Occurrence Of Weed Species Research Articles

WEED-CROP ASSOCIATION: A CASE STUDY OF FARMLANDS LOCATED AT THE COLLEGE OF EDUCATION, WARRI, DELTA STATE

ABSTRACT The impact of weeds on crops has remained an enigma to achieving sustainable food security. The study was conducted in the College of Education, Warri South Local Government Area of Delta State, to assess the prevalence and occurrence of weed species as a prerequisite to identifying sustainable control measures. A field survey was carried out using a 29cm x 29cm size quadrant with seven samples from each field. Several weed species were identified, and the data was used to calculate each species' average frequency, density, and percentage frequency. Twenty-two (22) weed species distributed among 20 genera and 15 families were identified from the different farmlands. The results showed that the most dominant species were Ageratum conyzoides, with an average frequency of 104.14, an average density of 0.124 and relative frequency of 31.95%; Oldenlandia corymbosa with an average frequency of 72.57, average density of 0.086 and relative frequency of 21.65% and Veronica serpyllifolia with an average frequency of 40.43, average density of 0.049 and relative frequency of 12.41. The least dominant species was Sida acuta, with an average frequency of 0.14, an average density of 0.000, and a relative frequency of 0.04, followed by Alternanthera philoxeroides, with an average frequency of 0.43, an average density of 0.001 and percentage frequency of 0.13. Poaceae, with four species, had the highest abundance of species. The results obtained from this study would help develop a weed control program and make informed decisions regarding herbicide selection.

WEED SPECIES COMPOSITION IN TERRITORIES OF DIFFERENT TYPES IN VINNYTSIA REGION

The article highlights the results of studying the taxonomic composition, floristic features and occurrence of weed species in different types of territories in Vinnytsia region – 159 species of weeds belonging to 116 genera from 32 families were found in the investigated lands of different types – segetal (fields) and ruderal (field margins, field roads, highways). The largest number of species was documented on field margins (123 species), and the smallest number – on roadsides of highways (80 species). The number of identified species on fields and field roads is similar to that on field margins (117-111 species).The values of P. Jaccard’s floristic similarity coefficient indicate a high similarity of the species composition of fields, their roadsides, and field roads (65.2–69.6%) compared to the roadsides of highways (47.0–55.0%). This trend indicates a close interrelation of weed species composition of the main habitat types that make up each agroecosystem (fields, field margins and field roads), which is the reason for the need for regular monitoring of weeds not only in fields, but also in their margins and surrounding field roads.It was found that the distribution of species by families is irregular. The first places by the number of species for all comparison positions are occupied by the families Asteraceae Dumort. and Poaceae Barnhart., with the family Asteraceae significantly exceeding other families by the number of recorded species.It was established that most of the registered weed species belong to the dominant families. It was found out that 59 weed species were registered on all studied types of habitats. A comparative analysis of the obtained data showed that the species are represented in different types of localities to different degrees.The weed species composition in Vinnytsia region is characterized by the unity and stability of the taxonomic structure over a long period of time and regardless of the type of habitat. High indicators of similarity lead to a comprehensive study of weed species compositions of the main habitat types that make up each agroecosystem (fields, field margins, and field roads).

Occurrence of weed species due to the implementation of a crop succession system and early fertilization

Occurrence of weed species due to the implementation of a crop succession system and early fertilization

Annual Ryegrass (Lolium rigidum), Wild Oats (Avena spp.) and Sowthistle (Sonchus oleraceus) Are the Most Commonly Occurring Weeds in New South Wales Cropping Fields

Weeds are a major impediment to crop and pasture production and profitability in Australian farming systems, and knowledge of their occurrence is vital in devising weed management solutions. This study examined the relationships between weed and crop species from observations made during surveys of randomly selected fields in grain and/or pasture production. Between 2013 and 2017, 996 fields across New South Wales (NSW) were surveyed to record the occurrence and density of weed species. Annual ryegrass (Lolium rigidum) (69% of fields), wild oats (Avena spp.) (60%), and sowthistle (Sonchus oleraceus) (34%) were the most common species identified, with a total of 65 weed species recorded to be occurring in NSW cropping fields. Densities of occurring weeds were low, at one plant per square metre or less. Multiple species of wild oats were recorded, with their occurrence varying between survey regions; for example, Avena sterilis subsp. ludoviciana was more prevalent in the north and Avena fatua in the south. Differences in weed species occurrence were noted between this survey and those previously conducted in NSW, with marked increases in annual ryegrass and sowthistle, and this is attributed to the change in crop production practices between survey periods. The study of variable distribution patterns of weed species across cropping systems allows for informed decision-making regarding weed management research and development planning.

