Weed Infestation Of Crops Research Articles

English

The use of allelopathic bacteria to combat weed infestation in crops is regarded as an effective technology for sustainable agriculture and environment. In this regard, six bacterial strains from the genus Pseudomonas were selected for their ability to inhibit the germination and growth of Leptochloa chinensis (L.) and Dactyloctenium aegyptium (L.) while promoting the growth of rice. These strains were applied to the target weeds and rice using different application methods viz. seed priming, liquid application, and foliar application. The results showed that all strains possessed herbicidal activity and significantly reduced growth of L. chinensis. Shoot length, root length, and fresh biomass of D. aegyptium were also significantly reduced in all strains by 60, 55, and 76%, respectively, with the exception of R15-4. Additionally, the growth suppression of both weed species was more prominent in the liquid application. The selected allelopathic strains also demonstrated plant growth-promoting traits and improved the growth and physiological parameters of rice in all three application methods, with the best results achieved with liquid and foliar applications. The survival efficiency of the bacterial strains was also tested using four different carrier materials, where the press mud was found the best carrier for controlling L. chinensis and D. aegyptium.

АГРОТЕХНИЧЕСКИЕ МЕРЫ БОРЬБЫ С ЗАСОРЕННОСТЬЮ ПОСЕВОВ ПОСРЕДСТВОМ ОБРАБОТКИ ПОЧВЫ В ОРОШАЕМОМ АГРОЦЕНОЗЕ

Purpose: to study methods to control weed infestation of crops by resource-saving methods of soil tillage, ensuring improvement of the phytosanitary condition of the irrigated agrocenosis. Materials and methods. The test scheme included studying the impact of moldboard plowing at different depths, flat-cut and surface primary tillage on weed infestation of crops. The features of agrotechnical methods in weed control were studied on experimental plots in Saratov region in 2021–2023. The experimental methodology is generally accepted. Results. The influence of different methods of primary tillage on weed infestation of agricultural crops in the crop rotation link under irrigation is considered. It is revealed that with the use of pre-sowing tillage and inter-row tillage during the crop vegetation period, a significant decrease in weed infestation of lands for the next crop is noted. For the first crop of the link – Sudan grass – the highest weed infestation was noted in the variant of minimum cultivation at 8–10 cm, the number of weeds was 26.0 pcs./sq. m. During the vegetation period, due to the high density of standing, the weed infestation of crops before harvesting decreased in all variants of the experiment. On the second crop of the link – spring wheat – and the third crop – soybean – the weed infestation varied insignificantly in all variants of the experiment. Weed control provided the biological yield of green mass of Sudan grass of 32.7–37.5 t/ha, spring wheat grain – 3.30–3.59 t/ha, soybean – 4.09–4.35 t/ha according to the variants of the experiment. No significant difference in the impact of the method of primary tillage on crop yield was revealed. Conclusions. Using the example of soybeans, Sudan grass and spring wheat, it has been proven that during their cultivation, using ploughing with furrow slice upside-down in the fall in combination with pre-sowing tillage and inter-row tillage during the crop vegetation is effective.

Estimation of the efficiency of the herbicide ‘Axial Cross’ for grain crops

The current paper has presented the results of a two-year study (2018–2019), the purpose of which was to study the efficiency of the herbicide ‘Axial Cross, EC’ (45 g/l of pinoxaden + 5 g/l of florasulam + 11.25 g/l of antidote cloquintoset-mexil) in 6 regions of the Russian Federation, namely on the crops of winter wheat variety ‘Ershovskaya’ in the Volgograd region, on the crops of winter wheat varieties ‘Skipetr’ (2018) and ‘Snigurka’ (2019) in the Voronezh region, on the crops of spring wheat variety ‘Altaiskaya Zhnitsa’ in the Altai Territory, on the crops of spring wheat variety ‘Uralosibirskaya’ in the Omsk Region, on the crops of spring barley variety ‘Acha’ in the Sverdlovsk Region, on the crops of winter barley variety ‘Rubezh’ in the Krasnodar Territory. The trials were laid on plots of 25 m2 in four sequences. The weed infestation of crops was estimated by a quantitative method before the treatment, in 30 and 5 days after it and before harvesting. The efficiency of the herbicide was calculated in relation to the untreated control. There has been established that the use of ‘Axial Cross, EC’ at application rates of 0.7–0.9–1.1 l/ha has provided a high degree of suppression of both cereals and dicotyledonous weeds. At the maximum rate of application, there was a 100 % efficiency of the herbicide against yellow-foxtail grass, wild oats, green-foxtail grass, blind weed, canker rose and black bindweed, 97.4 % against loose silky bent, 95.6 % against airif (catchweed). There was up to 68.1–77.7 % efficiency against Canadian thistle, corn sow thistle and field bindweed. The greatest yield increase after the use of the herbicide ‘Axial Cross, EC’ was obtained from the winter wheat varieties ‘Skipetr’ (0.88 t/ha) and ‘Snigurka’ (1.65 t/ha) in the Voronezh region.

