b"How does aphanomyces function? Weve had a significant number of Aphanomyces is a highly specialized path- fields in 2020 with significant root rot in ogen of legumes with long-lived restingthem. When you look back at the his-spores that are able to germinate when wetory, those fields had pulses, either peas have a favourable environment, which isor lentils, in 2016. That reinforces the fact John Ippolito usually warm soil temperatures and exces- that not only do we need long rotations, Crops Extension Specialist sive soil moisture. It was virtually unheardbut we probably have to pay attention to Saskatchewan Ministry ofof in Saskatchewan until 2012.what happened the last time we had that Agriculture crop growing. John has a B.Sc. in agricultureHow does one tell the difference between from the University ofaphanomyces and fusarium? How long are recommended rotations if apha-Saskatchewan. Since joiningWith aphanomyces, youre going to seenomyces is present?the Saskatchewan Ministryyellowing of the shoots above ground,We're currently saying a minimum of six of Agriculture, he has helda pinching of the stem right at the soilrotations. Ideally, we'd like to see some of the positions of extensionsurface. The one most commonly referredthem go to eight, as Mira said. In one field agrologist, agribusinessto is the honey-brown colour on roots,that was identified as having aphanomy-development specialist, andas opposed to fusarium where the topces in 2017, the grower actually had been is currently crops extensionmay still look healthy, but the infectionpracticing a four-year rotation and the last specialist in Kindersley. is started where the seed is attached, andId heard from him, he said he wasnt sure quite often blackens the taproot in particu- when hed try to put pulses back on there. lar. To be honest, over the years, in a lot of cases we visually identified fusarium whenCan you speak to the efficacy of seed treat-aphanomyces could have been present asments, if any?well.There is seed treatment available for suppression of aphanomyces in particu-Why is the problem getting worse? lar, and then of course the normal seed 2012 was the first time aphanomyces wastreatments we would use on pulses have positively identified in Western Canada.an impact on fusarium and other patho-There was extensive surveying done aftergens. Unfortunately, what were finding that. There were actually samples collectedwith these root rots is the control effect or from roadsides, native and tame foragesuppression effect from the seed treat-fields as well, and it was found that aph- ments is not nearly long-lived enough. anomyces was present in those fields asWere finding quite often its into June and well, only at much lower levels. That leadsmaybe even early July when we get a rain-us to believe that it has probably alwaysfall event that were seeing the pathogens been here, naturally occurring, but someexpress themselves. I would advise using of our cropping practices over the last 30seed treatments for things like fusarium, to 40 years have multiplied the pathogenbut in terms of expected control of aph-significantly. Some natural or native hostanomyces, theyre probably not going to plants such as purple prairie clover andgive the desired result. white prairie clover have acted as hosts. On roadsides, of course, alfalfa can also beIs there a fungicide available to help?a host. No. Theres no kind of in-crop manage-ment tool for this disease. Thats why its What conditions can exacerbate the problem? so critical that we manage it up front. Tight rotations with peas and or lentils have definitely contributed to the buildupHow transferrable is aphanomyces between of aphanomyces. Soil texture as well playsfields on equipment? a role. Were finding this is most preva- Given that it is soilborne, you might want lent on clay loam and clay soils that haveto almost treat your equipment like you less-than-ideal drainage. Soil compaction iswould treat it for clubroot in terms of also a contributing factor.cleaning it off from field to field. JANUARY 2021 GERMINATION.CA 35"