1 silicon (Si). Assessments included mycelial growth and germination in vitro; disease severity; number and diameter of lesions; pathogen sporulation on leaves; activities of the enzymes peroxidase, polyphenol oxidase and β‑1,3‑glucanase, and leaf levels of phenolic compounds. The application of Si-based sources had no effect in vitro, nor did it affect lesion diameter and sporulation. Disease severity was lowest after five days of inoculation for treatments with 56 and 84 mg L−1 Si, but there was no disease control after three and seven days. The number of lesions was smallest from 28 to 112 mg L−1 Si, after five days of inoculation, and at 56 mg L−1 Si after seven days of inoculation for the treatment K2SiO3 + Cu, as well as at 56 and 112 mg L−1 Si after five days and at 84 and 112 mg L−1 Si after seven days of inoculation for K2SiO3. In general, there were no differences between the tested silicates. Enzyme activities and phenolic compound levels were not influenced by Si. The reduction in the disease severity and in the number of lesions, even if dependent on Si concentration or day of evaluation, demonstrated the possible viability of Si in controlling cucumber target spot, especially after further studies. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) have a high surface/volume ratio and small size (100 ≤ nm, these characteristics allow its use in the management of plant diseases in small quantities. The objective of this study was to evaluate the efficiency of silver (Ag) and copper oxide (CuO) NPs in the control of coffee rust (Hemileia vastatrix Berkeley & Broome). The effect of these NPs at doses of 0, 50, 100, 200 and 400 mg/L on the germination of spores of H. vastatrix and the control of rust in coffee seedlings in a greenhouse was evaluated. The CuO NPs 250 mg/L was also compared with other commercial copper fungicides: copper hydroxide, cuprous oxide and copper chelate (Ethylenediamine tetraacetic acid - EDTA). The incidence and severity of rust were evaluated every seven days, after the appearance the first pustules and the data obtained were transformed into area under disease progress curve for incidence (AUDPCI) and severity (AUDPCS). The 400 mg/L dose of Ag and CuO NPs inhibited 99.8 and 98.4% of H. vastatrix spore germination, respectively. In the greenhouse, in the experiments with Ag and CuO NPs, the lowest AUDPCS was also observed at the dose of 400 mg/L with 97.5 and 92%, respectively. The efficacy of NPs CuO 250 mg/L was equal (p < 0.05) to cuprous oxide, with a reduction of 84.2 and 83.1% of AUDPCS, respectively. Therefore, the potential of Ag and CuO NPs to inhibit the germination of H. vastatrix spores and to control rust in coffee seedlings was verified. [ABSTRACT FROM AUTHOR]

Maize (Zea mays) is the most commonly produced grain worldwide. One of the factors that can lead to a decrease in productivity is the Southern Leaf Blight caused by Bipolaris maydis. This is common in the main producing regions and can promote losses of up to 70% under suitable conditions. A few genotypes are resistant to this fungus, and there is no record of fungicides for the disease in Brazil. In order to search for alternative control measures with lower environmental impacts, the objective of this study was to investigate the use of polysaccharide fractions extracted from shiitake or aloe, as well as acibenzolar-S-methyl (ASM), as potential inductors of resistance in maize against B. maydis. Tests were conducted with maize plants (hybrids P1630H and BM3063) to evaluate the effects of the products on reducing disease severity, inhibiting pathogen germination and activating guaiacol peroxidase and phenylalanine ammonia-lyase (PAL) activities. Aloe and ASM were not efficient to control the disease. Fraction PS1 from shiitake reduced the disease severity in both hybrids by approximately 60%. Meanwhile, fraction PS2 was efficient only in hybrid BM3063, where it promoted an increase in PAL activity. However, these fractions did not affect the spore germination of B. maydis. Therefore, the polysaccharide fractions from shiitake have the potential to control Southern Leaf Blight (B. maydis) in maize probably through the activation of plant defense mechanisms. [ABSTRACT FROM AUTHOR]

