Update on potato tuber moth in South Africa

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Potato tuber moth remains a concern to many potato producers in South Africa’s key production areas. This pest causes severe damage to potatoes, which results in losses to growers due to its impact on quality. The spread of this disease can be attributed to high summer temperatures.

Potato tuber moth reaches the potatoes underground through cracks in the soil and producers can reduce these cracks through irrigation. This practice is unfortunately challenged by the current intense load shedding the country faces. Infected potatoes are a source of a secondary infestation, which is why they must be discarded and buried at a depth of at least 50cm.

Read more about moth damage on potatoes here.

Potatoes SA commissioned a research study by Prof Hannalene du Plessis of the Unit for Environment Sciences Management at the North-West University to evaluate the status of susceptibility of potato tuber moth to some of the registered insecticidal options. This study showed a shift in the sensitivity of the pest to some of the important insecticides. It is advised to rotate existing insecticides to optimise efficient insecticidal control.

The following is a nine-point plan to mitigate potato tuber moth infestations:

  • T – Take note of population trends by monitoring.
  • U – Understand the product label.
  • B – Bury infected tubers at least 50cm deep.
  • E – Engage with neighbours to align treatment strategies.
  • R – Rotate insecticides according to their modes of action based on guidelines from the Insecticide Resistance Action Committee (IRAC). Click here to download a copy of the guidelines.
  • M – Manage cracks through ridging and irrigation management.
  • O – Optimal coverage.
  • T – Timely application based on label recommendations.
  • H – H2O: do not cut water volumes and use irrigation to manage cracks.

For more information, send an email to Dirk Uys of Potatoes SA at dirk@potatoes.co.za or to Prof Hannalene du Plessis of the Integrated Pest Management Programme of the Unit for Environment Science Management at North-West University at hannalene.duplessis@nwu.ac.za. – Press release, Potatoes SA

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