Integration of Elymus repens control and post-harvest catch crop growing in organic cropping systems

In Northern Europe, Elymus repens (L.) Gould infestations are traditionally controlled by repeated stubble cultivation in the period from harvest to ploughing in autumn. However, in organic farming, post-harvest tillage is undesirable due to the need for retaining nutrients in the cropping system. The soil is mostly cropped in that period, limiting post-harvest tillage. Two control strategies against E. repens are presented that merge the objectives of achieving a significant reduction of E. repens while having the soil covered with plants during the post-harvest period. Strategy I is an integration of rhizome fragmentation by soil cultivation within two days after harvest in early August with subsequent sowing of a catch crop to suppress shoot growth from the rhizome fragments. Strategy II also includes growing a catch crop but is preceded by a mid-summer fallow period lasting 4-6 weeks where repeated soil cultivations are conducted to fragment, weaken and desiccate the rhizomes. Strategy II controlled 91-90% of the E. repens population while strategy I only controlled up to 40%, mainly because of the weakening and desiccation of rhizomes caused by repeated cultivations. However, the fallow period may lead to undesirable nutrient leaching from sandy soils and the grower will have to desist from growing a profitable maturing crop, aspects that should be counterbalanced against the urgency for E. repens control and other possible control options. Strategy I appears to be more relevant for low infestation levels of E. repens while strategy II would be more appropriate where infestations have become large

The track record of the Commission's forecasts - an update

This paper has updated the assessment of the Commission's forecasts' track record from 1999 by extending the observation period from 1969-1997 to also take into account the forecasts and outcome for the years 1998-2005. This update has also included some further tests on e.g. informational efficiency and undertaken a comparison with the forecasts of other international institutions and those of market participants. The tests were carried out on the forecasts for real GDP growth, total investment, inflation, the unemployment rate, the general government balance and the current account to GDP ratio. Data have been processed in a broadly similar manner compared to the study of 1999 to ensure comparability to the greatest degree possible. Overall, the Commission's forecasts continue to dispose a reasonable track record. For instance, the forecast error for the GDP forecast, as measured by the mean absolute error, has improved by 0.03 percentage point (pp.) to 0.5 pp. for the current-year outlook and by 0.08 pp. to 0.86 pp. for the year ahead. This implies that the Commission's forecasts for GDP growth has, on average, proven to be 0.5 pp. too high / low for the current year. Forecasts for the EU generally seem to be unbiased, efficient and display a high success rate for directional accuracy. The same holds true for the outlook for most Member States, although there are individual examples to the contrary. Moreover, in view of the importance of the international environment in explaining past forecast errors, it is reassuring to note that the forecasts for the largest non-EU countries generally seem to perform well. Finally, the Commission's forecasts' track record for GDP is broadly comparable with the ones of Consensus, the IMF and the OECD.forecasts, projections, economic outlook, GDP, growth, Melander, Sismanidis, Grenouilleau

The dynamics of Cirsium arvense and Elytrigia repens in long-termed organic crop rotation experiments

Cirsium arvense and Elytrigia repens are perennial weeds prevalent in organic cropping systems in Scandinavia. This study analysed the population dynamics of both species in long-termed crop rotation experiments conducted at three sites (coarse sand, silt and sandy loam) in Denmark from 1997-2009. The purpose was to gain insights into the factors influencing perennial weeds population changes over time, especially those important for outbreaks of C. arvense and E. repens infestations. Data were obtained from three cycles of four-year crop rotations with various cash crops and annual grass-clover subjected to four treatment combinations: with and without animal manure and with and without catch crops. The perennials were controlled by different tillage and mowing strategies between and within crops. The experiment on coarse sand was quickly infested with E. repens while C. arvense gradually invaded the experiment on sandy loam. At the third site, perennial weeds did not become noteworthy problems in the 12-year period. The reason for this could not be explained in differences of fertility among sites but rather in site characteristics and weed management measures employed. Pulse crops and spring cereals caused the highest population increases of E. repens on coarse sand, especially when preceded by grass-clover. However, grass-clover with mowing had the opposite effect on C. arvense growth on sandy loam and crops succeeding grass-clover were predominantly least infested. Similar to E. repens, vigorous C. arvense growth was associated with pulse crops but spring cereals versus winter cereals were not markedly different in their suppressing abilities against C. arvense. Potatoes grown in ridges that were rotary tilled and winter rye suppressed the E. repens population, but tillage between crops was necessary to decrease the population. In contrast, stubble cultivation had very little effect on C. arvense. Manuring generally reduced E. repens growth by 28% whilst no differences were seen for C. arvense between manured and non-manured treatments. Apparently, the improved crop growth caused by fertilisation increased crop competition enough to counterbalance any growth stimulation of C. arvense. This study clearly revealed the importance of benefitting from significant crop suppression for the management of perennial weeds under circumstances with no access to strong weed control methods such as herbicides. Well established and fast growing crops producing large quantities of crop biomass might be valuable tools for the suppression of perennial weeds in organic cropping systems, especially C. arvense while this is less clear for E. repens. Grass-clovers and similar crops suited for mowing also play an important role for the control of C. arvense while mechanical interventions are more important to supplement the management of E. repens