Weed Types and Dynamics Associations with Catena Landscape Positions: Smallholder Farmers’ Knowledge and Perception in Zimbabwe

Weed infestation is considered as one of the major biotic stresses of dryland crop production. Weed species occurrence, abundance, and densities differ due to spatial soil fertility variability, and management practices by farmers. Weed surveys are therefore vital for tracking such changes and in turn developing appropriate weed management strategies for farmers. A weed survey was carried out in Wedza, eastern Zimbabwe to assess farmer knowledge and perceptions of major weeds in maize fields across catena landscape positions. A multistage sampling procedure was used, involving random sampling of six villages within a 20 km radius, divided according to the catena position and economic status of the farmer. Two hundred and forty-nine (249) households were interviewed using a structured questionnaire. The data were coded and processed using the CSPro software package, and then analysed using the SPSS program. Factors that predicted the spatial distribution of weeds were determined using a binary logistic model. From the survey, 52.8% and 42.3% of farms are on the upper catena and lower catena, respectively, and only 4.8% are on the middle catena. Thirty-one weed species belonging to 15 families were listed by respondents and identified by enumerators in the study area and were categorised into three main groups (broadleaf, grasses, and sedges). Acanthospermum hispidum and Striga asiatica were considered as problem weeds in maize fields on the upper and lower catena, respectively. Xanthium strumarium was perceived as a new invasive weed in low-lying arable fields. The binary logistic model predicted farm location on the landscape and fertiliser use as the main factors affecting weed types, distribution, and abundance. Moreover, farms on lower catena had more Striga infestations compared to upper catena. The results suggested an integrated weed management approach to control A. hispidum, Striga species, and the invasive fast-spreading X. strumarium in the area.

Weed vegetation in conventional and organic farming in West Bohemia (Czech Republic)

The paper presents species richness and composition of arable weed vegetation in the region of West Bohemia (Czech Republic) in different types of farming (conventional and organic) and grown crops (winter and spring cereals, wide-row crops). During the field survey in the years 2007 to 2017, 105 phytocoenological relevés were recorded. The average species richness in one relevé was significantly higher in organic farming, as well as total weed cover. The lowest species richness was found in wide-row crops. Recently widespread species belonged to the most frequent species in our study. Based on multivariate statistics, the effects of variables on the occurrence of weed species were found as statistically significant. Most of the variability in data was explained by crop, following by type of farming. Weed species of Fabaceae Lindl. family (especially Vicia L.) and many perennial species positively correlated with the organic type of farming. Endangered species were found mainly in organic farming and cereals. Less intensive cultivation with a higher weed cover is beneficial for the promotion of biodiversity.

Effects of Crop Rotation on Spring Wheat Yield and Pest Occurrence in Different Tillage Systems: A Multi-Year Experiment in Finnish Growing Conditions

Crop rotation and soil tillage are among key factors impacting cropping system productivity, pest management and soil health. To assess their role in northern cropping systems, we quantified the effects of crop rotation on spring wheat yield in different tillage systems based on a long-term (2005–2017) field experiment in southwestern Finland. In addition, effects of crop rotation on weeds, plant pathogens, and pest insects were assessed. Three types of crop rotation were compared: monoculture (spring wheat), 2-year rotation (spring wheat—turnip rape—spring wheat—barley) and 4-year rotation (spring wheat—turnip rape—barley—pea) under no-tillage and plowing. A diversified crop rotation improved spring wheat yield by up to 30% in no-tillage and by 13% under plowing compared with monoculture. Overall, the yield quantity and quality differences between crop rotations were higher in no-tillage plots than in plowed plots. The occurrence of weed species in spring wheat before herbicide control was highest in the four-year crop rotation and lowest in the wheat monoculture. For plant diseases, wheat leaf blotch disease severity, mainly caused by Pyrenophora tritici-repentis, was lowest in the most diverse crop rotation. On average, wheat leaf blotch disease severity was 20% less when wheat was grown every fourth year compared with wheat monoculture. The effect of crop rotation on stem and root diseases became apparent after 6 years of rotation and the disease index was lowest in the most diverse crop rotation. Neither rotation nor tillage affected the control need of wheat midge (Sitodiplosis mosellana). Based on our results, diverse crop rotations including cereals, oilseed crops, and legumes increase yield and reduce plant disease severity of spring wheat in Finland, with the magnitude being larger in no-tillage systems.

