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Control of brome grasses ( Bromus L. spp.) in winter cereals
Summary
The complete article is written in German
The spread of brome grasses, in particular of barren brome grass (Bromus sterilis L.), caused among others by ploughless tillage, requires an optimal use of herbicides in winter cereals. In a study with 20 field trials, performed between 2000 and 2005, treatments with application sequences in autumn and spring turned out to be the most effective control measures. In autumn the herbicides Herold (a.i. flufenacet + diflufenican) or Atlantis (a.i. mesosulfuron + iodosulfuron) can be used. At spring treatment with Attribut (a.i. propoxycarbazone) or Monitor (a.i. sulfosulfuron) the effectiveness can be improved clearly by splitting application in mixture with a suitable adjuvant. With this herbicide strategy yield losses between 30 and 60 % can be prevented. Because of limited selectivity these optimal control measures can employed only in winter wheat.
Comparative benefit assessment of various broad-spectrum herbicides
Summary
The complete article is written in German
Important properties determining the use of broad-spectrum herbicides like amitrole, diuron, glyphosate, glufosinate, paraquat can be characterized by their weed spectrum, herbicidal activity in pre- and/or post-emergence, their uptake and translocation behaviour in plants, soil mobility, speed of action as well as duration and extent of their residual activity.
In standard experiments paraquat is showing a comprehensive activity spectrum in post-emergence treatments against most grass and broadleaf weeds, whereas this active ingredient shows no activity in pre-emergence treatments. Preplant incorporation of paraquat in mineral soil with differently adjusted clay levels led to complete inactivation even in soils with clay content below 2 % within 24 hours after treatment. After pre-emergence use crop selectivity to seedlings of wheat, maize, oilseed rape, field peas and sugar beets was dependent on the development stage of seedlings at the time of application after seeding, but independent of the clay content. The particular strength of paraquat results from a combination of different characteristics: superior weed spectrum to grass and broad-leaf weeds, lack of phloem mobility, rapid speed of action, exclusive post-emergence activity to green plant parts only, lack of residual activity, mode of action with potential use in resistance management to prevent development of resistance to other active ingredients. A comparative benefit assessment of herbicides should therefore consider and balance all these parameters.
Evaluation of trials on minimum effective dose related to the needed dose of herbicides
Summary
The complete article is written in German
For the authorisation of plant protection products data have to be submitted demonstrating that the applied dose is necessary to achieve sufficient efficacy. Fixing the minimum effective dose is an essential requirement laid down in the German Plant Protection Act in connection with Directive 91/414/EEC. Due to the reduction programme of chemical plant protection the minimum effective dose is of special relevance. Long-term practical experiences and investigations have indicated that in certain cases the needed dose is much lower than the authorised one. Therefore during the efficacy assessment a more extensive and systematic evaluation of the herbicide potential may be required in order to deliver information for the users. Trials on minimum effective dose are principally appropriate to quantify extend and conditions where doses can be reduced without a loss of effectiveness. Therefore a sufficient number of trials at different climatic and agricultural conditions is needed as well as a good documentation and evaluation. Corresponding requirements are stated in the EPPO guidelines, especially in PP 1/225 (Minimum effective dose). This paper suggests how to improve the process and evaluation of efficacy trials and how to implement the findings in order to specify the needed dose.
Reduction of herbicide inputs in winter cereals by the adjustment of herbicide mixtures and variation of dose to the target infestation – results of the trials in the states Brandenburg, Hessen, Saxony, Saxony-Anhalt and Thuringia
Summary
The complete article is written in German
At the usual weed control time in autumn, in the BBCH (EPPO) growth stage 10-11 of cereals, broad-leaved weeds and grasses have often not emerged. Herbicide application practice is often preventive. This evaluation consisted of 476 untreated plots of field trials in 1995-2004. The later assessment in untreated plots indicated that Apera spica-venti L. (silky bentgrass) required control in only 50 % of all the investigated cases. The broad-leaved weeds should be controlled in less than 30 %. In field trials in the five states herbicide mixtures were tested. The results show that despite the use of reduced application rates, good control of the target infestations was achieved. With these herbicide combinations the input of active ingredient/area can be better adapted to the treatment frequency index. The second treatment in spring is only necessary in exceptional cases of higher infestation of target weeds.
