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A dual infection of two microscopic fungi on common milkweed (Asclepias syriaca) in Hajdúság region (East-Hungary)
189-195Views:194Common milkweed (Asclepias syriaca L.) is one of the most noxious and invasive weed species in Hungary. A. syriaca invades arable lands, horticultural and forestry plantations, natural and semi-natural habitats too. In cases of field crops it can cause considerable yield losses mostly in maize (2–10%), soybean (12–32%) and sorghum (4–29%), but only with high rate of coverage. It can also increase these problems that the common milkweed can be serve as reservoir and host for viruses, other pathogens and pests.
Because of the importance of common milkweed and in spite of demand to develop effective biological control, until now has not been developed a proper control program against A. syriaca. The aim of our research was to identify the necrotrophic fungal pathogens, which were involved in notable disease occurrence on this weed in different parts of Hajdúság region of Eastern-Hungary in 2016.
To the isolation of fungi from leaves and their identification were based on morphological colony characters on potato dextrose agar (PDA) and Sabouraud dextrose agar (SDA). To the description of conidia features were used PDA for Alternaria and synthetic low-nutrient agar (SNA) for Fusarium species, respectively. The examination of axenic cultures revealed that the fungi isolated from the leaves of common milkweed were Fusarium sporotrichioides and Alternaria alternata. -
Preliminary estimation of the efficacy of Fusarium sporotrichioides Sherb. as biological control agent against common milkweed (Asclepias syriaca L.)
201-204Views:307A study of fungi responsible for severe leaf spots of common milkweed (Asclepias syriaca L.) in the Hajdúság region (East Hungary), Fusarium sporotrichioides and Alternaria alternata were isolated from infested leaf tissues. F. sporotrichioides was the most virulent fungus in pathogenicity tests conducted on healthy leaves of common milkweed plants. Inoculation of common milkweed (A. syriaca) in different growth stages with F. sporotrichioides yielded similar symptoms as the original ones. Spray mixtures containing 1.0×106 conidia/ml gave effective control when common milkweed plants were sprayed until runoff occurred. Laboratory (wet chamber) and field experiments showed that asexual spores of the fungal pathogen, F. sporotrichioides, exhibited bioherbicidal activity against common milkweed (A. syriaca).
More efficient control efficacy was observable on elder plants (at flowering stage) than younger ones. These results initiate that this fungus may be a biocontrol agent for controlling this invasive weed but should clarify its hosts because it could infect cultivated plants as well.
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Allelopathic effect of invasive plants (Eriochloa villosa, Asclepias syriaca, Fallopia x bohemica, Solidago gigantea) on seed germination
179-182Views:317The aim of this study was to determine the allelopathic potential of invasive species woolly cupgrass (Eriochloa villosa), common milkweed (Asclepias syriaca), bohemian knotweed (Fallopia x bohemica), and giant goldenrod (Solidago gigantea Ait.) on germination crop (Lepidium sativum L.). Experiments were conducted under laboratory conditions to determine effect of water extracts in petri dish bioassay. Water extracts from fresh biomass (leaves and stem) of invasive weeds in concentrations of 4 and 8 g/100 ml were investigated. All invasive plants showed allelopathic effect on germination. In giant goldenrod stem water extract experiment, allelopathic effect was less pronounced.
The cress germination was greatly suppressed with the woolly cupgrass, common milkweed and the giant goldenrod. The experiment showed that the seed germination depended on the concentrations and the plant material used (leaves and stem).