b"Phosphite Resistance?Phosphite resistance might not be to blame if potato protection is starting to lack. BY: ASHLEY ROBINSONONE QUESTION Jeff Miller has been getting a lot recently isjust aren't as strong of a fungicide as the Mefenoxam is.if phosphite resistance is a thing? He has been hearing this moreThe second tests they did looked at application timing. A often as people are using phosphites more and are starting to seeprevious study done by Gefu Wang-Pruski with Dalhousie more disease on their potato crops.University found the longer the amount of time a phosphite has The questions have been asked, are we developing resistanceto absorb into a plant the more uptake there is. Miller says this in the phosphites? Or perhaps is irrigation interfering withshows that if you want to irrigate, you need to choose an interval the use of our product? Miller, president and CEO of Millerwhich will allow for phosphite uptake in the plant.Research, says during a potato storage management workshopMiller has heard recommendations of waiting 48 hours after in Portage la Prairie, Man. on Dec. 8, 2021. Or is the timing ofphosphite application to irrigate. However, in southern Idaho application optimal? Is there a way to improve how when wewhere Miller Research is based, theyre unable to wait 48 hours make those sprays? due to how hot it gets during the summer.To find out if this is in in fact the case, Miller and his team haveUsually in the heat of the summer, we may be able to have the completed a number of tests.pivots off for half a day, maybe a day, we might be able to go 24 First, they experimented to see if application rates affecthours, but there's no way we could go 48. So that could be a deal protection levels. Miller and his team tested in a lab to see howkiller out the gate, he says, adding this could be why growers fungus reacts to application concentrations. At a lower rate theare finding phosphites arent working as well.fungus grows, but as the fungicide concentration increases, theMillers team then tested irrigation timing. They used a 48-hour relative growth rate drops. It was found it takes almost 10 timesrevolution on a centre pivot. Plots throughout the field were the concentration of phosphorus acid as it does Ridomil to getsprayed in order for the pivot to water them at various time frames.the same level of growth reduction. What we took from this is that maybe we don't need to wait The take home message here is that the phosphorus acids48 hours. In fact, it doesn't appear that we're gaining anything are weak fungicides when it comes to managing pink rot. Andby waiting longer than 12, he explains, adding they tried to that's why we have to use rates that are so high, Miller explains.replicate these results in future but didnt get adequate pink rot He adds current recommended usage rates are high and areinfection in field. necessary for adequate disease control. Grower shouldnt useMiller doesnt doubt though there is more phosphite uptake reduced rates as they wont see as good results. the longer you wait to irrigate, but he found plant protection It does suggest that or indicate that we aren't seeing resistancelevels off at around 12 hours. to the phosphites. This also does point out that the phosphites SPUDSMART.COM Winter 202243"