Field control programs
Three approaches are used to manage insects on waxflowers.
- Crisis approach, where in response to a insect infestation an insecticide spraying program is used to control insects before they cause damage. An example of this is controlling ring barking weevil infestations. In this case an infestation will require treating the soil and root system by injecting an appropriate insecticide.
- Preventive approach, where a regular spraying program is used to prevent the insect from becoming established in plants. This approach is usually required at a specific time of the year. For example, to control waxflower leaf webbing moth larvae preventative spraying needs to start during the autumn months. It is too late once the moth has laid its eggs and the larvae has hatched out and started to eat leaves.
- Integrated pest management (IPM) involves identification and monitoring of insects on flowers and spraying if numbers are sufficiently high. Insect numbers should be managed to within the capacity of the postharvest disinfestation system being used such that it can deal with insect numbers remaining on flowers after field treatment. Applying this approach to thrips involves monitoring insect numbers during the flowering season and once they reach threshold levels, usually 10 per bunch, to start spraying. As many native insects do not damage flowers but co-exist with them, there is no need to spray while flowers are still opening and are not ready to be picked. Spraying needlessly can cause chemical build-up and will cause an imbalance encouraging the movement of more aggressive insects into flowers.
Insect monitoring
This can be done by sampling bunches of flowers and shaking them out over a white surface and estimating the number of insects present. This method also allows type of insect to be identified, which will aid in selecting a suitable insecticide treatment to be used if necessary. The other approach is to install white sticky traps in the field and estimate insect numbers weekly or fortnightly. By keeping records of when numbers of insects get high it will be possible to estimate when spraying is necessary.
In Western Australia, insect numbers are low during July to mid-September and then increase as the weather warms up. Numbers tend to peak when surrounding pasture or crop dries off in mid-October and insects migrate onto waxflowers seeking a food source (the oasis effect). The exact timing will depend on location.
Waxflower varieties that flower later in mid-September to November are at highest risk of being infested with high insect numbers. Flowers should be sampled and insect numbers per bunch estimated after spraying to determine the effectiveness of field spraying treatment and following postharvest disinfestation to determine the effectiveness of the postharvest treatment.