Providing adequate nutrition to coffee plants is required to maintain plant health. The effect of five doses (0.05, 0.25, 0.50, 1.0, 2.0 and 4.0 mg L−1) of boron (B), zinc (Zn) and manganese (Mn) on the severity of rust on coffee plants grown in nutrient solution was evaluated. Micronutrients were supplied to seedlings having two pairs of fully developed leaves. The seedling plants were inoculated with spores (106 ml−1) of the coffee rust pathogen (Hemileia vastatrix). Five assessments of the severity of the rust symptoms were made starting on the 43rd day after inoculation. The area under the disease progress curve for severity (AUDPCS) was calculated. There was a statistical difference in AUDPCS (p < 0.05) with all micronutrients tested. With B and Mn, there was a 15.1% and 52.3% reduction in severity of coffee rust at doses of 4.00 and 0.25 mg L−1, respectively. With Zn there was a 78.0% decrease in AUDPCS. The three micronutrients significantly affected the concentration of total soluble phenols, nevertheless, only Mn influenced the concentration of lignin. [ABSTRACT FROM AUTHOR]

Market information was combined with predicted input-output relationships in an economic analysis of alternative nutritional management for dual-purpose member herds of the Genesis farmer organization of central coastal Veracruz, Mexico. Cow productivity outcomes for typical management and alternative feeding scenarios were obtained from structured sets of simulations in a companion study of productivity limitations and potentials using the Cornell Net Carbohydrate and Protein System model (Version 6.0). Partial budgeting methods and sensitivity analysis were used to identify economically viable alternatives based on expected change in milk income over feed cost (change in revenues from milk sales less change in feed costs). Herd owners in coastal Veracruz have large economic incentives, from $584 to $1,131 in predicted net margin, to increase milk sales by up to 74% across a three-lactation cow lifetime by improving diets based on good quality grass and legume forages. This increment is equal to, or exceeds, in value the total yield from at least one additional lactation per cow lifetime. Furthermore, marginal rates of return (change in milk income over feed costs divided by change in variable costs when alternative practices are used) of 3.3 ± 0.8 indicate clear economic incentives to remove fundamental productivity vulnerabilities due to chronic energy deficits and impeded growth of immature cows under typical management. Sensitivity analyses indicate that the economic outcomes are robust for a variety of market conditions. [ABSTRACT FROM AUTHOR]

Feed chemical and kinetic composition and animal performance information was used to evaluate productivity limitations and potentials of dual-purpose member herds of the Genesis farmer organization of central coastal Veracruz, Mexico. The Cornell Net Carbohydrate and Protein System model (Version 6.0) was systematically applied to specific groups of cows in structured simulations to establish probable input-output relationships for typical management, and to estimate probable outcomes from alternative management based on forage-based dietary improvements. Key herd vulnerabilities were pinpointed: chronic energy deficits among dry cows of all ages in late gestation and impeded growth for immature cows. Regardless of the forage season of calving, most cows, if not all, incur energy deficits in the final trimester of gestation; thus reducing the pool of tissue energy and constraining milking performance. Under typical management, cows are smaller and underweight for their age, which limits feed intake capacity, milk production and the probability of early postpartum return to ovarian cyclicity. The substitution of good-quality harvested forage for grazing increased predicted yields by about one-third over typical scenarios for underweight cows. When diets from first parturition properly supported growth and tissue repletion, milk production in second and third lactations was predicted to improve about 60%. Judiciously supplemented diets based on good quality grass and legume forages from first calving were predicted to further increase productivity by about 80% across a three-lactation cow lifetime. These dual-purpose herd owners have large incentives to increase sales income by implementing nutritional strategies like those considered in this study. [ABSTRACT FROM AUTHOR]

The northern root-knot nematode ( Meloidogyne hapla) is a prominent root vegetable pest in the Czech Republic. Effects of several plant essences for M. hapla management on carrot ( Daucus carota) were tested. The tested compounds included commercially available plant essences from Ocimum basilicum (sweet basil), Mentha arvensis (field mint), Tagetes erecta (Mexican marigold), and commercial product of neem seed ( Azadirachta indica). Two further essences from Eugenia caryophyllata (clove) and Origanum majorana (marjoram) were obtained by distillation. Tests were conducted on container-grown carrots maintained under field conditions. The delivery method involved absorbing the tested essences in perlite particles placed in a substrate. The results showed a negative correlation between gall numbers of the carrots and treatment concentrations, especially for clove and majoram. Similar results were achieved when considering M. hapla egg numbers. Furthermore, the same treatments showed significant differences ( P ≥ 0.05) in fresh and dry root weights. Based on these results the management of M. hapla using plant essences seems to be possible, however, further research is desirable to determine the appropriate dosage needed for efficient and most appropriate delivery method of these substances under field conditions. [ABSTRACT FROM AUTHOR]