Cyperus rotundus L. CYPRO (purple nutsedge) and Cyperus esculentus L. CYPES (yellow nutsedge) are problematic weeds on every continent. At present there is no comprehensive means of controling these weeds.. The primary means of control is herbicides, although the weeds are becoming more resistant. Bioherbicide control of purple and yellow nutsedge is an important avenue of research, with much of the focus being to increase the virulence of current fungal pathogens of C. rotundus and C. esculentus. The primary aim of this study was to increase the virulence of a fungal pathogen of C. rotundus and C. esculentus, with the objective of creating a viable bioherbicide. A possible means of increasing the virulence of a pathogen would be to increase the amount of amino acid produced by the fungus. This was proposed as a means of increasing the virulence of Dactylaria higginsii (Luttrell) M. B. Ellis. Overproduction of amino acids such as valine and leucine result in the feedback-inhibition of acetolactate synthase (ALS), an enzyme which is a target for many herbicides currently on the market. By applying various amino acids to tubers of purple nutsedge and comparing the results with a reputable herbicide, glyphosate, it was possible to determine the success of the amino acid applications. Only glutamine treatment at 600 mg.r1 resulted in significantly less (P<O.OOI) germination compared with the water control, while the glyphosate application resulted in no germination. Four treatments were significantly different (P<O.OOI) from the water control in terms of shoot length, but no pattern or conclusion could be drawn from the results. Injecting amino acids and glyphosate into the leaves of the plants gave similar results to those obtained with the tubers, with no visible damage on those plants injected with the amino acids and complete plant death of those injected with glyphosate. Amino acids had little effect on the growth of the C. rotundus plant or tuber. It was later determined by a colleague (Mchunu1 , unpublished) working on the same project, that D. higginsii does not infect the local ecotypes of C. rotundus in Pietermaritzburg, South Africa. A second fungus, Cercospora caricis Oud., was isolated from C. rotundus growing in the region, and confirmed as a Cercospora species by conidial identification. Like many Cercospora species, C. caricis produces a phytotoxin, cercosporin. An increase in production of cercosporin would theoretically lead to an increase in virulence of C. caricis. Mutation of hyphae by i J Makhosi Mchunu: Address: National department ofAgriculture; Private Bag 3917; Port Elizabeth; 6056 Email: Makhosimc@NDA.agric.za ultraviolet-C light was perfected on C. penzigii Sacc., where 5 min exposure to DV-C light resulted in approximately 99% cell death. Surviving colonies were analysed by spectrophoresis, and the surviving mutant gave an absorbance value of approximately 5% more than the median. Samples were analysed by high-performance liquid chromatography (HPLC) to determine the presence of cercosporin. No definitive result was obtained. Exposure of C. caricis to DV-C for 5 min. resulted in approximately 65% hyphal cell death, with 20 min. resulting in approximately 95% death. A spontaneous mutant was observed in a colony that had been exposed to DV-C. This mutant showed sectored growth with red and grey growth patterns. The red section of the mutant was subcultured and analysed by spectrophoresis and HPLC. The red C. caricis gave an absorbance reading of approximately 140 on HPLC compared with about 22 from the grey colony. HPLC analysis of the wild-type C. caricis did not produce a peak corresponding to that of the cercosporin standard, although no conclusion could be obtained on the presence or absence ofthe toxin. The virulence of the mutant C. caricis could not be determined as inoculation experiments were unsuccessful, and had to be discontinued due to time constraints. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

