Plant Pathology Commons^™

Abiotic Stress Impacts On Macrophomina Root Rot And Nano-Encapsulated Citrus Oils To Control Fruit And Foliar Pathogens Of Strawberry, Marina J. Gutierrez

Master's Theses

Disease remains one of the major constraints to the productivity and economic success of the California strawberry industry. The most important soilborne pathogen is Macrophomina phaseolina, causing Macrophomina root rot (MRR). The most economically significant airborne pathogens include Botrytis cinerea, causing Botrytis fruit rot (BFR), and Podosphaera aphanis, causing powdery mildew (PM).

Disease severity of MRR is highly dependent on environmental factors. Therefore, understanding which abiotic stressors contribute most to disease development is crucial for effective management. A two-year field experiment at Cal Poly, SLO (2024 and 2025) evaluated the effects of drought stress, two elevated chloride …

The Development Of Tools For The Production Of Fusarium Oxysporum Race 4 Resistant Cotton Varieties, Thomas Rylands

All Theses

Fusarium oxysporum race 4 (FOV4) is a fungal pathogen that infects cotton (Gossypium spp.) plants, resulting in fusarium wilt (FW) disease that causes significant wilting, yield loss, and eventually death. Since cotton is such an important crop globally, with tens of millions of bales of fiber produced and sold worldwide each year, it is critical to develop effective strategies to combat this pathogen. This research aims to achieve that goal through two projects: (i) develop an efficient co-culture system to test fungal treatments in vitro, and (ii) develop a computer vision pipeline to more accurately assess plant resistance …

Breeding For Disease Resistance In Melon And Watermelon, Venkata Rao Ganaparthi

All Dissertations

Watermelon and cantaloupe are two widely consumed cucurbits, but their acreage in the United States reduced by nearly 50% in last two decades. Fusarium wilt caused by a soil borne pathogen Fusarium oxysporum f. sp. niveum(Fon) race 2 is a major limiting factor in watermelon production as it reduces yields by 80%. Grafting watermelon plants onto the root stock of wild, disease-resistant varieties like ‘Carolina Strongback’ is the best strategy to manage Fon race 2. Though effective, this approach increases production costs.

Part of this dissertation focused on finding more sustainable, cost-effective solutions to control Fusarium wilt …

Fungicidal Management Of Spring Dead Spot Using Improved Modeling And Application Strategies, Michael Vincent Battaglia

Graduate Theses and Dissertations

Spring dead spot (SDS) is a destructive disease of bermudagrass (Cynodon Rich. spp.) in parts of the world that experience winter dormancy. Fungicides are often necessary to properly manage SDS, and significant research has been conducted to improve fungicidal effectiveness. Several studies were conducted with the objectives of improving fungicide application timing, method of fungicide application, and long-term fungicidal efficiency. In the fungicide application study, a cooling degree-day (CDD) model based on soil temperatures was developed. The CDD model showed that isofetamid was highly effective against SDS during a wide application window in autumn, while tebuconazole was inconsistently effective and …

Effect Of Planting Date, Insecticide Efficacy, And Hail Injury On Soybean Gall Midge (Resseliella Maxima Gagné) Infestation In Soybean, Natasha Hiromi Umezu

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Resseliella maxima Gagné (Diptera: Cecidomyiidae) is a recently described and economically significant pest of soybean (Glycine max (L.) Merr.) in the Midwestern United States. Since its identification in 2019, this species has become widespread and is now associated with substantial yield losses in parts of the region. Prior to its formal description, orange larvae were observed in soybean associated with plants damaged by hail, suggesting that plant injury may influence infestation. Given the pest’s economic importance, understanding the role of hail injury and developing effective, integrated management strategies are critical for mitigating its impact.

