How to keep spud plantings ahead of disease risk

Threat more prevalent this season

Changing rotations and reduced tillage could explain why a key disease is becoming more prevalent and damaging in potato crops.

Potato growers need to be alert to the threat of Rhizoctonia solani this spring – especially farms moving less soil between crops. Reduced tillage has been shown to encourage survival the pathogen in the soil.

There are also more species of plants being grown in some rotations, whether that is driven by a greater area of cover crops, environmental schemes, or more cash crop options.

In theory, this diversity could reduce the amount of available Rhizoctonia inoculum for susceptible crops – including potatoes. But it also provides more hosts for soil-borne persistence.

Farming systems have changed rapidly over recent years and this has created a knowledge gap that needs filling, says Rumiana Ray, professor of plant pathology at Nottingham University.

“Growers and agronomists need to know the current soil-borne disease situation to assess the impact of these practices and implement alternative or corrective measures, if needed,” says Prof Ray.

Identifying risk

Hutchinsons agronomist and potato specialist Andrew Goodinson says currently that leaves good husbandry, combined with the application of soil- and seed-applied fungicides, as the main control measures where risk is identified.

Where soil-borne risk is identified, Mr Goodinson recommends the use of in-furrow fungicides like azoxystrobin or fluxapyroxad – combining them with a seed treatment where needed.

There are liquid seed-treatment options like flutolanil-based RhiNo and Andrew sees these becoming much more popular in the future as seed is treated in the shed over a roller table ahead of planting.

This takes an operation off a busy planter operator already grappling with accurate seed spacing and in-furrow applications of fungicide and fertiliser, before even considering powder seed treatment application.

But Mr Goodinson says many of his potato growers are still using powder flutolanil formulation RhiNo DSG, as it gives flexibility, particularly where seed is delivered just-in-time for planting.

“But whatever seed treatment you decide to use, effectiveness does rely on excellent coverage. That makes correct setup, calibration, and maintenance of on-planter applicators crucial,” he adds.

Early nutrition

Planting conditions and adequate early nutrition are the final considerations, with timely cultivations and seed-bed preparations that avoid soil compaction key to seeing the crop grow away from the threat of Rhizoctonia.

“Anything that can reduce stress and encourage crop development is a good thing and we are using phosphite-based products as well,” says Mr Goodinson.

“Other biological products will play an increasingly important role in potatoes, but we are still learning about how and when they are best applied for consistent success.”

Save the date for Potatoes in Practice

This year’s Potatoes in Practice event – the annual showcase of the latest developments in the sector – takes place on Thursday, 7 August, at the James Hutton Institute’s Balruddery Farm at Invergowrie, near Dundee.

Profitable future

The one-day show is hosted by the James Hutton Institute through the National Potato Innovation Centre (NPIC) in partnership with Scotland’s Rural College (SRUC), and Agrii and is a must-visit for all those in the potato industry.

The NPIC brings together scientists and the potato industry to develop solutions that will help ensure the future of potato as a sustainable and profitable crop that provides nutritious food for all and supports the British economy.

A range of demonstrations will include cutting-edge research, trade exhibits, and a wealth of knowledge from experts in the field – making it a must-visit for those in the potato industry.

Aimed at fostering learning and innovation, exhibitors will include commercial breeders introducing new varieties, to agronomists demonstrating advancements in crop protection and researchers discussing their most recent findings.

Potatoes in Practice is the UK’s largest in-field event for the industry. Much of the day will focus on commercial potato production while addressing labour issues and growing technical challenges.