Field evaluation of an integrated Striga hermontica management in Sub-Saharan Africa: Synergy between Striga - mycoherbicides (biocontrol) and sorghum and maize resistant varieties
Summary
The root parasite Striga hermontica (Del.) Benth. constitutes a major biotic constraint to staple food production in Africa. Fusarium oxysporum Schlecht. (Foxy 2 & PSM197) proved to be highly virulent against their target weed S. hermonthica , host specific and they can be mass-produced. Thus, the antagonists offers a good prospect for Striga control in the future when incorporated into a long-term integrated Striga control program. This research focused on the development of an appropriate mycoherbicidal formulation, thereby reducing the amount of inoculum required for a practical field application. “Pesta” granules of both isolates were made by encapsulating their chlamydospore-rich biomass in a matrix composed of durum wheat-flour, kaolin and sucrose. Their efficacy in combination with Striga resistant and susceptible sorghum ( Sorghum bicolor (L.) Moench) and maize ( Zea mays L.) cultivars was tested under field conditions at two locations (Samaru & Bagauda) in Nigeria. 2.0 g of “Pesta” granules of each isolate were applied per planting hole in which 5 g of Striga seed-sand (1:20 w/w) were inoculated. Both granular mycoherbicides (Foxy 2 & PSM197) were very effective with same potential, in controlling Striga on both susceptible and resistant maize and sorghum cultivars tested. Cumulatively (on average), they reduced the number of emerged Striga plants per plot by 75.3 %, Striga dry weight by 74.4 %, Striga flowers by 83.6 %, and crop plant infested by 64.8 % compared to the controls. The resistant maize and sorghum cultivars enhanced clearly both mycoherbicides efficacy. For maize, the reduction in all Striga parameters assessed compared to the controls was clear and in most cases significant for both isolates while for sorghum the differences were small. When the different treatment x cultivar combinations were compared, the combination Pesta granules x resistant cultivar had the strongest suppressive effect on Striga Striga emergence and flowering as a result of combining mycoherbicides and host plant resistance is an important feature to prevent further Striga distribution and infestation. These findings are highly relevant to the realization of an integrated Striga control approach adoptable and applicable by subsistence farmers in Africa.
Impact of selective weeding on maize productivity in major and minor seasons – a comparative analysis from the Asian humid tropics
Summary
Weed management is vital in tropical food cropping systems to minimize competition for scare resources, especially under smallholder farming conditions, where hand weeding using family labor is a common feature. Hence, selective weeding could be practiced to maintain weed populations below economic threshold levels, and minimize competition. Field studies were initiated under rainfed conditions of Sri Lanka over the major and minor seasons that correspond to the two monsoons to determine the impact of selective weeding on growth and yields of maize (Zea mays L), the most popular highland cereal in these regions. The lack of weed control measures or the presence of the most abundant grass weeds reduced growth and yields of maize irrespective of the season. The adverse effects of the low number of sedges (Cyperaceae) was minimal, and that of broadleaves was lower than the impact of grasses. Comparative analysis of the effects of weeds in the two seasons highlighted the greater adverse effect in the minor season when the crop is subjected to water stress conditions. The weed numbers were greater, which affected the growth and yields of maize to a greater extent. However, the adverse effects of the different weed types did not change with seasons. The feasibility of adopting selective weeding to minimize adverse effects in rainfed farming systems of the humid tropics for procuring high yields is presented on the basis of this study. In contrast, clean weeding could develop other effects such as erosion
Factors affecting decision-making of farmers in weed management (case study of Tokat, Turkey)
Summary
This study analyses a weed management survey in Tokat province of Turkey. Four farmers did not use herbicides due to dry farming, unsuitable climatical conditions, low income, small-scale farms, etc. It was hypothesized that there is a relationship between factors taken into consideration while using herbicides and three variables of age, education and agroecological zones. Chi-square (x2) test results show that statistically significant relationships were found between education and dosage, destroying empty boxes or bottles of herbicides, knowledge about active ingredients of herbicides, and use of safety materials. There was also a statistically significant relationship between agro-ecological zones and dosage of herbicides and safety materials. A statistically significant relationship was found between age and destroying empty boxes or bottles and between age and safety materials. In addition, statistically significant relationships were found between weed management and farm size, ecological zones and crop rotation. On the other hand, no statistically significant relationship was found between weed management and irrigation possibility. 97 % of farmers do not have enough knowledge about the EU’s agroenvironmental policies (re-registration of agrochemicals). Farmers – scientists – extension staff – private pesticide dealer’s interaction is weak.