Field studies were conducted to …

Interview With Orca Award Winner James Van Etten, Unl Plant Pathology; Discoverer Of Giant Viruses, Mark Griep, James Van Etten

UNL ORCA Interview Series

Dr. James Van Etten was awarded the UNL Outstanding Research and Creative Activities Award in 1992. He was born in Virginia but grew up Peoria, Illinois. Something in his youth must have sparked an interest in science because he earned his bachelor’s degree in biology from Carleton College in 1960. Carleton is a well-regarded liberal arts institution in Northfield, Minn., about 400 miles from Peoria. Next, Jim earned a master’s and doctorate at the University of Illinois in Champaign-Urbana, both in plant pathology. For his postdoctoral work in 1965 and 1966, he did postdoctoral work in the Department of Genetics …

Detection Of Sweet Potato Feathery Mottle Virus Infection Via Remote Hyperspectral Imaging, Clayton Blake

LSU Master's Theses

In sweetpotato, global production exceeds 90 million tons annually, yet yields are threatened by numerous pathogens, including the potyvirus sweet potato feathery mottle virus (SPFMV). Virus infections can reduce yields by 25–40%, but surveillance is hampered by asymptomatic infections and the labor-intensive nature of detection. Hyperspectral imaging (HSI), combined with machine learning (ML), offers a promising pathway to scalable, non-destructive detection; however, studies focused on virus infection in sweetpotato remain limited.

This study demonstrates the feasibility of ML-enabled HSI for SPFMV detection under greenhouse conditions via a curated spectral library of two commercial cultivars, 'Beauregard' and 'Orleans', and the biological …

Evaluation Of Host Resistance To Rotylenchulus Reniformis In Sweetpotato Germplasm, Timothy S. Miller

LSU Master's Theses

The reniform nematode (Rotylenchulus reniformis) is an emerging plant-parasitic threat to sweetpotato production. Dissimilar from the galling caused by root-knot nematode infections, infections from the reniform nematode occur without visible damage to the root system. In the southern United States, heavily infested sweetpotato fields can lose up to 40% of their total yield. Growers rely heavily on fumigants and nematicides which provide inconsistent control and are not sustainable in the long-term. Past research has been more focused on the efficacy of chemicals than in the identification of host resistance or tolerance in sweetpotato germplasm. This study evaluated past …

Genetic Engineering For Pastures, W J. Peacock

IGC Proceedings (1977-2023)

The first genetically engineered food products from horticultural production systems are now entering the mnrke< and field trials of genetically engineered crop species are well advanced. We cnn expect that a range of crop cultivars, in which gene

Grassland For Sustainable Ecosystems, Malcolm Hadley

IGC Proceedings (1977-2023)

Grasslnnds present many advantages for examining issues related to sustainability. Grasslands include planted pastures as well as a variety of natural rangelands in situations ranging from semi-arid to subhumid. Diversity is also reflected in the spectrum of grassland users and uses, for example, nomadic pastoralism, extensive ranches, intensive pastures, wildlife tourism, game hunting. And in terms of sustainability of resource management, grasslands encompass a wide range of contrasting situations and conflicts in resource use. Heavy grazing pressure associated with increasing human populations in certain tropical savannas, the implications of rural depopulation to traditional pasture management in alpine regions, and the …

Grasslands For Our World, F Riveros

IGC Proceedings (1977-2023)

The present-day role of grasslands and fodder is reviewed with respect agriculture, animal production and environmental concerns. The world's grazing lands are a finite resource and, overall, arc being badly managed; in most developing countries action is required now, before it is too late. They will continue to be a major source of animal feed for the foreseeable future; encroachment from cropping will continue locally but, for much of what is now natural pasture, exploitation by the grazing animal .will remain the major means of obtaining an economic return; the task of grassland professionals is to assist the managers of …

Human Impact On Terrestrial Ecosystems - What We Know And What We Are Doing About It, H A. Mooney

IGC Proceedings (1977-2023)

At present the impact of humankind on the Earth System is substantial and will become greater as we continue to add over 80 million people to the global population each year. Collectively the human species utilises over a third of the total fresh water that is available, as well as an equivalent amount of the total terrestrial productivity. Possil energy is being consumed at a prodigious rate and fuels, among other things, over a half a billion vehicles. To support the large human population the Earth has been greatly reconfigured with much of the land utilised for grazing and agriculture. …

Science And Information For Our Grasslands, G A. Nores, R R. Vera

IGC Proceedings (1977-2023)

This paper favours a view of grasslands, and agricultural research in general, that extends well beyond the limits of the scientific community and promotes the active involvement of scientists in current societal debates from a scientific perspective. It is argued that in developed countries environmental concerns rather than production growth will tend to dominate future social debate. In developing countries there is a need to balance agricultural growth with responsible management of natural resources. Needs for new technology go beyond improving biophysical efficiency, and involve economic and social efficiency objectives. The relevance of grassland research is assessed in terms of …

