Percent Weed Research Articles

Influence of weed size on herbicide interactions for Enlist™ and Roundup Ready® Xtend® technologies

AbstractWeed size can nfluence herbicide performance and herbicide interactions in mixtures. To control a broad range of species in soybean or cotton, POST herbicide mixtures will likely be commonplace in Roundup Ready® XtendFlex® and Enlist™ technologies. The impact of weed size on herbicide interactions that could occur in Roundup Ready XtendFlex or Enlist crops was assessed in two field experiments conducted in 2015 and 2016 at the Northeast Research and Extension Center in Keiser, AR. Combinations of glufosinate, glyphosate, dicamba, and 2,4-D were applied to either 10-cm or 30-cm weeds and evaluated for percent weed control, height reduction, and density reduction, collected 5 wk after treatment. Colby’s method was used to analyze treatments for herbicide interactions for control of barnyardgrass, Palmer amaranth, and pitted morningglory. Antagonism was identified with at least one treatment on all species. Almost all treatments were antagonistic for percent weed control, height reduction, and density reduction on barnyardgrass. When glyphosate in mixture with 2,4-D or dicamba was applied to 30-cm barnyardgrass, control declined 9% for both mixtures relative to glyphosate alone. Glufosinate plus glyphosate was antagonistic when applied to both 30-cm pitted morningglory and barnyardgrass. Glufosinate plus dicamba provided less control and density reduction of Palmer amaranth than what was expected from Colby’s equation. Overall, antagonism was more likely to be identified when applications were made to 30-cm weeds compared with 10-cm weeds. The utility of a given herbicide mixture will depend on the species present in the field and the size of those species at the time of application.

Ubiranje soje kombajnom Claas Lexion 430 - ekploatacioni parametri

Soya (Glycine) is one of the most important crop plant. It produces products for human and domestic animals and processing industry. It is an important protein and oil plant. The soybean seeds contain more proteins (35-50%) and fats (17-24%) and fewer carbohydrates than others leguminous plants. Research of the Claas Lexion 430 combine harvester in a mercantile soybeans harvest shown that losses in uncut pods were in all measurements above tolerant 2% and ranged from 2.46% to 2.94%. Losses on the thresher in the free grain were ranged from 0.18% to 0.34% on average to 0.26%, which is satisfactory in relation to the given 0.3%. The average losses in the unthreshedpods are 0.35%, which is more than the projected level, but for the conditions of harvesting it can be accepted as satisfactory, due to the large percentage of weeds in the field.

Agronomic Practices of Maize and Farm Nutrient Status in Bako Tibe District, West Shoa Zone, Ethiopia: Lesson from Agronomic Panel Survey

Agronomic panel survey was conducted in Bako Tibe district to assess current farmers maize agronomic practices and associated actual maize grain yields. The survey was conducted using 100 households. Most of the maize farms (90%) were characterized as having strongly to strongly acidic soils, low to medium SOC, medium to high TN, very low to low av.P, high to very high exch. K, low to medium exch.Ca, and medium to high exch. Mg, high av. Zn and Fe and very high Mn contents. Most farmers (94%) grow improved maize varieties and 80% of them grew a pioneering hybrid Limu and Bako hybrids BH540 and BH543. Most farmers (97%) apply different inorganic fertilizers and of them >70% of them applied NPS+Urea or NPS alone. Farmers rarely retain crop residue. Most farmers (81%) maintain lower plant density at harvest than the recommended density and the density declined from vegetative to harvesting stage. About 99% of the farmers grow sole maize, 57% rotate maize with other. Percent weed cover of the farms were 25% on average but reached as high as 80%. About 87.5%, 86%, 75% of farmers harvested grain yield that was higher than the national, regional and zonal average, respectively. Since most maize farms (90%) were very strongly to strongly acidic, there is a need to apply lime to improve maize productivity and nutrient use efficiency in the area. The poor weed and crop residue management, sole cropping of maize and lower plant densities practiced by farmers were among the gaps observed that potentially reduce maize productivity in the study area unless the extension sector intervenes. However, the current trend improved maize varieties and inorganic fertilizers use is promising and needs to be encouraged for intensification of maize production in the study area.

