Yield losses caused by late blight (Phytophthora infestans (Mont.) de Bary) in potato crops in Ireland

peer-reviewedField experiments, using foliage blight susceptible cultivars, were conducted at Oak Park, Carlow from 1983 to 2007 to determine the loss in potato production caused by crop infection with Phytophthora infestans. In each of the 25 years an untreated control was compared with protectant and with systemic fungicide programmes to determine the effect of late blight on the defoliation percentage at the end of the season, the area under the disease progress curve, marketable tuber yield, total tuber yield and yield of blighted tubers. The earliest date of first recorded late blight was 22 June and the latest was 15 September, but in 15 of the 25 years, blight was first recorded between 17 July and 13 August. Disease reached epidemic proportions in all but 4 of the years. Yields varied considerably among years. The mean loss in total yield from not using a fungicide was 10.1 t/ha. Differences in yield were significant across the 25 seasons. No overall increase in aggressiveness of the pathogen could be detected over the 25-year period

Field Validation Of Four Decision Support Systems For The Control Of Late Blight In Potatoes

End of Project ReportField experiments were carried out between 2001 and 2003 to determine the efficacy of the NegFry, Simphyt, ProPhy and Plant Plus decision support systems (DSS) in controlling late blight of potatoes compared with routine fungicide treatments. The experiments were also used to determine the potential of the systems to reduce fungicide inputs. Over the three year period of the experiment the 7-day routine programme received an average of 13.7 fungicide applications while the DSS programmes varied between 5.7 and 12.3 applications. All decision support systems resulted in a reduction in the number of fungicide application (Fig. 2). Compared with the routine control, the NegFry and SimPhyt programmes resulted in a 58-44% reduction in application frequency. The ProPhy and Plant Plus programmes resulted in more modest savings of between 10 and 25% (Tables 1 & 2). All fungicide treatments significantly delayed the date of disease onset compared with the untreated control. Compared with the routine control treatment, the NegFry and Plant Plus significantly delayed disease onset in King Edward in 2001 as did NegFry and ProPhy in Rooster. In 2002 there were no differences between treatments in terms of delaying disease onset, while in 2003, disease developed significantly earlier the Plant Plus programme compared with the routine control. In general, the date of disease onset was not significantly different between routine programmes and DSS programmes irrespective of the cultivar. In each of the three years, all fungicide treatments significantly reduced the incidence of foliage blight at the end of the season compared with the untreated control. When compared with the routine control, no decision support system resulted in significantly more foliage blight at the end of the season, irrespective of the cultivar or year. Similar results were achieved when the treatments were compared using the area under the disease progress curve (AUDPC). These results would confirm that none of the DSS’s resulted in inferior disease control when compared with the 7-day routine application of fluazinam. All fungicide treatments resulted in significantly higher marketable yields compared with the untreated control in all years, irrespective of the variety. Within the fungicide treatments the DSS programmes generally out-yielded the routine fungicide treatment. However, these differences were only significant for Plant-Plus in King Edward in 2001. Within the DSS treatments there were no significant differences in marketable yield in any of the years or either of the varieties. Within the fungicide treatments there were no significant differences between treatments in terms of tuber blight control for the resistant variety Rooster. In the case of the more susceptible variety, King Edward, all the DSS programmes resulted in significantly lower levels of tuber blight than the routine Shirlan control in 2001 except for Simphyt. More importantly, the routine Shilan did not result in significantly better tuber blight control in any of the years when compared with any of the DSS programmes. This confirms that all DSS programmes give equivalent tuber blight control to the routine Shirlan application at 7-day intervals even with a very tuber blight susceptible variety

Epidemiology and control of pink rot in potatoes.

End of Project ReportRotting of tubers was reported in early potato crops in Co. Wexford in 1995. Geotrichum candidum, which causes a condition known as rubbery rot, was isolated from a sample of affected tubers. In further investigations in 1996 both G. candidum and Phytophthora erythroseptica, the cause of pink rot, were isolated from diseased tubers. In pathogenicity tests P. erythroseptica re-infected tubers while G. candidum did not. It was concluded that the disease was pink rot. In 1997 foliar applications of the systemic fungicide metalaxyl were evaluated for its control. The level of control obtained was insufficient to overcome the problem which pink rot can cause in early potatoes

Imaginary Stories in School: First Steps Toward Literacy

This essay holds that to forgo opportunities for children\u27s pretend play and conversation around storytelling in school is to distort the very nature of language development and literacy

Efficacy Evaluation Of Fungicide Programmes For The Control Of Late Blight In Potatoes.

End of Project ReportField experiments were conducted between 1989 and 1992 to compare the efficacy of different fungicide programmes to control late blight of potatoes. The protectant fungicide Shirlan, the translaminar fungicide Acrobat and the systemic fungicide Ridomil MZ followed by Dithane were compared with the protectant fungicide Dithane and an unsprayed control treatment. The longest delay in disease incidence was recorded following the use of Ridomil MZ and this together with Shirlan were significantly better than the Dithane control. All test treatments resulted in better foliage blight control compared with the Dithane control treatment. The lowest level of foliage blight at the end of the growing season was recorded following the Shirlan treatment, but this was not significantly better than Ridomil MZ or Acrobat treatments. All three test fungicides significantly reduced the level of tuber blight compared with untreated control. While all test fungicides gave better control of tuber blight than Dithane, these differences were only significant in some years. The three test chemicals all resulted in equivalent marketable yields when compared with the Dithane control. This would indicate that there were no phytotoxic effects from any of the test chemicals