Vegetation Dynamics In Grazed Systems: A Hierarchical Perspective, D D. Briske

IGC Proceedings (1977-2023)

Grassland vegetation consists of a series of hierarchical levels including the tiller, plant, population and community which collectively influence the productivity and stability of grazed systems. These hierarchical levels may respond uniformly to influence vegetation dynamics, but frequently additional complexity is encountered by the occurrence of opposing responses between or among hierarchical levels. Consequently, it is important to con­sider responses at several hierarchical levels to achieve an accurate interpretation of vegetation dynamics to graz­ing within the community. The significance of a hierarchical perspective to vegetation management is illustrated with examples from bunchgrass dominated rangelands at the level of the individual …

Forage Conservation And Physico-Chemical Conversion, E Zimmer

IGC Proceedings (1977-2023)

The factors on which the digestibility of organic matter (dMO) of forages depend are now well-known. In temperate forages, this digestibility depends mainly on the growth stage, the rank of the growth-cycle, and the botanical species. It is constantly decreasing with advancing age, especially during the first growth-cycle. In after­math growth-cycles, high temperatures accelerate the decrease of digestibility with age. Tropical forages follow the same laws, but tropical grasses are less digestible than cool-season grasses, especially at young stages and in warm weather. This is partly due to the fact that high temperatures increase cell-wall contents and lignification, and also …

The Feeding Value Of Forages, C Demarquilly

IGC Proceedings (1977-2023)

The lower productivity of legume based swards and their instability of yield from year to year compared with nitrogen fertilised grass swards continues to be a major constraint on the integration of leguminous nitrogen fixing species into present-day farming systems. Most legume systems have a high biological nitrogen fixation (BNF) potential which is rarely attained in the· field due to limiting environmental or management factors. Enhancement of BNF through manipulation of the Rhizobium and plant components of the symbiosis must be viewed as a long-term objective. Optimisation of nitrogen fixation in the short-term may best be achieved through optimisation of …

Nitrogen Fixation, Cycling, And Utilization, P M. Murphy, M T. Sherwood

IGC Proceedings (1977-2023)

The lower productivity of legume based swards and their instability of yield from year to year compared with nitrogen fertilised grass swards continues to be a major constraint on the integration of leguminous nitrogen fixing species into present-day farming systems. Most legume systems have a high biological nitrogen fixation (BNF) potential which is rarely attained in the· field due to limiting environmental or management factors. Enhancement of BNF through manipulation of the Rhizobium and plant components of the symbiosis must be viewed as a long-term objective. Optimisation of nitrogen fixation in the short-term may best be achieved through optimisation of …

La Prairie Dans Ses Usages Multiples: Conservation Des Sols, Protection De L'Environnement, Etc., M Skouri, J Poissonet

IGC Proceedings (1977-2023)

Les terres :i paturage couvrent une partie importante de la planete et presentent une extreme diversite de situations en fonction des conditions ecologiques et des facteurs socio-economiques et culturels qui s'exercent sur ces espaces. Ces facteurs ont engendre des transformations du milieu nature] permettant d'intensifier, et :i ]'extreme, de contr61er la production vegetale de ces ecosystemes. Si le role premier de ces formations herbacees a ete d'alimenter Jes herbivores afin que l'homme en obtienne une production (viande, lait, peaux, etc.), Jes autres fonctions de ces espaces ont une importance que !'on ne peut se permettre de negliger, que ce soit …

Quickening Snow Melting In Early Spring With Black Powder In Snowy District, A Imai

IGC Proceedings (1977-2023)

Experiments were conducted during 1977-1980 to quiken snow melting in early spring with three kinds of black powders at 450 m a.s.l.,Tsunan-machi, Niigata Prefecture. Snow melting materials involved blast furnace slag, di-amido lime and calcium silicate and their effects on snow melting were compared with each other at various application rates on snow surface in late March every year. Snow melting was earlier with 600 kg/ha di-amido lime resulting from lower albedo of 25 % and it could quicken the snow-off by 10-13 days as compared to the control plot. This early snow melting induced the higher soil temperature and …

Effect Of Fertilization In Autumn Or After Wintering On Dallisgrass Production In The Following Season, T Kobayashi