Nye strategier til at bekæmpe kvik

Traditionel bekæmpelse af alm. kvik med sort jord og harvninger om efteråret medfører tab af næringsstoffer fra rodzonen. Derfor burde jorden holdes plantedækket hele året, men så får kvikken for meget spillerum. Bekæmpelse af kvik kan dog godt forenes med ønsket om at holde jorden plantedækket det meste af efteråret

The Effect of Poor Parenting on Male and Female Dating Violence Perpetration and Victimization

This study examines the effects of poor parenting on dating violence perpetration and victimization among approximately 900 males and females from the National Longitudinal Survey of Adolescent Health (Add Health). Results revealed that more physical abuse and low parental warmth were linked to greater substance use and higher rates of delinquency. In addition, low parental warmth, more neglect, and greater delinquency had positive direct effects on dating violence perpetration, whereas more physical abuse, low parental warmth, and increased delinquency were all positively associated with dating violence victimization. Finally, delinquency mediated the link between low parental warmth and dating violence perpetration and victimization. The results provide some support for both social learning theory and an antisocial orientation perspective

Common Couch-grass control with less tillage

Control of Common Couch-grass often conflicts with the need to retain nutrients in organic cropping systems, as it involves intensive tillage in the post-harvest period. Thus, preferably the soil should be cropped through the entire year to prevent nutrient leaching from the root zone. Research has shown that new control strategies may combine the reduction of couch infestations and a soil cover with plants during the post-harvest period. This may have potential for practical implementation

Incompatibility between fertility building measures and the management of perennial weeds in organic cropping systems

Fertility building measures are important components in improving the productivity of organic cropping systems without livestock. However, some measures seem to be incompatible with the control of perennial weeds that can have adverse effects such as significant weed competition. The influence of fertility building measures (N2-fixing crops in the crop sequence, cover crops and manuring) and the abundance of perennial weeds were studied in a long-term crop rotation experiment at two locations in Denmark. The aim was to gain insight into the factors that influence the growth of perennial weed species occurring in mixed stands. Data were obtained from three cycles of four-year arable crop rotations comprising various cash crops in rotations with and without annual whole-year grass-clover as green manure and subjected to four treatment combinations: with and without animal manure and with and without cover crops. Severe outbreaks of perennial weed problems did not occur at the location that had the highest soil fertility, whereas the other site demonstrated dynamic growth of Cirsium arvense and Elytrigia repens. Grain legumes tended to promote the growth of C. arvense, while manuring was neutral to C. arvense but beneficial to E. repens. Cover crops assisted the growth of E. repens since prolonged mechanical interventions were not possible. Compatibility was only achieved with grass-clover and C. arvense, meaning that green manure crops suitable for cutting and mulching could offer an important management option against C. arvense but not against E. repens

Regulering af ukrudt

I økologisk plantedyrkning er ukrudtsreguleringen baseret på et samspil mellem forebyggelse og bekæmpelse, hvor forebyggelse spiller en langt større rolle end i den konventionelle dyrk-ning. I korn og andre tætsåede afgrøder er forebyggelsen den væsentligste komponent i ukrudtsreguleringen, hvorimod det er den direkte bekæmpelse, der udgør grundlaget for dyrk-ning af rækkeafgrøder så som gulerødder, løg, roer og kartofler. Den økologiske ukrudtsregu-lering kendetegnes ved kompleksitet, da der dels anvendes mange forskellige metoder, og dels anvendes metoder med langsigtede effekter i dyrkningssystemet. Formålet med denne artikel er at give overblik over de anvendte metoder. Artiklen er opbygget således at der først er et afsnit om behovet for ukrudtsregulering, derefter et afsnit om muligheder for forebyggelse mod ukrudt og endelig et afsnit om metoder til di-rekte bekæmpelse. Artiklen afsluttes med at afsnit om forskning vedrørende ukrudtsregule-ring. Artiklen er en gennemgang af principper og metoder - ikke konkrete anvisninger på hvordan ukrudtsbekæmpelsen i praksis skal udføres. Disse kan f.eks. findes i “Ukrudtsbe-kæmpelse på økologiske brug” udgivet af Landbrugets Rådgivningscenter (Anonym 95) og i andre af de citerede kilder