What are Spider Mites?
Spider mites are tiny arachnids that are sap-sucking pests and typically only 0.5mm long, but with the ability to wreak havoc on bonsai trees. During Autumn and Winter they will be a red colour, while in Spring and Summer they are likely to be a pale green in colour.
Spider mites thrive in hot, dry conditions, greenhouses are perfect as are amongst the foliage of many bonsai trees.
What Trees do they infest?
They are commonly found on a wide range of plants, and can cause significant damage if they are left unchecked.
Spider mites can infest many type of bonsai including Junipers, Pines, Elms, Maples, Oaks and many other species.
How to Spot them
- Due to the small size, it is almost impossible to spot the mite itself
- Spider mites produce a very fine webbing during spring and summer, so keep an eye out for them
- A bonsai will loss of vigour, colour or with mottling on the foliage is likely to have a spider mite infestation
- Tap the foliage while holding a piece of white A4 paper underneath, you should be able to see the mites falling off on the paper to confirm an infestation
Non Pesticide Control
- Firstly, keep your bonsai in good health, a healthy tree is more able to resist the attack of spider mites allowing time for treatment
- As spider mites like hot and dry conditions so try to increase air flow, and humidity where possible
- The most common biological pest control for spider mite is Phytoseiulus Persimilis, which feed on the mites and their eggs
- Try using a non-biological washing up liquid mixture to spray the aphids, this will suffocate the insects and their eggs
- You can treat and kill off overwintering spider mite using Vitax Winter Tree Wash between November and February
- Also treat any winter storage areas such as a greenhouse or shelter
- SB Plant Invigorator combines a fatty acid based surfactant and nutrients to stimulate plant growth at the same time
- You can purchase SMC Spider Mite Control which is also a fatty acid based surfactant
- For persistent infestations you can use a chemical based insecticide such as Provanto Ultimate Bug Killer or Bug Clear Ultra to break the aphid cycle