The effect of asulam on two Lolium perenne swards containing Rumex obtusifolius

The effects of asulam applied in September 1970 at 0.55, 1.12 and 2.24 kg a.i./ha on Rumex obtusifolius (L.), Lolium perenne (L.), Other grasses and Trifolium repens (L.) growing in two swards in Wales were investigated. Good short-term control of Rumex was achieved by all rates of asulum although regeneration was occurring by the spring following treatment. Dry matter yields of L. perenne were slightly lowered by 2.24 kg a.i./ha 6 weeks after spraying but production in the spring following treatment was substantially greater than on untreated plots. Poa trivialis (L.) and Agrostis stolonifera (L.) were substantially reduced but invasion of the bare spaces by P. trivialis and P. annua (L.) seedlings tended to mask the success of this control. No harmful effects on T. repens were recorded.     

Response of ten cultivars of Lolium perenne to the ectoparasitic nematode Tylenchorhynchus dubius

The interaction between 10 cultivars ofLolium perenne andTylenchorhynchus dubius was studied to investigate the incidence of tolerance and resistance to ectoparasitic nematodes inL. perenne.Differences in tolerance were small; the nematode treatments yielded 67 to 76% of the dry shoot mass of the controls. Cultivars with a low leaf weight ratio and a low transpiration coefficient tended to have a somewhat better tolerance. Differences in resistance occurred, but resistance is of minor importance to reduce damage in theL. perenne/T. dubius host-parasite system.Samenvatting Om na te gaan of inLolium perenne tolerantie en resistentie t.a.v. ectoparasitaire nematoden voorkomt, werd de interactie tussen 10 cultivars vanL. perenne en de ectoparasitaire nematodeTylenchorhynchus dubius onderzocht.De verschillen in tolerantie bleken gering. Cultivars met een lage spruit/wortel-verhouding en een lage transpiratiecoëfficiënt waren in het algemeen wat toleranter. Er werden verschillen in resistentie gevonden, maar voor het verminderen van schade in het waardplant/parasiet-systeemL. perenne/T. dubius is resistentie van, weinig belang.     

Fungicide seed treatments to improve seedling emergence of perennial ryegrass Lolium perenne and the effect of different cultivars and soils

Seeds of perennial ryegrass Lolium perenne treated with four fungicides, benomyl, captan, iprodione and metalaxyl, used singly and in all combinations were sown in soil in pots. The soil was maintained at a low moisture content to predispose the seedlings to pre-emergence infection by soil-borne fungi. Thirteen of the fifteen fungicide treatments significantly increased seedling emergence and all but one contained benomyl and/or captan. In another pot experiment, a combination of benomyl and captan was tested against four similar treatments, carbendazim+captan, thiabendazole+captan, thiabendazole+metalaxyl and thiabendazole+thiram and also drazoxolon. Only benomyl+captan and drazoxolon did not increase seedling emergence significantly. A natural infection of the seedlings by powdery mildew Erysiphe graminis was reduced significantly by all treatments except thiabendazole+thiram and drazoxolon. Only car-bendazim+captan significantly increased the dry weight of seedlings per pot 98 days after sowing. Benomyl+captan seed treatment significantly increased seedling emergence in 9 of 16 soils collected from widespread sites. One perennial ryegrass cultivar, Parcour, was used in the above experiments and in a comparison with 12 other diploid cultivars its response to benomyl seed treatment was about mid-range.     

多年生黑麦草中小麦矮腥黑穗病菌PCR 检测方法的建立

寄生于多年生黑麦草的Tilletia属腥黑粉菌共有4种,即小麦矮腥黑穗病菌Tilletia controversa（TCK）、黑麦草腥黑粉病菌T.lolii、T.vankyi、黑麦草粒腥黑穗病菌T.walkeri。本研究分析了黑麦草上冬孢子形态非常相似的3种腥黑粉菌的DNA序列差异,设计了TCK的特异引物,成功建立了TCK菌丝基因组DNA的特异PCR检测方法和冬孢子的套式特异PCR检测方法。     

Simulation of the host/parasite system Lolium perenne/Tylenchorhynchus dubius. 2. The effect of T. dubius on L. perenne