Biological control of Salvinia molesta in South Africa revisited

The aquatic weed Salvinia molesta D.S. Mitch. (Salviniaceae) was first recorded in South Africa in the early 1900s, and by the 1960s was regarded as one of South Africa’s worst aquatic weeds. Following the release of the weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae) in 1985, the weed is now considered under successful biological control. However, the post-release evaluation of this biological control programme has been ad hoc, therefore, to assess the efficacy of the agent, annual quantitative surveys of South African freshwater systems have been undertaken since 2008. Over the last ten years, of the 57 S. molesta sites visited annually in South Africa, the weevil has established at all of them. Eighteen sites are under successful biological control, where the weed no longer poses a threat to the system and 19 are under substantial biological control, where biological control has reduced the impact of the weed. Since 2008, the average percentage weed cover at sites has declined significantly from 51–100% cover to 0–5% cover in 2017 (R2 = 0.78; P < 0.05). Observations of site-specific characteristics suggest that biological control is most effective at small sites and more difficult at larger and shaded sites. Our findings show that S. molesta remains under good biological control in South Africa, however, some sites require intermittent strategic management, such as augmentative releases of C. salviniae.

Prinos travno-detelinske smeše na kiselom zemljištu u trećoj godini nakon kalcizacije

Soil acidity is one of the most common reasons for low yields of forage crops. This paper analyzes the long-term effect of liming (control - without CaO; 3 t*ha-1 CaO; 6 t*ha-1 CaO) applied to an acid soil (pHH2O 4.8) before stand establishment on the productivity of a mixture of red clover (Trifolium pratense L.) and tall oat grass (Arrhenatherum elatius L.) during the third year of production. Soil liming significantly increased hay yields in the first and second cuts by 17-25% and 46%, respectively, which resulted from an increase in the total yield and dry matter content of forage. In the third cut, soil liming had no effect on forage and hay yields due to the lower amount of precipitation in the second part of the growing season. Both lime application rates led to a significant reduction in the percentage of red clover in the first and second cuts, thus favoring the percentage of tall oat grass. In the third cut, only the percentage of weeds was lower in both lime treatments, as it decreased by more than 55% compared to the control.

Effect of mulches on some characteristics of a drought tolerant flowering plant for urban landscaping

Mulches are relatively new landscape components and are becoming recognized for their environmental and aesthetic outcomes on urban landscapes especially in arid environments. However, the effects of mulches on landscape plants have not been extensively discussed. This study examined the effects of organic and inorganic mulches on the performance of a widely used herbaceous drought tolerant flowering plant, Zinnia elegans, toward low maintenance landscaping. This study was designed as a randomized complete block design with three replications. Four widely commercially available and utilized mulches, including wood chips, pine needles, scoria (volcanic stone) and black polyethylene were used as the treatment mulches. The study contained plots with only bare soil as the control. The results showed that utilizing the selected mulches demonstrated positive effects on the plant growth, and increased the fresh and dry weight of shoots (p<0.05) compared to the control. In the Zinnia, the highest fresh and dry weights were recorded for the wood chip treatment. The decreased the percentage of weeds (p<0.01) compared to the bare soil. The highest water use efficiencies were recorded when polyethylene, wood chips (M=16 kg/m3) and pine needles were used as mulches, respectively. Mulches increased the flowering period up to 6 days and decreased the number of days to flowering up to 19 days with polyethylene mulch compared to the control treatment. Therefore, utilizing organic and inorganic mulches for improving landscape quality, performance and aesthetics especially in arid environments is to be recommended.

Efficacy and economics of imidazolinone herbicides in cluster bean and their residual effect on mustard

A field experiment was carried out at two different locations, research area of CCS HAU Hisar and farmer's field (Kheri Batter) to study efficacy and economics of imidazolinone herbicides in cluster bean during Kharif 2013 and their carryover effect on mustard was observed during Rabi 2014. Significantly higher herbicide efficiency index (HEI) was observed under PE application of pendimethalin + imazethapyr 1000 g/ha and tank mixture 500 g + imazethapyr 50 g/ha at 30 DAS and these two treatments also provided better control of weeds at 60 DAS without any phytotoxic effect on cluster bean at both the locations. At 30 DAS, less dry weight of weeds was recorded under pendimethalin 1000 g/ha as PE, but at 60 DAS, due to new emergence of weeds, percent weed control reduced due to more dry weight of weeds, thus HEI was lower under pendimethalin 1000 g/ha PE. At 60 DAS, PoE application of imazethapyr 100 g/ha fb propaquizafop 62.5 g/ha provided the highest HEI which was at par with pendimethalin + imazethapyr (ready and tank mixture), but at Hisar, HEI of imazethapyr + imazamox at all the doses was lower due to heavy infestation of T. portulacastrum as compared to other herbicidal treatments. The lowest weed index (WI) was observed under pendimethalin 500 g + imazethapyr 50 g/ha (tank mixture) as PE which was significantly at par with pendimethalin + imazethapyr (RM) 1000 g/ha as PE and imazethapyr 75 and 100 g/ha fb propaquizafop 62.5 g/ha, but significantly higher WI was recorded under imazethapyr + imazamox due to lower efficacy against T. portulacastrum. The highest biological yield, seed yield, maximum net returns and increase over weedy check were obtained under pendimethalin 500 g + imazethapyr 50 g/ha (tank mixture) as PE and pendimethalin + imazethapyr (RM) 1000 g/ha as PE, but both were statistically similar to each other and similar to PoE imazethapyr 100 g/ha fb propaquizafop 62.5 g/ha at both the locations. No injury was visible at 2 WAS, 4 WAS and later stages on mustard.

