Early bird may avoid verticillium woes in potatoes – Manitoba Co-Operator Achi-News

Verticillium wilt is a problem for many crops in Manitoba, including canola, sunflowers and alfalfa.

In potatoes, the fungus Verticillium dahlia is the main cause of potato early dieback complex. In an interview in 2021 with the Collaborator, Mario Tenuta, a University of Manitoba soil scientist and lead researcher with the Canadian Potato Premature Dying Network, suggested the condition can cause a yield loss of five to 20 percent. Other US research puts that number as high as 50 percent.

It also becomes a marketing problem when shrink spud doesn’t match processor preferences.

Verticillium wilt in potatoes can significantly reduce yields and, as it is soil borne, is difficult to control.

Preliminary research results suggest that earlier planting of risk-prone fields may reduce losses, in part due to cooler soil temperatures earlier in the season.

Unlike other potato fungal issues that can be tackled with a foliar fungicide, verticillium hides in the soil.

“Typically we use soil fumigation and that’s very expensive,” said Julie Pasche, a plant pathologist with North Dakota State University.

There are options. In 2017, it expanded labels for the fungicide Aprovia, Syngenta’s broad-spectrum solution for leaf spot or powdery mildew in various horticultural crops. In-furrow verticillium prevention for potatoes was added to the label.

There has also been interest in biofumigation. Mustard has been tagged as a potential companion crop for potatoes, thanks to its production of glucosinolate and the isothiocyanate substance that inhibits pathogens and pests.

Last fall, producers learned that a new sterile mustard variety designed specifically for bio-fumigation had been cleared for sale in Canada, although seed supplies for 2024 are expected to be thin. AAC Guard was specifically noted for its effectiveness against verticillium wilt.

Timing is everything

Researchers at NDSU want to study the advantage of natural plant growth patterns.

“What we would like to look at are other things we can do differently, like verticillium fertility control and water control, as well as some other areas and how they might be affected by planting date,” said Pasche.

The idea is to find a chink in the fungus’ life cycle.

Verticillium infects roots in the spring. From there, it colonizes the plant, moving through the root vascular tissue and into the stem. This is the cause of vegetative wilting in the season, Pasche pointed out.

As it progresses, plant cells die, leaving black dots on dead tissue. Magnifying those dots reveals what look like dark bunches of grapes – small spheres containing melanized hyphae, a resting form of the fungus called microsclerotia.

The dark color comes from melanin, the same pigment found in human skin. This pigmentation protects the microsclerotia from ultraviolet light.