Tomato-potato psyllid

Active from late spring through summer and autumn, October to April, and year-round in greenhouses.

The tomato-potato psyllid, or TPP, is a tiny sap-sucking insect that arrived in New Zealand in 2006 and hits tomatoes, potatoes, capsicums and tamarillos hard. Beyond direct feeding damage it spreads a bacterium that yellows and stunts plants and rots potato tubers, so early action matters.

How to identify

• Adults like tiny winged cicadas about the size of an aphid, jumping when disturbed
• Yellow, stalked eggs along leaf edges and tiny scale-like nymphs on undersides
• Yellowing, purpling and upward cupping of leaves
• Stunted plants, poor fruit set and sugary white waxy deposits called psyllid sugar on leaves
• Brown streaking inside potato tubers when cut open

How to prevent

• Cover tomatoes, potatoes and tamarillos with fine insect mesh from planting
• Remove volunteer potatoes and weedy nightshades that carry psyllids over winter
• Lay silver or white reflective mulch under plants to confuse incoming adults
• Inspect and isolate new seedlings, since psyllids hitch in on transplants
• Clear and bag infested host plants over winter rather than leaving them standing

How to control organically

• Hang yellow sticky traps to monitor adults and time other measures
• Spray neem oil over leaf undersides, repeating every 5 to 7 days to catch nymphs
• Use a soap spray on light infestations, covering undersides thoroughly
• Encourage and protect ladybirds, lacewings and the parasitic wasp Tamarixia, the main natural enemies
• Remove and bag the worst-affected plants to cut the source quickly