Citrus gall wasps are a common pest that can wreak havoc on citrus trees, causing deformities, reduced fruit production, and general stress to the plant. If left untreated, the galls they create (swellings on branches caused by their larvae) can severely weaken the tree. Thankfully, with the right techniques and timely intervention, you can control citrus gall wasps and maintain healthy, thriving citrus trees. Here’s a guide to help you deal with this troublesome pest.
Understanding Citrus Gall Wasps
The citrus gall wasp is native to Australia and primarily targets citrus trees, including oranges, lemons, and limes. Adult wasps are small and black and typically emerge in spring when they lay their eggs inside the soft, new shoots of citrus trees. The eggs hatch into larvae, which develop inside the branches, forming galls that grow larger over time.
These galls disrupt the tree’s natural growth and sap its energy. By the time the galls are noticeable, the larvae are often well-established, making it crucial to act at the right time to prevent future infestations.
1. Prune Affected Branches
One of the most effective ways to control citrus gall wasps is to prune off the affected branches that contain galls. Here’s how to do it:
- Timing Matters: Prune during late winter or early spring, before the wasps emerge from the galls and lay new eggs.
- Dispose Properly: Do not leave the pruned branches on the ground, as the larvae can still hatch. Instead, burn or bag the branches in a sealed plastic bag and dispose of them responsibly.
Pruning not only removes the current infestation but also encourages new, healthy growth on your tree.
2. Use Citrus Gall Wasp Traps
Traps are an excellent preventative measure to control citrus gall wasps before they can lay eggs. These traps work by attracting the adult wasps and preventing them from reproducing.
- Sticky Traps: Place sticky traps in your citrus tree during early spring when the wasps begin to emerge. These traps use a pheromone or color to lure the wasps and trap them on a sticky surface.
- Positioning: Hang the traps close to the canopy of the tree for maximum effectiveness.
Using traps reduces the population of adult wasps and prevents future infestations.
3. Avoid Excessive Fertilising
Over-fertilising your citrus trees, especially in late summer and autumn, can encourage the growth of soft, new shoots that are highly attractive to citrus gall wasps. To avoid this:
- Apply Fertiliser Sparingly: Fertilise in early spring and mid-summer to promote healthy, moderate growth.
- Use Balanced Fertilisers: Avoid high-nitrogen fertilisers, which can lead to excessive leafy growth.
Controlling the timing and amount of fertiliser can make your tree less appealing to gall wasps.
4. Apply Wasp Deterrents
Protective sprays can be applied to your citrus trees during the active season of the citrus gall wasp. These sprays create a barrier that prevents the wasps from laying eggs.
- Kaolin Clay Spray: This organic spray coats the branches in a fine layer of clay, making it difficult for the wasps to deposit their eggs. Reapply as needed during spring and early summer.
- Horticultural Oils: Some oils can also help deter egg-laying and suffocate any larvae in their early stages.
Choose environmentally friendly products to protect beneficial insects in your garden.
At Sage Horticultural you can find Vasili’s Citrus Guard White Spray in 2 different sizes:
- Vasili’s Citrus Guard White Spray – CGWS – 200g
- Vasili’s Citrus Guard White Spray – CGWS – 600g
5. Encourage Natural Predators
Encouraging biodiversity in your garden can help keep citrus gall wasps under control. Several natural predators, such as parasitic wasps, prey on citrus gall wasp larvae.
- Plant Companion Plants: Include nectar-rich plants near your citrus trees to attract beneficial insects.
- Avoid Pesticides: Broad-spectrum pesticides can harm natural predators, so opt for targeted or organic control methods instead.
By fostering a balanced ecosystem, you reduce the likelihood of citrus gall wasp infestations.
6. Monitor Your Trees Regularly
Regular monitoring is key to early detection and management of citrus gall wasps. Inspect your trees frequently, especially during the active season in late spring and early summer.
- Look for Galls: Check for any swelling or lumps on branches and take action promptly if you spot any.
- Check Traps: Monitor traps to gauge the severity of the infestation and adjust your control measures accordingly.
Staying proactive helps you prevent small problems from becoming big issues.