The effect of the ectoparasitic nematodeTylenchorhynchus dubius on various processes that determine the growth of the grassLolium perenne was studied using dynamic simulation. An equation was formulated for the relation between nematode density in the rhizosphere and the cell penetration rate per nematode. Various hypotheses on the effect of cell penetration on plant growth processes were formulated and then introduced in a SUCROS-type growth model of the host. The plausibility of the hypotheses was tested by their ability to simulate experimental results with given population data.The simulations showed that it is unlikely that all cells penetrated byT. dubius will die. The effect ofT. dubius cannot be attributed to the nematodes' consumption of dry matter. Growth reduction may be attributed to the nematode negatively affecting the roots' permeability.Samenvatting Het effect van de ectoparasitaire nematodeTylenchorhynchus dubius op het grasLolium perenne werd bestudeerd met behulp van dynamische simulatie. Er werd een vergelijking opgesteld om de snelheid waarmee de nematode epidermiscellen op de wortels aanprikt te berekenen uit nematodendichtheid in de rhizosfeer. Er werd een aantal hypotheses geformuleerd voor de manier waarop de groeiprocessen in de plant door aanprikken van de cellen beïnvloed worden en deze werden ingebouwd in een op SUCROS gebaseerd groeimodel voor het gras. Door middel van berekeningen met het model werd nagegaan in hoeverre de hypotheses het effect van gegeven nematodenpopulaties op de plant zoals dat in proeven gevonden was konden verklaren.Uit de simulaties bleek dat het onwaarschijnlijk is dat alle doorT. dubius aangeprikte cellen dood gaan. Het effect vanT. dubius kan niet toegeschreven worden aan onttrekking van droge stof. De groeireductie kan wel toegeschreven worden aan een door de nematoden veroorzaakte verhoging van de wortelweerstand voor wateropname.     

进境苇状羊茅和多年生黑麦草种子携带内生真菌带菌率的研究

苇状羊茅内生真菌和多年生黑麦草内生真菌曾给一些国家的畜牧业造成巨大损失.为防止内生真菌随进境草籽传入我国并在中国扩散危害,我们对该2种进境草籽内生真菌的带菌率进行了研究.首先通过分离培养,得到了苇状羊茅内生真菌和黑麦草内生真菌,然后采用染色法对1998年以来收集到的从天津口岸进境的部分苇状羊茅和黑麦草种子进行了初步检验,经检验,37份苇状羊茅样品中有18个品种带菌,34份多年生黑麦草样品中14个品种带菌,带菌率最高可达86.7%.早熟禾、剪股颖等其它禾本科草籽目前尚未发现带有内生真菌.     

不同浓度香豆素水溶液对黑麦草幼苗的影响

在温室条件下,采用土壤盆栽技术研究不同浓度的香豆素水溶液对多花黑麦草(Lolium multiflorum)幼苗生理生化变化的影响。结果表明,在香豆素水溶液浓度分别为0mg/kg、100mg/kg、200mg/kg、500mg/kg、1000mg/kg和2000mg/kg处理下,多花黑麦草幼苗根基部呈暗黄色且易断,叶尖枯黄;随着浓度的升高,叶片颜色加深,叶基部和叶尖坏死,致死率也逐渐升高;长度、鲜重、干重和叶绿素含量降低,丙二醛(MDA)含量升高,可溶性糖(SS)和脯氨酸(PRO)含量先升高后降低,这表明多花黑麦草对低浓度的香豆素有一定的抵抗能力,但在高浓度的香豆素水溶液处理下则受到伤害。     

Paraquat tolerant Lolium perenne L.: effects of paraquat on germinating seedlings

A cultivar of Lolium perenne L. (Causeway) selected for tolerance to foliar-applied paraquat was shown also to be tolerant at seed germination and establishment. When seeds were germinated in paraquat solutions (1, 3, 9, 27 ppm), Causeway was more than ten times as tolerant as a normal cultivar of L. perenne. When germination and survival were studied in a soil which had been sprayed with paraquat (0.0, 0.3, 0.9, 2.7 kg/ha) before sowing, Causeway was nearly three times as tolerant as a normal cultivar. Holcus lanatus L. was about equal to normal L. perenne, but Poa trivialis L. was less tolerant. Phytotoxicity was greater in a 10.5% organic than a 4.8% organic soil. It is concluded that the mechanism of paraquat tolerance operates in the non-photosynthetic tissues of germinating seedlings as well as in the photosynthetic tissues of older plants, although the degree of tolerance varies according to the mode and stage of application of the herbicide. There might be advantages in using a paraquat tolerant cultivar of L. perenne when direct drilling grass after sward destruction by paraquat.     

Cytology of the host-pathogen interactions between Lolium perenne and Drechslera dictyoides

The interactions between Drechslera dictyoides and Lolium perenne resulting in the development of the net blotch lesion were examined using light and electron microscopy. Following appressorium formation a reorganization of the network of cytoplasmic strands in underlying epidermal cells resulted in the accumulation of cytoplasm and the migration of the nucleus towards the appressorium. Successful penetration was followed by extensive colonization of the invaded epidermal cell. Abortive penetration attempts often resulted in the formation of hyphae within the epidermal cell wall. During lesion development, advancing hyphae came into contact with unmodified host cells which responded with the production of wall appositions. Hyphae were sparsely distributed within the developing lesions and their sparingly branched, predominantly linear pattern of growth resulted in the formation of discrete net lesions. Prior to the commencement of sporulation, the density of hyphae increased and the invasion of moribund cells of the senescent host tissue was observed.     

