scholarly journals Weeds in spring cereal fields in Finland - a third survey

2001 ◽  
Vol 10 (4) ◽  
pp. 347-364 ◽  
Author(s):  
J. SALONEN ◽  
T. HYVÖNEN ◽  
H. JALLI
Keyword(s):  
Average Density ◽  
Grass Species ◽  
Species Number ◽  
Total Biomass ◽  
Weed Species ◽  
Stellaria Media ◽  
Organic Farms ◽  
Weed Biomass ◽  
Cereal Fields ◽  
Crop Stand

A survey of weeds in spring cereal fields was conducted in 16 regions of southern and central Finland in 1997-1999. Data were collected from conventional and organic farms, both of which applied their normal cropping practices. A total of 690 fields were investigated by counting and weighing the weed species from ten sample quadrats 0.1 m2 in size in late July - early August. Altogether 160 weed species were found, of which 134 were broad-leaved and 26 grass species. The total number of weed species ranged from 41 to 84 between regions. In organically farmed fields, the average species number was 24 and in conventionally farmed fields 16. The most frequent weed species were Viola arvensis 84%, Stellaria media 76% and Galeopsis spp. 70%. Only 18 species exceeded the frequency level of 33%. The average density of weeds was 136 m-2 (median= 91) in sprayed conventional fields, 420 m-2 (374) in unsprayed conventional fields and 469 m-2 (395) in organic fields. The average air-dry above-ground biomass of weeds was 163 kg ha-1 (median=63), 605 kg ha-1 (413) and 678 kg ha-1 (567), respectively. Weed biomass accounted for 3% of the total biomass of the crop stand in sprayed conventional fields and for 17% in organic fields. Elymus repens, the most frequent grass species, produced the highest proportion of weed biomass.

scholarly journals Composition of weed flora in spring cereals in Finland - a fourth survey

2008 ◽  
Vol 20 (3) ◽  
pp. 245 ◽  
Author(s):  
J. SALONEN ◽  
T. HYVÖNEN ◽  
H. JALLI
Keyword(s):  
Crop Production ◽  
Average Density ◽  
Grass Species ◽  
Species Number ◽  
Weed Species ◽  
Stellaria Media ◽  
Weed Flora ◽  
Elymus Repens ◽  
Spring Cereals ◽  
Galium Spurium

The weed flora in conventionally and organically grown spring cereals was investigated in southern and central Finland during 2007–2009. The survey was conducted in 16 regions, 283 farms and 595 fields (72 organically cropped and 523 conventionally cropped fields, of which 503 were treated with herbicides). The occurrence of weeds was assessed in late July–early August. Altogether 148 weed species were identified, of which 128 were broad-leaved and 20 grass species. In organically cropped fields, the average species number per field was 21 and the most frequent species were Chenopodium album 96%, Stellaria media 94%, Viola arvensis 94% and Elymus repens 89%. In conventionally cropped fields, the average species number was 12 and the most frequent weed species were Viola arvensis 83%, Stellaria media 65%, Galeopsis spp. 59% and Galium spurium 59%. The average density of weeds was 160 m-2 (median = 112) in sprayed conventional fields and 519 m-2 (468) in organic fields. The average air-dry biomass of weeds was 167 kg ha-1 (median = 82) and 775 kg ha-1 (563), respectively. Elymus repens, the most frequent and abundant grass species, produced the highest proportion (about 30%) of the total weed biomass in both cropping systems. The frequency of Galium spurium in conventional cropping and Fumaria officinalis in organic cropping had increased substantially since the previous survey in 1997–1999. The average size of the weed seedbank in the 5 cm surface layer was about 1 700 seeds m-2, the most predominant seeds being of C. album. Although the weed flora in Finnish spring cereal fields consists of numerous species, only a fraction of them severely threaten crop production in terms of their frequency and abundance. Weeds in conventional cropping were effectively controlled with available herbicides whereas weed management in organic cropping calls for urgent measures such as direct mechanical weed control in crop stands, which was not practised at all in survey fields.;

