Are your lemons an unusual shape? Are your oranges distorted? Wondering why your mandarins have developed separate fingers? It might be citrus bud mite. Find out more about these citrus tree pests, whether they are harmful and what you can do about them.
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What are citrus bud mites?
Citrus bud mite (Aceria sheldoni) is a tiny mite that feeds in the leaf and flower bids of citrus trees. It is so small (less than 0.2mm) that you can’t see it with the naked eye. The mites themselves are like tiny, pale coloured worms. Mites are prevalent from spring, through summer and into autumn and can have around 20 generations of mites during that time. A female mite lays up to 50 eggs during her life, so it’s easy to see how a tree can get infested quite quickly.
Types of citrus affected by citrus bud mite
Lemons (like Eureka and Lisbon lemons) and naval oranges are more likely to be affected by citrus bud mites. However, any other types of citrus can be affected too. In my garden, only my potted mandarin is affected by these annoying pests.
How can I tell if my citrus tree is affected by mites?
Because the citrus bid mites are so small, they are hard to see even with a magnifying lens. The fact that they live inside the buds also makes it difficult. So the main way to tell if your tree is affected is by noticing changes to the fruit and leaves.
Damage to leaf buds can cause leaves and branches to twist and distort. You can see from the photo below that the leaves on my mandarin have unusual indentations.
Where flower buds are affected by mites, the flowers can turn black and drop off. If the flower does go on to produce fruit, the fruit can be quite strangely deformed – like the many fingered mandarin from my tree above..
How to treat citrus bud mite
Once you start to notice oddly shaped fruit and leaves, it’s usually too late to do anything about citrus bud mites. The time to treat is before your citrus tree starts to form leaf and flower buds. In other words, before the mites have settled into the buds to feed.
Should you treat it at all?
Some people say that you don’t need to treat trees with citrus bid mites at all, because your citrus trees will continue to produce fruit that is still edible. Certainly if you only have a minor infestation, you might just put up with a few oddly shaped lemons, oranges or mandarins. They can be quite a talking point after all!
However, in my experience, once a tree is infested with citrus bud mites it does affect fruit production. My mandarin tree certainly has less fruit, which is smaller and more prone to falling off before it ripens properly. Fruit that does mature can be so distorted in shape that it is next to inedible – like the weirdly shaped mandarin above. Not only that, it seems to be more vulnerable to other citrus pests.
Trees affected by citrus bud mites can also have badly distorted foliage and leaves. Whether you treat your trees will depend on how much the appearance bothers you.
Avoid using insecticide sprays if possible
If you do decide to treat your citrus trees for bud mites, please think carefully about using an insecticide or mite spray. You might end up killing the good insects and predatory mites that help keep your tree healthy.
For a lemon, orange or other citrus tree with only a few affected buds, you could choose to just prune or remove the affected branches, foliage and fruit. Place the pruned sections in a plastic bag in the sun for a few days to ensure the mites are dead before disposing of.
If you need to spray
If you have a more severe infestation of mites, you can opt to spray with a horticultural oil. Unfortunately this can still affect the beneficial insects and mites too. My poor mandarin really did need some attention, so I have applied a citrus spray containing natural pyrethrum mixed with canola oil. It’s still an insecticide, but is at least a little less toxic than some other options and is suitable for organic gardening. Using an oil may help interrupt the citrus mite lifecycle.
For a more effective treatment, you can use a citrus spray containing sulphur to control citrus bud mites if sprayed a couple of months before flowering. Personally I’d only do this as a last resort.
When spraying your citrus trees, try to do this in the early morning or the evening to minimise harm to beneficial insects. Don’t spray when the weather is too hot, windy or when it’s forecast to rain. Aim to apply any treatment before buds are ready to open into flowers or leaves.
Disclaimer: These notes about spraying are for general information only. If you have any questions about whether a product is suitable for your needs, speak to your local garden centre or contact the manufacturer. Please also make sure to read and carefully follow any instructions on the labels of citrus pest sprays.
Prevention is better than cure
Weakened citrus trees are more prone to attack from pests like citrus bud mite. If you look after your citrus trees well by feeding and watering regularly, this will help to keep pests at bay and avoid the need to use sprays, organic or otherwise.
References and more information
For more information about citrus bud mites, see the following references we’ve referred to in this post:
- NSW Department of Primary Industries, Mite Pests of Citrus
- NSW Department of Primary Industries, Growing Lemons in Australia – A Production Guide – Pests
You might also like to read our post about another citrus pest, citrus gall wasp.
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