Aster yellows integrated management in Western Canada and the United States Upper Midwest

Abstract The aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is considered to be a significant pest in the Western Canadian Prairies and the United States Upper Midwest due to its ability to transmit a bacterial plant pathogen known as Aster Yellows phytoplasma (AYp) to several plant species. Aster Yellows (AY) disease can be devastating to growers and home gardeners, as common symptoms in infected plants include altered pigmentation of leaves, changes in size and structure of grain heads, and sterile pods. Since there are no resistant crop varieties and leafhoppers remain infective for life, control strategies primarily focus on surveillance of populations on both crops and weedy hosts and on managing aster leafhopper populations. Several crops and wild species can sustain leafhopper populations; however, cereals are optimal hosts for their reproduction and development. Depending on environmental conditions, aster leafhoppers can complete between 2 and 5 generations per growing season. Collaborative research efforts across multiple institutions have expanded our understanding of this pathosystem, including leafhopper movement at various scales, seasonal changes in AY infection levels, and the effectiveness of different management tactics. The development of diagnostic tools has improved the identification of infection sources, which, alongside action thresholds, can help guide decisions on the need for additional insecticide applications. This article compiles this information into a single extension resource.