Developing and disseminating potato virus management strategies for northeastern growers
There are economic and environmental imperatives for the development of biological disease control strategies for Potato Virus Y (PVY). PVY is an economically important crop disease that reduces yield and, in the worst cases, causes crop failure in many solanaceous crops, including potatoes, tomatoes, tobacco, peppers, and eggplants. PVY presents a daunting management challenge, because it is transmitted rapidly by a vast array of aphid species and infected plants can be difficult to identify in the field. Current strategies, such as pesticide applications and removal of infected plants from the field, are not effective, needlessly increasing chemical inputs at both an economic and environmental cost.
The goal of this project is to develop and disseminate a biological disease control strategy for potato growers that minimizes PVY spread by enhancing naturally occurring aphid natural enemy populations. To begin this work, a total of twenty-two farms were surveyed for aphids, aphid natural enemies, and PVY over two growing seasons, and the landscape composition of the area surrounding the farm was analyzed using ArcGIS software. Though analysis is not complete, in 2012 there was a significant direct relationship between the amount of agricultural land surrounding a farm and the end of season PVY prevalence; the more agriculture in the area, the more PVY there is, given an introduction of the virus in the potato seed tubers. The insect community across the region is extremely diverse, including at least 54 species of aphids, and the aphid natural enemy assemblage includes seven species of ladybugs, as well as lacewings, and pirate bugs. This diversity affected the final PVY prevalence; there was a significant positive relationship between aphid species richness and abundance and PVY prevalence, and a negative significant relationship between ladybug predator species richness and PVY prevalence.
1) Survey the main aphid vector species, common natural enemies of aphids, and the distribution and spread of PVY on small farms across several counties in New York State: In 2013, I monitored the presence and spread of PVY by sampling plant tissue in potatoes and all other solanaceous crops grown on twenty-one farms using an enzyme-linked immunosorbent assay (ELISA). I trapped and surveyed aphid natural enemy and aphid populations in potato fields throughout the growing season. I have conducted this survey for two field seasons and have now completed this aspect of the project.
2) Evaluate the influence of landscape-level effects: Using GIS software, I analyzed the landscape composition of the area surrounding the potato fields at six scales: within radiuses of 0.5km, 1km, 1.5km, 2km, 2.5km, and 3km. Land use was quantified as %agricultrual, %forested, %developed, etc. Analyzing the 2012 data, I have tested whether or not the complexity of the landscape surrounding the potato field affects aphid natural enemy populations, aphid populations, and PVY prevalence among all solanaceous crops. In the coming year, I will complete analysis of the 2013 data (this requires the 2013 Crop Data Layer, which will be released by the USGS in January 2014) with respect to these questions.
3) Evaluate the influence of aphid community composition on PVY prevalence and spread: In field experiments scheduled for the summer of 2014, I will examine the impact of aphid species diversity and evenness on PVY prevalence and spread, focusing on the major vector species found in the surveys.
4) Evaluate the effect of natural enemy community composition on PVY prevalence and spread: In field experiments scheduled for the summer of 2014, I will test the effect of aphid natural enemy diversity and abundance on PVY prevalence and spread by introducing the most commonly found natural enemies to treatments developed in Objective 3. This work will allow me to determine the most effective naturally occurring biological control agents.
5) Disseminating disease control management strategies: Analyzed cumulatively, the data from Objectives 1-4 will result in management recommendations for growers to maximize disease control on their farms through appropriate farm layout and potato growing practices. I will disseminate this and related information through multiple media channels.
Over the past year, I have processed the remaining 2012 samples and analyzed them, and run a landscape level project at twenty-one farms. Over the summer, I conducted a survey of aphids, aphid natural enemies, and PVY at these sites. Following this field season, I have analyzed approximately 3000 plant tissue samples using enzyme-linked immunosorbent assay (ELISA). I have also sorted 884 trap samples and identified approximately 700 aphids.
In the future, I need to identify the ladybug predators caught in 2013, analyze the landscape using the 2013 Crop Data Layer (which will be released by the USGS in January 2014) and conduct a series of field experiments analyzing the impact of aphid and aphid natural enemy diversity on PVY prevalence and spread, which should occur in the summer of 2014.
My project has proceeded as expected and I have learned a great deal over the course of the last year. I have gained project management and mentorship experience and learned several research techniques necessary for the project, which will allow me to be more efficient during the next field season.
Impacts and Contributions/Outcomes
The data I have collected so far will provide useful information about the most common PVY aphid vectors and aphid natural enemy species, as well as the prevalence of PVY on small-scale farms across the Finger Lakes region. This will allow for more effective estimation of the risk of in-season disease spread. Further work will yield information that should inform farm planning. Identifying a biological control agent that suppresses the major aphid vectors would reduce dependence on ineffective control measures, such as pesticides, increasing overall sustainability.
Over the last year, I mentored an undergraduate student who contributed to the landscape level project. I will continue mentoring undergraduate assistants and I am preparing to disseminate my project results through factsheets to participating growers.
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