Suppression of Bromus sterilis L. in winter wheat – Evaluation of a four-year field trials in the states Brandenburg, Hessen, Saxony, Saxony-Anhalt and Thuringia
Summary
The complete article is written in German
The suppression of Bromus sterilis L. (sterile brome) in winter wheat was demonstrated in field trials in the years 2001-2004. The herbicides Attribut + additive Frigate, Monitor + additive MonFast and Atlantis WG + additive were tested both as single applications with different timings and as split applications. The results indicate that the weather conditions during and after the application influence the control more than the stage of growth on the density of Bromus sterilis. Under a spring drought in 2003 split applications were the only effective methods. The investigations show that the remaining Bromus plants are strong suppressed but they can produce fertile seeds. Complete control of Bromus sterilis can be achieved within a whole crop rotation.
Testing possibilities for chemical control of Iva xanthifolia in soybean
Summary
In the last few years the weed species Iva xanthifolia Nutt. has been intensively spreading from nonagricultural areas to crops, in Serbia-Vojvodina region. Danger from spreading of false ragweed is reflected in its robust look (over 2 m high), strong competition with the crop (uniform germination) and in very high seed production (up to 105,000 seeds/plant).
In this paper we are presenting results of different possibilities of control of false ragweed in soybean crop. Area of the experiment contained natural weed infestation of false ragweed at about 400-680 plants/m2. Applications were made with 8 pre-emergent herbicides (single application and combinations of herbicides) after planting and before crop germination, and 16 post-emergent herbicides. Weather conditions improved the effect of soil herbicides, so the efficacy of all applied herbicides was between 89 and 100 %. For post-emergence applications, insufficient efficacy was observed with tifensulfuron-methyl and oxasulfuron (one or split-application). Other compounds showed 98-100 % efficacy.
Obtained results show that, even in strong infestations, control of false ragweed in soybean can be very effective.
Impact of cover crops and herbicides usage on weed infestation, growth and yield of transplanted leek
Summary
Cover crops can improve the soil structure, enrich the soil, reduce nitrate leaching and soil erosion, inhibit weed emergence and in case of leguminous species, enhance soil nitrogen availability. On the other hand, cover crops may have negative influences, as absorption of soil moisture or allelopathic activity. The current studies were carried out between 2003-2005 in order to evaluate the influence of three production systems on herbicide efficiency, the dynamics of weed occurrence and growth, and finally on yield of transplanted leek. Leek was cultivated in a conventional way (without cover crops), with cover crop residues left on the soil surface and with cover crop residues cut and incorporated 10-12 cm deep into the soil. Cover crops (rye and hairy vetch) were sown in the autumn, desiccated with glyphosate or crumbled and finally incorporated into the top soil in spring. In the experiment the following parameters were evaluated: weed infestation during the entire growing season, leek growth (number of leaves, height, thickness and biomass of one plant), leaf chlorophyll content of leek, leek leaf area index, relative variable chlorophyll fluorescence and yield of leek. Weed density in the conventional method of leek cultivation was higher than in the cover crop systems. Herbicides used on plots with surface-applied cover crop residues were less efficient than in conventional plots and in plots with incorporated cover crop residues. The highest yield of leek, cultivated without herbicides, was harvested on plots with cover crop residues left on the soil surface.
