b'Research Roundup:Potato Early Dying ComplexScientists continue to study the disease. An integrated management approach is still the best option for growers.BY: MELANIE EPPPOTATO EARLY DYING COMPLEX (PED) is one of the most economically devastating diseases Canadian potato growers face each year, and incidence has been on the rise in fields across the country. With few registered chemicals available, an integrated management approach is the best means of control. Early dying in potato occurs when potato plants fail to reach full maturity. As its name suggests, early dying is a complex issue due to a combination of factors, including soil, crop conditions, pathogens and pests. The primary cause of the complex is the soil-borne fungus Verticillium dahliae, which infects potatoes through a plants root system, colonizing and clogging the plants vascular system causing wilt. While infection can occur when V. dahliae alone is present, wilt may occur even earlier or be more pronounced if damage from a root lesion nematode called Pratylenchus penetrans has occurred.Some researchers believe other soil-borne pathogens also contribute to the complex. V. albo-atrum, V. nonalfalfae, soft rot bacteria (Pectobacterium sp.) and black dot (Colletotrichum coccodes) have been pointed out as potential problems. Pathogenic nematodes and nutrient deficiencies can also contribute to early dying.DISEASE SYMPTOMS PED is a devastating disease that has the ability to completely compromise plant health. It can decrease crop quality and lower overall yield, sometimes by asTudor Borza is a research associate at Dalhousie University.much as 50 per cent, according to the Michigan State University (MSU) Extension Bulletin Potato Early Die Complex. Tudor Borza, a research associate at Dalhousie University, explains further.Symptoms of PED first appear in the form of wilt, says Borza. Infected plants will show signs of decline much earlier than those that reach maturity. The leaves of infected plantsmostly the lower leaveswill show chlorosis, and some stems will yellow and die. Inside the stem, the vascular systems will turn a brownish colour. According to the MSU bulletin, there are factors that make V. dahliae even more confounding. For one, the pathogen has a wide range of host crops, including bell pepper, tomato, mint and eggplant. Additionally, microsclerotia produced by the fungus can survive in soil and plant debris for up to 10 years, even in harsh winters. It does not, however, thrive in overly wet soil or under high-temperature conditions.Surviving microsclerotia awaken each spring when stimulated by root secre-tions. The pathogen easily makes its way into roots that have been damaged by nematodes. Once it has entered the vascular system it causes chlorosis, necrosis and foliar wilt.Dahu Chen is an Agriculture and Agri-Food Canada research scientist at the Dead plant material creates space for even more microsclerotia to develop.Fredericton Research and Development Centre.38 SPUDSMART.COM WINTER 2020'