Magistrantūros studijų baigiamajame darbe pateikiami tyrimų duomenys apie piktžolių dygimą, sunykimą ir bendrą jų skaičių žieminių kviečių spelta pasėlyje nuo sėjos iki derliaus nuėmimo. Apie žieminių spelta kviečių piktžolėtumą, piktžolių sausųjų medžiagų masę g m‾², jų rūšinę sudėtį ir dirvos piktžolių sėklų banką 0-10 ir 10-20 cm armens sluoksnyje: Darbo objektas –žieminių kviečių spelta veislės 'Franckenkorn' agrofitocenozės piktžolėtumo dinamika kintančio klimato sąlygomis, sėjos laiko fonuose. Darbo metodai: Piktžolių dygimo ir sunykimo dinamika spelta žieminiuose kviečiuose nustatyta visuose laukeliuose, atsitiktine tvarka įrengus po 3 pastovias piktžolių išdygimo ir sunykimo stebėjimų aikšteles (viso 24 stacionarios piktžolių apskaitos aikštelės). Piktžolėtumo vertinimas nustatytas kiekiniu svoriniu metodu. Piktžolės buvo suskirstytos į rūšis pagal biologinę- agronominę klasifikaciją (Montsvilaitė, 1996). Darbo rezultatai. Piktžolių sudygimas, sunykimas ir bendras jų skaičius esmingai priklausė nuo eksperimento tiriamųjų veiksnių – spelta žieminių kviečių sėjos laiko, piktžolėtumo apskaitos laiko ir jų sąveikos. Vėlyvesnės sėjos pasėlyje nustatytas intensyvesnis piktžolių sudygimas, galimai dėl vėlyvesnio kviečių sudygimo ir lėtesnio pasėlio vystymosi. Tik gegužės mėnesį intensyvėjant piktžolių sudygimui, ankstyvesnės sėjos pasėlyje nustatyta piktžolių sudygimo didėjimo tendencija lyginant su vėlyvesnės sėjos pasėliu. Piktžolių sunykimas nustatytas tik sausio – kovo... [toliau žr. visą tekstą] / Master's thesis presented research data on the germination of weed, the decline and the total number of winter wheat spelta crop from sowing to harvesting. The weediness of winter wheat spelta, weed dry weight g m -², their species composition and soil weed seed bank of 0-10 and 10-20 cm soil layer: Object of the work – weediness dynamics of the winter wheat spelta 'Franckenkorn' agrophytocenoses of different sowing time in a changing climate conditions. Method of the work weed germination and death dynamics of the winter wheat spelta in arranged stacionary plots (total 24 stacionary observation plot side). Assessment of the weed quantitatively weighted method. Crop weedines were assesedby the quantitative-weighing method. Weeds were grouped according to the biologic-agronomic classification of weeds (Mostvilaitė, 1996). The results of work. Weed germination, death and the total number essentialy depende on the experimental factors - winter wheat spelta sowing time, weed ccounting time and interaction of the factors. The more intensive crop weed germination was established in the latersowe drop, possibly due to later wheat germination and slower crop development. In earlier sowed winter wheat spelta crop only in May with increase of weed germination was established intensivification of weed germination comparing it with the crop of later sowing time. Decline of weed number was found in January - March. The higher total weediness of the winter wheat spelta crop was... [to full text]

Magistrantūros studijų baigiamajame darbe pateikiami įsėtų įsėlių įtakos pasėlio piktžolėtumui, morfometriniams ir produktyvumo rodikliams tyrimo duomenys. Darbo objektas – kukurūzų (Zea mays) monopasėlis, tarpiniai įsėliniai augalai, piktžolės. Darbo metodai: Eksperimentas vykdytas 2009-2011 m. Aleksandro Stulginskio universiteto (buvęs LŽŪU) Bandymų stotyje sekliai glėjiško karbonatingo išplautžemio (Calc(ar)i-Epihypogleyic Luvisol, LVg-p-w-cc(sc)) dulkiško priemolio sąlygomis. Eksperimento variantai: 1. ravėjimas 1-2 kartus (kontrolinis variantas) (R2K); 2. vasarinių rapsų (Brassica napus L.) tarpinis pasėlis (VRTP); 3. baltųjų garstyčių (Sinapis alba L.) tarpinis pasėlis (BGTP); 4.vasarinių miežių (Hordeum vulgare L.) tarpinis pasėlis (VMTP); 5. gausiažiedžių (vienamečių) svidrių (Lolium multiflorum Lamk.) tarpinis pasėlis (GSTP); 6. apyninių liucernų (Medicago lupulina L.) tarpinis pasėlis (ALTP); 7. persikinių dobilų (Trifolium resupinatum L.) tarpinis pasėlis (PDTP); 8. raudonųjų dobilų (Trifolium pratense L.) tarpinis pasėlis (ADTP). Darbo rezultatai. Piktžolių bendroji sausoji masė priklausė nuo tarpinių įsėlinių augalų masės. Nustatytas priklausomumas tarp tarpinių įsėlinių augalų sausosios masės ir visų piktžolių sausosios masės (r=-0,444). Labiausiai piktžolės išplito tarpiniuose pasėliuose, anksti šienavimo metu eliminuotuose iš kukurūzų tarpueilių: baltųjų garstyčių, vasarinių miežių bei vasarinių rapsų. Mažiausia sausoji piktžolių masė nustatyta... [toliau žr. visą tekstą] / In the final work of master degree studies there is given data of investigation of influence of living mulch on crop weediness, morphometric and productivity indicators. The object of the work – maize (Zea mays) monoculture, living mulch plants, weeds. The methods of work: The experiment was performed in 2009-2011 in the Experimental station of Aleksandras Stulginskis under the conditions of silty loam Luvisol ((Calc(ar)i-Epihypogleyic Luvisol, LVg-p-w-cc(sc)). The treatments of experiment: 1. Hand weeding (control variation) (R2K); 2. Spring rape (Brassica napus L.) living mulch (VRTP);3. White mustard (Sinapis alba L.) living mulch (BGTP); 4. Spring barley (Hordeum vulgare L.) living mulch (VMTP); 5. Italian ryegrass (Lolium multiflorum Lamk.) living mulch (GSTP); 6. Black medic (Medicago lupulina l.) living mulch (ALTP); 7.Persian clover (Trifolium resupinatum L.) living mulch (PDTP); 8. Red clover (Trifolium pratense L.) living mulch (ADTP). The results of the work: The total dry mass of the weeds was dependant upon the mass of mulch plants. The dependence indicated between the dry mass of mulch plants and the dry mass of all weeds (r=-0,444). Mostly weeds expanded in the intermediate crops which were moved from the interrows of maize: white mustard, spring barley and spring rape. The lowest dry mass of weeds was indicated in the mulch of ryegrass, Persian and red clover. These mulches produced essentially highest biomass. In the field experiment the most of... [to full text]