Efficiency and long-term effects of certain herbicides against Canada thistle [ Cirsium arvense (L.) Scop.]
Summary
In a maize field the following herbicides were investigated regarding their efficay against thistles: 2,4-D + florasulam + rimsulfuron; iodosulfuron + foramsulfuron and clopyralid + rimsulfuron. The herbicides were applied at the 5-7 leaves stage of maize when thistles were in rosette stage. The effects were evaluated by mapping the coverage of thistles twice a year and by determining the level of translocation and root damage of herbicides by digging out the roots. The combination of iodosulfuron and foramsulfuron and the combination of 2,4-D, florasulam and rimsulfuron had no long-term effects on the coverage of thistles. The estimation of the ground coverage showed that the combination of rimsulfuron and clopyralid had a good effect on thistle emergence over one year. One year after the herbicidal treatment still 60 % decrease was observed in ground coverage.
Economic analysis of herbicide usage in wheat fields
Summary
This study analyses herbicide usage in wheat – grown under dry and irrigated conditions – from economic point of view. Amasya province of Turkey was chosen as research area because wheat is a major crop grown in the study area. A survey was applied to 78 farms which 70 of them use herbicides and 8 of them do not use herbicides in wheat growing. Herbicide usage resulted in 29.09 % yield increase (from 3322.20 kg/ha to 4288.60 kg/ha) under irrigated conditions and 10.53 % under dry conditions (from 2666.70 kg/ha to 2947.50 kg/ha). Under irrigated conditions the share of total herbicide cost in variable cost and production cost were 5.77 % and 3.69 %, respectively. Under dry conditions the values were found as 5.28 %, and 3.81 %, respectively. Gross profit was higher in the farms using herbicides (181.47 $/ha) than those not using herbicides (28.06 $/ha) under irrigated conditions. But, under dry conditions it was low in the former (45.38 $/ha), compared to the latter (74.38 $/ha). Gain threshold under both irrigated and dry conditions were calculated as 244.40 kg/ha, and 176.40 kg/ha wheat, respectively.
Long-term effect of herbicides on mass ratio of weeds in Hungary
Summary
The study examined the effect of herbicides applied over a 26-year period in a long-term, two-factorial, split-plot experiment without a crop (main plot: two tillage variants, sub-plot: 7 herbicide treatments and 2 control plots) on the mass ratio of certain weed species. A total of 112 weed species were found on the experimental field, the majority being annuals. On the basis of weed mass (g m-2), 10 kg ai ha-1 rates of simazine and atrazine had the best herbicide effect. These were followed, with moderate efficiency, by 5 kg ai ha-1 ametryn, 10 kg ai ha-1 linuron and 2+2 kg ai ha-1 2,4-D, while 5 kg ai ha-1 prometryn and 10 kg ai ha-1 monolinuron gave the poorest results. Ploughing to a moderate depth once a year, in autumn, reduced the weed mass by 36.5 %. The weed-reducing effect of the herbicides depended on the tillage variant, and there was also a considerable year effect. The exponential growth in weed mass from the 17th year of the experiment on plots treated with simazine and atrazine indicated the appearance of resistant biotypes of Amaranthus retroflexus and Conyza canadensis .
Estimation of harmfulness of weeds at various stages of potato-growing
Summary
Nine selected "critical" stages of potato crop development were examined and the correlation-regressive dependence of potato tuber yield and weed mass, without reference to the potato-growing stages was determined.
When considering the potato tuber yield, the most successful treatment was the one in which the weeds were controlled during the first two stages of potato-growing until the shoots of potato reached 15-20 cm. At that stage of development weeds were supressed by the potatoes. Having calculated the correlation-regressive dependence on potato tuber yield with respect to the weed mass, the potato yield was inversely proportional to the weed mass.
