It is spoken about persistentent weed called Scentless Mayweed in this graduation theses, whose became more expandable hand in hand with gradual passage of some companies to the minimisational methods of the soil processing. The biology and morfology of Scentless Mayweed is described in this theses, so as gadgetries of his diffusion and on this priciples of this knowledge the weedy si discussed. There are many methods of feedback control described {--} mechanical so as chemical and its subseqent economical evaluatin and its matching. This issue tries to clear up why the stress of this weed on arable crop is so hard, why it is so successful weed at the point of wiew of competitive relations and what sort of mechanisms are used. At the advances that were show round in Kluky in former Písek county it was found out the influence of the herbicides and subsequently the remedial measures for weed control were accepted.

Silverleaf nightshade (Solanum elaeagnifolium), a perennial broadleaf weed, has become a serious pest in many semi-arid areas of the world. Control of silverleaf nightshade is confounded by its ability to produce thousands of viable seeds from a single mother plant, a deep and well-developed root system and the ability to propagate vegetatively from creeping lateral roots, root fragments and from rhizomes. Exacerbating factors are longevity of its propagules in soil, particularly under adverse environmental conditions. Currently, in South Africa, it is one of the more serious weeds in cotton (Gossypium hirsutum L.) production, where its interference results in remarkable loss of product quantity and quality. Research has been done on the competition aspect of silverleaf nightshade with cotton but there is a serious lack of information on the allelopathic aspect. In this study, a series of experiments that included laboratory and glasshouse experiments were conducted to evaluate the allelopathic interference of silverleaf nightshade on early growth of cotton. Cotton seeds were exposed to silverleaf nightshade extract solutions or planted in soil into which silverleaf nightshade leaf material or ripe berries were incorporated. In all the experiments attempts were made to avoid or to reduce, at least, the influence of factors that could be potentially confounding. In this regard, PEG-6000 was used to evaluate the sensitivity of crop parameters to the osmolality of test solutions in order to ensure that osmotic inhibition was not a confounding factor in the bioassays where the biological activity (phytotoxicity) of plant extracts were assessed. Competition for growth factors was the other major potentially confounding factor that was considered throughout, and steps were taken to negate its influence. Germination and early seedling growth of cotton cultivars Sicala, CA 223, Siokra V15, Tetra and Delta Opal were inhibited by test solutions (silverleaf nightshade extracts) and by soil-incorporated residues of silverleaf nightshade. Inhibitory effects of silverleaf nightshade solutions were observed when either a layer of filter paper or a thin layer of soil or quartz sand was used as substrate. In both laboratory and pot experiments, it appeared that cotton cultivar Sicala was the most sensitive to allelochemicals contained in extracts and residues of silverleaf nightshade. This finding of differential tolerance of crop cultivars towards allelochemicals contained in a weed is a rare occurrence in allelopathy research. Berries of silverleaf nightshade were generally more inhibitory to cotton than leaf material. For both types of plant material used, residues lost their inhibitory effect over time, probably as decomposition of allelopathic compounds in soil progressed. Information obtained from this study can be viewed as knowledge that contributes to the bridging of the gap between identification and isolation of allelochemicals from silverleaf nightshade, and confirmation of silverleaf nightshade allelopathy under natural conditions. Experiments involving soil as growth medium, in particular fieldwork, are needed to verify the validity of these findings under natural conditions. / Dissertation (MSc(Agric) Agronomy (Weed Science))--University of Pretoria, 2007. / Plant Production and Soil Science / MSc(Agric) / unrestricted

Cover crops not only improve soil conditions, but can also suppress weed growth. In a field experiment the influence of two cover crops, Secale cereale (stooling rye), and Lolium multiflorum (annual ryegrass), on the growth of Zea mays (maize) and C. esculentus (yellow nutsedge) was compared to the latter crop and weed’s growth at three control treatments which involved weed residues left on the soil surface, application of herbicides and weed control by hoeing. Maize emergence and growth were delayed in the presence of residues of both cover crop species, especially in annual ryegrass residues. C. esculentus growth was significantly inhibited in the area between the maize planting rows by the cover crops for the first 14 days after maize emergence, but this growth suppressing effect diminished after 28 days. In a controlled environment study, the influence of the same cover crops, together with Avena sativa (oats) and three cultivars of annual ryegrass were evaluated. Maize and C. esculentus growth were suppressed, especially by the root residues of the cover crops with the annual ryegrass cultivar ‘Midmar’ being the most suppressive. Chemical analysis of the leachate of root residues indicated the presence of phenolic acids and benzoxazolin-2(3 H)-one (BOA). It is suggested that weed growth could be reduced by the allelochemicals leached from cover crop residues but in order to achieve prolonged, effective weed control the combination of mulch retained on the soil surface and the application of herbicides will required. In an integrated weed management approach a possible reduction in the type and number of herbicide applications required for effective weed control, could be implemented. / Thesis (PhD)--University of Pretoria, 2012. / Plant Production and Soil Science / unrestricted