IGC Proceedings (1977-2023)

To improve dallisgrass (Paspalum dilatatum Poir.) pasture productivity, the effects of autumn or spring topdressing in a field experiment and autumn nitrogen (N) application levels in a pot experiment on the regrowth and carbohydrate accumulation until winter and on the early summer production were studied. Dallisgrass pasture was topdressed in either autumn (late September) or spring (early March) at 0.5 kg/a each of N, phosphate (P2O5), and potash (K20), after the final cutting in late September 1978. Plants in pots were topdressed at the rates of 0.5, 1, 2, and 4 kg N/a, just after cutting in early October …

Selenium Pellets Administration In Cows Grazing Continuously On Low Selenium Grassland In Japan, J Jachja, N Ishida, R Kawashima, K Otsuki, K Otsuki, M Kawano, F Hosoyamada

IGC Proceedings (1977-2023)

The effectof selenium (Se) supplementation in cows upon the growth of their newborn calves under the conditions of continuous grazing in a low Se pasture were studied. The selenium status of calves which were born from selenium treated cows were higher than that in calves from untreated control cows during the suckling period. Selenium supplementation to the dams showed no significant response upon the body measurement for their calves at birth or four months of age, but significant improvement in body weight and withers height at the weaning period. When cows grazed continuously in pastures containing a selenium content of …

Plant Introduction, Seed Production And Fodder Promotion In An Integrated Livestock And Pasture Development Programme In Kerala, India, A Shamsudeen, T V. Joseph, F Von Sury

IGC Proceedings (1977-2023)

An integrated pasture development programme for the state of Kerala, in the 1500-3500 mm rainfall area of southern India, is described. Kerala's agriculture is characterized by small holdings and intensive multicrop farming systems with coconut and rice as main crops. Dairy cattle rearing is an important subsidiary for many farmers. A plant introduction programme selected Panicum maximum ( cvs. Makueni and Riversdale), Brachiaria ruziziensis and Centrosema pubescens for intercropping in coconut gardens. Desmodium intortum and D. uncinatum were introduced for the grasslands of the high ranges. B. ruziziensis, Melinis minutiflora, Setaria anceps ( cvs. Kazungula and N arok), Stylosanthes guianensis …

Development Of Legume-Based Pastures For Livestock Production In Yunnan, Peoples Republic Of China- Preliminary Studies With Trifolium Semiplosum Cv. Safari And Temperate Legume Cultivars, M J. Mathison, M/S T. Wang, Z Y. Yang, M H. Dunning, Y N. Al, Z Z. Ma, H X. Al, L W. Peng, H Yang, D C. Zhang, C G. Zhang, G R. Yang

IGC Proceedings (1977-2023)

Aiming to improve livestock production from extensive grassland areas in Yunnan Province south west China, forage cultivar evaluation experiments are in progress as part of the China-Australia Technical Co-operation Programme. Preliminary results are given from introduced temperate legumes sown in 1983 in replicated swards in cultivated and uncultivated grassland. South west monsoon climates sampled range from alpine-temperate to tropical. In alpine sites red clover and annual species e.g. vetches, persian and subterranean clovers were among top dry matter yielders in the first year on cultivated land, Annual clovers failed or were outyielded by white, red clovers and, in one locality, …

Development Of Legume- Based Pastures For Livestock Production In Yannan, Peoples Republic Of China - Preliminary Studies With Tropical Legume Cultivars, M J. Mathison, M.S T. Wang, Z Y. Yang, Y N. Ai, Z Z. Ma, H X. Al, L W. Peng, G R. Yang

IGC Proceedings (1977-2023)

As part of the Australia -China technical cooperation programme investigations to raise livestock production with improved pastures began in 1983 in Yunnan province, south west China. Preliminary results with ungrazedintroduced tropical legume cultivars sown in cultivated and uncultivated grassland are given for 2000-2500m altitude subtropical sites and a 500m alt. tropical site. Only Jotononis, silverleaf and greenleaf desmodiums were productive in the second year at subtropical sites. At the tropical site annual lab lab produced most dry matter in the first year. Most perennial species grew well there in the second year. The best cul ti vars for cultivated land …