Composted manure and straw amendments in wheat of a rice–wheat rotation system alter weed richness and abundance

AbstractIn a rice (Oryza sativa L.)–wheat (Triticum aestivumL.) rotation system, a study was conducted to determine the effects of different fertilization regimens (no fertilization, replacement of a portion of chemical fertilizer with composted pig manure, chemical fertilizer only, and straw return combined with chemical fertilizer) on the weed communities and wheat yields after 4 and 5 yr. The impact of the long-term recurrent fertilization regimen initiated in 2010 on the composition and diversity of weed communities and the impact of the components and total amount of fertilizer on wheat yields were assessed in 2014 and 2015. Totals of 19 and 16 weed species were identified in experimental wheat fields in 2014 and 2015, respectively, but the occurrence of weed species varied according to the fertilization regimen. American sloughgrass [Beckmannia syzigachne(Steud.) Fernald], water starwort [Myosoton aquaticum(L.) Moench], and lyrate hemistepta (Hemistepta lyrataBunge.) were adapted to all fertilization treatments and were the dominant weed species in the experimental wheat fields. The greatest number of weed species were observed under the no-fertilization treatment, in which 40% of the weed community was composed of broadleaf weeds and the lowest wheat yields were obtained. With fertilizer application, the number of weed species was reduced, the height of weeds increased significantly, the density of broadleaf weeds was significantly reduced, the biodiversity indices of weed communities decreased significantly, and higher wheat yields were obtained. Only the chemical fertilizer plus composted pig manure treatment and the chemical fertilizer–only treatment increased the density of grassy weeds and the total weed community density. The treatment with chemical fertilizer only also resulted in the highest density ofB. syzigachne. Rice straw return combined with chemical fertilizer yielded the lowest total weed density, which suggests that it inhibited occurrence of weeds. The different fertilizer regimens not only affected the weed species composition, distribution, and diversity, but also the weed density. Our study provides new information from a rice–wheat rotation system on the relationship between soil amendments and agricultural weed infestation.

Phyto-sociological attributes of weed flora in brown mustard growing areas of temperate Kashmir valley

A study on weed flora was conducted to evaluate the weed species distribution across different brown mustard (Brassica rapa var. brown sarson) growing areas of Kashmir valley during Rabi (2016–17 and 2017–18). The occurrence of weed species was assessed on the basis of different phyto-sociological attributes, viz. weed species density, relative density, relative frequency and importance value index. These were computed from the data collected during the month of March. In all twenty weed species were identified of which sixteen were broad-leaved. The crop was highly infested with the weed species of Poaceae family with the dominance of Poa annua (IVI of 84.9, 50.6 and 44.1 in Pulwama, Anantnag and Kulgam, respectively). Among the broad-leaved weeds, Veronica persica was the most dominant species found in Budgam with the abundance value of 17.25 and IVI of 34.5. Budgam had the highest weed species distribution with Simpson's diversity index (D) of 0.120123.

The impact of different weed control methods on weed infestation in maize (Zea mays L.)