scholarly journals Weed flora and weed management of field peas in Finland

2008 ◽  
Vol 14 (2) ◽  
pp. 189 ◽  
Author(s):  
J. SALONEN ◽  
T. HYVÖNEN ◽  
H. JALLI
Keyword(s):  
Weed Management ◽  
Chenopodium Album ◽  
Good Control ◽  
Organic Production ◽  
Grass Species ◽  
Weed Species ◽  
Stellaria Media ◽  
Cropping Practices ◽  
Weed Flora ◽  
Crop Stand

The composition of the weed flora of dry pea (Pisum sativum L.) fields and cropping practices were investigated in southwestern Finland. Surveys were done in 2002–2003 in 119 conventionally cropped fields and 64 fields under organic cropping. Herbicides were applied to 92% of conventionally cropped fields where they provided relatively good control but were costly. Weeds were controlled mechanically only in five fields under organic production. A total of 76 weed species were recorded, of which 29 exceeded the 10% frequency level of occurrence. The average number of weed species per field was 10 under conventional cropping and 18 under organic cropping. The most frequent weed species in both cropping practices were Chenopodium album, Stellaria media and Viola arvensis. Elymus repens was the most frequent grass species. The difference in species composition under conventional and organic cropping was detected with Redundancy Analysis. Under conventional cropping, features of crop stand and weed control explained 38.7% and 37.6% of the variation respectively. Under organic cropping the age of crop stand and field location (y co-ordinate) respectively explained best the variation. Weeds could be efficiently managed with herbicides under conventional cropping, but they represented a significant problem for organic production. Mixed cultivation of pea with cereals is recommended, particularly for organic cropping, as it favours crop competition against weeds.;

scholarly journals Weed flora in organically grown spring cereals in Finland

2001 ◽  
Vol 10 (3) ◽  
pp. 231-242 ◽  
Author(s):  
J. SALONEN ◽  
T. HYVÖNEN ◽  
H. JALLI
Keyword(s):  
Chenopodium Album ◽  
Control Measures ◽  
Grass Species ◽  
Total Biomass ◽  
Weed Species ◽  
Stellaria Media ◽  
Weed Flora ◽  
Elymus Repens ◽  
Spring Cereals ◽  
Organically Grown

The weed flora in organically grown spring cereals was investigated in southern and central Finland in 1997-1999 with the primary purpose of determining the species composition and the level of weed infestation. Altogether 165 fields were surveyed in the middle of the growing season. A total of 126 weed species were found, of which 42 exceeded the frequency level of 10%. The most frequent weed species were Chenopodium album, Stellaria media, Galeopsis spp. and Viola arvensis. Elymus repens was the most frequent grass species. The average density of weeds was 469 plants m-2 (median 395), and the air-dry biomass was 678 kg ha-1 (median 567) which accounted for 17% of the total biomass of the crop stand. Infestation by Chenopodium album and the perennial species Elymus repens, Cirsium arvense and Sonchus arvensis is of major concern. Weed control strategies should include direct control measures to overcome weed problems related to the conversion period from conventional to organic growing.

scholarly journals Performance of reduced herbicide doses in spring cereals

1993 ◽  
Vol 2 (6) ◽  
pp. 537-550
Author(s):  
Jukka Salonen
Keyword(s):  
Dose Reduction ◽  
Biomass Production ◽  
Spring Wheat ◽  
Spring Barley ◽  
Total Biomass ◽  
Weed Species ◽  
Hordeum Vulgare L ◽  
Weed Biomass ◽  
Significant Difference ◽  
Weed Infestation