BARLEY CULTIVATION TECHNOLOGY IN A LONG-TERM FIELD EXPERIMENT OF RUSSIAN TIMIRYAZEV STATE AGRARIAN UNIVERSITY

В статье приводятся сведения по результатам научных исследований в Длительном полевом опыте, отметившем свое 110-летие в 2022 г. Схема опыта предусматривает сравнение бессменных посевов сельскохозяйственных культур с севооборотом, в котором они представлены в соответствующем сочетании. Под бессменные культуры и в севообороте были изначально разработаны и использованы схемы внесения органических и минеральных удобрений с использованием извести и без её применения. В опыте возделываются бессменно и в севообороте одни и те же культуры и чёрный пар. В статье рассмотрена только часть вариантов по их влиянию на отдельные показатели роста, развития, урожайность ячменя, засорённость посевов в бессменных посевах и в севообороте. Основная цель – изучить влияние удобрений, известкования на рост, развитие, формирование урожайности агроценозами ячменя, на засорённость посевов культуры. Урожайность бессменного ячменя свидетельствует в пользу вариантов NРК и NРК + навоз с известкованием и без него, причём последняя система удобрения лидировала и в севообороте. Дальнейшая цепочка распределения урожайности ячменя в порядке уменьшения: навоз – азот – контроль 1 – контроль 2 по фону внесения извести и при его отсутствии. В севообороте расположение в порядке уменьшения урожайности: NРК – N – контроль. The article provides information on the results of scientific research in the long-term field experiment which celebrated its 110th anniversary in 2022. The scheme of the experiment provides for a comparison of permanent sowing of crops with crop rotation in which they are presented in the appropriate combination. For permanent crops and in crop rotation schemes for the application of organic and mineral fertilizers using lime and without its use were initially developed and used. In the experiment the same crops and dead fallow are cultivated permanently and in crop rotation. The article considers only a part of the options for their influence on individual indicators of growth, development, barley yield, weed infestation in permanent crops and in crop rotation. The main goal is to study the influence of fertilizers, liming on the growth, development, formation of yield by barley agrocoenosis, on weed infestation of crops. The yield of permanent barley indicates in favor of NRK and NRK + manure options with and without liming, the latter fertilizer system also leading in the crop rotation. The further chain of barley yield distribution is in decreasing order: manure – nitrogen – control 1 – control 2 according to the background of lime application and in its absence. In the crop rotation the order of yield reduction is NRK – N – control.

INFLUENCE OF MAIN ELEMENTS OF CULTIVATION TECHNOLOGY ON WEED INFESTATION OF CROPS AND SPRING WHEAT YIELD

A distinctive feature of the North-West region is sufficient, and in some years, excessive moisture supply, under which weeds form a significant vegetative mass and cause great harm to cultivated crops, including spring wheat. The aim of the research was to assess the effect of seeding amount, seed size, nitrogen nutrition and herbicide treatment on weed infestation of crops and spring wheat yield in the North-West region of the Russian Federation. According to the research results, it was revealed that introduction of medium (by 0.8-13.6%) and high (by 1.5-14.1%) doses of nitrogen fertilizers leads to significant increase of initial weed infestation of spring wheat, while seeding amount and seed size did not have a significant impact on the number and cover of weeds. Among all the factors studied in the experiment, herbicide treatment had the strongest positive effect on formation of spring wheat crop (by 1.5–4.5 times), but only in the conditions of strong and complex types of weed infestation. Application of average dose of nitrogen led to a significant increase of spring wheat yield throughout the research years (by 19.3-82.8%), whereas effectiveness of high dose directly depended on moisture conditions of initial stage of vegetative period. Seeding amount and especially fractional composition of the seed material had a slight effect on yield and main elements of the structure of spring wheat crop. Interaction of such factors as application of nitrogen fertilizers and herbicide treatment contributed to significant increase of spring wheat yield (by 23.4-183%). The highest grain yield of spring wheat throughout all research years was obtained on seed plots with a seeding amount of 6 million viable seeds/ha, application of a high dose of nitrogen fertilizers and herbicide application (51.1; 29.7 and 40.9 q/ha).

