The main pest insects recently discovered to be damaging plantain crops are two species of looper caterpillars commonly referred to as plantain caterpillars or plantain moth(s).
There are also two species of leaf-roller caterpillars and the vegetable weevil that have been observed damaging crops.
Plantain crops most at risk
It appears that a few critical factors contribute to insect damage. Plantain sown as a monoculture, or in conjunction with just clover, appears particularly vulnerable to insect attack.
While first year crops are relatively untouched by pests, those in the second or third year can be badly hit.
Hot dry summers favour plantain moths and can greatly increase caterpillar numbers, while the same factors put stress on plantain, slowing its growth and making it more susceptible to insect damage.
The recent sowing of large plantain crops has meant a huge food resource is available for the pests, which has allowed them, at least temporarily, to outstrip their natural enemies.
Controlling plantain pests
Control options are currently limited and insecticide intervention is likely to be the most successful strategy. For plantain moths and leaf rollers, which have several generations a year, insecticide applied in December may prevent the build-up of very high caterpillar numbers in late summer and autumn.
Look early for the presence of insect pests, especially in plantain only and plantain/clover crops.
If pests are present, control them immediately to prevent population build-up and significant damage to get the best return for money spent.
For more information on plantain establishment and management visit dairynz.co.nz/plantain
This article was originally published in Inside Dairy December 2014