Perennial Weed Species Research Articles

Differential germination response of Navua sedge (Cyperus aromaticus) populations to environmental factors

AbstractNavua sedge [Cyperus aromaticus (Ridl.) Mattf. & Kuek.], is a hard to control C4 perennial weed species in tropical regions of Australia. Knowledge of its seed biology could help to develop integrated weed management programs for this species. This study was conducted under laboratory and screenhouse conditions to evaluate the effect of alternating day/night temperatures, light, pretreatment high temperatures, burial depth, and flooding depth on the germination and emergence of two populations (Ingham and Tablelands) of C. aromaticus. Both populations germinated at temperatures ranging from 20/10 to 35/25 C; however, the Ingham population germination (76%) was greater than the Tablelands population (42%) at the highest temperature regime (35/25 C). None of the populations germinated at 15/5 C. Darkness completely inhibited germination in both populations, suggesting that the seeds are positively photoblastic. Seeds (dry and wet) of both populations germinated after exposure to pretreatment temperatures of up to 100 C for 5 min. After pretreatment at 150 C, only the Ingham population germinated, and germination was greater for dry seeds (62%) than for wet seeds (1%). Neither population germinated after exposure to 200 C. For both populations, maximum germination was observed for seeds at 0 cm; a burial depth of 0.5 cm completely inhibited emergence of the Tablelands population, and a burial depth of 2.0 cm completely inhibited germination of the Ingham population. A flooding depth of 10 cm greatly reduced emergence in both populations compared with 0 cm (62% and 78%) but 12% to 14% of seedlings still emerged, suggesting the need to integrate flooding with other management tools. The results also suggest that the Ingham population may have a greater potential to spread into new areas or become more invasive than the Tablelands population. Knowledge gained from this study can be used to manage C. aromaticus by fire/burning, tillage, and flooding.

Varying tillage promotes weed diversity, while a perennial alfalfa–grass mixture promotes weed control in an organic tillage system experiment in Germany

AbstractIn organic farming the control of perennial weed species, in particular Cirsium arvense, can be a major concern for farmers, especially if there is no regulation through perennial forage production. To test whether the stubble cleaner (SC), an enhanced skim plow (PL), is as effective in the control of C. arvense and other weeds as conventional ploughing and perennial forage production, an organic field experiment was established. Three different tillage/crop rotation systems were compared: an SC system and a PL system, both in a cereal-based crop rotation and an additional PL system in a crop rotation that included a perennial alfalfa–grass mixture (PLALF). In the SC system, tillage was carried out solely with the SC, while in the PL and PLALF systems, ploughing was alternated with chiseling. In the fifth year, each main plot was divided into subplots, and seven different cover crop treatments were integrated into each of the three systems. The effects of the three systems and the cover crop treatments on weed cover and density, weed biomass, and weed diversity in the sixth and seventh year of the experiment are the subjects of this paper. The choice of cover crop species was of minor importance for weed control. The PLALF system was generally more effective in controlling C. arvense than the PL and SC systems. No significant differences between the PL and SC systems regarding the control of C. arvense could be identified in four of five assessments. The SC system had significantly higher total weed density than the PLALF and PL systems in both years. However, the differences in weed emergence between the PL and SC systems diminished until the assessment of weed cover and biomass in the main crops, when no significant differences between these two systems (2012) or no differences at all (2013) could be identified. Species richness was not significantly influenced by the tillage/crop rotation system in both years. Evenness and Shannon–Wiener index were significantly higher in the PLALF and PL systems than in the SC system on most assessment dates in 2012. In 2013 there was no clear trend regarding evenness and Shannon-Wiener index probably due to a hoeing operation.. In conclusion, for weed control, the choice of crop rotation was more important than the choice of tillage method, while for the diversity of the weed community, the choice of tillage method was more important than the crop rotation.

