Potato tuber moth (Phthorimaea operculella, PTM) remains one of the main insect pests affecting potato crops in New Zealand, particularly in the upper North Island. Under hot, dry conditions, infestations can cause yield losses of up to 40%. Field cracking also allows the pest easier access to tubers.
Growers now have a new option for control with the registration of CAPRA®, an insecticide developed by Agrisource and approved by the Agricultural Compounds and Veterinary Medicines (ACVM) authority after four years of local trials.
© Potatoes New Zealand
CAPRA is a Group 22A insecticide containing indoxacarb, an active ingredient from the oxadiazine class of chemistry that targets lepidopteran pests. Indoxacarb has long been used internationally, including in the United States, for managing potato tuber moth.
According to Potatoes New Zealand, the registration of indoxacarb provides an additional mode of action for local growers. Resistance to insecticides is an ongoing issue for PTM management, and having access to a Group 22A product allows for rotation with other chemical groups to help reduce selection pressure.
Field trials in New Zealand compared CAPRA with other commonly used products such as Benevia® (Group 28), Coragen® (Group 28), and Karate® Zeon® (Group 3). Results showed comparable or improved control of PTM when applied according to label directions.
CAPRA functions primarily as a larvicide, protecting by inhibiting feeding soon after exposure. The product also affects eggs and young larvae. The main route of entry for pests is ingestion of treated foliage, with some absorption through the insect cuticle. Feeding stops within several hours, and mortality occurs within two days.
The insecticide is moderately translaminar, allowing it to penetrate leaf tissue for residual protection, and remains stable under varying environmental conditions, including rainfall or irrigation.
Application is recommended at 400 millilitres per hectare, mixed with a non-ionic surfactant. Treatments should begin at the first signs of moths or foliage mining and be repeated every 7–15 days, depending on pest pressure. Crop monitoring is advised to determine if reapplication is necessary.
For resistance management, no more than two consecutive applications or four total applications should be made in a single crop, with subsequent treatments rotated with products from other chemical groups.
Agrisource, based in Pukekohe, worked to secure potato-specific registration for indoxacarb, noting the industry's need for additional tools to manage PTM. CAPRA is currently the only indoxacarb-based product registered for use on potatoes in New Zealand.
© Potatoes New ZealandFor more information:
Potatoes New Zealand
Tel: +64 (0) 800 399 674
Email: [email protected]
www.potatoesnz.co.nz