The aim of the study was to evaluate the occurrence and development of weed species as actual weed infestation of maize in sustainable farming systems. The specific goals of the study were to assess the dynamics of occurrence of each weed species in integrated and ecological farming systems, and to evaluate the impact of farming system, manure or fertiliser application and year on the presence of weeds in maize stands from 2014 to 2016. In the integrated non-fertilised maize cropping system, the following weed species were dominant in the spring: Amaranthus retroflexus, Cirsium arvense, Chenopodium album, Persicaria maculosa and Echinochloa crus galli. In the integrated fertilised maize cropping system, the following weed species were dominant in the spring: Amaranthus retroflexus, Chenopodium album, Cirsium arvense, Echinochloa crus galli, Convolvulus arvensis and Cardaria draba. In the integrated maize cropping system, Silybum marianum occurred as a weed at medium density. Silybum marianum was cultivated two years ago and its seeds were in a state of dormancy for that time. The efficacy of the herbicide treatment in the integrated system was excellent. In the ecological non-fertilised maize cropping system, the following weed species were dominant in the spring: Amaranthus retroflexus, Chenopodium album, Cirsium arvense, Avena fatua and Sonchus oleraceus. In the ecological fertilised maize cropping system, the following weed species were dominant in the spring: Amaranthus retroflexus, Chenopodium album, Echinochloa crus galli, Avena fatua, Persicaria maculosa, Cirsium arvense and Convolvulus arvensis. In the ecological farming system, due to insufficient mechanical weed control, a higher level of maize infestation with Avena fatua as an annual grass weed species was detected.

Zbiorowiska użytków zielonych w okolicach miejscowości Piasek Wielki (Okręg Staszowski, Polska Południo

This paper presents the results of field research on meadow vegetation in the neighbourhood of Piasek Wielki village (Staszów Region, Świętokrzyskie voivodeship – Southern Poland). The aim of the study was to identify and determine the composition of phytocoenoses of pasture and meadows, because these areas have been never examined in this aspect. In the summer season, in July and August 2013, 50 phytosociological relevés were made in the vicinity of Piasek Wielki village. As a result, four plant communities were observed: Cirsietum rivularis Nowiński 1927, Epilobio-Juncetum effusi Oberd. 1957 in a typical and dried form, Arrhenatheretum elatioris Br.-Bl. ex Scherr. 1925 and Lolio-Cynosuretum Büker 1941. When analysing the results of field research, it should be noted that the areas around Piasek Wielki village create favourable conditions for the development of meadows and pastures. However, in the distinguished phytocoenoses, there are signs of neglect in the management, which is manifested by the occurrence of weed species from Artemisietea class.