The effect of spore titer, virulency, and carrier systems on biological control of giant foxtail (Setaria faberi hermm.) with a species of Phoma isolated from this weed wereinvestigated. The lowest concentration of Phoma conidia which significantly affected (lowered) growth of giant foxtail was 1x106 conidia/ml. In conducting Koch's postulates, all but one (FF2) of the Phoma, isolates tested infected giant foxtail. Isolates FF1 and FF9 were the most virulent against giant foxtail. No correlation was apparent between virulency and fungus germination rate. No visible difference occurred with in vitro germination rates of spores incubated upon pea vsr water agar media; nutrient rich vs. nutrient poor media, respectively. These results suggest that Phoma spores already contain sufficient nutrients required for infection of foxtail. A definitive answer as to the effect of carrier system (e.g. surfactant, sticker, spreader, etc.) on efficacy of Phoma to infect foxtail could not be determined from results obtained, based upon statistical analysis of variance (ANOVA) for the single experiment performed. Several of the surfactant treatments (e.g. Silwet 77 and 408) did produce significant biomass losses against foxtail due to the phytotoxicity of the carrier system alone, and not reflective of fungal (Phoma) infection. Inoculation of foxtail plants with a conidial suspension amended with carriers of either Tween 20 (0.05%-0.1%) or methylcellulose (0.1%) should optimize chances for sufficient infection resulting in biological control of this weed. / Department of Biology

Inoculation studies were conducted in controlled environments with isolates of a Phoma sue. collected from leaf spot lesions on the weed giant foxtail. Limited host specificity studies resulted in this potential bioherbicide fungus killing all three foxtail species tested including Setaria faberi (giant), a. viridis (green) and S. lutescens (yellow). Several agronomically important plant species tested exhibited a hypersensitive-type response to infection, but these plants soon grew out of this symptom and appeared healthy. This bioherbicide preferred cool temperatures, exhibiting optimal biomass loss (100%) or death against foxtail seedlings following 120 hours leaf wetness with plants incubated at 20°C. At more conducive growth temperatures for the weed (25'C-300C), optimum biomass loss achieved was only 70% following 50 hours leaf wetness. Susceptibility to this Phoma sue. greatly decreased as foxtail seedlings attained 4 or more leaves per plant. To kill this weed, the author recommends inoculation of foxtail seedlings in early evening to take advantage of cooler temperatures and to inoculate plants between cotyledon to 3-leaf stages of growth. / Department of Biology

An understanding of the distribution of the Bracken fern (Pteridium aquilinum (L.) Kuhn) is critical for providing an appropriate management strategy. In this regard, remote sensing can play a critical role in mapping and modelling such distribution. In this study, an integrated approach using the random forest, maximum likelihood and vegetation indices was developed and tested to determine the capability of WorldView-2 multispectral eight band image in characterising the Bracken fern. Results based on the WorldView-2 were further compared to SPOT-5 multispectral (MS) image findings. The WorldView-2 (WV-2) image was spectrally resized to four traditional bands (blue, 450-510nm; green, 510-580 nm; red, 630-690 nm and NIR1, 770-895 nm) and four additional bands (coastal blue, 400-450 nm; yellow, 585-625 nm; red-edge, 705-745 nm and NIR2, 860-1040 nm) to evaluate the practicality of the spectral resolution in mapping the Bracken fern. The results from this analysis showed that the spectrally resized additional bands were more successful in general land cover mapping and characterising the Bracken fern. The result’s overall accuracy was 79.14% while the user’s and producer’s accuracies were 97.62% and 91.11% respectively. The second part of the study sought to improve the classification accuracy by applying a robust machine learning algorithm, the random forest. Since the random forest does not automatically choose the optimal bands, the backward variable elimination technique was employed to identify the optimum wavelengths in WV-2 for the identification of the Bracken fern. Respective out-of-bag (OOB) errors of 13.1% and 9.17% were achieved when the WV-2’s eight bands and optimally selected bands (n= 5) were used. These bands lie in the green (510-580nm), near-infrared1 (770-895nm), red-edge (705-745nm), near-infrared2 (860-1040nm) and the coastal blue (400-450nm) regions of the electromagnetic spectrum. These findings confirm the importance of the additional bands in vegetation analyses. The vegetation indices computed from these regions of the spectrum were superior to those in the visible region. The classification accuracy using WV-2 bands was superior to that from the commonly used SPOT 5 image. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

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Thesis (M.A.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 78-85). / vii, 85 leaves, bound 29 cm

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