Camera-guided Weed Hoeing in Winter Cereals with Narrow Row Distance

Farmers are facing severe problems with weed competition in cereal crops. Grass-weeds and perennial weed species became more abundant in Europe mainly due to high percentages of cereal crops in cropping systems and reduced tillage practices combined with continuous applications of herbicides with the same mode of action. Several weed populations have evolved resistance to herbicides. Precision weed hoeing may help to overcome these problems. So far, weed hoeing in cereals was restricted to cropping practices with row distances of more than 200 mm. Hoeing in cereals with conventional row distances of 125–170 mm requires the development of automatic steering systems. The objective of this project was to develop a new automatic guidance system for inter-row hoeing using camera-based row detection and automatic side-shift control. Six field studies were conducted in winter wheat to investigate accuracy, weed control efficacy and crop yields of this new hoeing technology.A three-meter prototype and a 6-meter segmented hoe were built and tested at three different speeds in 150 mm seeded winter wheat. The maximum lateral offset from the row center was 22.53 mm for the 3 m wide hoe and 18.42 mm for the 6 m wide hoe. Camera-guided hoeing resulted in 72–96% inter-row and 21–91% intra-row weed control efficacy (WCE). Weed control was 7–15% higher at 8 km h−1 compared to 4 km h−1. WCE could be increased by 14–22% when hoeing was combined with weed harrowing. Grain yields after camera-guided hoeing at 8 km h−1 were 15–76% higher than the untreated control plots and amounted the same level as the weed-free herbicide plots. The study characterizes camera-guided hoeing in cereals as a robust and effective method of weed control.

Evaluation of currently registered herbicides for fall bearing year red sorrel (Rumex acetosella L.) management in lowbush blueberry (Vaccinium angustifolium Aiton)

Red sorrel is a common creeping herbaceous, perennial weed species in lowbush blueberry fields and reproduces asexually via ramets from creeping roots. Ramets emerge throughout the season but remain vegetative due to a vernalisation requirement for flowering. This weed may therefore be managed with fall herbicide applications, but few currently registered herbicides have been evaluated for fall red sorrel management in lowbush blueberry. The objectives of this research were to (i) determine the effect of various herbicide treatments on red sorrel shoot and root biomass in the greenhouse, (ii) determine the effect of fall bearing year herbicide applications on overwintered red sorrel ramet density in the field, (iii) determine if reduced overwintered ramet density reduces flowering ramet density in the field, and (iv) estimate the potential for red sorrel to recover from fall bearing year herbicide applications. Dicamba, tribenuron-methyl, and glufosinate reduced red sorrel shoot and root biomass in the greenhouse and reduced overwintered ramet density in the field. Clopyralid, sulfentrazone, and flumioxazin reduced shoot and root biomass in the greenhouse but exhibited limited efficacy in the field. Nicosulfuron + rimsulfuron and glyphosate were ineffective in both the greenhouse and field. Dichlobenil and pronamide reduced overwintered ramet density in the field. Reduction of overwintered ramet density did not consistently reduce flowering ramet density. Dichlobenil reduced seedling density at two sites, but no herbicide consistently reduced summer non-bearing year ramet density. Fall herbicide applications alone, therefore, do not appear to maintain red sorrel suppression in lowbush blueberry fields.

Long-Term Control of Hedge Bindweed (Calystegia sepium L.) with Single, Tank Mixture, and Sequential Applications of Glyphosate, 2,4-D, and Dicamba

