Many special techniques had been devised to grow and especially to store kūmara so it did not rot. Careful storage and use of was essential to prevent unauthorised use. Seed kūmara in particular were highly . The main problem for kūmara growers were native caterpillars. Early European explorers reported that Māori often ringed a garden with burning vegetation in an attempt to control caterpillars. Māori continued to use traditional fern roots — — as a normal part of their diet into the mid-19th century.