Decision aid to support the use of curative late blight fungicides

Late blight, caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary remains a severe threat to potato production in temperate regions and necessitates a high volume of fungicide inputs. A recent focus of research has been to improve the application of Integrated Pest Management (IPM) principles to the control of late blight. Extensive monitoring programmes and warning systems are currently delivered via online platforms, and growers also have access to information on fungicide properties and the relative resistance of different cultivars to the pathogen. Growers and agronomists would benefit from additional tools which aid the decision-making process and allow improved integration of available control strategies. A strong example of this is the use of curative fungicides. Fungicides which can act curatively (within the incubation period of pathogen development) are an increasingly important component of late blight control, and there is scope to improve their deployment. The aim of this study was to produce a simple decision aid that can be used by growers and agronomists to inform their decision to use a fungicide with curative properties following weather conditions associated with a high risk of infection. Guidance available before the development of this decision aid was somewhat subjective, and did not take into account factors that may modify the efficacy of curative fungicides for which there is very little published information. Several contemporary P. infestans isolates were characterised in this study for their growth rates, both visually and sub-clinically using a qPCR assay. These data were then used to test a range of potential pathogen growth models which have been used by previous authors to model temperature-dependent growth in other biological systems. Many of these models provided good descriptions, and the best performing was used to predict pathogen development with the decision aid. Characterisations of the curative effect for a representative curative fungicide (propamocarb-HCl + fluopicolide) were generated for selected isolates in both laboratory assays and under field conditions. Within the laboratory bioassay, more frequent sampling (4 hour intervals) than is usually reported in experiments of this nature was used to assess the nature of the curative effect over a time frame of up to 72 hours post inoculation. Curative control declined rapidly with increasing pathogen development, with the relationship best described by a logistic function. This function, and the parameters generated from the bioassays, were used within the decision aid to predict the likely outcome of curative treatments

Volatile organic compounds associated with neonectria ditissima infection in apples (Malus pumila cv Gala)

Postharvest diseases in apples during long term storage result in loss and waste. This is mainly caused by fungal pathogens. Fungal contamination and rot can change some of the volatile organic compounds (VOC) emitted by apple fruits. In this study, disease free Gala apples were inoculated with Neonectria ditissima. The aim was to identify VOCs associated with N. ditissima infection in gala apples. The inoculated apples were placed in 5L glass flask, sealed, and incubated at 20oC for one hour after which a charcoal filtered airflow of 1 L/min was maintained for one hour through the Volatile Capture Trap (VCT) with volatile emissions captured on a porapak-Q absorbent filter. Captured volatiles were eluted using 1 mL of dichloromethane (DCM) into a standard Agilent 1.5 mL HPLC vial. Eluted volatiles were analysed using Gas Chromatography coupled with Mass Spectrometry (GC/MS). Volatiles were capture in three replicates for both inoculated and healthy control groups at 2 days, 8 days, 14 days, 21 days, 28 days, 35 days, and 42 days post-inoculation. The N. ditissima discriminatory volatile were identified/discriminated qualitatively based on the unique volatile compounds detected and quantitatively based on variation in peak area of certain combinations of volatile compounds. Some of the discriminatory volatiles such as dodecyl hexanoate, 9-decen-1-yl hexanoate, hexyl butanoate and pentyl acetate were detected in the early stages of the infection. Styrene, terpinene-4-ol, ethyl hexanoate, ethyl butanoate, ethyl pentanoate and 2-methylpentyl formate constituted the main VOCs emitted during apple fruit decay. Other compounds such as alpha Farnesene and hexyl acetate were common to both healthy and inoculated apples but the peak areas in the healthy apples were well above the peak areas in the inoculated apples. However, these compounds expressed a decline in peak area over time. Apples are stored commercially in sealed stores for months making visual observation for early detection of disease almost impossible. Disease of stored apples are most times only detected at advanced stages when it has become nearly impossible to prevent losses. These discriminatory volatile metabolites detected at early stages of infection are important for early non-visual detection of N. ditissima in stored apples. Further research is recommended to the use of these compounds in early detection of the disease caused by N. ditissima

Abstracts of the 18th Triennial Conference of the European Association for Potato Research : July 24-29, 2011 Oulu, Finland

Peer reviewe

The Potato Crop

Life sciences; Agriculture; Nutrition   ; Plant breeding; Food—Biotechnology; Agricultural economic

Scientific review of the impact of climate change on plant pests: a global challenge to prevent and mitigate plant pest risks in agriculture, forestry and ecosystems.

Climate change represents an unprecedented challenge to the world?s biosphere and to the global community. It also represents a unique challenge for plant health. Human activities and increased market globalization, coupled with rising temperatures, has led to a situation that is favourable to pest movement and establishment. This scientific review assesses the potential effects of climate change on plant pests and consequently on plant health. The evidence assessed strongly indicates that climate change has already expanded some pests? host range and geographical distribution, and may further increase the risk of pest introduction to new areas. This calls for international cooperation and development of harmonized plant protection strategies to help countries successfully adapt their pest risk management measures to climate change.bitstream/item/224381/1/Scientific-review-of-the-impact-of-climate-2021.pd

Translational Genomics for Crop Breeding: Biotic Stress, Volume 1

Genomic Applications for Crop Breeding: Biotic Stress is the first of two volumes looking at the latest advances in genomic applications to crop breeding. This volume focuses on genomic-assisted advances for improving economically important crops against biotic stressors, such as viruses, fungi, nematodes, and bacteria. Looking at key advances in crops such as rice, barley, wheat, and potato amongst others, Genomic Applications for Crop Breeding: Biotic Stress will be an essential reference for crop scientists, geneticists, breeders, industry personnel and advanced students in the field

Diversity and ecology of the potato : the use of spatial analysis in crop science

Spatial variation is a fundamental characteristic of agriculture, but crop scientists have largely ignored it, particularly at levels beyond the field scale. This thesis provides examples of analysis of spatial variation over larger areas. It contributes to our knowledge of the potato crop and its wild relatives, and to methodological progress in the use of geographic information in crop science. Part I deals with management of genetic resources. Methods that can be used to improve data quality in biological collection databases, and to assess the presence of spatial biases are discussed. The spatial distribution of wild potato species is analyzed, and the value of geographic, ecological, and taxonomic factors to predict the presence of frost tolerance in wild potatoes is studied. Part II deals with aspects of agro-ecological zoning approaches for research management. First, gobal potato distribution is described and analyzed. This is followed by a constraint-specific agro-ecological zoning study for potato late blight; a study on the potential impact of frost resistant potatoes; and an assessment of the effect of climate change on global potato production. In the final chapter, research needs and challenges to the further use of GIS in crop science are discussed