Flame Weeding at Archaeological Sites of the Mediterranean Region

Archaeological sites of the Mediterranean region are widely colonized by weed species causing various problems both to the monuments and the functionality of the sites. Due to recent regulatory restrictions for herbicide use at archaeological sites, flame weeding was studied as an alternative weed management method. The objective of the study was to test two propane doses (99 kg ha−1 and 129 kg ha−1) applied two, three, or four times at three archaeological sites of Greece (Kolona, Ancient Messene and Early Christian Amfipolis). Percent weed control and weed heights were significantly affected by flaming treatments. Visual evaluation of percent weed control suggested that the propane dose of 129 kg ha−1 applied four times provided excellent weed control (&gt;90%) for over 2 months. Annual broadleaf weeds were controlled better with flaming than grasses and perennial broadleaf species. The high propane dose applied four times reduced average vegetation height to about 10 cm, which was the desirable vegetation height wanted by the managers of the archeological sites suggesting that flame weeding has the potential to be used effectively for weed management in archaeological sites of the Mediterranean region.

Duration of Soil Activity of Foramsulfuron Plus Thiencarbazone-methyl Applied to Weed Species Typical of Sugar Beet Cultivation

The duration of the soil activity of an acetolactate synthase-(ALS) inhibiting herbicide which is currently under approval for sugar beet cultivation was determined in a field trial series in Germany in 2013 and 2014. The herbicide containing foramsulfuron (FSN; 50 g L−1) and thiencarbazone-methyl (TCM; 30 g L−1) was applied in different dosages (25+15, 37.5+22.5 and 50+30 g FSN+TCM ha−1) to the bare soil. Five weed species (rapeseed, common lambsquarters, wild chamomile, blackgrass, barnyardgrass) were sown at 5, 10, 15 and 20d after application. The duration of the soil activity was assessed by determining percent weed control in the treated plots. The longest duration was observed after applying 50+30 g FSN+TCM ha−1, but the influence of environment was much stronger than the dosage effect. The mean duration of soil activity was 10 to 15 d in 2013 and longer than 20 d in 2014. Differences among weed species in their response to the herbicide treatments were small.

Use of remotely sensed data to characterize weed competition in forest plantations

ABSTRACTCharacterization of weed size using remotely sensed data could provide a useful means of scheduling post-plant weed control in plantation forests. Data from four forestry stands, which included field measurements of weed competition and multispectral data collected from an unmanned aerial vehicle (UAV) and satellite platform (WorldView3), were used to (i) develop models to predict overall weed percentage cover (C), height (H), and a competition index, CI, (C × H/100) derived from these two metrics; and (ii) determine the optimal spatial resolution for imagery from these two platforms for characterizing these measures of weed competition.Bivariate analysis of the three weed metrics showed the optimal spatial resolution to be 5 m for the WorldView3 data and 1 m for data obtained from the UAV. The best multiple regression models developed to predict C, H, and CI had coefficient of determinations (R2) of, respectively, 0.33, 0.68, and 0.56 for data derived from WorldView3 and, respectively, 0.56, 0.79, and 0.71 for data derived from the UAV. Vegetation indices, derived from the multispectral UAV data and satellite imagery, were strong predictors of weed metrics for all but one of the six models developed. These results suggest that it may be possible for forest managers to use satellite imagery and UAV data to schedule weed control operations.