Potencijalni rizici i problemi kod gajenja višegodišnjih energetskih useva

Second-generation biofuel production systems are significantly better than first-generation systems. However, the size of areas in which the energy crops are grown depends on public support, and it decreases if public support is missing. Despite all the environmental and economic benefits, perennial energy crops do not currently play a significant role. It is believed that available land areas will be a basic limiting factor for cultivating biofuel crops in the EU. On the other hand, there is significant untapped potential for bioenergy production in abandoned and marginal land in Southeast Europe. At the same time, perennial energy crops are investments with certain risks. Economically viable production of dedicated energy crops will be difficult to achieve on most lands classified into V-VIII land capability classes. In terms of the risk of farming investments, maize has an advantage over all perennial energy crop systems. We have identified 10 types of risks for successful production of energy crops: (1) Crop water supply; (2) Weed infestation in crops; (3) Risks of frost damages; (4) Crop lodging; (5) Crop diseases and pests; (6) Short harvest periods and variable yields; (7) Economic viability of cultivation on land areas of lower land capability class; (8) Influences of agricultural practices and agro-ecological conditions on biomass quality; (9) Storage of harvested biomass and fire hazard; and (10) economic sanctions, war, and war surroundings. Although the cultivation of perennial energy crops has a perspective, it must be systematically planned and further improved.

Complex of agrotechnical methods for different varieties of winter wheat

Increasing grain production and improving its quality are of great importance for our country. A special role is given to winter wheat as a highly productive and valuable food crop, which occupies about 2 million hectares in the Central Black Earth Region. Winter wheat also occupies significant areas in Belgorod region, which, according to agroclimatic zoning, is included in the zone of unstable moisture. Under these conditions, the development and opening up resource-saving adaptive technologies for the cultivation of crops, in particular winter wheat, as the most important grain crop, which would be assessed not only by productivity, but also by the degree of anthropogenic load on ecological systems, are of particular importance. The aim of the research is to change the agrophysical and biological properties of the soil, weed infestation of crops, yield and quality of different varieties of winter wheat, depending on preceding crops, new types of fertilizers and growth regulator. In this work, for the first time for the Central Black Earth Region, the complex effect of preceding crops, new types of fertilizers and growth regulator on changes in agrophysical, biological properties of soil, yield and quality of cultivated varieties of winter wheat Maiskaya Yubileinaya and Almera was studied. A complex of agrotechnical techniques for different varieties of winter wheat, identified on the basis of the research results, based on the use of optimal preceding crops, new types of fertilizers and plant growth regulators, allows the development of energy and resource-saving technologies of the cultivated crop. The expediency of using the most adaptive for the conditions of the region combination of agricultural practices for promising varieties of winter wheat is shown.

