How to protect plants from white cabbage moth
May 27, 2016
Many people at this time of year ask me how to stop caterpillars eating their vegetables. The content below is based on our trials of testing various approaches over the last 4 years.
The cabbage moth and the cabbage white butterfly* are the source of the caterpillars that can devour the winter vegetables growing in the garden. The moth/butterfly lays it’s egg under the leaf of the plant and the eggs hatch caterpillars. The caterpillars will leave large holes in the leaves, usually starting with the outside leaves first. If you don’t act quickly they will destroy the plant.
If you have an issue in your garden I’m sure you’ve seen the little moths flying around. The only real way to protect the plants is to prevent the moths landing and laying their eggs. Check your plants for the eggs/caterpillars daily and remove them. The image below shows what they look like. They can be removed by simply gently wiping them off with your finger.
The moths love brassica (kale, cabbage, broccoli, bok choy, cauliflower etc).
Additional step: Spray the plant with Dipel, I believe that it is suitable for organic gardens. I have not tried it to date.
Here are some of the things I have done to try to prevent these pests eating our vegetables:
Many years ago I read an article that said these moths do not tend to lay eggs where there are other moths already in the area. Based on this my son and I made some clay moths and painted them white. They stayed in the garden for the season and had questionable results. I only used them the one season. I have seen online images of similar versions but made by tying white cloth to a stick to look like a moth. The school garden uses foam balls stuck on sticks and painted with eyeballs to deter them.
Some plants are said to repel the moth. The main one being sage. White pansies are also recommended as the little white flowers are said to look like the moth. I continue to use sage in the garden for this purpose.
The white pansies I used one year and they looked pretty but I can’t say they really had an impact, although the image below was taken when I did do this and the plants look pretty healthy and hole free so maybe it did work…
Nasturtiums are said to attract these moths and can be planted near by to act as a decoy as the moths will go for them first and hopefully then leave the vegetables alone. I am testing this this year. I have planted some broccoli and kale beside a big rambling nasturtium and a sage plant, otherwise these plants are unprotected.
As mentioned above, the only way to prevent your vegetables being eaten by the caterpillars of the moth is to prevent them from landing on the plants. This year I am testing the following:
Once I have raised the seeds to the point of going into the garden I have put them under the cover of a cloche, I used old jars.
As the plant grows too large for the jars they can be replaced with a larger cover to prevent the moths landing. I use an old fire grill.
The plant is generally strong enough once it outgrows this cover. You will need to keep up regular inspections of the plants to ensure that you are removing any eggs and keeping the caterpillars at bay once the cover is removed.
If you really want to allow these winter plants to grow pest free you will need to plant them together in one area and net it with exclusion netting (not bird netting). My version of this is not very pretty but to date has been wonderfully effective. Exclusion netting has a fine tight weave but allows light and rain through.
You would use poly pipe and create a tunnel for a neater look. You can see from my image that I used what I had on hand, mainly the edges of the beds beside the planting area. I added some frames to keep it high and nailed it down all the way around using strips of wood against the current beds, except at the front so that I can get in to harvest my amazing pest free produce at some point in the future! The most important thing is that the area is sealed. It is not the most beautiful addition to the garden, getting the suplas material at the edges under control is tricky. You may have guess that I did this myself without the help of Mr Fresh I am sure he would have done a neater job but he was busy and I wanted it finished. The little plants are growing strongly, unhindered by pests so far.
For a container based option the Vegepod is a great solution. Along with these other exclusion methods I am currently testing I have also planted a few cabbage, broccoli and kale in my pod.
I hope this helps. Happy growing.
*Yates provide a useful summary of the difference between the moth and butterfly here.
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