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I’ve been growing Lupins for over 20 years and, unfortunately, am no stranger to the pests that will take a liking to your Lupins. Generally, Lupins don’t seem to suffer too badly from pests and diseases. However, the two main culprits are slugs/snails (which I class as 1 pest), which usually take a liking to new foliage but will also attack older foliage as shown in my main picture above. The other pests that I tackle on a yearly basis are greenflies that like to suck the sap out of the plant. The good news is both a treatable with organic methods and pesticides, it’s more about keeping on top of them before they get out of hand.
Here are the main pests that will be eating your lupins and, more importantly, what to do about them.
Aphids (Mainly the lupin aphid/greenfly)
If you find black, brown or green tiny flies on your lupin leaves and stems, plus some tiny holes, aphids are probably eating your lupins. The most common aphids to attack lupins are greenflies. Small though they are, they can cause a lot of damage by disfiguring the leaves. This affects how the plant is able to develop the blooms. These are easy to spot and identify and very common.
What to do
You can scrape the aphids off the leaves by hand, but the damage is done. And you have to keep on doing this repeatedly. Starting a treatment of a spray of horticultural oil as soon as you notice the problem should remove the aphids which are there and discourage more from moving in.
Snip off any heavily infested leaves and stems – they’ve too far gone to save plus, this will encourage more growth and flowers. And remember that ladybirds are the natural enemies of aphids and feast on them. Encourage a ladybird population into your garden (Did you know you can even buy some on Amazon)?
Your last resort should be a pesticide to remove the aphids. Bear in mind that these solutions also kill beneficial insects as well though, so I like to try and avoid them if I can, but sometimes it’s the only method that seems to be effective. Just look for any bug care labelled to kill greenfly and aphids.
Snails and slugs
Snails and slugs come out in the spring. You can see them actually eating your lupins, especially the young shoots and seedlings. Holes of various sizes are left in the leaves, once again disfiguring them and affecting their growth.
What to do
Discourage slugs and snails by keeping the area tidy by clearing dead debris from around plants as they like to shelter under this. Another option is to buy copper rings and place them around plants before they get too big. If you grow lupins in pots, you can also stick copper tape around the pots. Slugs and snails hate to cross copper and should stay away.
You can also buy some commercial slug pellets to do the same job. Look out for those that are wildlife friendly to preserve the rest of your garden environment. I also like to lay a few slug traps which are organic and can be very effective.
If you have the time, consider this an ongoing problem that you need to address every day. Every evening, manually pick off the snails and slugs from your lupins and get rid of them. This does take some time but if you only have a few snails or slugs, it does work.