The Influence of Reflective Mulches and Lettuce Types on the Incidence of Aster Yellows and Abundance of its Vector, \u3ci\u3eMacrosteles Fascifrons\u3c/i\u3e (Homoptera: Cicadelidae), in Minnesota

Five commercial lettuce cultivars representing different genetic types were grown through aluminum-coated paper, through black polyethylene film, and on bare soil. For each variety, the aluminum mulch reduced the numbers of Macrosteles fascifrons (St~l), reduced the incidence of aster yellows, and increased yields when compared to uncovered controls. The head lettuce cultivar \u27Minetto\u27 was most susceptible on unmulched plots (74.3%) while the leaf cultivar \u27Grand Rapids\u27 was least susceptible (33.8%). The latter also had the greatest infestation of leafhoppers which may indicate either resistance to the aster yellows agent or shorter feeding times by the vector leafhopper. The abundance of aster leafhoppers on the romaine cultivar \u27Valmaine\u27, the butter head cultivar \u27Buttercrunch\u27, and the bibb cultivar \u27Summer Bibb\u27 was much lower than that of the other two and might explain the lower percentage of aster yellows on these types as compared with \u27Minetto\u27

Cultivar and Year-to-Year Variation of Phytosterol Content in Rye (Secale cereale L.)

Intake of phytosterols (and -stanols) has been shown to decrease the level of low-density lipoprotein cholesterol and thus protect against development of cardiovascular diseases. Therefore, studies on the cultivar and year-to-year variation in phytosterol content in rye grains have been performed. The phytosterol content and composition of different rye cultivars, grown under identical conditions on the same field in three consecutive years, were analyzed. Both cultivar and year-to-year variation in sterol content were statistically significant (p < 0.0001). The total sterol content varied from 1007 ± 21 mg/kg in the highest yielding cultivar, Tsulpan 3, to 761 ± 10 mg/kg in the lowest yielding cultivar (Amando in the 1999 harvest). Because the meteorological conditions varied substantially between the different years, it was possible to deduce the impact of varying weather conditions on phytosterol content in the different cultivars. The studied cultivars had all the lowest phytosterol contents in the dry and warm harvest season of 1999. Although there were statistically significant cultivar and year-to-year variations in the sterol composition (p < 0.0001), these were only between 2 and 4% of the total sterol content

Mixtures of modern and historical wheat cultivars under organic management in western Canada

Two historic (Red Fife and Marquis) and two modern (5602HR; AC Barrie) wheat (Triticum aestivum) cultivars were assessed to determine if cultivar mixtures provided a benefit to grain yield and disease and weed suppression in Manitoba over 3 site-years. 5602HR was the highest yielding sole cultivar while Marquis and AC Barrie were the lowest yielding sole cultivars. Red Fife yielded similar to 5602HR in several cases. Orthogonal contrasts across all site-years showed that 3 and 4 cultivar mixtures yielded similar (P>0.05) to 5602HR, the highest yielding monocrop

Arkansas Soybean Performance Tests 2008

Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the state, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producer

Increasing Cultivar Diversity of Processing Tomato under Large Scale Organic Production in California

At an organic farm in California, higher plant diversity was hypothesized to enhance ecosystem functions and services. Plant diversity was manipulated temporally and spatially: mustard cover crop vs. no cover crop (fallow) in winter, and mixtures with one (farmer’s best choice), three, or five processing tomato cultivars in summer. Soil N, soil microbial biomass, crop nutrient uptake, canopy light interception, disease, GHG emissions and biomass were measured. Results show that the mustard cover crop reduced soil nitrate (NO3-) in winter and also during the tomato crop, which was associated with decreased growth and canopy development. All cultivar mixtures had fairly similar yield and shoot biomass. The ‘choice cultivar’ (i.e. farmer’s best choice) showed plasticity depending on the mixture, tending to have higher biomass production in mixtures. This study shows the complexity of cultivar-mixture interactions. To achieve the greatest benefit for ecosystem functions in organic farming, mixtures require greater understanding of cultivar plasticity and phenological and physiological trait diversity

Arkansas Soybean Performance Tests 2007

Soybean cultivar performance tests are conducted each year in Arkansas by the University of Arkansas Division of Agriculture. The tests provide information to companies developing cultivars and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for soybean producers

Arkansas Wheat Cultivar Performance Tests 2013-2014

Wheat cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for small-grain producers

Apple and Pear Cultivars for Organic Production in a Cool Climate

Only early ripening cultivars of apples and pears may be grown successfully in the short and rather cool growth season of the fruit producing areas of Norway. Due to a combination of high yield, good fruit quality and scab resistance, the Swedish cultivar ‘Aroma’ is recommended as major cultivar for organic apple production today. ’Philip’ is recommended as cultivar for organic pear production. During 5 years 21 apple cultivars and 15 pear cultivars have been tested in organic orchards in comparison with ‘Aroma’ and ‘Philip’. Several cultivars in the trial are promising for use in organic production

Cultivar diversity as a means of ecologically intensifying dry matter production in a perennial forage stand

The relationship between genotypic diversity and productivity has not been adequately explored in perennial forage production systems despite strong theoretical and empirical evidence supporting diversity\u27s role in ecosystem functioning in other managed and unmanaged systems. We conducted a two-year field experiment with six cultivars of an agriculturally important forage grass, Lolium perenne L. (perennial ryegrass). Dry matter production of L. perenne and the weed community that emerged from the soil seed bank were measured each year in treatments that ranged from cultivar monocultures to three- and six-way cultivar mixtures, all sown at a constant seeding rate. Mean L. perenne dry matter production increased with increasing cultivar diversity and was highest in mixtures that contained cultivars representing the greatest additive trait range (calculated on rankings of three traits: winter hardiness, heading date, and tolerance to grazing). Mixtures had greater yields than those predicted by the mean of their component monoculture yields, but there was evidence that highly productive cultivars may have dampened over-yielding in mixtures. Weed abundance was correlated with L. perenne dry matter, but not L. perenne cultivar diversity. These results suggest that multi-cultivar mixtures may have utility as an approach to ecologically intensifying perennial forage production. Additional research will be necessary to determine the mechanisms responsible for the over-yielding observed in this study and the generality of these findings