The consequences of dose reduction of three new herbicide formulations were studied for the control of annual broad-leaved weeds in fields of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The herbicide formulations were MCPA/mecoprop-P, MCPA/dichlorprop-P and MCPA/fluroxypyr. The efficacy of the lowest recommended dose and a 30% lower rate were tested and compared with the reference herbicide tribenuron-methyl. Trials were conducted at seven sites for three years. Considerable annual fluctuations in weed infestation were recorded. Although the dose reduction occasionally caused considerable decline in control (on %-scale), suppression of weed biomass was still satisfactory in most of the trials. On average, a 75% reduction of weed biomass in spring barley and an 83% reduction in spring wheat were achieved with reduced herbicide doses. Use of reduced herbicide doses for three years in the same fields caused neither a significant increase in weed infestation nor changes in the species composition of weed populations compared with treatments at recommended rates of application. There was a significant difference in biomass production between weed species. Consequently, the total biomass production of annual dicotyledonous weeds correlated only weakly (r=0.48) with the total weed density. Even in untreated plots the weed biomass at harvest constituted, on average, only 3.1-3.6% of the total vegetative biomass of crop stands. Thus, the crop yield responses to chemical weed control remained low.

scholarly journals Weeds of cereal stubble-fields on various soils in the Kielce region. P. III. Black, alluvial and rendzina soils

2013 ◽  
Vol 47 (2) ◽  
pp. 39-51
Author(s):  
Maria Jędruszczak ◽  
Jan Majda
Keyword(s):  
Alluvial Soil ◽  
Cirsium Arvense ◽  
Species Number ◽  
Weed Species ◽  
Stellaria Media ◽  
Polygonum Aviculare ◽  
Soil Features ◽  
Perennial Weeds ◽  
Weed Flora ◽  
Myosotis Arvensis

The weed flora growing stubble-fields area is determined by soil features. Weeds found in cereal stubble-fields on black soils formed from sands and loams, medium and haevy alluvial soils as well as brown and chernozem rendzina soils are presented in the paper. The 273 phytosociological records were worked out. They were collected from 87 stands situated in 76 localities of Kielce region. The results showed that species number and species composition were dependent on the soils (black. alluvial, rendzina). The existance of 118 (medium alluvial soil) to 140 (brown rendzina soil) weed species, including 73 common for all of the soils considered, was found there. Relatively high per cent (29-35) of them belonged to perennial weeds. From 22 (brown rendzina soil) to 35 (heavy alluvial soil) of species reached high constancy degrees (V-III). <i>Stellaria media, Myosotis arvensis, Polygonum aviculare, Agropyron repens</i> and <i>Cirsium arvense</i> predominated on the all of the soil examined. Among the weed flora registered, 25 species, recorded only on rendzina soils, were distinguishable for that soils.

Managing invasive plants on sub-Antarctic Macquarie Island

2017 ◽  
Vol 39 (6) ◽  
pp. 537 ◽  
Author(s):  
Brian M. Sindel ◽  
Paul E. Kristiansen ◽  
Susan C. Wilson ◽  
Justine D. Shaw ◽  
Laura K. Williams
Keyword(s):  
Invasive Plant ◽  
Native Plants ◽  
Soil Seed Bank ◽  
Cold Climate ◽  
Grass Species ◽  
Ecosystem Structure ◽  
Weed Species ◽  
Stellaria Media ◽  
Weed Invasion ◽  
Macquarie Island

The Antarctic region is one of the most inhospitable frontiers on earth for weed invasion. On Australia’s world heritage sub-Antarctic Macquarie Island only three species of invasive weeds are well established (Poa annua L., Stellaria media (L.) Vill. and Cerastium fontanum Baumg.), although isolated occurrences of other species have been found and removed. These weed species are believed to have initially been introduced through human activity, a threat which is likely to increase, although strict biosecurity is in place. All three weeds are palatable and may have been suppressed to some extent by pest herbivore (rabbit) grazing. Given the high conservation value of Macquarie Island and threats to ecosystem structure and function from weed proliferation following rabbit eradication, well targeted invasive plant control management strategies are vital. We propose that a successful restoration program for Australia’s most southerly rangeland ecosystem should integrate both control of non-native plants as well as non-native herbivores. Of the non-native plants, S. media may most easily be managed, if not eradicated, because of its more limited distribution. Little, however, is known about the soil seed bank or population dynamics after rabbit eradication, nor the effect of herbicides and non-chemical control methods in cold conditions. A current research project on this non-grass species is helping to fill these knowledge gaps, complementing and building on data collected in an earlier project on the ecology and control of the more widespread invasive grass, P. annua. With an interest in off-target herbicide impacts, our work also includes a study of the movement and fate of herbicides in the cold climate Macquarie Island soils. Research in such a remote, cold, wet and windy place presents a range of logistical challenges. Nevertheless, outcomes are informing the development of effective, low-impact control or eradication options for sub-Antarctic weeds.