ВЛИЯНИЕ СРЕДСТВ ХИМИЗАЦИИ НА ОПТИЧЕСКИЕ СВОЙСТВА АГРОЦЕНОЗА ЯРОВОГО ЯЧМЕНЯ С ПОДСЕВОМ МНОГОЛЕТНИХ ТРАВ

The purpose of the research was to study the effect of mineral fertilizers and plant protection system on the vegetation index NDVI and its seasonal dynamics in agrocenoses of spring barley with overseeding of perennial grasses in the North-West of Russia. The data obtained indicate that against the background of the deficiency of the main elements of mineral nutrition in the second half of the growing season of spring barley, a significant phytomass of perennial grasses is formed in the crop, which account for 36.7%. This leads to a smaller decrease in the NDVI index (by 0.06) than in the fertilized variants (0.20). The value of NDVI index reflects not only the state of cultivated plants and weed infestation of crops, but also the level of development of crops, growing under vegetation. The influence of mineral nutrition developed during the period of maximum values of the index, which were recorded 6-8 weeks from the sowing date and 26-30 weeks from the beginning of the year. Under the influence of average doses of fertilizers, the NDVI index increased by 0.09...0.2 (on average 0.13), under the influence of high doses – by 0.13...0.26 (on average 0.18). The influence of plant protection system was expressed by a decrease in the phytomass of weeds (by 49.4...68.9%), at the same time the mass of spring barley and perennial grasses increased (by 1.7...18.5% and by 11.7...43.5% respectively). Carrying out the whole complex of protective measures led to a decrease in the NDVI index values by 0.01...0.06, depending on the phytosanitary situation in the agrocenosis. The most reliable forecast of the yield of spring barley can be implemented in the period from 5 to 7 weeks from the beginning of the emergence of barley shoots, especially against the background of the use of plant protection products that eliminate the influence of harmful organisms on the formation of the crop and the optical properties of crops

Testing of herbicidal systems for maize cultivation in the Steppe of Ukraine

Goal. To determine the agrarian and economic efficiency of different technological systems for herbicidal protection of maize depending on the weed harmfulness level and weather conditions.
 Methods. Field experiment — for the weeds and maize yield accounting, and calculation method — for determining of the technical and economic efficiency of herbicide systems.
 Results. We recorded a significant decrease in the inhibitory effect of soil herbicides without precipitation, at elevated air temperature and hot dry wind in the first 5—7 days after their application. Also we specified the best pre-emergence herbicide Acris SE containing the active ingredients: Dimethenamid P (280 g/l) + Terbuthylazine (250 g/l). The number of weeds was indicated according to the experiment variants before spraying crops and 21 days after the application of toxicants. The technical and economic efficiency of combined (pre-emergence + post-emergence herbicides) and mixture of post-emergence products for protection systems of maize was determined.
 Conclusions. Under arid conditions, within 5—7 days after the application of pre-emergence herbicides (in 2018, the average background weed infestation of crops — 37 pcs/m2), the chemical plant protection system based on a tank mixture of post-emergence herbicides was ahead in terms of technical efficiency, yield and profitability grain production: Frontier Optima CE (Dimethenamid, 720 g/l) + Stellar RK (Topramezone, 50 g/l + Dicamba, 160 g/l) + Metolat wetting agent. The manifestation of soil herbicide phytotoxicity in favorable weather (in 2019—2020, background weed infestation of crops 129—147 pcs/m2) was more effective when using a combined system for controlling harmful species in the maize production technology: Dual Gold KE (S-metolachlor, 960 g/l) — before sowing + Stellar RK (Topramezone, 50 g/l + Dicamba, 160 g/l) + Metolat wetting agent — post emergence application. The best pre-emergence chemical product was Acris SE (Dimethenamid P, 280 g/l + Terbuthylazine, 250 g/l).

Impact of main tillage methods on weed infestation of crops in the winter maize, wheat, dried peas rotation

The paper presents ways of suppressing weed plants, including a complex of agricultural practices aimed at reducing their harmful effects and further distribution. Many methods to control weed vegetation are known in the field cultivation technology. They differ in terms of the amount of expired costs and labor, economic and technical efficiency. As a result of our research, the impact of some tillage methods on the effectiveness of weed suppression on the main field crops in selected Kabardino-Balkaria natural climatic conditions is identified. The goal of the research is to determine the effectiveness of main tillage methods on the Ciscaucasian carbonate chernozems in different zones of the republic. In research conducted in 2015-2018 in the Kabardino-Balkaria steppe zone in crop rotation, with an alternation of maize-winter wheat-pea crops in the suppression of weed plants, a soil treatment system is allocated when the soil treatment on 12-14cm is combined with plowing to a depth of 25-28 cm with the use of related chemical herbicides of various spectrum of actions.

