Camera steered mechanical weed control in sugar beet,maize and soybean

In sugar beet, maize and soybean, weeds are usually controlled by herbicides uniformly applied across the whole field. Due to restrictions in herbicide use and negative side effects, mechanical weeding plays a major role in integrated weed management (IWM). In 2015 and 2016, eight field experiments were conducted to test the efficacy of an OEM Claas 3-D stereo camera^® in combination with an Einböck Row-Guard^® hoe for controlling weeds. Ducks-foot blades in the inter-row were combined with four different mechanical intra-row weeding elements in sugar beet, maize and soybean and a band sprayer in sugar beet. Average weed densities in the untreated control plots were from 12 to 153 plants m^?2 with Chenopodium album, Polygonum convolvulus, Thlapsi arvense being the most abundant weed species. Camera steered hoeing resulted in 78% weed control efficacy compared to 65% using machine hoeing with manual guidance. Mechanical intra-row elements controlled up to 79% of the weeds in the crop rows. Those elements did not cause significant crop damage except for the treatment with a rotary harrow in maize in 2016. Weed control efficacy was highest in the herbicide treatments with almost 100% followed by herbicide band-applications combined with inter-row hoeing. Mechanical weed control treatments increased white sugar yield by 39%, maize biomass yield by 43% and soybean grain yield by 58% compared to the untreated control in both years. However, yield increase was again higher with chemical weed control. In conclusion, camera guided weed hoeing has improved efficacy and selectivity of mechanical weed control in sugar beet, maize and soybean.     

Sprouting Ability and Seasonal Changes of Sugar Concentrations in Rhizomes of Calystegia sepium and Roots of Convolvulus arvensis

Journal of Plant Diseases and Protection - Factors influencing the sprouting ability of rhizome pieces of Calystegia sepium and root pieces of Convolvulus arvensis were analyzed in four...     

Winter wheat yield loss in response to Avena fatua competition and effect of reduced herbicide dose rates on seed production of this species

Journal of Plant Diseases and Protection - Avena fatua is one of the most abundant and competitive grass weed species in cereal cropping systems worldwide. Despite its main occurrence in summer...     

Kartierung und geostatistische Analyse der Unkrautverteilung in Zuckerrübenschlägen als Grundlage für eine teilschlagspezifische Bekämpfung

Mapping and geostatistical analysis of weed distribution in sugarbeet fields for site-specific weed management
Field experiments were conducted to study the distribution of weeds in 18 sugarbeet fields of 3 ha each. The distance between each sampling point was 7.5–20 m. Weed density was counted and maps were plotted for the distribution of Chenopodium album and Solanum nigrum using linear interpolation. Geostatistical methods were applied to analyse the variance of weed density between the sampling points. A clear detection of weed patches was possible when the variance of weed density at a single sampling point 'nugget effect' was low and a high continuity between neighbouring grid points existed. If soil conditions or cultivation methods are not homogeneous in the field (drift), no continuity between the sampling points was found. Geostatistical analysis of the weed distribution in agricultural fields provide helpful information for a site-specific weed management.     

Plasma heparin values and hemostasis in equids after subcutaneous administration of low-dose calcium heparin

Different doses of heparin were given to equids SC to establish 0.05 to 0.20 U of heparin/ml of plasma. Plasma heparin values and antithrombin III activities were assayed, using chromogenic substrate methods. Activated partial thromboplastin and thrombin times were determined, using conventional coagulation assays. Tests were run every hour (or every 2 hours for antithrombin III) for 12 hours from 5 groups of 5 equids each after single injection of 40, 60, 80, 100, or 125 U of calcium heparin/kg of body weight and from 11 equids after injection of 150 U of calcium heparin/kg. The smaller dose (40 U/kg) did not or only insufficiently increase plasma heparin values. After 150 U of heparin/kg, plasma heparin concentrations were increased for 11 hours and were significantly (P = 0.05) increased between postadministration hours 2 and 7. The desired range beyond 0.05 U of heparin/ml was achieved between postadministration hours 2 and 6. Antithrombin III, activated partial thromboplastin time, and thrombin time were not significantly affected by any heparin dose. In cumulative studies, 2 equids were given 150 U of heparin/kg 7 times at 12-hour intervals. After the 3rd injection, a mean plasma concentration of 0.20 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.22 U of heparin/ml. Four equids were given 150 U of heparin/kg initially, followed by 125 U of heparin/kg 6 times at 12-hour intervals. After the 3rd injection, a maximal plasma heparin concentration of 0.12 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.18 U of heparin/ml. Repeated SC heparin injections caused moderate swelling at the injection sites.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two-Year Weed Seedling Population Responses to a Post-Emergent Method of Site-Specific Weed Management