Hedge bindweed (Calystegia sepium L.) is a widespread troublesome perennial weed species that has strong rhizome regenerative capacity. Four pot trials with randomised, complete block designs were conducted in 2015 to evaluate long-term control of hedge bindweed using individual, tank mixture, and sequential applications of selected herbicides. Two different formulations of N-(phosphonomethyl) glycine (glyphosate; isopropylamine, trimesium salts) were applied at 2000 g active ingredient (a.i.) ha−1. Additionally, two synthetic auxins were applied as 3,6-dichloro-2-methoxybenzoic acid (dicamba) at 500 g a.i. ha−1 and the dimethylamine salt of (2,4 dichlorophenoxy)acetic acid (2,4-D) at 1000 g a.i. ha−1. Tank mixtures and sequential applications (12/24 h separation) of these different herbicides were also included. Long-term control of hedge bindweed, Calystegia sepium L., growth was evaluated 8 months after treatments, as comparisons of shoot and rhizome growth (biomass) between untreated and treated plants. There were no differences between the two formulations of glyphosate alone, with shoot and rhizome biomass reductions of 83% and 42%, respectively. Dicamba alone inhibited shoot and rhizome biomass by 86% and 67%, respectively. By itself, 2,4-D provided the greatest reductions in shoot and rhizome biomasses, 93% and 79%, respectively. Antagonism was seen in the tank mixtures of glyphosate and dicamba or 2,4-D. Tank mixtures were generally comparable to treatments of glyphosate alone, and were less effective compared to dicamba or 2,4-D alone. The greatest reduction of bindweed rhizome biomass was for sequential glyphosate trimesium salt followed by 2,4-D 12 h later, thus showing significantly greater efficacy over glyphosate isopropylamine salt (94% vs. 84%; p ≤ 0.05). These data for reductions of the growth of the rhizome biomass show that the sequential application of glyphosate followed by 2,4-D significantly improves long-term control of hedge bindweed.

The effects of tillage on weed suppressive ability, leaf area, seed yield and protein content of Mucuna pruriens var. utilis

In the field of the Agricultural University of Athens, the effects of tillage on weed suppressive ability, leaf area, seed yield and protein content of velvet bean (Mucuna pruriens) were evaluated under the climatic conditions of Greece. The experiment was carried out in a randomized complete block design with three replicates. The three experimental treatments were: control (untreated), one hoeing for weed seedlings’ elimination at 7 days after sowing, and two hoeings for weed seedlings’ elimination at 7 and 15 days after sowing. Findings revealed that one hoeing reduced annual weeds’ density by 42% as compared to control treatment. Two hoeings resulted in a 47% lower density for annual species as compared to the untreated check. The density of perennial weeds recorded in the plots of one-hoeing treatment was 52% lower than the value recorded in the plots of control treatment. It was also shown that two hoeings can result in a 61% lower density regarding perennial species. Regarding velvet bean’s vegetation growth, one hoeing increased velvet bean leaf area per plant by 26% whereas, in the plots of two-hoeings treatment, the value of leaf area per plant was by 22-36% higher than the corresponding value recorded in untreated control plots. Two hoeings can increase velvet beans seed yield by 44% as well as seeds’ protein content by 17%. Further research is needed to optimize the use of velvet bean as a cover crop and seek for agronomic practices that might enhance its competitiveness against both annual and perennial weed species.

Occurrence of Weeds in an Orchard due to Cultivation of Long-Term Perennial Living Mulches

The living mulch permanence along with the succession of their weed infestation in an apple orchard were evaluated at the Research Station, Wrocław University of Environmental and Life Sciences. The perennial cover crops: white clover and colonial bent grass, as well as the annual dwarf nasturtium, were sown as living mulches in apple tree rows, in the year of establishing the orchard. Blue fescue was sown one year later to replace the dwarf nasturtium. The percent of covers and temporal dominance dynamics of weeds were estimated during the first 13 years of the orchard maintenance. The occurrence of annual weeds, which had been abundant in all the living mulches in the year of their sowing, decreased in the following years of orchard maintenance. Conversely, the dominance of several perennial weed species increased as the orchard reached the full cropping period. White clover exhibited the lowest permanence. Dynamic spreading of <em>Elymus repens </em>(L.) Gould and other species from the Poaceae family was the direct cause of this cover crop disappearance. The presence of perennial dicotyledonous weeds, primarily <em>Taraxacum officinale </em>Web. and <em>Convolvulus arvensis </em>L., also contributed to the diminished sod of all the living mulches. Blue fescue maintained satisfactory dominance relative to colonial bent grass for nearly the entire first decade of the research. Nevertheless, both grass living mulches were present on less than half of the tree row soil surface area, in the thirteenth year after planting of the apple trees.

