One thing Northwest potato growers can count on every year is white mold showing up.
Why? Because the prevalent disease is long-lived in the soil and it grows on other host crops, such as dry beans, making crop rotation difficult. The destructive disease can take a big bite out of potato yields.
“White mold is a fungal disease in the genus Sclerotinia that can cause extensive damage to your potato crop,” says John Aigner, Technical Service Lead of Specialty Crops at UPL. “Also known as Sclerotinia stem rot, white mold can affect over 400 plant species, but it’s commonly found in potatoes across North America.”
The fungus thrives in high moisture areas with moderate temperatures below 85 degrees F. Sclerotia germinate in spring and produce small, inverted, mushroom-like structures called apothecia that shoot spores into potato foliage.
“The disease presents as water-soaked lesions that will develop a white cottony growth that can spread fast between stems and leaves, especially if there’s a lot of moisture or humidity in the canopy,” says Aigner. “One of the best ways to keep it in check is to prevent before it starts.”
If white mold does not find an acceptable host, the fungus will be incapable of continuing its life cycle. Cultural practices to limit white mold include eliminating weed hosts and crop rotation with non-susceptible hosts, such as corn, for multiple years.
Besides several cultural practices, one rotational option preferred by many growers is TOPSIN® M WSB fungicide from UPL. “It’s a broad-spectrum, Group 1 fungicide that provides reliable control of white mold, particularly when growers start protective programs during bloom,” says Aigner.
A systemic fungicide, TOPSIN-M fungicide moves from top to bottom and upward and outward within the leaves and stem of the potato plant. For resistance management, UPL recommends that TOPSIN be rotated with fungicides in different FRAC groups.
“Another advantage is that TOPSIN-M can be tank-mixed with products like MANZATE® PRO-STICK™ fungicide, which is used for early and late blight control,” adds Aigner. A standard in almost any disease-management program, MANZATE PRO-STICK has effectively been used for decades without a reported incidence of resistance.
To hear John Aigner interviewed by Pacific Northwest Ag Radio Network, click here.
For more information on UPL or products, contact your local sales representative.
