Das Faltblatt beschreibt die Biologie und die Verbreitung der Samtpappel Abutilon theophrasti in Sachsen und zeigt Abbildungen aller Entwicklungsstadien vom Keimling bis zur ausgewachsenen Pflanze. Die erstmals im Jahr 2000 vom amtlichen Pflanzenschutzdienst in Sachsen als Ackerunkraut registrierte Samtpappel wurde bereits im Jahr 2004 an 41 Standorten in Sachsen vorgefunden. In Zuckerrüben wurde die höchste Verbreitung auf Grund einer Wirkungslücke der eingesetzten Herbizide festgestellt. In Mais und Getreide zeigen viele Herbizide eine gute Wirkung. Die Samen der Samtpappel können von importiertem Saatgut oder von Importfuttermitteln auf die Äcker gelangen.

No description available.

Three isolates of Curvularia belonging to Curvularia tuberculata (isolates 93-020 and 93-022) and Curvularia oryzae (isolate 93-061) were obtained from diseased Cyperus difformis, Cyperus iria, and Fimbristylis miliacea, respectively, in the Philippines in 1993. Under greenhouse conditions, these fungal isolates caused high mortality and significant plant dry weight reduction in C. difformis, C. iria, and F. miliacea when sprayed at the rate of 1 x 108 spores/m3. Cross-pathogenicity of the isolates was demonstrated in three other sedge weed species. C. difformis, C. iria, and F. miliacea were killed but C. rotundus was resistant. Most of the thirteen rice varieties tested were resistant to the fungal isolates. The order of decreasing pathogenicity to rice was C. oryzae (93-061), C. tuberculata (93-020), and C. tuberculata (93-022). The infection process of C. tuberculata and C. oryzae was similar. Spore germination was polar for C. tuberculata and bipolar for C. oryzae. Germ tube growth was random and branching. Appressoria were formed preferentially over epidermal cell wall junctions on sedge hosts and over stomatal apertures in rice. Complex infection cushions were observed only on sedge hosts. Infection hyphae developed inter- and intracellularly, causing epidermal cell walls to separate and mesophyll cells to shrink and collapse. The vascular bundles were not invaded. Colonization of susceptible weeds was rapid and conidiophores emerged from the stomatal aperture between 96 to 120 hours post inoculation (HPI). Resistance to C. tuberculata and C. oryzae in C. rotundus and rice was expressed as a delay in appressorial formation, inhibition of fungal growth after penetration, and lack of sporulation.

The effect of cover crops on N and weed dynamics was assessed within a pea (Pisum sativum L.) – cover crop – sweet corn (Zea mays L.) rotation. Cover crops of oat (Avena sativa L.), perennial rye (rye) (Secale cereale L.), oilseed radish (OSR) (Raphanus sativus L. var. oleoferus Metzg Stokes), and OSR plus perennial rye (OSR+rye) increased plant available N (PAN) over the cover crop growing season compared to the no cover control at the Bothwell site only. However, at neither site did cover crops result in increased PAN for the sweet corn, indicating that these cover crops will not reduce required N fertilizer applications. Also, cover crops posed neither an increased or decreased need for weed management during sweet corn production. However, OSR may be useful in pesticide reduced programs due to its potential ability to reduce fall herbicide applications, provided it does not set viable seed.

Research objective. The study was aimed to establish the competitive peculiarities of the multi-component agrocenose (maize, living mulches, weeds) and its effects on soil properties under sustainable farming conditions. Research tasks. To accomplish the research objective the following tasks were set - to study: 1. The influence of living mulches, grown in a maize monocrop, on soil physical properties (soil moisture dynamics, shear resistance, penetration resistance, soil structure and its stability), chemical characteristics (total nitrogen, available phosphorus and potassium content, pH) and biological characteristics (urease and saccharase activity); 2. The dynamics of biomass accumulation of living mulches and weeds; 3. The impact of living mulches on weed infestation in a maize crop and on weed seed contamination in a ploughlayer; 4. Maize crop irradiance conditions and their influence on different components of the agrophytocenose; 5. Projection coverage of maize inter-rows; 6. Maize productivity and biometric indicators; 7. The relationships between the factors tested. / Tyrimų tikslas – įvertinti daugiakomponentės agrocenozės – kukurūzų, tarpinių augalų, piktžolių – konkurencinius ypatumus ir jos poveikį dirvos savybėms tvaraus ūkininkavimo sąlygomis. Tyrimų uždaviniai. Tyrimų tikslui pasiekti numatyta ištirti: 1. Įsėlinių tarpinių augalų, augusių kukurūzų monopasėlyje, poveikį dirvos fizikinėms (dirvos drėgnio dinamikai, šlyties pasipriešinimui, kietumui, dirvos struktūrai ir jos patvarumui), cheminėms (suminio azoto, judriojo fosforo ir kalio kiekiui, pH), biologinėms (ureazės ir sacharazės aktyvumui) savybėms; 2. Įsėlinių tarpinių augalų ir piktžolių biomasės kaupimosi dinamiką; 3. Įsėlinių tarpinių augalų poveikį kukurūzų pasėlio piktžolėtumui bei armens užterštumui piktžolių sėklomis; 4. Kukurūzų pasėlio apšvitos sąlygas ir jų poveikį skirtingiems agrofitocenozės komponentams; 5. Kukurūzų tarpueilių projekcinį padengimą; 6. Kukurūzų produktyvumo ir biometrinius rodiklius; 7. Tiriamųjų veiksnių sąsajas ir poveikio priežastingumą.