ЗАБУР’ЯНЕНІСТЬ ПОСІВІВ ГОРОХУ ОЗИМОГО ЗА ДІЇ ГЕРБІЦИДУ, РЕГУЛЯТОРА РОСТУ РОСЛИН І МІКРОБНОГО ПРЕПАРАТУ

Weed infestation of agricultural crops in Ukraine is growing and is becoming a big threat to stable and high yields. Therefore, today, it is impossible to do without the development of science-based measures to control the level of weed infestation in crops, adaptation of herbicides to ecological farming methods and energy-optimized cultivation technologies. The analysis of the results of studies of weediness of winter pea crops at different rates of application of MaxiMox herbicide (0.8; 0.9; 1.0 and 1.1 l/ha) separately and in tank mixtures with plant growth regulator Agriflex Amino at the rate of 1.0 kg/ha on the background of seed treatment before sowing with the microbial preparation Optimize Pulse at the rate of 3.28 l/t, and without treatment is given. Spraying of vegetating plants with herbicide and their tank mixture with a plant growth regulator was carried out in the phase of 3-4 developed runners (BBCH 13–14) of the crop. Weed infestation of winter pea crops was counted on the thirtieth day after plant treatment with preparations. Weeds were counted by the quantitative weight method per 1 m2 according to the method of S. A. Tribel. Statistical processing of the data was carried out according to the generally accepted methods. It has been established that with the combined application of different rates of MaxiMox herbicide with plant growth regulator Agriflex Amino on the background of seed treatment before sowing with the microbial preparation Optimize Pulse, the technical efficiency of weed control increases, both in terms of quantity and weight. The greatest number and weight of destroyed weeds was noted in variants with the introduction of MaxiMox herbicide at the rates of 0.8; 0.9; 1.0 and 1.1 l/ha in combination with plant growth regulator Agriflex Amino at the rate of 1.0 kg/ha on the background of seed treatment with the microbial preparation Optimize Pulse at the rate of 3.28 l/t, where the percentage of destroyed weeds averaged 91–99 % quantitatively and 94–100 % in mass. The increase in the effectiveness of the studied preparations obviously occurred due to the improvement of biometric indices of winter pea plants under the direct action of the plant growth regulator and microbial preparation, which eventually increased the competitiveness of the crop to weeds.

Влияние севооборота с люпином и способов основной обработки почвы на засоренность посевов в условиях Брянской области

Tests have been done on gray forest soil in the South-West of the Non-Chernozem zone of Bryansk re-gion in the stationary experiment in the All-Russian Lupin Research Institute in 2015–2018. The aim of the test was to evaluate the effect of the intensity of the basic soil cultivation on crop weed infestation in lupin crop rotation. The experiment has been done during a rotation of the field crop rotation (winter wheat – bare oats – winter triticale – lupin) turned in time and space in the fields of white lupin and win-ter wheat where lupin has been cultivated as a predecessor. During the test years 7 weeds species have been fixed at tillering phase of winter wheat, its number made 9.4–15.4 units/m2. The number of the main weeds decreased to 11 species at the end of the vegetation season (at ripeness stage) and made 9.7–15.9 units/m2. There have been noticed 8 weeds species in white lupin crops, the number made 33.6–55.8 units/m2. The deep non-moldboard soil cultivation decreased weeds number in crop rotation. At dif-ferent basic soil cultivation 8 weeds species occurred in crops. The others were either in the deep non-moldboard soil cultivation or in the surface one. The number and ratio of weeds species changed when the grass component increased to the final field of crop rotation. The annual dicotyledonous species made 45.0–60.5% decreasing at the surface cultivation. Perennial weeds made 38.5–55.0% of the total weeds coenosis. Their number decreased in the case of deep cultivation. Crop infestation degree and as a result the weeds twice during the rotation at the surface soil cultivation.

Влияние технологий применения минеральных удобрений на засоренность полевого севооборота

The article provides the results of many years of research conducted in 2005-2010 on leached chernozem in the forest-steppe of Volga region. The subject of the research is species and quantitative changes in weed infestation of crops during crop rotation under the influence of differentiated and averaged doses of fertilizers. It is established that the species composition of weeds depended on the cultivated plant in crop rotation, and their number depended on the predecessor and weather conditions of vegetation. In the Sudanese grass, a late sowing plant, there were late spring weeds (Redroot Pigweed, Barnyard grass) which were practically absent in wheat and barley, the early sowing crops. The influence of fertilizers application on the plant weediness in crop rotation was insignificant. At the same time, in comparison with the control, there was a significant decrease in the number of weeds by 11 -27%. In arid conditions of 2010 the effect of fertilizers on weed infestation was not significant. In favorable moisture years fertilizers had a positive effect not only on the growth and development of cultivated plants, but also stimulated the weeds growth. The quantitative change in weed infestation of crops primarily occurred under the influence of cultivated crops and was less dependent on the technology of fertilizers application. In all experiments with fertilizers, the number of weeds increased by 78-87 % from the first crop in rotation to fallow and decreased after it by 80-87%, more evident in variants with fertilizers. Differentiated application of fertilizers contributed to the reduction of weed weight by 7 % compared with the control and by 11% compared with traditional fertilizer application.

