Thesis--Auburn University, 2009. / Abstract. Includes bibliographic references (p.139-160).

The thesis is focused on the evaluation of the behavior of herbicides in the growth of kohlrabi. The theoretical and general information on pesticides and herbicides on their behavior in the soil, phytotoxicity (plant injury) and vegetables, are presented in the beginning of the thesis. A central part deals with the differences in behavior of herbicides in soil with active ingredients metazachlor and pendimethalin, their interaction when applied in a combination and how they behave in the soil when applied separately. It also deals with the results of half-life of applied herbicides. Whether among them was a significant difference in the use of adjuvants, and what kind of effect have the irrigation influenced the experiment. It also evaluates the effect of active substances on the expression of phytotoxicity kohlrabi. The closing part is focused on the statistical evaluation of the particular options of the applied herbicides. Based on the results the hypothesis has been confirmed. The behavior of the active substances in the soil, which have been applied in the form of mixtures, was differed from the applied herbicides separately. It was found that the applied substance in the mixture have a greater effect on weed control in the crop kohlrabi , longer half-life and their effect on the crop plants is manifested phytotoxic. The significant impact on the overall evaluation has have the irrigation, which should be an integral part of the application process herbicidal compositions and a follow-up care of a vegetation.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη της τύχης της ζιζανιοκτόνου ουσίας Πεντιμεθαλίνης σε εδαφικούς και υδάτινους αποδέκτες. Η τύχη των φυτοφαρμάκων στο φυσικό περιβάλλον αποτελεί μια άκρως ενδιαφέρουσα μελέτη. Η έρευνα της προσρόφησης των οργανικών ουσιών στο έδαφος αποσκοπεί στον υπολογισμό των συγκεντρώσεων που βρίσκονται στο χώμα μετά την αποκατάσταση της ισορροπίας, αλλά και πως αυτές διαφοροποιούνται αλλάζοντας σε συνάρτηση με το pH και την ιοντική ισχύ. Καθοριστικό ρόλο στην μελέτη της τύχης των φυτοφαρμάκων στους εδαφικούς αποδέκτες, παίζουν οι μηχανισμοί ρόφησης, η σύσταση του εδάφους καθώς και οι φυσικοχημικές ιδιότητες του εδάφους και των φυτοφαρμάκων. Από την άλλη πλευρά, οι ποσότητες που καταλήγουν στο νερό, λαμβάνοντας υπόψη τη δοσολογία χρήσης των φυτοφαρμάκων, φανερώνουν πόσο σημαντικοί είναι οι παράγοντες που επηρεάζουν τη μεταφορά μέρους των φυτοφαρμάκων στα επιφανειακά νερά, για την εκτίμηση της τύχης τους στους υδάτινους αποδέκτες. Η προσροφητική ικανότητα της Πεντιμεθαλίνης στους τέσσερις τύπους εδαφών που μελετήθηκαν με διαφορετικά φυσικοχημικά χαρακτηριστικά μειώνεται καθώς μειώνεται και η περιεκτικότητα τους σε οργανική ύλη. Τα πειραματικά δεδομένα, που προέκυψαν από τη μελέτη της προσρόφησης του ζιζανιοκτόνου στους τέσσερις τύπους εδαφών, προσαρμόζονται σε κάθε περίπτωση πολύ καλά στην λογαριθμική εξίσωση Freundlich, όπως φαίνεται από τον υψηλό συντελεστή συσχετίσεως. Η αλλαγή του pH του συστήματος εδάφους-νερού δεν έχει πολύ σημαντική επίπτωση στην προσρόφηση της Πεντιμεθαλίνης από τη στιγμή που το τελευταίο δεν είναι ιονιζόμενη ένωση. Αύξηση της ιοντικής ισχύος είχε ως αποτέλεσμα την αύξηση της προσρόφησης της Πεντιμεθαλίνης. Η Πεντιμεθαλίνη ανιχνεύτηκε σε υδατικά δείγματα ποταμού, ο οποίος διέρχεται μέσα από καλλιεργήσιμες εκτάσεις σε μέγιστη συγκέντρωση 40 ng/l σε σύντομο χρονικό διάστημα μετά την εφαρμογή του στο έδαφος. / -

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 119-127).