The current state of abandoned lands in the northern forest-steppe zone at the Republic of Bashkortostan (Southern Ural, Russia)

This paper presents the results of the state of postagrogenic ecosystems (18-20 years after the land was taken out of crop rotation) in the northern forest-steppe zone, Republic of Bashkortostan (South Ural) where soil cover is represented by postagrogenic gray-humus soils (Regosols). Probably, the unfavorable physical and agrochemical soil properties were a limiting factor in obtaining a profitable crop yield, and it was a reason for the withdrawal of land from agricultural use. Eighteen to twenty years since agricultural fields were taken out of crop rotation, a diverse vegetation cover has formed on postagrogenic soils. Analysis of the NDVI (Normalized Difference Vegetation Index) showed that more than 50% of the territory is covered by average and high vegetation development (low-grass meadows and forest communities). The active renewal of natural vegetation is conducted in the studied territory, which develops under the influence of zonal type vegetation and is in the transition stage from ruderal communities to low-grass meadows and different-aged secondary forests with domination of broad-leaved and light-coniferous tree species. The low content of organic carbon and basic nutrients in postagrogenic soils, at this stage of restoration, does not influence the formation and diversity of vegetation cover. However, vegetation continues to suffer the consequences of long-term agricultural use (mainly mechanical impact), resulting in a well-defined mosaic of vegetation communities, the poverty of the floristic composition and the presence of perennial weed species occurring in high abundance. It is better to maintain the land abandoned to further improve soil properties and reduce erosion.

Relationships between soil, forage, and grazing parameter effects on weed incidence in Missouri pastures

AbstractDuring the 2015, 2016, and 2017 growing seasons, a survey of 63 pastures in Missouri was conducted to determine the effects of selected soil and forage parameters on the density of common annual, biennial, and perennial weed species. Permanent sampling areas were established in each pasture at a frequency of one representative 20-m2 area per 4 ha of pasture, and weed species and density in each area were determined at 14-d intervals for a period from mid-April until late September. The parameters evaluated included soil pH, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), sulfur (S), zinc (Zn), manganese (Mn), and copper (Cu) concentrations, as well as tall fescue density, forage groundcover density, and stocking rate. An increase of 1 unit in soil pH was associated with 146 fewer weeds per hectare, the largest reduction in weed density in response to any soil parameter. Increased soil pH was associated with the greatest reduction in perennial grass weed density, along with an average reduction of 1,410 brush weeds per hectare for each 1-unit increase in soil pH. Common ragweed, a widespread weed of pastures, could be reduced by 3,056 weeds ha−1 when soil pH was 1 unit greater. A 1-ppm increase in soil P was correlated with a decrease of 206 biennial broadleaf weeds per hectare. Perennial broadleaf weed density was reduced in soils with greater concentrations of P, K, and Ca. Additionally, for every 1% increase of tall fescue and forage groundcover, there was a decrease of 18 and 38 perennial broadleaf weeds per hectare. The results from this research indicate that the density of many common weed species can be reduced with higher soil pH and adjustments to soil macro- and micronutrient concentrations, especially P.

ОСЕННЕЕ ПРИМЕНЕНИЕ ГЕРБИЦИДОВ В ПОСЕВАХ ОЗИМОЙ ПШЕНИЦЫ В УСЛОВИЯХ ЦЕНТРАЛЬНОГО ЧЕРНОЗЕМЬЯ

The relevance of this study was to reduce the risk of negative aftereffect on winter wheat of the studied combined herbicidal preparations for their autumn use field experiments. The purpose of these experiments was to solve two problems: the assessment of biological efficiency relation to wintering, spring and perennial weed species; determination of economic efficiency of autumn application of herbicides. Studies were carried out on small-scale experiments of a branch of the FSBI “FNTs them. I.V. Michurina in winter wheat crops Scepter. The studies used herbicides Alistair Grand MD 1.0 l/ha, Attribute VG 0.06 l/ha, Fenizan BP 20 l/ha, mixed forms Prima Donna EF 0.50 l/ha + Zontran KKR 0.50 l/ha and Fenizan BP 20 l/ha + Zontran KKR 50 l/ha. The weed component winter wheat crops the conditions of the north-eastern part of the Central Black Earth Region is represented by wintering, spring and perennial species. A high biological assessment of herbicides has been shown for autumn use against perennial and wintering weeds. The economic efficiency confirming the herbicidal activity was determined against the background of fungicidal and insecticidal treatments. The main weeds of winter wheat sowings were revealed: the autumn period, the wintering weed is a violet field (Viola arvensis Murr.), In the spring period - white mar (Chenopodium album L.), a shchirina thrown back (Amaranthus retroflexus L.), before cleaning - a field bindweed (Convolvulus arvensis L.), Chistell annual (Stachys annua). The advantage was that the autumn application of herbicides tested by us did not have a negative effect on the overwintering of the crop, and the phytosanitary condition of the field improved. The impact of herbicides was reduced to the death of a part of weeds the autumn period and the deterioration of the physiological state of the surviving weeds, due to which they subsequently died during the wintering season.

