What’s a good Kiwi meal without spuds? We may have to contemplate that prospect as the tomato/potato psyllid (TPP) makes inroads into a favourite vege.

While not a mortal threat to the potato crop, TPP drastically reduces tuber yields and quality, and may cause some growers to cash in their chips.

The psyllid, a plant-feeding insect, transmits diseases that cause leaf yellowing, plant death, and brown markings – the ‘zebra chip’ symptom – which give a burnt flavour to cooked potatoes.

Worst affected are the floury varieties most suited to processing – so those World Rugby Cup TV snacks may end up costing more as growers battle with the beetle.

Research and Innovation Manager for Franklin growers A S Wilcox and Sons, Monty Spencer says: “We’re managing the problem, but at a price and eventually it will cost the consumer.”

Crop impacts (yield and quality), control costs (extra insecticide spray applications) and other expenses such as seeds, monitoring and compliance all contribute to the $120 million borne by the potato industry since TPP’s discovery in 2006.

Monty emphasises that extensive (and expensive) research on predators and introduced disease and fungal pathogens requires much time and care before implementation, to avoid upsetting existing ecosystems.

“There are also lots of studies of spraying techniques, but it’s very hard to get adequate coverage to the bottom of the canopy and on the underside of  leaves where the psyllids live. They are good flyers, making them difficult to contain.”

Timing of sprays is crucial and must be accompanied by constant monitoring for the presence of insects. Coming into summer insect populations increase with the temperature. The Auckland area, producing 27% of the national potato crop, is second worst affected by TPP (Hawkes Bay’s hot, dry summers suit the insect best).