Competition between maize and Abutilon theophrasti (Medik.) in additive experiments
Summary
Small plot experiments were set up in order to study the effect of Abutilon theophrasti density (1, 2, 5 and 10 plants m-2) and some herbicides on maize under field conditions. It was concluded, that because of extreme high amount of rainfall during the vegetation period competition between maize and A. theophrasti was not considerable, not even at the highest weed density of A. theophrasti. Slight, but significant (15 %) yield loss was observed due to 2 A. theophrasti plants m-2. It can be explained by the fact, that intraspecific competition among A. theophrasti plants at low density was not so strong, than at higher density. It was well expressed from seed production data of A. theophrasti. The greatest yield loss was observed in weedy plots, where the average yield was reduced by 34 %, as compared to weed free control. Herbicide treatments with active ingredients of pendimethalin, dimethenamid, bentazon, dicamba and nicosulfuron gave good weed control effect without any toxicity on maize during the vegetation period.
Weed control in millet corn ( Panicum miliaceum )
Summary
The complete article is written in German
For dry and warm regions millet corn is an alternative crop. However, during crop establishment phase millet corn is very sensitive to weed competition. Critical period starts between 4- to 6-leaf stage of the crop. After 6-leaf stage crop development is very fast and late emerging weeds have no chance to influence crop yield. Because of this short critical period a single treatment of leaf active herbicide is sufficient for weed control. Even if perennial weeds like Convolvulus arvensis are of importance, a partly efficient herbicide is good enough due to strong competition of the crop. Several herbicides are available for weed control in millet corn, which are efficient and selective. Pendimethalin is an exception. This herbicide causes strong damage to millet corn.
Postemergence herbicide treatments in maize against difficult to control weeds in Hungary
Summary
In South-East Hungary the weather conditions generally are dry in spring so efficacy of preemergence weed control methods is not sufficient. Experiments were conducted in Hódmezovásárhely, southern part of the Great Hungarian Plain in 2003 and 2004 to study different postemergence weed control methods in small plots in maize. The characteristic weeds on the experimental plots were the Sorghum halepense, Datura stramonium, Chenopodium album, C. hybridum, Amaranthus retroflexus, Stachys annua. The results of the two years were very similar. The efficacy of the herbicide combinations was a bit quicker in 2004. It can be explained by the rainy and hot weather conditions. The nicosulfuron + dicamba + bentazone combined with different adjuvants controlled the S. halepense and dicot weeds with a very good result. Foramsulfuron + isoxadifen-ethyl, foramsulfuron + 2,4 D, foramsulfuron + isoxadifen + iodosulfuron-methyl-Na and rimsulfuron + mesotrione also provided a good herbicide effect. Mesotrione + atrazine killed only the dicot annual weeds excellently so the cover of Johnsongrass was high at the time of harvesting. Significant yield loss of maize was observed caused by the high weed infestation on this plot and on the untreated one.
Efficacy of several herbicides in controlling weeds in wheat
Summary
Field trials were carried out in winter wheat at Jabuka site (Southern Banat) in 2001, 2002 and 2003 to evaluate the efficacy of several active ingredients and their combinations, namely: amidosulfuron + iodosulfuron (Secator), tribenuron-methyl (Granstar 75 WG), triasulfuron + dicamba (Lintur), 2,4-D + florasulam (Mustang), 2,4-D EHE (Lentemul D), bentazone + dicamba (Cambio), fluroxypyr (Starane-250), tritosulfuron (Certo) and tritosulfuron + dicamba (Arrat). Trials were set up in wheat crop (cv. Evropa 90), applying OEPP/EPPO methods (1998). A random block design with four replicates and plot size 25 m2 was applied. The herbicides were applied at the end of tillering and efficacy was estimated three and six weeks after application. The acquired results show that the tested herbicides can be successfully applied to control weeds in wheat in the area of Southern Banat.