Potato Breeding at Oak Park 2000-2006

End of project reportThe potato breeding programme at Oak Park was started in the 1960's and has consisted of a number of distinct phases. In the first phase the focus was on the evaluation of the main domestic and foreign varieties for suitability for the Irish market. This was followed by a breeding programme for the domestic market, with particular emphasis on the production of a blight resistant replacement for Kerr’s Pink. The emphasis then switched to breeding for the export market, with the focus on the UK and Mediterranean markets. Since then the breeding programme has been focused on both the domestic, processing and export markets. The process of breeding, testing and multiplying a new potato variety from the making of the initial cross until the new variety can be commercially grown takes about 15 years (see Appendix 1). This report covers the period 2001-2006 (RMIS NO 4720).Irish Potato Marketing Ltd.National Development Pla

Breeding, disease resistance screening and seed production of new potatoe varities.

End of Project ReportThe potato breeding programme at Oak Park was started in the 1960's and has consisted of a number of distinct phases. In the first phase the focus was on the testing of the main domestic and foreign varieties in field trials in the main potato growing areas of the country. This was followed by a breeding programme for the domestic market, with particular emphasis on the production of a blight resistant replacement for Kerr’s Pink. The emphasis then switched to breeding for the export market, with the focus on the UK and Mediterranean markets. Since then the breeding programme has been focused on the domestic, processing and export markets. The process of breeding, testing and multiplying a new potato variety from the making of the initial cross until the new variety can be commercially grown takes about 15 years (see Appendix 2). The objectives of the present Potato Breeding Programme are: 1. Breeding improved varieties for the seed export trade. 2. Developing high yielding early maincrop and maincrop types with resistance to potato cyst eelworm Globodera rostochiensis and or Globodera pallidae with quality suitable for the UK market. 3. Developing a high dry-matter red skinned early maincrop or maincrop variety suitable for the home ware trade with a high level of disease resistance especially to late blight. 4. To select early maincrop or maincrop types suitable for processing into crisps and chips. 5. Breeding 1st and 2nd early varieties suitable for Irish and UK conditions with improved quality and disease resistance

Genetic Analysis of Irish Populations of Phytophthora Infestans

End of Project ReportPhytophthora infestans (Mont.) de Bary, the causal agent of potato late blight is best known for its role in the great Irish famine of 1845-1849 which resulted in the deaths of over 1 million people. Since then, the disease has become established in all potato growing countries and is the most important pathogen of potatoes worldwide. The appearance of resistance to the phenylamide fungicides in the late 1970’s indicated that populations of P. infestans were changing. An antiresistance strategy was developed for growers in an effort to reduce the spread of resistant strains. Subsequently the A2 mating type of the fungus was discovered in 1989 promoting fears that a super strain of the fungus could evolve through sexual reproduction. Populations of the fungus have been monitored from 1981 to 1998 for levels of phenylamide resistance and since 1988 for the A2 mating type. Physiological race surveys were conducted in 1983 and 1996. Prior to the 1980s no reliable methods were available for adequate identification of genotypes. Development of molecular markers specific to P. infestans has made this possible and a survey was conducted on isolates from the 1996 population. Results confirm that the anti-resistance strategy for phenylamide based fungicides has been effective in preventing the build up of metalaxyl resistant populations of P. infestans. During the 1990’s the distribution of phenylamide resistance has remained stable at about 50% of crops tested compared to a high of over 80 % in 1981. The level of A2 in the population has also fallen from a high of 35% of isolates tested in 1989 to a static level of 3-4 % in the 1990’s. Physiological race composition has become much more complex since 1983 and 16 different physiological races were found in Ireland in 1996. The population was dominated by race 3.4.7.10.11 which accounted for over 54% of isolates tested. This change has taken place without a corresponding change to varieties with a complex Rgene base. Twelve different genotypes of the fungus were uncovered using the multilocus probe RG57. Races of the fungus were independent of genotype. One particular genotype IE-2 was predominantly associated with phenylamide resistance. The low population diversity discovered suggests that sexual reproduction between A1 and A2 types has not been a major factor in disease epidemiology to date. Super strains similar to those identified in the USA could not be confirmed. The overall level of variation in the Irish isolates of Phytophthora infestans would confirm that the population has become progressively more diverse during the last forty years. However, the population is much less complex than that found in the highland tropics of central Mexico.Teagasc Walsh Fellowship Programm

Environmental Consequences of a Power Plant Shut-Down: A Three-Dimensional Water Quality Model of Dublin Bay

A hydro-environmental model is used to investigate the effect of cessation of thermal discharges from a power plant on the bathing water quality of Dublin Bay. Before closing down, cooling water from the plant was mixed with sewage effluent prior to its discharge, creating a warmer, less-saline buoyant pollutant plume that adversely affects the water quality of Dublin Bay. The model, calibrated to data from the period prior to the power-plant shut-down (Scenario 1), assessed the water quality following its shut-down under two scenarios; (i) Scenario 2: continued abstraction of water to dilute sewage effluents before discharge, and (ii) Scenario 3: sewage effluents are discharged directly into the Estuary. Comparison between scenarios was based on distribution of Escherichia coli (E. coli), a main bathing quality indicator. Scenarios 1 and 2, showed almost similar E. coli distribution patterns while Scenario 3 displayed significantly higher E. coli concentrations due to the increased stratification caused by the lack of prior dilution