Effect of application rate and irrigation on the movement and dissipation of indaziflam

Indaziflam is a new preemergence herbicide for the control of annual grass and broadleaf weeds in various cropping systems including pecan orchards. The objectives of this study were to (1) determine the mobility and dissipation of indaziflam and (2) evaluate herbicide efficacy in a flood-irrigated pecan orchard in southern New Mexico, USA. Indaziflam was applied at 0, 36.5, and 73.1g/ha in areas with (impacted) and without (unimpacted) tree injury symptoms. Soil samples were collected at 0–15, 15–30, and 30–46cm depths 26, 63, 90, and 126days after the first herbicide application. Additional soil samples were collected 4, 30, and 56days after the second application. Indaziflam was detected in soil samples collected at each depth, suggesting movement with irrigation water. Indaziflam concentrations decreased with increasing soil depth and time. Indaziflam mass recoveries were greater in the unimpacted area than in the impacted area after the first and second applications. Dissipation half-lives of indaziflam in the soil ranged from 30 to 86days for total indaziflam recovered from the entire soil profile after the first and second applications in both areas. The percent weed control was similar in the impacted and unimpacted areas for both rates of indaziflam on 26 and 63days after application; however, on 90days after the application, percent weed control was lower in the impacted than unimpacted area.

Combate de malezas, en monocultivo de maní forrajero (Arachis pintoi).

We evaluated four chemical treatments (herbicides) used to fight weeds, as compared to manual weed picking and using a witness treatment. All treatments had a rotational handling with 6.5 animal units (12 animals of 250 kg per five haurs). We used a proteid bank or monoculture of forage peanut, in an arca of 1080 sq.mt., with a 30 days break. In order to evaluate the many variables, we used an experimen-tal design of complete random blocks, with six treatments and tree repetitions per treatment. In order to determine the coverage of the culture, its tolerance to the active ingredient and the level of treatment control, we carried out four evaluations: 0, 30, 60, and 90 days of treatment application. We found differences (P&lt;0.01) between treatments related to the degree of coverage of the forage peanut plants. With Gliphosate and manual weeding, we obtained a dominant coverage of forage peanut, while with the witness treatment the degree of coverage was inferior. The production of dry matter from the weeds, as well as their percentage in the pasture, decreased in a significant way (P&lt;0.01), through the sampling process. With the witness treatment we obtained the largest amount of dry matter in the weeds, and also the highest percentage of weeds in the pasture.

Study of bio-efficacy and Phytotoxicity of New Generation Herbicides on Triafamone and Ethoxysulfuron in Direct Seeded Rice (Oryza sativa)

The herbicides triafamone + ethoxysulfuron at (200g/ml/ha and 225 g/ml/ha) and triafamone (225 g/ml/ha) applied at 15 days after planting recorded the zero weed counts of individual species viz., grasses, sedges and broad leaf weeds, weed dry matter production and weed control index favoring to higher grain yield of (5.2 and 5.34 t/ha). Triafamone + ethoxysulfuron (175 g/ml/ha) recorded the least weed count, weed dry matter and cent percent weed control index recorded at 42 days after application (DAA). Ethoxysulfuron (150g/ml/ha) was next in order. No phytotoxicity symptoms was observed in the treatments including double the recommended dose of triafamone + ethoxysulfuron (450 g/ml/ha and 225 g/ml/ha) in respect of leaf chlorosis, tip burning, necrosis, epinasty, hyponasty, vein clearing, wilting and rosetting.

Early-Season Palmer Amaranth and Waterhemp Control from Preemergence Programs Utilizing 4-Hydroxyphenylpyruvate Dioxygenase–Inhibiting and Auxinic Herbicides in Soybean

Palmer amaranth and waterhemp have become increasingly troublesome weeds throughout the United States. Both species are highly adaptable and emerge continuously throughout the summer months, presenting the need for a residual PRE application in soybean. To improve season-long control ofAmaranthusspp., 19 PRE treatments were evaluated on glyphosate-resistant Palmer amaranth in 2013 and 2014 at locations in Arkansas, Indiana, Nebraska, Illinois, and Tennessee; and on glyphosate-resistant waterhemp at locations in Illinois, Missouri, and Nebraska. The twoAmaranthusspecies were analyzed separately; data for each species were pooled across site-years, and site-year was included as a random variable in the analyses. The dissipation of weed control throughout the course of the experiments was compared among treatments with the use of regression analysis where percent weed control was described as a function of time (the number of weeks after treatment [WAT]). At the mean (i.e., average) WAT (4.3 and 3.2 WAT for Palmer amaranth and waterhemp, respectively) isoxaflutole +S-metolachlor + metribuzin had the highest predicted control of Palmer amaranth (98%) and waterhemp (99%). Isoxaflutole +S-metolachlor + metribuzin,S-metolachlor + mesotrione, and flumioxazin + pyroxasulfone had a predicted control ≥ 97% and similar model parameter estimates, indicating control declined at similar rates for these treatments. Dicamba and 2,4-D provided some, short-lived residual control ofAmaranthusspp. When dicamba was added to metribuzin orS-metolachlor, control increased compared to dicamba alone. Flumioxazin + pyroxasulfone, a currently labeled PRE, performed similarly to treatments containing isoxaflutole or mesotrione. Additional sites of action will provide soybean growers more opportunities to control these weeds and reduce the potential for herbicide resistance.