Специфіка анемохорії багаторічних видів бур’янів на орних землях

One of the most perfect ways to spread the seeds of weeds is the transfer of fruits and seeds by wind (anemohoria). Such powerful perennial types of weeds as the Syrian woolblast - Asclepius siriaca L. and the currant pink - Cirsium arvense L. also use anemochoria to spread its offspring to new territories. The aim of the research was : To carry out in 2015-2018 the estimation of the intensity of the processes of seed and fruit dispersal with anemon-species species of perennial weeds on the arable land of the Kyiv region. Methods and conditions for conducting research . The studies were field-based. They were performed in the laboratory of herbology at the Institute of Bioenergetic Cultures and Sugar Beet NAN. For researches among a large number of anemohorous weed species, the Syriac wafer and thistle rose were chosen. The calculations of the intensity of the processes of scattering and translocation of seeds of anemofor species of weeds were carried out within 20 days of the time they were reached and started to be separated by airflows (leaflet opening or opening of baskets with seeds on weed plants). On the determined scheme of experiments distances from model plants certain types of weeds: 16; 32; 64; 125; 250; 500; 1000m set up catching tables (an area of 0.25m2 each). At each distance, 4 hatching tables were displayed. Their total surface area is 1m2. Experiments were carried out in 4 repetitions. The obtained results were analyzed over the years and the general laws were determined and statistically processed and generalized. Results and discussion As a result of the recorded records, the distribution of seeds of Syriac waders found that at a distance of up to 16 m from maternal plants an average of 16.31 units was recorded for 20 days. seed / m 2 . At a distance of 1000 meters from the place of formation of seeds on maternal plants, the number of weed seeds per m 2 , which occupied the surface of the field decreased to 0.004 st/m 2 . Compared with the indicators at the first distance (16m), the intensity of the arrival of seeds of the Syrian driller per unit area of the field decreased 4077.5 times. Investigation of the peculiarities of the distribution of pinkish-thistle seeds was found on the tables, which were located at a distance of 16 m from maternal weed plants, an average of 31.54 st/m 2 of weed seeds was recorded. At a distance of 500 meters from the mother plants, the level of settling of arable land with thistle seeds rose to 0,028 st/m 2 . At a distance of 1000 meters from the mother plants, the area occupied by the seeds of thistle rose was 0.006 seeds/m 2 or 5256.7 times less than the presence of seeds at a distance of 16 meters. Conclusions . The presence of specific adaptations in the fruits and seeds that provides them with high sailing, allows the flow of air to successfully translate and populate such perennial species of weeds large areas. Even at a distance of 1000 m from the mother plants for each m 2 of the surface of the field comes from 0.004 to 0.006 seeds of such dangerous and highly competitive types of weeds.

First Detection of Wheat streak mosaic virus in Two Perennial Weed Species, Agropyron cristatum and Hordeum jubatum subsp. intermedium, in Canada

First Detection of <i>Wheat streak mosaic virus</i> in Two Perennial Weed Species, <i>Agropyron cristatum</i> and <i>Hordeum jubatum</i> subsp. <i>intermedium</i>, in Canada

A Meta-Analysis of Field Bindweed (Convolvulus arvensis) Management in Annual and Perennial Systems