Occurrence of Weed Species in Pear Orchards in Chungnam Province of Korea

Occurrence of Weed Species in Pear Orchards in Chungnam Province of Korea

전남 장성지역 한국잔디 재배지 잡초발생 현황

본 연구는 전라남도 장성지역의 한국잔디 재배지의 발생 잡초를 확인하기 위하여 2014년 9월(1차 조사)과 2016년 5월(2차 조사)에 전남 장성군 삼서면 일대에서 한국잔디 재배포장을 밭 토양과 논 토양으로 구분하여 발생잡초 분포조사를 수행하였다. 잡초분포 조사결과 밭 토양에서는 27과 66종(일년생 49종, 다년생 17종)으로 일년생잡초 74.2%, 다년생잡초 25.8%의 발생을 확인하였다. 과별로 보면 국화과(Compositae)가 19.7%로 가장 많이 발생하였고, 그 다음으로 벼과(Gramineae) 13.6%, 콩과(Leguminosae) 10.6% 순이었다. 논 토양에서는 22과 69종(일년생 53종, 다년생 16종)으로 일년생잡초 76.8%, 다년생잡초 23.2% 비율의 발생을 확인하였다. 과별로 보면 국화과(Compositae)가 18.8%로 가장 많이 발생하였고, 그 다음으로 벼과(Gramineae) 14.5%, 사초과(Cyperaceae) 7.2% 순이었다. 밭 토양의 1차 조사에서는 벼과의 바랭이(8.49), 2차 조사에서는 괭이밥과의 괭이밥(7.26)이 가장 우점하였고, 논 토양의 1차 조사에서 국화과의 개망초(9.52), 2차 조사에서는 닭의장풀과의 닭의장풀(5.08)과 벼과의 뚝새풀(5.08)이 가장 우점하는 잡초종으로 확인되었다. 잡초발생 현황을 조사시기와 토양조건을 구분하여 비교한 결과 논 잡초와 밭 잡초가 혼생하는 것으로 확인되었다. 조사시기 또는 토양조건에 상관없이 공통적으로 발생하는 초종의 비율이 49.2%로 비교적 높게 나타났다. 따라서 한국잔디 재배지에서 제초제를 이용한 효율적인 방제효과를 위해서는 재배토양에 상관없이 논 잡초와 밭 잡초를 모두 잘 방제할 수 있는 약제를 선택해야 할 것으로 판단되었다. This study was conducted to provide basic information for weed control by surveying the occurrence of weed species in turf sod production areas. Surveys of weed species occurred in turf sod production areas were conducted in Jangsung-gun, Jeonnam province from September 2014 to May 2016. Total 50 sites of turf sod production areas in two soil conditions were investigated. On the upland soil condition in turf sod production areas, 66 weed species in 27 families were identified and classified to 49 annuals and 17 perennials and on the paddy soil condition, 69 weed species in 22 families were identified and classified to 53 annuals and 16 perennials. Based on the importance values, the most dominant weed species on the upland soil condition in the first survey (September 2014) was Digitaria ciliaris (8.49%), followed by Erigeron annuus (7.94%) and Rorippa indica (6.56%). In the second survey (May 2016) was Oxalis corniculata (7.26%), followed by Capsella bursa-pastoris (6.21%) and Conyza canadensis (6.21%). Whereas the most dominant weed species on the paddy soil condition in the first survey (September 2014) was Erigeron annuus (9.52%), followed by Mazus pumilus (7.41%) and Cyperus iria (6.82%). In the second survey (May 2016) was Commelina communis (5.08%), followed by Alopecurus aequalis (5.08%) and Erigeron annuus (4.79%). This information could be useful for estimation of future weed occurrence and effective weed control methods in turf sod production areas in Jangsung-gun, Jeonnam Province.

Weed species in tomato production and their role as alternate hosts ofTomato spotted wilt virusand its vectorFrankliniella occidentalis

Tomato spotted wilt virus (TSWV) is an important plant virus that infects a wide range of hosts including weeds making its management difficult. A survey was undertaken to establish the occurrence of weed species in tomato production systems in Kenya and their role as hosts of TSWV and its vectors. Selected weed species were further evaluated for their reaction to TSWV, transmission efficiency by Frankliniella occidentalis and ability to support thrips reproduction. Of the 43 weed species identified in the field, 29 species had been reported as hosts of TSWV, two were non-hosts and 11 had no record of their status. Among the more common species, Amaranthus hybridus, Solanum nigrum, Tagetes minuta and Datura stramonium were susceptible to the virus and supported high levels of thrips reproduction. The TSWV could not be transmitted to Galinsoga parviflora and Sonchus oleraceus by F. occidentalis despite them being highly susceptible in mechanical transmission tests. There was a significant correlation between feeding damage and number of larvae of F. occidentalis on different weeds. Occurrence of weeds that support thrips reproduction and are good hosts of TSWV is a clear indicator of their role in epidemiology and the importance of their management for disease control.

