Early dying complex in potatoes at first appearance is seemingly inexplicable. The plants were thriving, then they were dying. At that point, a grower has no options.
Because there are no rescue treatments for potato early dying, efforts to manage the disease must be put in place at or before planting. This includes managing the nematodes that can increase the severity of the disease.
"Early dying complex is caused by the soilborne fungal pathogen Verticillium dahliae. Root-lesion nematodes facilitate disease development by feeding on potato roots, which can increase the rate of infection by the pathogen. There is an interaction between lesion nematode and Verticillium wiltthat causes early dying," said Saad Hafez, a University of Idaho nematologist based at the Parma Research and Extension Center.
Managing nematodes, then, not only can increase both quality and yield but can also impact the cost of bringing the crop to harvest and decrease the risk of losing a field to disease.
Managing potato early dying involves an integrated strategy of selecting less susceptible varieties, practicing long crop rotations to non-host crops, reducing plant stress and promoting crop growth, and the management of root lesion nematodes. The first step to successful nematode management is learning which nematodes are putting pressure on a field and at what levels. Growers generally take soil samples in the fall and submit the samples to diagnostic laboratories for analysis.
"About 90 percent of the Snake River Plain potato acreage is infested with the root lesion nematodes of one species or the other," said Kelly Luff, Bayer potato technical representative for Idaho. "A grower needs to keep an eye on the nematode populations, take soil samples, and keep them monitored. If nematodes aren't reduced, the populations can escalate until they are difficult to manage, and result in a significant reduction of tuber yield and quality."
The economic threshold for treatment varies across states, is specific to the species of nematode, and considers the field history.
"Essentially most acres have a nematode issue of one sort or the other. That doesn't mean the population meets the threshold for treatment, but it will be there," Luff said. "So, a grower needs to keep an eye on the populations, keep them monitored."
To make an effective treatment decision, growers should couple their nematode sample report with information on the field history.
"lf the field had early dying in the past, the grower needs to treat at any level of the root lesion nematode," Luff explained.
Combine Tools to Manage Nematodes
A field under low pressure from nematodes can be treated with a combination of Velum® Prime and Movento HL®. At higher nematode levels, the same treatments can be used following a fall soil fumigation treatment. Any crop management plan, of course, must comply with label instructions for each material.
Luff recommends two sequential applications of Velum Prime, one at planting, and the second in ½ to ¾ inches of water at the 6- to 10-inch plant stage or at row closure, depending on the nematode species and population. Roughly 21 days after the last Velum Prime application, Luff recommends treating with Movento HL and then making a second sequential Movento HL application 14 days later.
Velum Prime and Movento HL can also be used to augment an oxamyl program. Application timings are flexible depending on nematode and disease pressure in a given field.
Luff also recommends tank mixing a protectant fungicide with Velum Prime applications, between applications where applicable and ending the season with additional protectant applications. Those fungicides can add disease protection and help with resistance management.
The Payoff: Higher Yield and Improved Quality
"The big advantage of using Velum Prime is the nematode management plus the disease management," Luff said. "We talk a lot about early dying complex, but we can't forget the role that early blight, white mold, botrytis and black dot play in the complex . Velum Prime offers suppression of these diseases."
Data shows a Velum Prime plus Movento HL program increases yield up to 82 hundredweight per acre. With systemic activity, Movento HL offers sustained in-season nematode protection and prevents juvenile nematodes from developing. The disease and nematode control offered by Velum Prime add to the return on investment. Velum Prime offers wide-spectrum nematicidal activity and is an excellent management tool for root-lesion nematodes. Velum Prime also suppresses early blight, white mold and other diseases that can contribute to potato early dying. The overall impact of improved root health also helps create a healthy bottom line.
Whichever direction a grower takes, the goal is efficient, effective nematode management to protect potato roots and increase yield and quality.
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