Mites under the microscope through levy‑funded IPM program

The investment Management of six-spotted mite in WA avocado orchards – phase 2 (AV19002) is delivering effective options for the integrated pest management (IPM) of six‑spotted mite in avocado orchards.

Beginning in 2019, it follows previous levy-funded project Pest status and management of six-spotted mite (Eotetranychus sexmaculatus) in WA avocado orchards (AV15012), which sought to assist growers in monitoring mite populations and implementing appropriate management techniques, as well as investigating the role that predatory mites could play during production. The project team produced the Monitoring for six-spotted mite in avocado orchards guide and laid the groundwork for this phase two investment to further industry understanding of how to manage the pest.

In order to develop a comprehensive integrated pest management plan for growers – which will be extended via demonstration sites, online materials and articles in the levy-funded Talking Avocados – the research team is investigating:

• The use of mass-reared predatory mites as a form of six-spotted mite management
• The role of naturally occurring predatory mites
• The relationship between tree health, mite numbers and leaf fall
• Chemical application recommendations based on resistance management, impact of chemicals on beneficial species, and the impact that timing and/or application methods have on the level of pest mite control.

Meet Frank Cousins, avocado grower from Channybarup, Western Australia

Frank Cousins is the commercial manager at Treen Brook Farm, a 67 hectare avocado orchard in Channybarup, WA. With his brothers in law, Frank is part of the management at other Ipsen managed farms making up a total of 400 hectares of avocados in the south-west of WA.

What is the challenge?

“Six-spotted mite is an issue in our region that we’ve been trying to deal with for a while. It can have severe consequences to fruit currently on the tree and for fruit for the next year due to leaf defoliation. We need to figure out when and how to manage them because sprays are expensive and we need to be mindful of future chemical resistance.”

What have you learned so far from this project?

“Identifying the species that are on the leaves can be challenging as they’re so small. And they’re not all pests, some are beneficials – the predatory mites. The team are getting some better images of the different mites to help improve identification.”

Identifying the species that are on the leaves can be challenging as they’re so small. And they’re not all pests, some are beneficials – the predatory mites. The team are getting some better images of the different mites to help improve identification.” Frank Cousins, avocado grower

“There were definitely some positives from the project, like showing that an autumn application is the best one. If you get that right, you can potentially get away without doing a spring spray. This is important as it coincides with the flowering/pollination period. Other things for good management also came out, like the right temperature for using some miticides, the correct water application rate – making sure it’s not too low. Coverage to make sure the miticide reaches the underside of the leaves is critical as this is where the mites are found.”

What future benefits do you think this project will bring industry?

“In the long-term using monitoring, good coverage and timing in the right conditions will help prevent the development of resistance to insecticides. Each year is different so having the seasonal data across different orchards helps make the right decision. A better understanding of tree health and the wider beneficial ‘insect’ community and their role in pest management will also help with the system approach.”