Distribution, significance and control of foxtail, Setaria spp. and crabgrass, Digitaria spp. in the Netherlands, and the situation within Europe

After its introduction in the early 1960s, maize (silage) became the largest arable crop in the Netherlands. It is often grown in monoculture or in rotation with grass leys as in a large part of Europe too. Its introduction and monoculture induced weed shifts. Although initially not considered problematic, the C4 species Setaria viridis and Digitaria ischaemum became more prominent due to changing crop husbandry systems since the mid 1990s. Tolerance of these weeds to triazines and metolachlor forced farmers to adapt weed control strategies, i.e. use of herbicides with other modes of action. Also, reduced nutrient input, earlier sowing dates, and low tillage caused a slower early crop development and increased the need for adequate weed control in general.In today's herbicide portfolio in the Netherlands, control of S. viridis and D. ischaemum is marked as being most efficient with dimethenamide-P, isoxaflutole, S-metolachlor, and topramezone. The last one compound has a much higher degree of contact action than the predominant soil acting former three. This gives topramezone a rather unique position and, thus, Dutch crop advisors claim topramezone to be indispensable. In neighbouring countries the situation is comparable to the Dutch situation. In more Southern European countries (France, Spain) topramezone is not available, leading to a higher use of pre-emergence herbicide applications.The different weed control strategies for S. viridis and D. ischaemum, including non-chemical alternatives, are discussed together with economic aspects.Keywords: Control, Digitaria, distribution, Europe, Setaria, topramezoneVerbreitung, Bedeutung und Bekämpfung von Unkrauthirsen der Gattungen Setaria und Digitaria in den Niederlanden und die Situation in EuropaZusammenfassungNach seiner Einführung in den frühen 1960er Jahren wurde (Silo)Mais die bedeutendste landwirtschaftliche Kulturpflanze in den Niederlanden. Mais wird meist in Monokultur oder in Rotation mit Grünland angebaut, wie in großen Teilen Europas auch. Seine Einführung und die Monokultur induzierten Verschiebungen im Unkrautartenspektrum. Obwohl anfangs nicht als problematisch betrachtet, wurden die C4-Arten Setaria viridis und Digitaria ischaemum ab Mitte der 1990er Jahren aufgrund geänderter Ackerbausysteme bedeutender. Toleranz dieser Unkräuter gegen Triazine und Metolachlor nötigten Landwirte ihre Unkrautbekämpfungsstrategien anzupassen, d.h. Einsatz von Herbiziden mit anderen Wirkungsmechanismen. Darüber hinaus bedingte eine reduzierte Düngung, eine frühere Aussaat und reduzierte Bodenbearbeitung eine langsamere Jugendentwicklung der Kultur und erhöhte die Notwendigkeit einer angemessenen UnkrautbekämpfungIm heutigen Herbizidportfolio der Niederlanden sind Dimethenamid-P, Isoxaflutole, S-Metolachlor und Topramezone am besten bewertet für die Kontrolle von S. viridis und D. ischaemum. Topramezone hat dabei eine vergleichsweise stärkere Kontaktwirkung als die vorherrschend über den Boden wirksamen anderen Wirkstoffe. Dies verleiht Topramezone eine verhältnismäßig einzigartige Position und Niederländische Berater bezeichnen Topramezone deshalb als unverzichtbar. In den Nachbarländern ist die Situation vergleichbar wie in den Niederlanden. In mehr südeuropäischen Ländern (Frankreich, Spanien) ist Topramezone allerdings nicht verfügbar, was die Nutzung von Vorauflaufherbiziden bedingt.Die verschiedenen Unkrautbekämpfungsstrategien für S. viridis und D. ischaemum werden diskutiert, einschließlich nicht-chemischer Alternativen und wirtschaftlichen Aspekte.Stichwörter: Bekämpfung, Digitaria, Europa, Setaria, Topramezone, Verbreitun

Essential features of Chiari II malformation in MR imaging: an interobserver reliability study—part 1