Сорные растения полевых севооборотов

The purpose of the research is to trace the dynamics of weed infestation and determine the species composition of weeds in field crop rotations, to show the impact of crop rotation, agricultural background and time on weed infestation of crops. Studies were carried out in 1998 - 2017 in the conditions of the Republic of Mari El on sod-podzolic medium-loamy soil with a high content of mobile forms of phosphorus and exchangeable potassium. The biomorphological spectrum of weed species showed that the share of juvenile weeds accounted for 26 species, perennial-9 species. During the research in the studied agrocenosis there was an increase in weed abundance: in the first rotation - 60.78 pcs/m2, in the second - 67.48 pcs/m2, in the third rotation - 75.95 pcs/m2. During the research there was an increase in the number of such annual weeds as Polygonum aviculare, Erodium cicutarium (L.), Veronica polita, Capsella bursa-pastoris, Viola arvensis, Fumaria officinalis and Stellaria media. The number of Chenopodium album and Echinochloa crus-galli increased significantly, especially in the last six years of research. Every year the infestation with Galeopsis tetrahit, Centaurea cyanus, Apera spica-venti and Amaranthus retroflexus was decreasing . The greatest annual weed infestation (71.86 pcs/m2) was in grain rotation, and the least - in grain-fodder fallow rotation (54.83 pcs/m2). The maximum number of perennial weeds was found in the I crop rotation - 14.08 pcs/m2. The variant without fertilizers showed the least infestation with annual weeds- 59.95 pcs/m2. Against the background of N60P60K60 their number increased by 8.98 pcs/m2 (LSD05 - 5.50).

Planting density impact on weed infestation and the yield of Miscanthus grown on two soil types

The assessment of the weed infestation effect on biomass yield of Miscanthus × giganteus in the first year of its commercial yield was conducted on two types of soil with different productive ability – Luvic Chernozem and Calcic Gleysol. The formed mass of weeds was higher on Luvic Chernozem and the infestation had grown according to the stages of Miscanthus growth. The biomass of weeds depended on the planting density of Miscanthus as well as on the weather conditions during the studied years. Weed infestation of crops very significantly influenced the formation of aboveground biomass of Miscanthus, so that the yields in the first year of commercial harvesting in the control where the weeds were removed manually were significantly higher compared to the crops in which weeds were not removed. The obtained results showed that weeds significantly affect the initial growth and development of Miscanthus plants that are, in general, slow, especially in the year of the crop establishment. The study evaluates the impact of a manual method of suppression and weed infestation of crops on the commercial yield of Miscanthus.

Вплив короткоротаційних сівозмін і системи удобрення на забур’яненість посівів буряків цукрових

Вплив короткоротаційних сівозмін і системи удобрення на забур’яненість посівів буряків цукрових

Weed infestation of crops in different soils in the protective zone of Roztocze National Park. Part I. Winter and spring cereals

The study on weed infestation of crops in different soils in the protective zone of RPN was conducted in the years 1991-1995. The characterization of weed infestation of winter and spring cereals was based on 306 phytosociological records. made with the use of Braun-Blanquet method. The degree of weed infestation in the fields in the protective zone of RPN depended on environment conditions. Both winter and spring cereals in majority of soils were most infested by: <i>Cenaturea cyanus, Apera spica-venti</i> and <i>Vicia hirsta</i>. In the lightest podsolic soils, made of loose sand and slightly loamy sand. winter and spring cereals were additionally infested by <i>Equisetum arvense</i> and two acidophylic species: <i>Seleranthus annuus</i> and <i>Spergula arvensis</i>. The crops in brown loess soil were infested by <i>Matricaria maritima</i> subsp. <i>inodora</i>. The most difficult weed species in brown soil formed from gaizes and limestone soil were: <i>Convolvulus arvensis, Papaver rhoeas</i> and <i>Galium aparine</i>. Moreover winter cercals in limestone soil showed high or medium infestation with <i>Consolida regalis, Aethusa cynapium, Lathyrus tuberosus</i> and low infestation with <i>Apera spica-venti</i> and <i>Centaurea cyanus</i>. Spring cereals were less infested than winter cereals. <i>Apera spica-venti</i> and <i>Centaurea cyanus</i> were less common with spring cereals than with winter cereals. Also, spring cereals showed high or medium infestation with <i>Convolvulus arvensis</i>. Spring cereals in some soil units were infested by <i>Chenopodium album</i> and <i>Stellaria media</i>. There was also higher infestation of spring cereals in limestone soils with <i>Avena fatua, Veronica persica, Sinapis arvensis</i> and <i>Sonchus arvensis</i>, compared to winter cereals in limestone soils.