Small plot field experiment carried out in 2015 on Demonstration and experimental field of Czech University of Life Science in Prague. Objective of the experiment was get new knowledge of efficiency and selectivity of selected herbicides in kohlrabi. Main objective of the experiment was described of influence of irrigation and use of adjuvant on efficiency and selectivity of herbicides. The kohlrabi was growed from transplant. Herbicides were applicated five days after transplanting. Herbicides were applicated in few variant: separately, with adjuvant, two level of irrigation (basic irrigation 15 mm / intensive irrigation 65 mm). During growing season rained 70 mm. Efficiency and selectivity of herbicides was assessed by estimation method using a percentage scale from 0 to 100 %. Efficiency of herbicides was assessed on weeds: Thlaspi arvense, Chenopodium album and Solanum nigrum. Next objectives were: yield of above ground biomass and market tubers, weight of roots, contain of vitamin C, glucosinolates and herbicide residues in tuber. Efficiency of herbicide Stomp 400 SC was significantly higher than efficacy of Butisan 400 SC on Thlaspi arvense and Chenopodium album. Intensive irrigation caused higher efficiency. On the other side tank mix of herbicides and combination herbicides with adjuvant caused insignificantly higher efficiency. Butisan 400 SC had the highest effectivity on Solanum nigrum compared to efficacy of herbicide, Stomp 400, but efficiency efficacy of herbicide Stomp 400 SC was sufficient. Stomp 400 SC demaged kohlrabi more than Butisan 400 SC, especially on plots with intensive irrigation. Herbicide Stomp 400 SC had negative influence on roots. On plots treated by herbicide Stomp 400 SC was showed lower weight of roots about 56 % compared to hand-weeding plots. Kohlrabi on plots treated Stomp 400 SC with intensive irrigation produced not market weight of tuber (less than 200 g/plant) in harvest time. From these reason, the harvest time must have been put off one week. Residues of metazachlor (Butisan 400 SC) were not detected in tuber. Residue of pendimethalin (Stomp 400 SC) was found on every plots treated by herbicide Stomp 400 SC. Found concentration of pendimethalin was not higher than maximal residue limit (0,05 mg/kg). The highest concentration of vitamin C and glucosinolates was found in tuber damaged by tank mix combination of Butisan 400 SC + Stomp 400 SC. On the other side the lowest concentration of vitamin C and glucosinolates was found in tuber from hand weeding plots, but differences among treatments were not significantly.

Physical and chemical properties of pesticides may vary significantly. Pesticides can be acidic, neutral or alkaline. Some compounds containing phosphorus, other sulfur, nitrogen or halogens. These atoms can be important for the detection of pesticides. Some of the compounds are volatile, others on the contrary not evaporate, which is also one of the important properties for chromatography. The diversity of pesticides actually makes it impossible to create a universal method, which is very impractical in terms of quality and time determination. Because that pesticides are one of the most chemicals in most countries. In the food and drinking water are limits on pesticides in order to avoid negative impact on public health. For residues in soil or surface water limits are set. (Lutz et al., 2006) The objective of this thesis is to evaluate the possibility of using two types of chromatographs with different detectors for the analysis of pesticide. Pendimethalin which was chosen for this work, will be analyzed usinga liquid chromatograph with UV detektor and gas chromatography with mass detector. Both this method will be compared as well two extraction methods (Soxhlet extraction and shaking), and two extraction agents (methanol and acetonitrile). Another point of the work is to provethe hypothesis that, for the determination of pendimethalin in soil is by gas chromatography using a mass spectrometer in comparison with the high performance liquid chromatography time and more expensive, but will achieve a higher yield and a lower detection limit of the pesticide.

No description available.

No description available.

An abundance of waste products from the forestry industry (sawdust and paper pulp) lead to the concept of using them as growing media for high value crops on a field scale. However, management of subsequent weed growth posed a problem as the impact of these novel media on the performance and fate of herbicides was unknown. Three aspects of sawdust and paper pulp waste were examined and compared to two cropping soils, viz. their effect on herbicide behaviour with regard to crop selectivity, weed control efficacy and the environmental fate of selected chemicals. Cropping species such as lettuce and onions were more susceptible to alachlor and chlorpropham in sawdust than in paper pulp. The two cropping soils evaluated (Horotiu sandy loam and Mangateretere silt loam) tended to be intermediate although the former was often close to the sawdust and the latter to the paper pulp in terms of herbicide phytotoxicity to the crop plants. For the less water soluble herbicide pendimethalin, the differences in crop selectivity in the different media were not significant. The effect of the media on the efficacy of weed control was evaluated through plant species with a much lower tolerance to the herbicides evaluated in contrast to the above species. For these plants the efficacy of the herbicides was generally lower in both the sawdust and paper pulp than in the two soils. The effect was more pronounced with the more soluble alachlor, where efficacy was reduced by factors of 5 – 10, compared to pendimethalin where efficacy reduction was by factors of 0 – 3. The two high organic media had contrasting effects on the various environmental behaviour indices evaluated. Herbicide adsorption as quantified by distribution coefficient (Kd) was higher in the two novel media compared to both the Horotiu and Mangateretere soils. However, when the Kd was normalised to organic carbon (Koc), there was less variation amongst the media indicating that organic matter is an important factor in controlling sorption in these media. However, despite the high level of adsorption in the sawdust, herbicides were most prone to leaching in this medium. Conversely the paper pulp tended to be more retentive while the two soils were intermediate. The degradation as quantified by half-lives (t½) of the herbicides was generally slower in the two novel media, probably reflecting the higher sorption in these two media but also due to the lower level of microbial activity in the sawdust and paper pulp. The study shows that herbicide behaviour in these carbon based media differs significantly from that expected from soil organic matter, mainly due to the non-humified nature of the organic matter in the media and its poor biological activity.