J. Holec

Efficacy and Selectivity of Pre-emergent Sunflower Herbicides under Different Soil Moisture Conditions

Chenopodium album, Echinochloa crus-galli, Amaranthus retroflexus, Mercurialis annua, and Solanum physalifolium ) was only slightly affected by the soil moisture and these herbicides can be used in arid and semiarid regions. The efficacy of linuron, prosulfocarb, and pethoxamid was strongly affected by soil moisture and was insufficient under dry conditions. The majority of herbicides showed good selectivity for sunflower. Crop injury rate of 5–15% was recorded after application of flurochloridone and ace tochlor. For flurochloridone, the phytotoxicity increased due to irrigation after herbicide application. The highest sunflower injury rate (27–35%) was recorded after application of oxyfluorfen.

POST Herbicide Combinations for Velvetleaf (Abutilon theophrasti ) Control in Sugarbeet

Abstract Velvetleaf is one of the most significant and fastest spreading alien weeds in Europe, and it is a difficult weed to control in conventional sugarbeet. Laboratory experiments were carried out in 2007 and 2008 and field experiments were carried out in 2006, 2007, and 2008 with the aim of finding effective herbicide combinations and optimum timing of control. Herbicides containing the active ingredients phenmedipham, desmedipham, ethofumesate, clopyralid, and triflusulfuron were all tested at different timings. Phenmedipham + desmedipham + ethofumesate gave 87% velvetleaf control in pot experiments when applied at the growth stages of velvetleaf cotyledons and one true leaf, but only 27 to 42% control in field trials. Triflusulfuron gave 76% control in pot experiments and 83 to 88% control in field experiments. The timing of the first and second herbicide applications was very important: the first application of herbicides must be at the cotyledon stage of velvetleaf. A 1-wk delay in first application reduced herbicide efficacy by 8%. A 5-d period between the first and second treatments gave 93% control, while a 10-d period between the first and second treatments gave only 77% control. Sugarbeet yield decreased by 60 to 86% due to competition with velvetleaf when a standard herbicide combination (phenmedipham + desmedipham + ethofumesate) was used, and the velvetleaf produced between 6,700 and 14,800 seeds m−2. Inclusion of triflusulfuron in the herbicide treatment significantly reduced velvetleaf seed production to between 200 and 4,700 seeds m−2. In most cases, inclusion of triflusulfuron increased sugarbeet yield. Better velvetleaf control occurred in years when the sugarbeet canopy developed early and the index of leaf area of sugarbeet was higher. Nomenclature: Clopyralid; desmedipham; ethofumesate; phenmedipham; triflusulfuron; velvetleaf, Abutilon theophrasti Medik.; sugarbeet, Beta vulgaris ssp. vulgaris var. altissima L

Environmental and agronomic monitoring of adverse effects due to cultivation of genetically modified herbicide tolerant crops

Herbicide tolerance allows a specific crop variety to survive a herbicide treatment without injury despite the fact that the herbicide cannot be used selectively in a common variety of the same crop. Widely adopted and used worldwide are genetically modified herbicide tolerant (GMHT) crops with tolerance to the non-selective herbicide active ingredients glyphosate and glufosinate. Development of GMHT crops has substantially changed weed control systems and sometimes crop rotations and soil tillage systems. Attention must be given to the environmental and agro-environmental aspects and sustainability of agro-ecosystems based on HT crops because some adverse effects with this technology can appear, especially if used without knowledge of the risks involved and their prevention. This paper identifies main areas that should be monitored and discusses such potential adverse effects as hybridization with related taxa, occurrence of feral crops, and evolved herbicide resistance within weed communities. If there is no principal difference between conventional and GM crop cultivation, we propose monitoring approaches shall be based mainly on existing methods and monitoring networks. Scientific approaches as basis, decentralization with site-specific focus, as well as reasonable extent of data collection and their effective utilization should be the main features of the monitoring.

Splash erosion in maize crops under conservation management in combination with shallow strip-tillage before sowing

Brant V., Kroulík M., Pivec J., Zábranský P., Hakl J., Holec J., Kvíz Z., Procházka L. (2017): Splash erosion in maize crops under conservation management in combination with shallow strip-tillage before sowing. Soil & Water Res., 12: 106−116. Soil under maize cropping is among the most endangered by erosion. The effect of conservation tillage management on values of splash erosion when using shallow strip tillage before sowing maize was evaluated in the Central Bohemian region (Czech Republic) during the period 2010–2012. The following types of tillage management using conventional technology and shallow tillage were evaluated: ploughed plots with mulch formed by weed biomass (PLW), ploughed plots with mulch from perennial ryegrass plants (PLPR), ploughed plots without mulch (PL) and shallow tillage (ST) where the mulch was formed by cereals straw. Furthermore, values of the splash erosion, plants and plant residues coverage ratio of soil by image analysis and the stability of soil aggregates were monitored during the whole experiment. The average value of splash erosion (MSR) was higher by 18.7% in the variant of PLW, lower by 35.9% in PLPR, and lower by 39.5% in ST, than in the control treatment PL (MSR value for PL = 100%) for the whole evaluated period (2010–2012). The average values of the soil surface plant coverage ratio in the plots with mulch ranged from 1.5 to 43.0% at the beginning of the vegetation period, and from 4.9 to 85.5% in the second half of the vegetation period. A positive correlation was observed between the average values of the stability of soil aggregates and the plant coverage ratio of the soil surface in 2010 and 2011.

Cytoplasmic male sterility as a biological confinement tool for maize coexistence: Optimization of pollinator spatial arrangement

Cytoplasmic male sterility (CMS) allows efficient biological confinement of transgenes if pollen-mediated gene flow has to be reduced or eliminated. For introduction of CMS maize in agricultural practice, sufficient yields comparable with conventional systems should be achieved. The plus-cultivar-system in maize offers a possibility for biological confinement together with high and stable yields whereas pollinator amount and distribution within the CMS crop is crucial. The aim of this EU-funded study was to identify the best proportion (10, 15, and 20%) and spatial arrangement (inserted rows, mixed seeds) of the pollinator within the CMS maize cultivar under field conditions in the Czech Republic, in Germany and in Spain. In Germany and in the Czech Republic, a pollinator proportion of 10% produced significantly lower yield than the treatments with a pollinator proportion of 15% and 20%. Differences in yield between row and mix arrangements were not detected. No differences between the tested arrangements occurred in Spain. With respect to practical conditions, a pollinator proportion of 15% can be recommended for achieving a satisfactory yield. CMS maize cultivar released no or merely a small amount of pollen and self-pollinated plants developed no or only a small number of kernels indicating that currently recommended isolation distances between genetically modified (GM) and non-GM fields can be substantially shortened if the CMS confinement tool is used