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SPUDSMART.COM SUMMER 201524 inoculum is the recipe for disease but we often have very little control over the amount of moisture and temperature she says noting that growers often dont have a great deal of latitude to be able to manipulate such factors in storage. We know that there are trade-offs when that happens. Its impossible to really give specific parameters but generally speaking the cooler you can store your bin and the lower the humidity this is going to help reduce disease development says Shinners-Carnelley adding that this strategy for disease management must be balanced with maintaining the end use quality of the potatoes. Shinners-Carnelley notes that once potatoes start getting shipped out of storage this elevates the silver scurf risk even further through the movement and disruption of tuber piles which causes spores to spread. You get these secondary infections that come with that she says which can explain why people are so often surprised by the amount of silver scurf they see in the pile compared to what they observed going into storage. The amount of inoculum the storage conditions and the time in storage are really going to determine the level of disease that can develop and what will impact the crop Shinners-Carnelley says. Silver scurf spores can hide away in infested surfaces like concrete and wood within storage facilities. To help prevent the disease showing from one storage season to the next a sensible precaution is making sure the bin is as clean and disease-free as possible before the next batch of potatoes goes in. Its always best practice to be doing a good job of cleaning and disinfecting your storage bins between crops says Shinners-Carnelley. PHOSPHORUS ACID Among the newer weapons against the disease emerging in recent years are phosphorous acid- based fungicides for control of late blight and pink rot that have also demonstrated to be useful in suppressing silver scurf. Research has shown that the post-harvest application of a phosphorous acid product can be an effective treatment measure for controlling the disease in storage particularly when infection levels are low to moderate. Shinners-Carnelley says she participated in storage trials that tested the efficacy of phosphorus acid products for silver scurf suppression back in 2009-10. That was about the time there was a lot of interest in phosphorus acid and what a great chemistry it could be to help with post-harvest issues she says. The testing showed that a yellow potato variety treated with two phosphorous acid products Confine which is currently registered for silver scurf suppression in potatoes in Canada and Phostrol which is currently not registered for silver scurf in Canada had significantly less silver scurf than untreated control potatoes. According to Shinners-Carnelley post-harvest phosphorus acid applications have become standard practice for many growers catering to the fresh market. Its had a significant impact on reducing the level of silver scurf that we see she says. will impact the crop Shinners-Carnelley says. To help prevent the disease season to the next a sensible precaution is making sure the bin is as clean and disease-free as possible before the next batch of Its always best practice to be doing a good job of Tracy Shinners-Carnelleys silver scurf presentation along with other presentations delivered at this years Manitoba Potato Production Days are available online at mbpotatodays.ca2015presentations.html. WHERE ON THE WEB