management of lesion nematodes and potato early dying with rotation crops.soil-incorporated rotation/green manure crops were evaluated for management of potato early dying caused by verticillium dahliae and pratylenchus penetrans. after two years of rotation/green manure and a subsequent potato crop, p. penetrans numbers were less after 'saia' oat/'polynema' marigold, 'triple s' sorghum-sudangrass, or 'garry' oat than 'superior' potato or 'humus' rapeseed. the area under the disease progress curve (audpc) for early dying was lowest after saia oat/marigold, and tuber y ...200619259461
the effect of marigolds (tagetes spp.) and other cover crops on pratylenchus penetrans and on following potato crops.root-lesion nematodes (primarily pratylenchus penetrans) were monitored in two marigold cultivars (tagetes tenuifolia cv. nemakill and cv. nemanon), annual ryegrass (lolium multiflorum cv. lemtal), red clover (trifolium pratense cv. florex), and soybean (glycine max cv. proteus), and in the following potato (solanum tuberosum cv. superior) crop during three growth sequences. meadow fescue (festuca elatior cv. miner) and bee plant (phacelia tanacetifolia cv. gipha) were added to the trial in the ...200019271006
the potential of thiarubrine c as a nematicidal agent against plant- parasitic nematodes.thiarubrine c, a polyacetylenic 1,2-dithiin isolated from the roots of rudbeckia hirta (asteraceae), exhibited strong nematicidal activity in in vitro and growth chamber assays. thiarubrine c was toxic, in the absence of light, to the plant-parasitic nematodes meloidogyne incognita and pratylenchus penetrans at lcs of 12.4 ppm and 23.5 ppm, respectively. a minimum exposure time between 12 and 24 hours was the critical period for nematode mortality due to thiarubrine c. although thiarubrine c was ...199819274210
flavonols: pigments responsible for ultraviolet absorption in nectar guide of flower.the petals of the black-eyed susan (compositae: rudbeckia hirta) contain three flavonol glucosides (6,7-dimethoxy-3',4',5-trihydroxyflavone-3-o-glucoside, patulitrin, and quercetagetin). these compounds, which show intense spectral absorption at 340 to 380 nanometers, are restricted in distribution to the petal bases, which are ultraviolet absorbing as a result. such ultraviolet-absorbing petal zones, known as "nectar guides," are invisible to us, but are visible and of orientation value to the ...20165050486
wild bees preferentially visit rudbeckia flower heads with exaggerated ultraviolet absorbing floral, we report on the results of an experimental study that assessed the visitation frequency of wild bees to conspecific flowers with different sized floral guides. uv absorbent floral guides are ubiquitous in angiosperms, yet surprisingly little is known about conspecific variation in these guides and very few studies have evaluated pollinator response to uv guide manipulation. this is true despite our rich understanding about learning and color preferences in bees. historical dogma indicates ...201424585774
growth and landscape performance of ten herbaceous species in response to saline water irrigation.ten herbaceous perennials and groundcovers were grown in raised beds from june to september in a dry, hot desert environment and micro-spray drip irrigated with synthesized saline solutions at electrical conductivity of 0.8 (tap water), 3.2, or 5.4 ds/m. plant height and two perpendicular widths were recorded monthly to calculate the growth index. landscape performance was assessed monthly by visual scores. salinity did not affect the visual scores in achillea millefolium l., gaillardia aristata ...200720585473
indirect effects on mutualisms: parasitism of bumble bees and pollination service to plants.researchers increasingly recognize the important role of mutualisms in structuring communities and view positive interactions in a community context rather than as simple pairwise interactions. indirect effects, such as those that predators have on lower trophic levels, are a key process in community ecology. however, such top-down indirect effects have rarely been extended to mutualisms. antagonists of one mutualist have the potential to negatively affect the second mutualist through negative e ...201323691664
nonstomatal versus stomatal uptake of atmospheric mercury.atmospheric constituents may be deposited to and incorporated into plant leaves, with gases entering via stomata, and gas and particles being sorbed at the surface and in some cases traversing the cuticle, possibly reaching the epidermis. plants are known to be a sink for atmospheric mercury (hg), and the current paradigm is that uptake of gaseous elemental hg occurs by way of the stomata. four plant species, rudbeckia hirta, sorghastrum nutans, andropogon gerardii, and populus tremuloides, were ...200919350905
monoclonal antibodies against an arabinogalactan-protein from pressed juice of echinacea purpurea.pressed juices of the aerial parts of echinacea purpurea are used as non-specific immunostimulants, and arabinogalactan-proteins (agps) have been shown to be part of the active principle. monoclonal antibodies against an agp from pressed juice of echinacea purpurea with complement-stimulating activity have been established by means of hybridoma techniques. to test the specificity of the antibodies, several other arabinogalactan-proteins from suspension cultures of echinacea purpurea, the roots o ...200415386194
profiling the chlorogenic acids of rudbeckia hirta, helianthus tuberosus, carlina acaulis and symphyotrichum novae-angliae leaves by lc-ms(n).introduction: chlorogenic acids (cgas) are a family of esters formed between quinic acid and certain cinnamic acids, most commonly caffeic, p-coumaric and ferulic acid. they show a variety of biological activities like antioxidant, anti-inflammatory, anti-hiv, anti-hbv and inhibition of mutagenesis and carcinogenesis, and are considered to be beneficial to human health. we have selected well-established plants of asteraceae family and these are used in folk medicines as antivirals. objective: in ...201121495103
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