b"Dymtro Yevtushenko, research chair in potato science at the University ofOne disease that stands out in the Lethbridge, reports there were a few instances of P. infestans spores beingpast few years is PED, explains detected by the Potato Pest Monitoring Network in Alberta last year, but notMacKinnon. Because weve been enough to raise alarm bells. having warm, dry summers, It wasnt above a certain threshold that makes us concerned, he says.we're seeing a lot of challenges For the last two years now, there has been no late blight incidence, whichwith potato early dying, and is great.this is impacting yields for Because of the mild and moist Maritime climate in Atlantic Canada, Princethe processing varieties Edward Island and New Brunswick have historically had more issues with lateProducers here are quite blight than most other potato-growing regions in the country. But conditionsconcerned about it.have changed in recent years, with warmer, dryer summer weather thatsFumigation, which kills reduced the threat posed by P. infestans pathogens.the verticillium and root lesion Because of the weather pattern that we've been in for the last four ornematodes associated with PED, five years, late blight has dropped way down on the list diseases of concern,is a common control measure forA potatoexplains Lorraine MacKinnon, potato industry co-ordinator with P.E.I.s Depart- the disease, but its not permittedplant infected ment of Agriculture and Land.in P.E.I. MacKinnon says as a result,with black dot disease. We have gone a few seasons now with no detection of late blight sporesIsland potato producers may be lookingPHOTO: VIKRAM on the Island. There hasnt been inoculum sitting around, she adds. Thereat adding a biofumigant crop to theirBISHTare also changing strains of late blight that are perhaps a little less aggres- rotations this year.sive in the foliage, and we do have a lot of effective control products. Mustard is becoming quite common for a couple of reasons. Studies MacKinnon, along with the other experts, cautions growers againstshow mustard to be effective against verticillium in the soil, but it has some letting down their guard against late blight, which is capable of wiping outbenefits for wireworm control as well, says MacKinnon. an entire potato field in a matter of days and also affects the quality andThere's also a lot of research being done on the effect of sorghum-sudan-storability of tubers.grass, pearl millet and other rotational crops that can reduce the amount of Theres always a risk that late blight will return to P.E.I. fields. Weath- verticillium and/or root lesion nematode in the soil.er-based predictive modelling and spore traps are very effective in in-season,Van Dyk says while PED may not be as big a problem in Ontario as it is the but they cant predict the situation in advance of a growing season, she says.Maritimes, its definitely on the radar of growers in his province with growers Khalil Al-Mughrabi, a pathologist at the Potato Development Centre withwho had problems with it, fumigating and looking into other soil health the New Brunswick Department of Agriculture, Fisheries and Aquaculture,measures. agrees with the sentiment as late blight has not been found in the MaritimesWe had a fairly good harvest, so if growers were going to apply a fumi-the past three years. He notes though that through a national researchgant for fields that they thought were high in verticillium and nematodes, they program, work continues on developing new disease management strategieshad an opportunity to do that in the fall because there was time to do it, he as well as assessing the efficacy of registered fungicide products against theexplains.predominant strains of the late blight pathogen. Bisht notes black dot and verticillium wilt, both within the PED complex Al-Mughrabi says in New Brunswick, a late blight forecasting programof diseases which cause early dying, have been increasing in importance in based on weather conditions conducive for late blight development, and aManitoba in recent years. While the weather plays a large role in the incidence spore trapping system which covers the potato growing regions in the prov- of both diseases, Bisht expects disease pressure will remain high this coming ince, are being actively implemented in order to predict for late blight. season in areas with a history of black dot and verticillium wilt.Van Dyk notes Ontario is keeping an eye out for a new late blight strain,Yevtushenko says concern over PED is increasing in Alberta as well as a US-25, as well as a late blight look-a-like, Phytophthora nicotianae, which ischanging climate is raising the risk of it.a related species to P. infestans and causes foliar symptoms similar to late The planting area is expanding, and crop rotations may get shorter, and blight. Both have been detected next door in New York state, so growers arethis will eventually lead to higher accumulation of verticillium in the soil, so urged to send samples of any plants exhibiting late blight symptoms in forwith higher pathogen pressure we anticipate that the incidence of this disease strain identification testing.will probably go up, he explains.PED PROVINCIAL BREAK DOWNWhile the late blight situation has improved, there is rising concern across theBlackleg in ManitobaAccording to Bisht, cool, wet planting conditions country about another crippling potato diseasepotato early dying (PED)last spring led to a relatively high incidence of the bacterial disease in complex.Manitoba potato fields last year which not only affected yields, but also SPRING 2021 SPUDSMART.COM 13"