The effect of different agrotechnical levels on weed infestation in crops of naked and husked varieties of oat (Avena sativa L.)

The present study was carried out in the period 2007- 2009 in the Experimental Farm in Bezek near the city of Chełm. The aim of the investigation was to compare weed infestation of the husked (Krezus) and naked (Cacko) oat cultivars cultivated under conditions of different weed control treatments. The following weed control levels were compared: A - control object; B - harrowing twice; C - application of the herbicide Mustang 306 SE; D - herbicide Mustang 306 SE + foliar fertilizer Insol 3; E - herbicide Mustang 306 SE + two foliar fertilizers: Insol 3 and FoliCare 18:18:18. The husked oat cv. Krezus was more competitive against weeds. Number of dicotyledonous weeds and of monocotyledonous weeds, total weeds, and air-dry weight of above-ground parts of weeds in the crop of this cultivar were all significantly lower compared to the naked cv. Cacko. From the group of dicotyledonous species, <i>Chenopodium album</i>, <i>Galinsoga parviflora</i>, <i>Matricaria maritima</i> ssp. <i>inodora</i>, <i>Polygonum aviculare</i>, and <i>Stellaria media</i> were the dominant species in the crops of the oat varieties under investigation, whereas among the monocotyledonous species <i>Echinochloa crus-galli</i>, <i>Setaria pumila</i>, <i>Apera spica-venti</i>, and <i>Elymus repens</i> occurred in greatest numbers. The application of the herbicide Mustang 306 SE decreased the number of dicotyledonous weeds and air-dry weight of weeds, compared to the treatment in which mechanical weed control had been used.

Dynamics of weed infestation of main agricultural crops in Belarus

In Belarus about 300 weed plant species are marked, dominated by 30 – 40 species which are found on practically all the fields. Changes in the numbers of each weed species depend on many factors. The data of itinerary inspections of agricultural crops done in 1981 – 1985 and 1996 – 2003 show the specific composition change of the main dominating weed plants in comparison with 1939. The reasons promoting change of the specific composition of crop weed infestation are shown.

Cover crops reduce weed seedbanks in maize–cassava systems in southwestern Nigeria

Weeds are a major constraint to crop production in smallholder farms in tropical Africa. The weed seedbank and annual recruitment are the main sources of weed infestation in crops. This study was carried out in Ibadan, Nigeria, to evaluate the effect on the seedbank of two types of planted fallow (alley cropping with leucaena and live mulch with tropical kudzu) and a natural bush fallow under four land-use intensities. Type of fallow was the main plot. Land-use intensities, consisting of continuous cropping of maize intercropped with cassava, 1 cropping yr of maize–cassava followed by 1, 2, and 3 yr of fallow, were the subplots. Averaged over a 3-yr period, the seedbank was 55% lower in the tropical kudzu plots and 43% lower in the leucaena plots compared with natural bush. The difference in seedbanks between plots cultivated after leucaena and natural fallow was 23%. Seed density of annual broadleaf weeds was high and dominated the seedbank of both planted and natural fallow. Overall, seeds of grasses occurred at low densities in all plots cultivated after 2 to 3 yr of fallow, whereas seeds of sedges occurred more in continuously cultivated plots and plots cultivated after 1 yr of fallow in all the fallow types. Seed density of perennial broadleaf weeds increased as land-use intensity decreased. Live mulch with tropical kudzu, especially when combined with 2 to 3 yr of fallow, lowered the seedbank more than the leucaena and traditional bush fallow systems.