Effects of fungicides on Drechslera spp. and leaf surface filamentous saprophytic fungi on Lolium perenne

Small plots of Lolium perenne were treated between February and September 1979 with benomyl, triadimefon and chlorothalonil and the incidence and relative abundance of sporulating filamentous fungi measured on distinct lesions and senescent areas of leaves.
Benomyl reduced the levels of most saprophytes but increased the levels of the two Drechslera species present. Triadimefon reduced levels of Drechslera species but allowed an increase in levels of Phoma and Epicoccum and in the number of naturally senescing leaves devoid of obvious filamentous fungal growth. In chlorothalonil-treated plots, levels of all filamentous fungi except Epicoccum were reduced and, by controlling Drechslera species, the number of healthy leaves increased.     

Influence of temperature and soil moisture on the relation between Tylenchorhynchus dubius and Lolium perenne

The relation between the ectoparasitic nematodeTylenchorhynchus dubius and the growth and production ofLolium perenne during the first month after sowing, was studied in pot experiments at several temperatures, and moisture levels.The nematode reduced the growth of the grass, mainly as a result of activity during the first weeks after seeding. The percentage decrease of dry matter yield was smaller when temperature was more favourable for plant growth. Decreased moisture content of the soil enhanced the effect of nematodes at 10°C.Samenvatting De relatie tussen de ectoparasitaire nematodeTylenchorhynchus dubius en de groei en produktie vanLolium perenne gedurende de eerste maand na inzaai werd bestudeerd in potproeven bij verschillende temperaturen en vochtgehaltes van de grond.De nematode veroorzaakte groeireductie die vooral een gevolg was van nematoden-activiteit in de eerste weken na inzaai. Het procentuele effect op de droge-stofopbrengst was kleiner naarmate de temperatuur dichter bij de optimumtemperatuur voor de groei van de plant lag. Bij 10°C versterkte een lager vochtgehalte van de grond het effect van de nematoden.     

Variation in ethofumesate tolerance in Lolium species and cultivars

The ethofumesate tolerances of seventy cultivars of Lolium perenne L., L. multiflorum Lam. and L. x hybridum Hausskn. were investigated by growing seedlings in a glasshouse in a potting compost treated with a critical level of the herbicide. The incidence of seedling deformity and death varied among cultivars, and was generally higher in diploids than in tetraploids, and in L. perenne than in L. multiflorum. Cv. Palaver was outstandingly tolerant. Eight cultivars were re-tested in pre- and post-emergence field experiments and relative tolerances were similar to those observed in the glasshouse. At the recommended doses for selective weed control, ethofumesate caused some seedling death in susceptible varieties in the pre-emergence experiment, and both seedling death and reduced herbage production in the post-emergence experiment. It is concluded that both varietal genotype and environmental factors contribute to the risk of ethofumesate damage in the field.     

Acetohydroxyacid synthase (AHAS) amino acid substitution Asp376Glu in Lolium perenne: effect on herbicide efficacy and plant growth

Journal of Plant Diseases and Protection - Recently, the acetohydroxyacid synthase (AHAS) amino acid substitution Asp376Glu was detected in a Lolium perenne population originating in France. This...     

The incidence of barley yellow dwarf virus isolates in perennial ryegrass (Lolium perenne) in south-western Victoria

Barley yellow dwarf virus (BYDV) was detected in perennial ryegrass cultivars examined from three sites in south-western Victoria (Balmoral, Mininera and Hamilton); the frequency of BYDV infection varied with cultivar. PAV-related isolates were prevalent at all sites, but the incidence of MAV- and RPV-related isolates varied with the site and cultivar. The PAV-related isolate was less frequent in cv. Ellett than in cv. Victorian at all sites. The implications for the epidemiology of the disease and its agronomic importance in Victoria are discussed.     

Effect of simulated mowing on the translocation of mefluidide in perennial ryegrass (Lolium perenne L.)

Young plants of perennial ryegrass (Lolium perenne L.) absorbed approximately 50% of an application of the grass growth retardant, mefluidide, while from 6.5 to 21.9% of the applied dose was translocated during a 2- or 7-day period respectively. After the 2-day period 93.4% of extractable radioactivity was identified as mefluidide. This potentially useful chemical was made unavailable as a result of mowing before or after spraying. Mowing before spraying increased the proportion of cut mature laminae and young laminae, neither of which translocated mefluidide to other plant organs as efficiently as intact, mature leaves. Mowing after spraying removed potentially translocatable mefluidide with the cut mature laminae and reduced mefluidide accumulation in untreated plant parts. While mowing treatments may be aesthetically desirable they probably increase the amount of mefluidide necessary for effective growth retardation.