scholarly journals Grain yield and competitive ability against weeds in modern and heritage common wheat cultivars are differently influenced by sowing density

2017 ◽  
Vol 11 ◽  
Author(s):  
Mariateresa Lazzaro ◽  
Ambrogio Costanzo ◽  
Dalia Hosam Farag ◽  
Paolo Bàrberi
Keyword(s):  
Grain Yield ◽  
Common Wheat ◽  
Weed Suppression ◽  
Strong Impact ◽  
Wheat Cultivars ◽  
Modern Cultivar ◽  
Weed Biomass ◽  
Growing Seasons ◽  
Viable Seeds ◽  
Crop Stand

Sowing density can have a strong impact on crop stand development during wheat growing cycle. In organic and low-input agriculture, and therefore with minimum or nil use of chemical herbicides, increased sowing density is expected to affect not only grain yield but also weed suppression. In this study we tested, under Mediterranean conditions, six common wheat cultivars (three modern and three heritage) and two three-component mixtures (arranged by combining the three modern or the three heritage cultivars). The different crop stands were tested at sowing densities of 250 (low) and 400 (high, similar to standard sowing density used by local farmers) viable seeds m-2 for two growing seasons. We did not detect a significant effect of crop stand diversity (single cultivars vs mixtures) on grain yield and weed suppression. Differences were ascribed to type of cultivars used (heritage vs modern). Compared to high sowing density, in modern cultivars grain yield did not decrease significantly with low sowing density whereas in heritage cultivars it increased by 15.6%, possibly also because of 21.5% lower plant lodging. Weed biomass increased with low sowing density both in heritage and modern cultivar crop stand types. However, heritage crop stands had, on average, a lower weed biomass (56%) than modern crop stands. Moreover, weed biomass in heritage crop stands at low density (6.82 ± 1.50 g m-2) was lower than that of modern cultivars at the same sowing density (15.54 ± 3.35 g m-2), confirming the higher suppressive potential of the former. We can conclude that lower sowing density can be advisable when using heritage crop stands as it keeps productivity while decreasing plant lodging and maintaining weeds under control.

scholarly journals A Plant Process Economic Model for Weed Management Decisions in Irrigated Onion

1999 ◽  
Vol 124 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Claudio M. Dunan ◽  
Philip Westra ◽  
Frank D. Moore
Keyword(s):  
Leaf Area ◽  
Plant Density ◽  
Light Extinction ◽  
Species Number ◽  
Yield Reduction ◽  
Weed Species ◽  
Early Application ◽  
Area Index ◽  
Variable Approach ◽  
Number Of Leaves

A simulation model was built as a decision aid for management of five weed species in direct seeded irrigated onion (Allium cepa L.). The model uses the state variable approach and simulations are driven by temperature and sunlight as photosynthetically active radiation (PAR). It predicts yield reduction caused by competition for PAR according to the ratio of crop leaf area index (LAI) to weed LAI and respective light extinction coefficients (k). Input variables are plant density by species and average number of leaves by species. Number of leaves per plant is used by the model to provide an estimate of initial leaf area per plant. The model calculates initial species LAIs by multiplying species density times average leaf area per plant. The model accurately describes competitive interactions, taking into account respective plant densities, time of emergence, and time of weed removal. It permits economic evaluation of management factors such as handweeding, chemical weed control, herbicide phytotoxicity due to early application, and control of weed flushes during the season. The model is also used to evaluate mechanisms of plant competition for sunlight. In a sensitivity analysis, onion yield loss was more sensitive to weed PAR interception than to PAR use efficiency, the latter a species-dependent constant in the model.

