Pound Disease to Produce Potatoes Aplenty

April 29, 2019

Learn how to control disease in potatoes to increase yield.  Learn the effective options growers have for controlling disease.

Ask Jeremy Shuler where a potato grower’s priorities are for crop management and his answer is immediate: getting crops in on time and preventing disease. A grower doesn’t have much control over timeliness, but today he has effective options for controlling disease.

“Fourteen or so years ago, it seems like we were using very, very few chemistries. But with the disease pressures we have today, what we’re putting on these crops has increased five times over what we used to do,” said Shuler, a sales manager for Wilbur-Ellis. “Yet, the chemistries are better for the environment. So, I think the quality of the food growers are raising is better and the yields are larger.”

The basics for controlling disease and nematodes in potatoes are similar to those of any crop. The devil is in the details.

  • Rotate crops

    Rotating with non-host crops decreases pest pressure.

    Rupert, Idaho, grower Randy Bauscher prefers a four-year rotation with potatoes. Depending on crop prices, however, that can constrict to a three-year rotation. “The more time the ground has to rest between crops, the better the potatoes will do,” Bauscher said. “But it’s driven economically. Grains are just a break-even crop and the potatoes make some money. So you try to put potatoes in as often as you can.”
  • Sample the soil

    Soil sampling is necessary to manage nematodes. Nematode management is essential to protect roots and reduce the opportunity for disease to enter the plants.

    “Sampling is important so we’re applying products when we need to apply them. Being smart about those applications and being good stewards of the chemistries that we have available to us is important for the future,” said Mike Hubbard, founder of Hubbard Ag Science, Connell, Washington.
  • Control nematodes

    Bayer Technical Service Representative Justin Luangkhot recommends sampling for nematodes, writing a field prescription based on the sampling results, then sticking to it.

    “If you are trying to decide if you want to use a nematicide to control nematodes and you wait and let the nematodes move into the plant, effectively you've already lost the battle. The damage has already been done,” Luangkhot said. “Ideally, you want to be ahead of them, control them before they move into the roots, protect the plant.”

    Luangkhot recommends using Velum® Prime in a fumigation-based program. “Come in with Velum Prime at-plant or your first chemigation. That way you're extending your management window. Velum Prime inhibits nematodes from feeding on the roots and it also provides some disease suppression because the active ingredient translocates up in the plant to suppress pathogens from moving within the plant.”
  • Diversify your programs

    To manage resistance, the rule was once to rotate between different modes of action. Today growers also incorporate the use of multiple modes of action in the tank for key applications such as row closure.

    “The majority of growers are trying to diversify their fungicide programs in a way that they’re not relying on a single mode of action,” said Jeff Miller, owner and principal investigator at Miller Research in Rupert, Washington. Miller Research annually surveys those who attend the grower meetings they host to evaluate which agronomic practices are in use. “Early on the surveys showed about 25 percent of growers were tankmixing. When we asked growers this question last year, about 80 percent said they were tankmixing.”

    The purpose of resistance management, of course, is to maintain product efficacy. Continued efficacy is one of the reasons Miller recommends Luna Tranquility® fungicide for control of white mold, black dot, Botrytis leaf spot and early blight, including strobilurin- and boscalid-resistant strains. Luna Tranquility offers two sites of action, effective control of all labeled diseases even when applied through chemigation and exceptional efficacy.

    “When we first started using Luna Tranquility we were getting about 100-percent control. It was amazing,” Miller recalled. “Today, we’re still in that 90-percent plus range. At the end of the year, my untreated checks will be about 25-percent defoliated and the Luna® usually is 5 percent or less. Because of that, for growers who are dealing with early blight and white mold, Luna Tranquility is the product of choice.”

    Put a disease control plan with resistance management in action and the result is higher yield and increased tuber quality, Shuler said.

    With Velum Prime, we have seen an increase in yield,” Shuler said. “And when you couple Velum Prime with Luna Tranquility – use both of those products in the same season at the timing that you think is best for that crop, depending on when it was planted – we've seen a bump in yield on the potatoes and we've also seen a bump in quality.”

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