Some aspects of the phenology of rice-field weeds

On the basis of their life-span, rice-field weeds may be classified as annuals and perennials; the latter forms a low percentage (24.7) and the former a high one (75.3). The largest number of perennials, however, are contributed by the &lt;i&gt;Gramineae&lt;/i&gt;. The maximum flowering of weeds (40.4 per cent) takes place in the period ranging from the monsoon, to the post-monsoon. Though not as high as this value, significant proportions of flowering occur in the season from the pre-monsoon to monsoon (11.8 per cent), from the monsoon to the winter via the post-monsoon (9.9 per cent) and monsoon alone (9.3 per cent). In the seasonal category of flowering, the &lt;i&gt;Gramineae&lt;/i&gt; also constitutes a great bulk of the weeds. The highest fruiting percentage of weeds (31.0) is found in the seasonal phase extending from .the monsoon to the winter through the post-monsoon. This is followed by the regime from the, monsoon to the post-monsoon (26.1 per cent) and the time from the post-monsoon to the winter (11.2 per cent). In the seasonal category of fruiting, the &lt;i&gt;Gramineae&lt;/i&gt; too contain a high number of weeds. Whether by single method (fruit and seed) or dual method of reproduction (rhizome, tuber, etc. in addition to fruit and seed), the &lt;i&gt;Gramineae&lt;/i&gt; finds a prominent place in the list of perennial species and the &lt;i&gt;Cyperaceae&lt;/i&gt; among the annuals. The implications of the above findings are discussed.

The influence of cover crop variety, termination timing and termination method on mulch, weed cover and soil nitrate in reduced-tillage organic systems

AbstractOverwintered cover crops mechanically terminated into mulch can be a weed management tool for reduced-tillage organic agriculture. However, the impacts of management options for cover cropping are not well understood, including cover crop variety, termination timing and termination method. In a field experiment, conducted in 2012 and 2013 in Western Washington, we examined three grains, four vetches and one barley–vetch mix terminated with two mechanical methods and at two different times. We determined the influence of cover crop variety and termination time on cover crop biomass production and tissue nitrogen (N), effectiveness of cover crop termination, soil nitrate–N and percent weed cover. We also determined the influence of termination method on percent weed cover. Cover crop biomass ranged between 3 and 9 Mg ha−1and was not influenced by termination time; the greatest production was from three varieties of grain. Rye varieties were more effectively terminated with a roller–crimper than barley. Mean soil nitrate–N levels ranged from 1.9 to 18 mg kg−1and were the greatest with vetches. Post-termination weed cover was greater in 2013 than in 2012 and the cover crop variety influenced weed cover at the Late termination time only. Neither plant N concentration in the cover crop mulch nor soil nitrate influenced weed cover. The results of this study indicate that cover crop biomass and termination timing are important factors influencing weed cover and termination effectiveness in cover crop mulch.

Chemical Control of Monocot Weeds in Wheat (&amp;lt;i&amp;gt;Triticum aestivum&amp;lt;/i&amp;gt; L.)

Due to similar growth pattern and morphology, monocot weeds offer more severe competition with wheat. A field experiment was conducted to screen herbicides most suitable for the control of monocot weeds in wheat. Seven herbicides viz., Puma super 69EW @ 862.5 g a.i. ha-1, Bristle 69 EW @ 1250 ml, Topik 15WP @ 37.05 g a.i. ha-1, Safener15WP @ 247g, Certain 80WD @ 395.2 g and Tremor 24EC @ 247 ml/ha were used. Weedy check where no weed control was practiced was kept as control. All herbicides were sprayed as post-emergence with second irrigation 38 days after crop sowing. The best weed control was accomplished by Safener 15WP 247 g ha-1 as significantly lower weed counts per m2 (11.0) and higher percent weed control (73.4%) were noted after 21 days of its spray. Wheat growth parameters like plant height, number of tillers per m2, spike length and number of spikelets per spike remained statistically at par among various treatments. Significantly higher number of grains per spike (55.67) and 1000 grain weight (36 g) were noted with Puma Super 69EW @ 1250 ml ha-1 and Certain 80WD 395.2 g ha-1, respectively. Although treatments did not differ significantly with respect to wheat grain and biological yields, yet the highest grain yield (3708.3 kg ha-1) and biological yield (10208.3 kg ha-1) were produced by Puma Super 69EW @ 1250 ml ha-1. Based on better weed control and wheat yield, Safener 15WP @ 395.2 ml ha-1 and Puma Super 69EW @ 1250 ml ha-1 were proved to be better in areas where wheat fields are predominantly infested by monocot weeds. Puma super, Bristle Tremore, Safener and Certain were found effective against Avena fatua and Polypogon monspelliensis, less effective against Phalaris minor and ineffective against Poaannua grass.