Effects of different herbicides and application times on the apical development and grain yield of wheat ( Triticum aestivum L.)
Summary
The influence of different herbicide treatments and application timings on the apical development of wheat ( Triticum aestivum L.) was evaluated in field trials conducted during two subsequent growing seasons in Aydin province of Turkey. Three common herbicides (tribenuronmethyl, 2,4-D amine and cladinafoppropargyl) were applied. The timing of herbicide application was adjusted to the apical development of wheat, which was continuously monitored by microscopy using wheat samples collected from field plots. Herbicide treatments were done before (early treatment) and after double ridge stage of wheat (late treatment).
Results showed that early 2,4-D amine treatments prolonged the spikelet development period (SDP), because the double ridge stage was reached earlier with this treatment. Tribenuronmethyl shortened the SDP and prolonged the floret development period. Grain yield values showed that the herbicide applications and the herbicide x variety interaction had a significant influence on grain yield. Early cladinafoppropargyl treatments gave the highest yield and corresponded with the untreated control. In general, the yield of untreated or early treated plots was significantly higher than the yield of plots treated after double ridge stage. Therefore, in order to ensure high yields and prevent crop injury it is recommended that the herbicides tested should be applied before double ridge stage.
Comparative study of fertilization effect on weed biodiversity of long term experiments with near field remote sensing methods
Summary
Since the decision of The Earth Summit in Rio (UN 1992), conservation of biodiversity is a critical environmental protection issue. However the sector specific arable land agro biodiversity was only defined a few years ago in OECD countries. The one-sided usage of herbicide led to the selection of several weed species, and some species need protection. In this study, we analyzed the rate of weed coverage and population in a 22 year long term field experiment. A coenological survey has been performed simultaneously to a maize field production test with the application of increasing doses of NPK and NPK-FYM.
Parallel with the conventional mapping, we also used a wide broad handy camera, taking images in NIR-R-G spectra, for mapping. The results of the image analysis significantly improved the reliability of field surveying in case of high weed cover (>25 %) compared to traditional surveying methods. Regarding NPK and NPK-FYM treatments: the results of the statistical analysis (Student’s t test) showed that the values of NDVI, weed cover (%) and the visual coenological survey (%) were significantly higher (SD = 5 %) for NPK-FYM treatments. We expressed the changes of the weed species constitution with the Shannon-index, well known in ecology. We evaluated the development of species number according to the different relations of nutrient supply. The application of increasing fertilizer doses reduced the number of occurring species in both treatments compared to control treatments. The information gained is suitable for the indication of biodiversity of other production sites, and can be a basis for optimising the cropping technology interferences.
Effect of different weed control strategies on the nitrogen efficiency in cereal cropping systems
Summary
Information on the long-term effect of a reduction of herbicides on the weed population, yield, and nitrogen balances are scarce. Therefore a 9-year field trial in Brandenburg, Germany, was conducted, which compared the effect of a situation-related herbicide treatment with a 50 percent reduced rate and an untreated control. This paper is restricted to winter wheat, winter barley and winter rye.
During the first period of the field experiment (1997-2001), the reduced herbicide treatment also received a reduced mineral fertilization. This caused a very small competitive ability of the cereal crops and caused a great population development of Apera spicaventi . Accordingly, the yield increase after application of the reduced herbicide rate was higher compared with the situation-related treatment, though the effectiveness was 10 to 30 percent lower. During the course of the experiment, an increase in the noxious weeds in the treatment with the reduced herbicide application occurred. This consequently caused only a small yield increase compared with the situation-related treatment. The relative yield increase after herbicide application was larger if a fungicide was applied, which reduced the infestation of fungal diseases. The efficiency of nitrogen fertilization was significantly increased after the application of herbicides due to yield increases.
Influence of herbicide and application timing on Alopecurus myosuroides Huds. control in winter wheat in Poland
Summary
Alopecurus myosuroides Huds. is a problematic weed only in some regions of Poland. In the last several years an increase of A. myosuroides – especially in south-west Poland – was observed.