Fodder Development In The Dry Zone Of Sri Lanka - A Pasture Scheme For Small Farms, P Berger, L R. Abeykoon, L Winkler

IGC Proceedings (1977-2023)

A pasture development scheme to improve fodder production by small farmers was introduces by the Sri Lanka - Swiss Livestock Development Project (SSLDP) in the easten dry zone of Sri Lanka. The procedure of the scheme is described. Emphasis was put on proper land selection, establishment procedures and management factors of pasture plots. To promote the scheme a subsidy is given to the farmers after inspections by the extension staff. The first experiences showed a better survival of the plots under a closer follow up. A marked decrease was observed during extreme climatical periods. It is proposed to intensify the …

Range Improvement In Tropical China: Gaopoling Model Cattle Farm, D L. Michalk, J F. Ayres, Fu Nanping, Zhu Chin-Min

IGC Proceedings (1977-2023)

New policies seek to increase beef output on China's rangeland by sowing legume-based pastures. "Model farms" provide a means of quickly transferring this technology to China. Gaopoling Model Cattle Farm was set up to improve beef production in dry tropical Hainan Island by introducing new legume species and better husbandry practices. With finance from Guangdong Province and technology from Australia, a program emphasising pasture research, performance recording of "improved" versus "traditional" cattle husbandry and commercial farm developmant was commenced in 1981. Though experimentation, recommendations for species combinations, fertilizer inputs and sowing methods were formulated for the major local soil types. …

Preliminary Fertilizer Requirements For Establishing Legume Based Pastures In The Alpine Zoone Of Yunnan, Jinjing Wang, J R. Bruce-Smith, Jixin Li, Mingliang Wang

IGC Proceedings (1977-2023)

Preliminary results of field trials designed to assess the soil fertility status for establishing improved legume based pastures in the alpine zone of Yunnan Province are presented. These trials were undertaken by a joint Chinese-Australian Project which is investigating ways to improve the livestock industry of the Province. The best treatments at one site in the North East yielded about 9000kg of total (grass + legume + weeds) pasture and 7000kg of this was attributable to clover production. At another site in the North West on the Southern Tibetan Plateau summer waterlogging confined the pasture yield to 4000kg DM. Tentative …

Preliminary Studies Of Fertilizer Requirements Of Tropical Legumes In Southern Yunnans Red River Valley, Jinjing Wang, J R. Bruce-Smith, Mingliang Wang, Jixin Li

IGC Proceedings (1977-2023)

As part of a joint Chinese-Australian Project to promote livestock development, a farm site in the lower Chinese section of Red River Valley was chosen as an area to study techniques suited to meeting these objectives through establishing and utilizing legume based tropical pastures. Preliminary results of fertilizer trials at Daliuhu Farm show that sulphur deficiency is the main nutrient problem retarding the growth of siratro and stylo legumes. The application of as little as 5, but optimally between 10 and 20kg of sulphur as gypsum Sor elemental S seems to adequately meet their growth requirements. The apparent adequate phosphate …

Studies On The Mountain Pastures Classification And Class Evaluation Of Guichou, China, Huang Weilian

IGC Proceedings (1977-2023)

The pastures of the mountain range in Guichou are a secondary succession type, which has been shaped since the forest was destroyed. They were formed by forest regressive succession; from forest to bushwood, and with further degeneration from bushes to pastures. Therefore, in the author's opinion, it is appropriate to use the secondary succession series method of geobotany to classify the mountain range pastures in southern China. This method can objectively describe the origin and developing stages of this range type, the features of the vegetation succession series in subtropical areas, and express their economic value and utilization, which form …

The Grass Hillsides Of Jiangxi Province, Fan Xie, Suehen Wang

IGC Proceedings (1977-2023)

For researching into vegetation on grass slopes, their types, characteristics, yield and prospect of application in livestock husbandry, a sampling investigation on the semi-location spot has been carried out. Jiangxi province is situated in Southeast China, belonging to the monsoon region in Southeast Asia. According to the principles of ecological condition and dominant species, the grass hillsides can be classified into 7 herbosa groups: Ischaemum ciliare grass-land on hilly land, Arundinella setosa grass-land on hilly land, Dicranopteris dichotoma grass-land on hilly land of low hills, Miscanthus sinensis grass-land on hilly land of mid-low hills, M. floridulus grass-land on hilly land …