The Effect of Time of Day on the Activity of Postemergence Soybean Herbicides

The effect of time of day (TOD) on the activity of six common POST herbicides was investigated in field trials from 2007 to 2009 at two locations in southwestern Ontario. Percentage weed control was assessed following application of bentazon, chlorimuron-ethyl, fomesafen, glyphosate, imazethapyr, or quizalofop-p-ethyl applied at 3-h intervals from 6:00 A.M. to midnight, when weeds averaged 15 cm tall. The effect of time of day varied with weed species, but weed control was generally reduced when herbicides were applied at 6:00 A.M., 9:00 P.M., and midnight. Herbicide activity on velvetleaf was most frequently reduced, especially for chlorimuron-ethyl, glyphosate, and imazethapyr. Control of common ragweed with glyphosate and imazethapyr was also affected by the timing of application, and pigweed species only showed an effect with glyphosate. Variation in temperature, relative humidity, and dew presence/absence at different times of the day, as well as morphological/physiological characteristics such as weed size at time of application and diurnal leaf movement in response to light intensity, may account for the variation in weed control at different times of the day. Significant soybean yield loss was not observed in this study, but may occur if herbicide efficacy is severely reduced by application at inappropriate times of day. These results provide valuable information for growers, and suggest that POST herbicides are most effective when applied midday, rather than in the early morning or late evening.

Performance of Low-maintenance Turfgrass Mixtures and Blends

Several studies have been conducted on low-maintenance turfgrass species; however, relatively few have evaluated mixtures or blends. The objective of this study was to evaluate low-maintenance turfgrass mixtures or blends for turf quality under minimal input conditions. Eight turfgrass mixtures or blends were planted in 2009 at the University of Minnesota Landscape Arboretum (Chaska, MN) on a low-fertility soil to assess their adaptability to low-input conditions (minimal water and fertilizer and no pesticides after establishment). The year after establishment, plots were divided into no-mow and minimal mow treatments. Plots were evaluated for establishment in 2009 and overall quality and percent weed cover in 2009, 2010, and 2011. Native grass mixtures established slowly with greater weed encroachment, but over time resulted in high-quality ratings. Under minimal mowing, the Tall Fescue Blend [tall fescue (Festuca arundinacea)] performed the best for quality, while three fine fescue (Festuca sp.) mixtures and the Tall Fescue/Kentucky Bluegrass Mixture [tall fescue + kentucky bluegrass (Poa pratensis)] also had acceptable quality ratings. The Kentucky Bluegrass Blend (kentucky bluegrass) was less competitive with weeds and had unacceptable quality ratings. Under no-mow conditions, the native grass mixtures and the Tall Fescue Blend had the highest overall quality ratings.

Weed management in winter wheat ( Triticum aestivum L.) influenced by different soil tillage systems

In this study, weed management in winter wheat influenced by different soil tillage systems was investigated. The experiment was carried out under Mediterranean conditions on a Luvisol, during two growing seasons (1996/1997 and 1999/2000). Two factors (different soil tillage systems and post-emergence weed control) were studied, with two levels each: Two soil tillage systems and two levels of post-emergence weed control. The conventional soil tillage system, performed for seedbed preparation after the emergence of a high percentage of weeds, increases the appearance of monocotyledons, especially Lolium rigidum Gaud. in wheat crops, when compared to their establishment in no-till system. As a consequence of the higher number of monocotyledons there is an increase in weed-crop competition. Without post-emergence herbicide treatment, the wheat crop yield is lower in the treatments with the conventional soil tillage system and yield reduction is less under no-till system compared to the respective treatments with post-emergence herbicide application. Key words: No-till system, weeds, wheat, herbicides.