경남지역 밭 잡초 발생분포 및 군락변화

본 연구는 경남지역의 밭에서 발생하는 잡초의 분포현황을 조사하기 위하여 수행하였다. 보리 재배지에서는 21과 55종, 마늘 재배지 22과 56종, 양파 재배지 19과 47종, 배추 재배지 26과 68종, 감자 재배지 22과 54종, 고구마 재배지 25과 62종, 고추 재배지 29과 87종, 옥수수 재배지 28과 79종, 콩 재배지 29과 84종이 발생되었다. 작목별 우점하는 초종은 보리 재배지 뚝새풀 20.7%, 마늘 재배지 황새냉이 12.3%, 양파 재배지 좀명아주 18.7%, 배추 재배지 쇠비름 8.1%, 감자 재배지 좀명아주 13%, 고구마 재배지 바랭이 12.6%, 고추 재배지 바랭이 12.6%, 옥수수 재배지 11.3%, 콩 재배지 바랭이 13.2%로 발생되었다. 동작물 재배지에서는 뚝새풀, 황새냉이 및 좀명아주가, 하작물 재배지에서는 바랭이, 쇠비름, 깨풀이 가장 문제시 되었다. 이러한 잡초 발생 정보는 경남지역 밭잡초 관리방안 수립에 기여할 것으로 판단된다. This study was conducted to provide basic information for weed control by surveying the occurrence of weed species in upland crop fields in Gyeongnam province of Korea. The result of this survey, 55 weed species 21 families in barley fields, 56 weed species 22 families in garlic fields, 47 weed species 19 families in onion fields, 68 weed species 26 families in Chinese cabbage fields, 54 weed species 22 families in potato fields, 62 weed species 25 families in sweet potato fields, 87 weed species 29 families in red pepper fields, 79 weed species 28 families in corn fields, 84 weed species 29 families in soybean fields. The most dominant weed species in upland crop fields of Gyeongnam province were Alopecurus aequalis var. amurensis 20.7% (barley fields), Cardamine flexuosa 12.3% (garlic fields), Chenopodium ficifolium 18.7% (onion fields), Portulaca oleracea 8.1% (Chinese cabbage fields), Chenopodium ficifolium 13% (potato fields), Digitaria ciliaris 12.6% (sweet potato fields and red pepper fields) and Digitaria ciliaris 11.3% (corn fields), 13.2% (soybean fields). This information could be useful for establishment of future weed control methods in Gyeongnam province.

Germination test as a fast method to detect glyphosate-resistant sourgrass

The occurrence of weed species with different levels of resistance to glyphosate has increasingly spread in agricultural areas. In Brazil, sourgrass is among the main species presenting issues in this regard. Thus, fast and reliable methods to detect glyphosate resistance are of special interest for this specie, either for research or rational management purposes. This study was carried out to verify the feasibility of using the germination test to detect glyphosate resistance in sourgrass. The experiment was conducted with two sourgrass biotypes, with different levels of susceptibility to glyphosate. The seeds were previously imbibed in solutions composed of 0, 0.1875%, 0.25%, 0.75%, 1.5%, 3% and 6% of glyphosate during two periods, five and ten minutes, and submitted to germination tests. The results indicate the germination test as a feasible and time-saving approach to evaluate glyphosate-resistant sourgrass, with results available in seven days.

충남지역 밭작물 재배지 잡초발생 및 분포현황

This study was conducted to provide basic information for weed control by surveying the occurrence of weed species. Surveys of weed species occurred in food crop (barley, maize, potato, soybean) fields were conducted in Chungnam province from April to September in 2014. Total 321 sites of food crop fields in 17 City / Gun in Chungnam province were investigated. From the result of this survey, 130 weed species in 36 families were identified and classified to 77 annuals, 27 biennials and 26 perennials. Based on the occurrence ratio, the most dominant weed species in Chungnam province food crop fields were Digitaria ciliaris (10.19%), followed by Conyza canadensis (7.82%), Portulaca oleracea (5.22%), Chenopodium album var. centrorubrum (5.21%), Capsella bursa-pastoris (3.47%) and Alopecurus aequalis (3.47%). Forty-four exotic weed species were identified. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in food crop fields of Chungnam province.

충남지역 배추재배지 발생잡초 분포특성

Abstract : This study was conducted in order to utilize the basic data for weed control by surveying the occurrence of weed species. Total 63 sites of upland Chinese cabbage fields in Chungnam Provinces were investigated. The result of survey, 71 weed species in 25 families were identified and classified to 39 annuals, 16 biennials and 16 perennials. Based on the occurrence ratio, the most weed species belonged to Compositae (20 species). 8, 6 and 5 weed species belonged to Poaceae, Cruciferae and Polygonaceae, respectively, and these 10 weed species in the most six families accounted for 50% of total weed occurrence. The most dominant weed species in upland Chinese cabbage fields were Portulaca oleracea (8.07%), followed by Digitaria ciliaris (7.54%), Rorippa palustris (6.44%), Chenopodium album (5.73%), Echinochloa crus-galli (5.02%) and Cyperus amuricus (3.95). Key words : Chinese cabbage, Upland field, Weed, Chungnam province *Corresponding author: Tel: +82-42-821-5726E-mail address: parkkw@cnu.ac.kr

Vliv rozdílné technologie zpracování půdy na druhové spektrum plevelů v ozimé řepce