Biocontrol has been critized because the target effects of biocontrol introductions have not been studied rigorously. The objectives of this thesis were 1)to assess quantitatively the efficacy of a classical biocontrol agent after its release and 2)to suggest factors that affect the density and distribution of the biocontrol agent. In 1997, Aphthona lacertosa, a root-feeding flea beetle that is native to Europe, was released for the biological control of leafy spurge in Alberta. The beetles had established at more than 75% of the release sites that were monitored in 1999. In 2000, the peak abundance of A.lacertosa across release sites ranged from low (<10 beetles m-2) to high (>70 beetles m-2). Sites with high beetle densities had a significantly greater local (ie. within 5m of release point) reduction of leafy spurge than sites with low beetle densities. The density and distribution of A. lacertosa are affected by cumulative degree-days (CDD) at the release site and plant lacertosa are affected by cumulative degree-days (CDD) at the release site and plant morphology, respectively. Beetle population growth may be enhanced by releasing A. lacertosa at sites where there are more CDD. It is expected that high densities of A. lacertosa will effectively control leafy spurge populations. / 93 leaves : ill. (some col.) ; 29 cm.

No description available.

This study examined the effect of density on rhizome bud production in quackgrass (Elytrigia repens (L.) Nevski). The treatments consisted of two biotypes (L8 and L9), and nine density levels ranging from 1 to 22 plants m$ sp{-2}$. The results showed that bud production per plant diminished with increasing density in both biotypes. However, biotype L8 was less productive at low densities, but almost equal to L9 at higher densities. A second experiment was undertaken to measure the expansion of clonal colonies and the distribution of shoots within these colonies. For both biotypes the growth rate was highest in late summer and early fall, but colonies of L9 grew more rapidly. Biotype L9 had 59% of its total biomass located within 40 cm of the centre as compared with 81% in L8. Overall, Biotype L9 produced more rhizome buds, responded more strongly to intraspecific interference, and grew more rapidly as a colony.

Field trials were conducted to evaluate the effect of quizalofop-ethyl on quackgrass plants in a potato cropping sequence. Fall and summer applications were compared for their quackgrass control potential. Season-long quackgrass control was obtained with quizalofop-ethyl at 96 g/ha following summer application. An increase in the rate of quizalofop-ethyl did not further improve control. Yields with quizalofop-ethyl at 96 g/ha were similar to standard treatments sethoxydim and fluazifop-butyl at recommended rates. Quackgrass control following a summer application was not maintained through to the following season. Fall applications did not result in adequate control of quackgrass the following season at any of the quizalofop-ethyl rates tested.

Reducing tillage in Canadian organic cropping systems is a priority to preserve soil quality and increase long term sustainability. Novel methods for management of cover crops offer farmers the opportunity to reduce both tillage and herbicide use during this phase of the crop rotation but require further investigation across a range of cropping systems. The objective of this study was to compare the blade roller, flail mower and wide blade cultivator (noble blade) with standard tillage for management of an annual pea-barley (Pisum sativum L. – Hordeum vulgare L.) green manure in the Canadian prairies. The experiment was conducted twice at Carman, Manitoba (long-term organic management) and Lethbridge, Alberta (previous herbicide and fertilizer use) from 2010-2012. The green manure was planted in spring of year 1 and grown until pea full bloom when five management treatments were applied; 1) standard tillage with a field disc 2) blade roller, 3) blade rolled once plus tillage in late fall and spring, 4) wide blade cultivator and 5) flail mower. Spring wheat (Triticum aestivum L.) was planted in spring of year 2. The effect of management treatment on surface residue, soil nitrogen, soil microclimate, weed population dynamics and subsequent spring wheat yield was evaluated. At Carman, managing green manure without tillage (blade roller or flail mower) significantly increased winter annual and perennial weed pressure and reduced soil nitrate availability; these factors contributed to wheat yield reductions in both years compared to standard tillage. Wide blade cultivation and blade rolling plus tillage maintained crop yield at one and both years, respectively, compared to tillage. Without sufficient mulch for weed suppression, soil disturbance was required to control weeds and ensure adequate nitrogen uptake in the crop. Replacing one tillage operation with blade rolling reduces energy costs and erosion risk without sacrificing yield. At Lethbridge, previous herbicide and fertilizer use masked the effect of green manure management. Markedly different results from Carman and Lethbridge emphasize that the adaptability of reduced tillage green manure management is site-specific due to differences in climate and cropping history. This research highlights important differences in the efficacy, erosion risk, weed control, nitrogen availability, main crop yield and energy savings associated with each management method.