scholarly journals Weed Species Diversity in the Czech Republic Under Different Farming and Site Conditions

2015 ◽  
Vol 63 (3) ◽  
pp. 741-749 ◽  
Author(s):  
Michaela Kolářová ◽  
Luděk Tyšer ◽  
Josef Soukup
Keyword(s):  
Czech Republic ◽  
Organic Farming ◽  
Chenopodium Album ◽  
Arable Land ◽  
Farming Systems ◽  
Weed Species ◽  
Organic Farms ◽  
Standard Size ◽  
The Czech Republic ◽  
Winter Cereals

The aim of this study was to explore the composition of weed vegetation on arable land in selected areas of the Czech Republic and to determine the level of γ-diversity. Our survey was conducted at 27 conventional and 35 organic farms from 2006–2008. In each sampled field, one phytocoenological relevé of a standard size of 100 m2 was recorded in the central part of the field. The species cover was estimated. The total γ-diversity was expressed as the total number of weed species recorded. γ-diversity of different farming systems, altitudes and crops was calculated. Subsequently, the species were divided on the basis of their perenniality. In total, 172 weed species were found – 123 and 162 in conventional and organic farming, respectively. The highest number of species was found in winter cereals and at medium altitudes. Chenopodium album was recorded as the species with the highest constancy in both types of farming. In total, 89 annuals, 17 biennials and 15 perennials were observed in conventional farming, and 109 annuals, 23 biennials, 28 perennials and 2 semiparasitic annuals were found in organic farming.

The critical weed-free period in glyphosate-resistant soybean in Ontario is similar to previous estimates using glyphosate-susceptible soybean

2019 ◽  
Vol 99 (4) ◽  
pp. 437-443
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Amit J. Jhala ◽  
Peter H. Sikkema
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Weed Species ◽  
Weed Biomass ◽  
Weed Density ◽  
Weed Interference ◽  
Beginning Of Flowering ◽  
Minimal Reduction

A study consisting of 13 field experiments was conducted during 2014–2016 in southwestern Ontario and southcentral Nebraska (Clay Center) to determine the effect of late-emerging weeds on the yield of glyphosate-resistant soybean. Soybean was maintained weed-free with glyphosate (900 g ae ha−1) up to the VC (cotyledon), V1 (first trifoliate), V2 (second trifoliate), V3 (third trifoliate), V4 (fourth trifoliate), and R1 (beginning of flowering) growth stages, after which weeds were allowed to naturally infest the soybean plots. The total weed density was reduced to 24%, 63%, 67%, 72%, 76%, and 92% in Environment 1 (Exeter, Harrow, and Ridgetown) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 soybean growth stages, respectively. The total weed biomass was reduced by 33%, 82%, 95%, 97%, 97%, and 100% in Environment 1 (Exeter, Harrow, and Ridgetown) and 28%, 100%, 100%, 100%, 100%, and 100% in Environment 2 (Clay Center) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 stages, respectively. The critical weed-free periods for a 2.5%, 5%, and 10% yield loss in soybean were the V1–V2, VC–V1, and VC–V1 soybean stages in Environment 1 (Exeter, Harrow, and Ridgetown) and V2–V3, V2–V3, and V1–V2 soybean stages in Environment 2 (Clay Center), respectively. For the weed species evaluated, there was a minimal reduction in weed biomass (5% or less) when soybean was maintained weed-free beyond the V3 soybean growth stage. These results shows that soybean must be maintained weed-free up to the V3 growth stage to minimize yield loss due to weed interference.

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