A community of weeds and crops is affected by a number of factors, including, among other things, also tillage. In the years 2000–2002, the composition of weed species in rape stands was evaluated on the fields with the total area of 551 hectares (1 hectar equals to some 2.47 acres). The evaluation was carried out with the application of methodology developed by Kühn (1982). On the fields located in the cadastral area of Olomouc – Holice, which had been cultivated in a traditional manner, 115 relevés were recorded. On the fields in the cadastral area of Bohuňovice, which had been cultivated with the application of reduced tillage, 97 relevés were recorded and evaluated. All of the above fields were subjected to the application of chemical agents reducing the occurrence of weeds. The data thus received were processed by means of multidimensional analysis of ecological data with the application of a RDA method (Redundancy Analysis). In the course of three years, 75 weed species were found on the fields under conventional tillage, on the average, 8.2 species per a relevé, while 66 weed species were found during the same period of time on the fields cultivated by means of reduced tillage, on the average, 8.6 species per a relevé. The application of RDA analysis enabled us to sort out the selected species of weeds (i.e. those the frequency of occurrence of which exceeded 15 %) into three groups. The conditions provided by the conventional tillage appeared to be more satisfactory for the weed species included in the first group (Arctium tomentosum, Elytrigia repens, Helianthus tuberosus, Chenopodium album, Lolium perenne and Papaver rhoeas). The species included in the second group, i.e. Alsinula media, Apera spica-venti, Atriplex patula, Bromus sterilis, Capsella bursa-pastoris, Equisetum arvense, Fallopia convolvulus, Myosotis arvensis and Thlaspi arvense., responded to reduced tillage by the increase in cover or by increased frequency of occurrence. The third group consists of species such as: Cirsium arvense, Chamomilla recutita, Galium aparine, Lactuca serriola, Matricaria maritima, Triticum aestivum and Viola arvensis. Their cover and frequency of occurrence were in a more degree influenced by factors different from the type of tillage. The manner of tillage appears to be only one of a number of factors that affect the occurrence of weed species. It influences them together with other factors and it is a factor of polyfunctional nature.

곰취밭에 발생하는 잡초양상

곰취밭에 발생하는 잡초발생 양상과 잡초로 인한 피해정도를 파악하여 곰취밭 잡초방제의 기초자료로 활용하기 위하여 2013년 5월부터 10월까지 5회 조사하였다. 곰취밭에 발생하는 잡초는 37과 104종으로 일년생잡초가 55종, 월년생잡초 25종 그리고 다년생잡초가 24종이었다. 이 중에서 외래잡초는 26종이 발생하였다. 우점도가 높은 잡초로는 명아주, 쇠별꽃, 돌피, 망초, 쑥 등이었으며, Ordination PCA 분석한 결과, 고마리-미국가막사리 군락, 명아주 군락 그리고 냉이 군락으로 분석되었다. 잡초에 의한 곰취의 피해 정도를 곰취 뿌리 무게로 비교한 결과, 잡초관리구에 비교하여 잡초방임구가 56% 작아져서 이듬해 곰취 생육에 영향을 줄 것으로 판단된다. This study was conducted in order to utilize the basic data for weed control by surveying the occurrence of weed species and the degree of damages caused by those weeds occurred in cultivated Ligularia fischeri fields. Survey was carried out five times, on May, June, July, August and October in 2013. The weed flora was composed of a total of 104 weeds, 37 families, of which 55 species were annual, 25 species were biennial, and 24 were perennial plants. Twenty-six exotic species were included as well. Dominance was the highest with Chenopodium album followed by Stellaria aquatica, Echiochloa crus-galli, Conyza canadensis, and Artemisia princeps etc. in order. In the PCA plot analysis, weeds occurred in cultivated L. fischeri fields were divided into three groups, Persicaria thunbergii-Bidens frondosa community, Chenopodium album community and Capsella bursapastoris community. The degree of damages in cultivated L. fischeri fields was investigated by weighing roots of L. fischeri. We found that 56% decreased root weight in no weeding plots comparing to that in weed management plots. We infer from this result that decreased roots will affect to the growing of L. fischeri in following year.