Between 2003 and 2005 the evaluation of herbicides’ efficacy used in autumn and in spring to control A. myosuroides was tested. For investigations the herbicides containing iodosulfuron, fenoxaprop-P-ethyl and a mixture of isoproturon and diflufenican were used.
The results of the experiments indicate a very high efficacy of fenoxaprop-P-ethyl applied in the spring. The autumn treatment was less efficient. The mixture of isoproturon + diflufenican was effective only during autumn application. Irrespective of the time of application iodosulfuron was not effective enough for A. myosuroides control.
Influence of weed infestation on the calorific value and chemical composition of maize ( Zea mays L.)
Summary
The influence of weed infestation on the calorific value in dry biomass, total energy production and chemical composition of maize was studied in 1998 to 2000. The studied variants were: 1. without weed eradication (control), 2. mechanically weeded from the beginning of the vegetation period till the 5-leaf stage of maize, 3. mechanically weeded from the 5-leaf stage of maize till the end of vegetation, 4. mechanically weeded throughout the whole vegetation period, 5. chemically weeded. The mechanical cultivation of the maize stands was done in 14-days intervals. Chemically weeded variant was treated by post-emergence herbicides application. The calorific value in dry matter of maize ranged from 16.57 to 18.13 kJ.g-1. Statistically significant difference (a = 0.01) among individual parts of plants was recorded. Total energy production of maize particularly depended on biomass yield. Weed infestation caused in variants 1 and 2 significant reduction of maize energy production by 17.23 % and 14.29 %, respectively. Lower energy content (NEL) and higher content of potassium, calcium and ash (a = 0.05) was observed in maize biomass with weeds in comparison with the same parameters in maize biomass from weeded variants.
Effect of mulching and cutting on weedy species in an upland meadow
Summary
Effect of cutting and different mulching frequencies on spread of weedy species in seminatural grassland was studied in upland of the Jizerské Mts. over a 5-year period (2000-2005). Before the establishment of the experiment dominant plant species were Dactylis glomerata , Festuca pratensis , Elytrigia repens , Aegopodium podagraria and Veronica chamaedrys . The grassland was occasionally grazed or mown before start of the study. Investigated treatments were unmanaged grassland, cut twice and mulched from 1 to 3 times per year. Prostrate species, namely Taraxacum spp. and Trifolium repens , were positively responding to higher frequency of defoliation, whereas unmanaged or grassland defoliated only once per year was favourable for tall plant species. Proportion of Taraxacum in sward evidently reflected frequency of defoliation in mesic grasslands thus its enhancement by frequent mulching as well as cutting can be generally expected. Plant species number increased in two cut, two or three times mulched treatments and decreased in plots with no management. The results of the study showed the ability of mulching performed at least twice per year to non-chemically restrict undesirable weeds such as Cirsium arvense , Urtica dioica or Elytrigia repens in mesic grasslands without utilization for forage production.
Efficacy of selected chemical weed control systems in maize
Summary
Dicotyledonous weeds such as Chenopodium album, Amaranthus retroflexus, Galium aparine, Solanum nigrum, Anthemideae and other different dicotyledons with high phytosociological stability contribute to the decrease in maize yielding on the black soil in the south-west region of Poland. Especially late-emerging Echinochloa crus-galli is very hard to control on areas where dicotyledonous taxons occur. Elymus repens growing on maize fields with reduced tillage is also very harmfull. Chemical weed control in integrated weed management systems were suitable to control this weed during the whole vegetation period and therefore the highest yield was achieved.
In the years 2000-2004 field experiments were carried out in the Institute of Soil Science and Plant Cultivation, Wroclaw.
Investigation involved weed community of:
A - Echinochloa crus-galli + dicotyledonous weeds control
B - Elymus repens + dicotyledonous weeds control
with the use of chemical weed control systems.
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