Fight against blight: Potato outgrade hygiene

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This report provides the best practice advice for potato outgrade control, which can act as a reservoir for blight infection.

The report focused on minimizing the impact of potato outgrades. This included easy access to outgrade piles away from potato crops and farm buildings, site piles on land not intended for any crop or any potato crop in the future, not to risk polluting watercourses, locate piles away from ditches and rivers or groundwater etc.

Control measures emphasised on adopting a zero tolerance approach to green foliage on outgrade piles by tackling it early; relying on a late application of glyphosate or diquat + paraquat is a high risk strategy as blight may already have spread by this point. The report also provides a strategy for the prevention of green foliage and highlight regulations for agricultural waste management in the UK.

Fight against Blight Issue 4: Volunteer Control (Groundkeepers)

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Growers’ advice to reduce the impact of blight through cultural methods and the use of herbicides to control volunteer potatoes.

Volunteer potatoes act as a primary infection source by over-wintering infected tubers, and provide unprotected foliage that can act as an entry point throughout the season for blight. They can also act as a reservoir or a host for other problems such as spraing, potato cyst nematodes (PCN), black scurf, black dot, powdery scab etc. Volunteers are also a host for aphids and aphid transmitted potato viruses. The report provides facts backed by evidence from trials about the problem and describes cultural and chemical methods of control as no single herbicide treatment is entirely effective.

An integrated control strategy was suggested emphasising on optimising tuber size distribution, applying maleic hydrazide, setting the harvester to lift smaller tubers where possible, keeping returned tubers near the soil surface, following with a competitive crop, hitting volunteers whenever possible, using selective herbicides in the following crops, using pre-harvest glyphosate, cleaning up stubbles with glyphosate and watching out for volunteers in shaded crops like winter oilseed rape and maize.