AbstractField bindweed (Convolvulus arvensisL.) is a persistent, perennial weed species that infests a variety of temperate habitats around the globe. To evaluate the efficacy of general management approaches and impacts on crop yield and to identify research gaps, we conducted a series of meta-analyses using published studies focusing onC. arvensismanagement in annual cropping and perennial systems. Our analysis of 48 articles (560 data points) conducted in annual systems indicated that 95% of data points measured efficacy over short time frames (within 2 yr of treatment). Furthermore, only 27% of data points reported impacts ofC. arvensismanagement on crop yield. In annual systems, herbicide control dominated the literature (~80% of data points) and was an effective management technique up to 2 yr posttreatment. Integrated management, with or without herbicides, and three nonchemical techniques were similarly effective as herbicide at reducingC. arvensisup to 2 yr posttreatment. In addition, integrated approaches, with or without herbicides, and two nonchemical techniques had positive effects on crop yield. There were few differences among herbicide mechanism of action groups onC. arvensisabundance in annual systems. There were only nine articles (28 data points) concerningC. arvensismanagement in perennial systems (e.g., pasture, rangeland, lawn), indicating more research effort has been directed toward annual systems. In perennial systems, biocontrol, herbicide, and non-herbicide integrated management techniques were equally effective at reducingC. arvensis, while competition and grazing were not effective. Overall, our results demonstrate that while chemical control ofC. arvensisis generally effective and well studied, integrated and nonchemical control practices can perform equally well. We also documented the need for improved monitoring of the efficacy of management practices over longer time frames and including effects on desired vegetation to develop sustainable weed management programs.

EFFICIENCY ESTIMATION OF STRIPTILL SOIL PROCESSING TECNOLOGY

This study explores the technology of chilling from the point of view of anthropogenic impact on soil. The influence of the arrangement of workers on technological rocessing is analyzed. The efficiency of resource-saving deep cultivation technology in production of row crops on example of sunflower growing in Volgograd region is estimated. We give technical and economic assessment of sunflower cultivation depending on the technological process of chilling. We defined a competitive technology of basic soil cultivation. Analysis of data obtained shows that the largest area of cross-section of the formation is produced when soil is treated with chisel tools as working organs are arranged such that they form a zone of continuous loosening, accordingly, it has the greatest anthropogenic impact. Field experiments also showed that deep loosening belts to a depth of 0.25...0.35 m, alternating with strips without treatment, are characterized by positive processes. Unprocessed areas become overcrowded (more than 1.3 g/cm3), so they create less favorable, in comparison with processed, conditions for the development of some species of perennial weeds. Studies have shown that, with the main soil-free tillage of the soil to a depth of 0.3 m, from the stubble of winter wheat, stubble conservation was consistent: 69.67% - over the treated band using striptill technology; 76.33% - on the processed strip by a chisel with a trail of 0.7 m; 68.67% for a chisel with a trail of 0.35 m. After the passage of the aggregates on the soil surface, all stubble remains within the requirements for SRT AIST 4.6-2010 (more than 60%). The use of striptill technology reduces fuel costs by 35.5% relative to the classical chiesel, and by 27.3% relative to the minimum technology. Accordingly, the cost of wages is reduced by 37.5% compared to the classical chisel and by 24.8% compared to the minimum chisel technology.

Efficacy of glufosinate-ammonium to control annual and perennial weeds on the ridges of paddy fields

This study was conducted to evaluate the efficacy and phytotoxicity of glufosinate-ammonium in controlling annual and perennial weeds on paddy ridges. Glufosinate-ammonium SL (900 g a. i./ha) and glufosinate-ammonium ME (600 g a. i./ha) mixed with fluthiacet-methyl (10 g a. i./ha) were tested in the field experiments. Five annual weed species, Glycine soja, Erigeron canadensis, Disitaria ciliaris, Poa annua and Echinochloa utilis, and four perennial weed species Elymus tsukushensis, Taraxacum platycarpum, Equisetum arvense and Artemisia princeps were identified on the paddy ridges. The results of this experiment indicated that these annual and perennial weeds could be effectively controlled by both the herbicides. Application of these herbicides did not negatively affect the number of tillers and plant height of rice grown near the treated paddy ridges. Therefore, it can be concluded that the non-selective glufosinate-ammonium can provide an effective control of weeds on the paddy ridges if application is properly made.

