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Tembotrione is a novel HPPD maize herbicide effective against a wide range of broadleaf and grass weeds. Some characteristics of this compound are described in this paper linking weed and crop responses following tembotrione applications to environmental parameters or use conditions. The activity of HPPD herbicides is very much dependant on the availability of light. Increasing illumination intensities following application augmented the activity levels of several comparable HPPD compounds in a growth chamber experiment. Tembotrione was shown to be more efficacious at low and high illumination intensities compared to standard herbicides applied at the same rate. At the high intensity, tembotrione retained its high efficacy from two up to four weeks after application showing a rapid and strong herbicidal activity. The activity following post-emergent treatments of tembotrione against broadleaf weeds was influenced by soil characteristics such as soil texture and organic matter content in a glasshouse test. The level of weed suppression clearly declined stronger on heavier soils than on lighter soils at a rather low application rate of 12.5 g a.i./ha and lower. This is a clear indication of residual efficacy of tembotrione. The selectivity of tembotrione was tested on numerous maize varieties following post-emergent treatment with tembotrione alone or in mixture with the safener isoxadifen-ethyl under field conditions in Germany in comparison to a standard herbicide. The level of crop phytotoxicity tended to increase in the following order: Tembotrione plus safener, standard herbicide to tembotrione alone. Only the mixture of tembotrione with safener did not cause significant adverse effects on maize. Another field experiment in the USA examined crop phytotoxicity using one maize variety in a situation of infurrow soil insecticide treatment followed by a post-emergent application of tembotrione (plus/minus isoxadifen-ethyl) and standard herbicides. The maximum observed crop response for tembotrione plus isoxadifen-ethyl was again negligibly low, while applications of tembotrione alone or standard herbicides caused instances of unacceptable maize phytotoxicity.

The natural emergence of black-grass (Alopecurus myosuroides) was observed on a wheat field over two growing seasons in 2009 and 2010. Under shallow tillage conditions, A. myosuroides emerged steadily between the months September and May. Peak emergence occurred after sowing until the middle of October followed by continuous emergence until winter. Another peak of emergence took place in spring through the beginning of May. Under conventional tillage conditions (ploughing) in 2010, almost no germination of A. myosuroides could be observed after the first herbicide treatment in autumn. In order to evaluate the soil activity of recommended post-emergence herbicides, two pot experiments with sterilized soil were carried out outdoors and under greenhouse conditions. The results show that all tested grass herbicides, ACCase-inhibitors and ALSinhibitors, demonstrated strong soil efficacy against A. myosuroides and Apera spica-venti in most cases. Especially the herbicides propoxycarbazone, pyroxsulam and mesosulfuron-methyl showed a high soil activity even at low doses. While the soil activity was consistent for clodinafop-progagyl, variable results were observed for fenoxaprop-P-ethyl and pinoxaden in the two experiments. We conclude that the soil activity of the tested herbicides is very variable and dependent on many factors which make it difficult to predict their activity especially under field conditions.

Nodes are interfaces between stems and leaves. Vascular bundles originate here and elongate into leaves and internodes. In Marantaceae, internodal bundles are highly diverse, including inverted bundles in the climbing genus Haumania. The objective of this paper is to characterize bundle forms, their position across the stem and their connection to leaves and short shoots in Haumania spp. and other unrelated African branch-angle climbers in the family (Hypselodelphys , Trachyphrynium). We question whether bundle inversion is a genus-specific trait in Haumania or related to the climbing growth form. Vascular bundles in internodes are scattered across the stem diameter in a characteristic pattern. Four (to five) bundle types follow each other in a centripetal order from highly sclerenchymatic 'a'-bundles close to the epidermis to 'd'-bundles in the centre with a low sclerenchyma proportion. Inverted bundles only appear in internodes of Haumania , making this trait a synapomorphy for the genus. The nodes show stem, leaf and short shoot bundles in a remarkably diverse pattern with partitioned phloem clusters and apparently augmented xylem elements. Our preliminary conclusion is that the inversion of bundles happens when leaf and short shoot traces join the main axis bundle layers. [ABSTRACT FROM AUTHOR]

Understanding vascular bundle systems in angiosperms is a challenge. On the one hand, the vascular tissue is extremely important in reconstructing the evolution and survivability of plants, but on the other hand, it forms a complicated three-dimensional system of controversially discussed phylogenetic and ontogenetic origin. To increase clarity, in this paper we briefly summarize histological, phylogenetic and molecular aspects of primary vascular bundle formation in angiosperms, adding histological data on early stages of vascular bundle formation, proposing a concept combining the different views and providing simplified illustrations to improve the understanding of primary vascular systems in angiosperms. Based on the auxin hypothesis, vascular bundle formation is stimulated by the development of leaf primordia. Provascular domains appear at the base of the leaf primordia and develop into two directions (leaf, internode). The low vs. high number of internodal bundles, their circular vs. scattered arrangement and the open vs. closed bundle construction in eudicots vs. monocots can be deduced to be due to processes below the shoot apical meristem. The most important processes distinguishing monocots from eudicots are the isolated bundle initiation outside the primary meristem, the enormous expansion of the leaf bases associated with a high number of vascular bundles and the early onset of primary thickening passively dislocating vascular bundles. [ABSTRACT FROM AUTHOR]