Field experiments were conducted to determine how a site-specific weed management practice in Zea mays L. influenced the numerical and spatial distribution of a naturally occurring weed infestation in Z. mays and the succeeding Beta vulgaris L. crop. Compared to conventional broadcast herbicide applications, site-specific herbicide applications reduced herbicide load by 11.5 and 98.0% in two separate Z. mays fields. The broad range in outcomes was attributed to the spatial aggregation and density of target weed populations. While herbicide use was successfully reduced at field locations with low weed density, most survivors of multiple control tactics were in locations with the highest initial density. A greater understanding of interactions between weed management and weed density would increase the likelihood that site-specific weed management offers long-term improvements over conventional approaches.     

Phylogeny,form and function of canine teeth in the horse

The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the Pliocene, it contributed to the fights between stallions, to ensure that the offspring only came from the strongest animals (preservation of the species). Form and construction of the canine tooth are described and discussed in detail under the above mentioned phylogenic and ethologic aspects.     

Serum and vitreous humor antibody titers in and isolation of Leptospira interrogans from horses with recurrent uveitis

OBJECTIVE: To measure antibody titers against Leptospira interrogans in serum and vitreous humor and determine the prevalence of L interrogans in vitreous humor of horses with recurrent uveitis. DESIGN: Cross-sectional study. ANIMALS: 242 horses (270 eyes) with recurrent uveitis undergoing vitrectomy and 39 control horses (54 eyes) without any history or clinical signs of recurrent uveitis undergoing euthanasia or enucleation for unrelated reasons. PROCEDURE: Serum and vitreous humor were tested for antibodies against 13 serovars of L interrogans. Vitreous humor was submitted for leptospiral culture; isolates were typed to the serogroup level. RESULTS: Leptospira interrogans was isolated from vitreous humor from 120/229 (52%) horses (126/252 [50%] eyes) with recurrent uveitis but was not isolated from vitreous humor from 36 eyes of 21 control horses. Duration of recurrent uveitis was > or = 1 year for 45 of the 120 (38%) horses from which the organism was isolated. Geometric mean antibody titers against L interrogans in the vitreous humor and serum of horses with recurrent uveitis were 1:1,332 and 1:186, respectively. Only 91 of 120 (76%) horses from which the organism was isolated had a 4-fold or greater difference between serum and vitreous humor antibody titers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that persistent ocular infection with L interrogans is common in horses with recurrent uveitis. A 4-fold increase in vitreous humor versus serum antibody titers may not be a sensitive test for the diagnosis of L interrogans-induced recurrent uveitis. We hypothesize that the immune component of recurrent uveitis can be directly induced and maintained by persistent infection of the eye with L interrogans.     

Features and applications of a field imaging chlorophyll fluorometer to measure stress in agricultural plants

Most non-destructive methods for plant stress detection do not measure the primary stress response but reactions of processes downstream of primary events. For instance, the chlorophyll fluorescence ratio F_v/F_m, which indicates the maximum quantum yield of photosystem II, can be employed to monitor stress originating elsewhere in the plant cell. This article describes the properties of a sensor to quantify herbicide and pathogen stress in agricultural plants for field applications by the F_v/F_m parameter. This dedicated sensor is highly mobile and measures images of pulse amplitude modulated (PAM) chlorophyll fluorescence. Special physical properties of the sensor are reported, and the range of its field applications is defined. In addition, detection of herbicide resistant weeds by employing an F_v/F_m-based classifier is described. The PAM-imaging sensor introduced here can provide in-field estimation of herbicide sensitivity in crops and weeds after herbicide treatment before any damage becomes visible. Limitations of the system and the use of a classifier to differentiate between stressed and non-stressed plants based on sensor data are presented. It is concluded that stress detection by the F_v/F_m parameter is suitable as an expert tool for decision making in crop management.