벼 어린모 기계이앙답에서 수면부상성 Benzobicyclon합제의 제초활성

This study was conducted to investigate the herbicidal efficacy of up granule formula of benzobicyclon mixtures, benzobicyclon + azimsulfuron + oxaziclomefone up granule (BAO UG) and benzobicyclon + bensulfuron-methyl + fentrazamide up granule (BBF UG) to control annual and perennial weed species in a rice paddy field. Four annual weed species including Echinochloa crus-galli L. and three perennial weeds were dominated in the experimental field. Application of BAO UG and BBF UG was highly effective to control both annual and perennial weed species. No phytotoxic effect was observed in the rice based on the plant height, the number of tillers, and culm and panicle length. Finally, rice yield in the BAO UG and BBF UG treatment was as much as that in the hand weeding. This study indicates that self-dispersible floating formula of benzobicyclon mixtures can be applied to control both annual and perennial weed species in rice paddy fields and contribute to save labor costs.

Effect of tillage systems on the level of contamination of nonarable land of Zhytomyr Polissya

The results of studies of the effects of different systems of the basic soil cultivation on weediness of land that is withdrawn from agricultural use in Zhytomyr Polissya are presented in the article. The effect of different tillage systems on the main species composition of annual and perennial weeds and quantitative composition of organs of vegetative propagation of perennial weeds is described. It was established that on land that is withdrawn from economic use in Zhytomyr Polissya, the application of different systems of the basic soil cultivation reduces weediness of lands to 53.7%. The smallest development of annual and perennial weed species occurs mainly during combination tillage.

Influence of Sun and Shade Conditions onGratiana boliviana(Coleoptera: Chrysomelidae) Abundance and Feeding Activity on Tropical Soda Apple (Solanaceae) Under Field Conditions

Summary Tropical soda apple is a perennial invasive weed species that has become a serious problem in both agricultural and natural areas of the southeastern United States. A field survey was conducted at a ranch in Madison County, Florida, to assess the effect of sun and shade conditions on the abundance and feeding activity of Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) on tropical soda apple. The results revealed that beetle abundance and their feeding damage were greater on plants growing in full sun exposure than on plants growing in shaded habitat.

Germination Strategies of Seeds of Cassia auriculata, a Perennial Weed Species of Arid and Semiarid Regions

The timing of seed germination is one of the critical events that determines the success of seedling establishment in wild species in their natural habitat. This is particularly so in species growing in arid and semiarid regions characterized by seasonal rainfall, which is irregular, often with long dry spells. Germination strategies of seeds of Cassia auriculata (Fabaceae, Caesalpinoideae), a perennial weed species of arid and semi-arid regions, were investigated both in petri plate cultures and under field conditions. The results show that seed dormancy is controlled by both physical (impermeable seed coat) and physiological (presence of germination inhibitors) mechanisms. The seeds are capable of withstanding repeated hydration and desiccation cycles during germination. The seeds sown in cultures as well as in the soil do not germinate simultaneously but show staggered germination over a period of several months. Many of the seedlings dry up during intermittent dry periods but many survive in the field during the ensuing summer months until the next rainy season. Staggered germination and ability to withstand repeated hydration and desiccation cycles are important ecological adaptations to maximize seedling establishment under arid and semi-arid environments.

Integrated Strategies for Management of Perennial Weeds

Multiple weed control strategies employed in combination can often aid the successful management of perennial weed species. This review article provides examples of integrated control programs that could aid in the management of several invasive perennial weed species that are problematic in the Pacific Northwest and elsewhere in North America. The development of an integrated management control program for wild chervil, a relatively recent invader to the Pacific Northwest of the United States and adjacent Canada, provides an example for this process. Through use of mechanical (mowing and tillage), cultural (establishment of competitive vegetation), and chemical (specific herbicides) strategies, control of this short-lived perennial species was greatly improved as compared to foliar herbicide applications alone. Such integrated strategies have been shown to enhance control of many perennial weed species, while potentially reducing the amount of herbicide applied, lessening the possibility of injury to adjacent desirable vegetation and increasing the stability of the ecological community at the site.