Item does not contain fulltextPURPOSE: Brain MR imaging is essential in the assessment of Chiari II malformation in clinical and research settings concerning spina bifida. However, the interpretation of morphological features of the malformation on MR images may not always be straightforward. In an attempt to select those features that unambiguously characterize the Chiari II malformation, we investigated the interobserver reliability of all its well-known MR features. METHODS: Brain MR images of 79 children [26 presumed to have Chiari II malformation, 36 presumed to have no cerebral abnormalities, and 17 children in whom some Chiari II malformation features might be present; mean age 10.6 (SD 3.2; range, 6-16) years] were blindly and independently reviewed by three observers. They rated 33 morphological features of the Chiari II malformation as present, absent, or indefinable in three planes (sagittal, axial, and coronal). The interobserver reliability was assessed using kappa statistics. RESULTS: Twenty-three of the features studied turned out to be unreliable, whereas the interobserver agreement was almost perfect (kappa value > 0.8) for nine features (eight in the sagittal plane and one in the axial plane, but none in the coronal plane). CONCLUSIONS: This study presents essential features of the Chiari II malformation on MR images by ruling out the unreliable features. Using these features may improve the assessment of Chiari II malformation in clinical and research settings.1 juli 201

Systems approaches to innovation in pest management: reflections and lessons learned from an integrated research program on parasitic weeds in rice

This paper provides a retrospective look at a systems-oriented research program, on the increasing occurrence of parasitic weeds in rainfed rice in sub-Saharan Africa, to qualitatively assess merits and identify challenges of such approach. We gained a broad contextual overview of the problem and different stakeholders' roles, which enabled identification of entry points for innovations in parasitic weed management. At the crop level parasitic weed infestation is associated with poor soil fertility and water management. Farmers' infrequent use of inputs to control them was caused by various factors, ranging from fears of undesired side effects (agronomic) to a lack of quality control of products (institutional). Furthermore, there may be enough extension agents, but they lack the required training on (parasitic) weed management to provide farmers with advice, while their organizations do not provide them with the necessary means for farm visits. At even higher organizational levels we observed a lack of coherent policies on parasitic weed control and implementation of them. Merits and challenges of an integrated multi-stakeholder and multi-level research project are discussed

Interobserver reliability and diagnostic performance of Chiari II malformation measures in MR imaging—part 2

PURPOSE: Brain MR imaging is essential in the assessment of Chiari II malformation in clinical and research settings concerning spina bifida. However, the interpretation of MR images of the malformation is not always straightforward. Morphometric analyses of the extent of Chiari II malformation may improve the assessment. In an attempt to select appropriate morphometric measures for this purpose, we investigated the interobserver reliability and diagnostic performance of several morphometric measures of Chiari II malformation on MR images. METHODS: Brain MR images of 79 children [26 with open spinal dysraphism, 17 with closed spinal dysraphism, and 36 without spinal dysraphism; mean age 10.6 (SD 3.2; range, 6-16) years] were evaluated. All children had been assessed for Chiari II malformation (defined as cerebellar herniation in combination with open spinal dysraphism; n = 23). Three observers blindly and independently reviewed the MR images for 21 measures of the cerebellum, brainstem, and posterior fossa in three planes. The interobserver reliability was assessed by an agreement index (AI = 1 - RRE) and the diagnostic performance by receiver operating characteristic analyses. RESULTS: Reliability was good for most measures, except for the degree of herniation of the vermis and tonsil. Most values differed statistically significantly between children with and without Chiari II malformation. The measures mamillopontine distance and cerebellar width showed excellent diagnostic performance. CONCLUSIONS: Morphometric measures may reliably quantify the morphological distortions of Chiari II malformation on MR images and provide additional tools to assess the severity of Chiari II malformation in clinical and research settings

Efficacy of cultural control methods for combating herbicide resistant Lolium rigidum

Herbicide-resistant populations of annual ryegrass (Lolium rigidum) are estimated to affect crop production on about 5000 farms in southern Australia. In order to manage resistant populations, some farmers have adopted a two-to-three-year pasture phase which allows use of grazing by sheep, and non-selective herbicides to deplete the weed seed-bank. However, in low-to-medium rainfall zones, where financial returns from pastures are relatively low, farmers have generally combined cultural practices for weed management with the use of alternative herbicides, mainly trifluralin. Used singly, none of the currently available cultural techniques provides an adequate level of weed control. However, when used in carefully planned combinations, extremely effective ryegrass control can be achieved. Some of the important cultural practices for ryegrass control include delayed sowing (sometimes in conjunction with a shallow autumn cultivation); stubble burning; cutting the crop for hay or green manure, increased crop density and capture of weed seeds at harvest. Selection of crop species and cultivars with superior weed suppression potential is also receiving considerable attention.Gurjeet S. Gill & John E. Holme