This study investigated the effects of the Triffid weed Chromolaena odorata on small and large mammals in Hluhluwe-iMfolozi Park. C. odorata is a widespread invasive alien plant that poses threat to the highly maintained natural vegetation in HiP and most other protected areas in KwaZulu-Natal. Following the opinion that the effects of invasive alien plants on all levels of biodiversity need to be recognised for their effective control, we compared small and large mammal species richness and diversity between areas with differing C. odorata invasion durations, areas with differing clearing times and an area with no history of invasion as a control area. Small mammal trapping was done using Sherman live traps and mark-recapture techniques. Track counts were used to estimate large mammal species abundance, richness and diversity. The control area had higher small mammal species richness and diversity than the invaded areas, which suggests that invaded areas were not suitable habitats for small mammals. It was also found that small and large mammal species richness and diversity decreased with the increase in invasion duration, which shows that the more time C. odorata is left to establish the more disturbance it causes to the habitat. We found the uninvaded treatment to have the highest diversity of large mammal species than all the invaded treatments, which suggests that large mammalian species show some degree of avoidance to the invaded areas. We also found that there were significant differences between the treatments with regard to large mammal species diversity indices. Some of the large mammalian species appeared to neither avoid nor prefer invaded areas. It is hypothesized that they use invaded areas to hide away from predators as most of them fall prey to many carnivores. Also, C. odorata invaded areas could provide suitable shelter from climatic extremes. The treatments cleared of C. odorata showed an increase in both small and large mammalian species richness and diversity, suggesting that clearing of this plant helps in rehabilitation of the ecosystem. However, large mammal species composition in the cleared treatments remained different to preinvasion state, which suggests that the habitat may remain changed for a long time after clearing. Managers of conservation areas should therefore prioritise alien plant removal in order to maintain healthy ecosystems. / Dissertation (MSc (Wildlife Management))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22481号 / 農博第2385号 / 新制||農||1075(附属図書館) / 学位論文||R2||N5261(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 縄田 栄治, 教授 北山 兼弘, 教授 冨永 達 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Pyroxasulfone is a VLCFA inhibitor labeled to control grasses and small-seeded broadleaf weeds. Little information is available regarding this herbicide being applied postemergence. Two field experiments were conducted to evaluate the efficacy of pyroxasulfone used postemergence. Pyroxasulfone applied to 2-leaf wheat controlled up to 83% of the green foxtail but had little to no effect on broadleaves. An additional field study was conducted to determine if pyroxasulfone could give supplemental green foxtail control when tank-mixed with ALS inhibitors. Few tank-mix combinations increased control, and the tank-mixes that did had inadequate control, <70%. Greenhouse experiments were also conducted. The first concluded that a wide range of grass species are susceptible to pyroxasulfone applied postemergence. The second demonstrated weed control with pyroxasulfone is almost exclusively due to root uptake. Contradicting levels of control between field and greenhouse experiments suggests more information is needed before pyroxasulfone can be utilized as a postemergence herbicide. / North Dakota State University. Department of Plant Sciences

No description available.

Cover crops play a part in improving sustainability by reducing negative environmental impacts such as soil erosion and nutrient runoff. Energycane could benefit from cover crops due to its row spacing. This study was conducted at the Bearden Dairy Research Center to determine differences in nitrogen accumulation, weed suppression, and energycane yield among treatments. Four cool-season species (planted in the fall of 2020 and 2021) [balansa clover (Trifolium michelianum), hairy vetch (Vicia villosa), white clover (T. repens) and winter pea (Pisum sativum subsp. arvense)], and four warm-season species (planted in the spring of 2021 and 2022 [alfalfa (Medicago sativa), alyceclover (Alysicarpus vaginalis), soybean (Glycine max), and sunnhemp (Crotalaria juncea)] plus negative and positive controls (0 and 168 kg N ha-1) were used. Regarding cool-season cover crops, significant differences were seen in all previously mentioned metrics. Warm-season cover crops only showed differences regarding nitrogen accumulation and weed suppression abilities.

Weed control is challenging for Mississippi peanut producers. Research was established during 2017 and 2018 at the Delta Research and Extension Center in Stoneville, Mississippi, to evaluate herbicide programs for weed control and reducing weed seed production in Mississippi peanut production. Treatments were combinations of acetochlor, clethodim, flumioxazin, lactofen, paraquat, and S-metolachlor with their respective adjuvants if needed. Treatments were applied: PRE, early-POST (EPOST), and/or mid-post (MPOST). All treatments included a PRE application followed by (fb) application of EPOST and/or MPOST application. Flumioxazin PRE fb lactofen plus clethodim MPOST provided greatest weed control and peanut yield. This treatment provided 88 to 100% control of barnyardgrass, hemp sesbania, Palmer amaranth, pitted morningglory, and prickly sida. Additionally, this treatment reduced total weed seed production 88% compared to the nontreated control. Flumioxazin PRE fb lactofen plus clethodim EPOST fb acetochlor MPOST provided similar weed control and peanut yield as flumioxazin PRE fb lactofen plus clethodim MPOST. This treatment provided 88 to 100% control of all weed species present and reduced total weed seed production 93%. Sequential applications of PRE, EPOST, and/or MPOST herbicide treatments provided the best season-long control of weeds and weed seed suppression in Mississippi peanut.

No description available.