I had several letters from readers this week about Busy Lizzies dying off prematurely and problems with cannas.
About three years ago there was an outbreak of a disease which caused Busy Lizzies to lose all their leaves and flowers.
They never recovered and all that was left was green stems, but these stems were still plump.
In previous years the same thing happened but the stems withered. When the plants were removed from the soil, no roots were left on the base of the stems. With further poking around in the soil, creamy white maggots were seen – vine weevil grubs.
At the time I wrote about this problem and we were fortunate because there was a product available which is now widely used to combat these little blighters. It is called Provado Vine Weevil Killer and is watered onto the soil.
The new problem is quite different though. The leaves and flowers have died off, the roots have very few white roots visible but the stems are still plump.
This is because it is a fungal disease which is causing the problem. I must stress this is a new disease as far as Busy Lizzies are concerned.
It has even effected plants in flower beds in the best of parks and I have been in touch with The Royal Horticultural Society in order to get you the best advice.
The fungus is called Downy mildew which is impossible for us amateur gardeners to control and the best advice is to remove the affected plants and take them out of the garden.
If a whole container is affected, remove the compost and take it to the recycling centre. Don’t put it on the compost heap.
If this means there will be gaps in the border and you want perfection straight away, pull out the Lizzies and replant Begonia semperflorens instead because they are not affected by this fungus.
Now to the cannas. Maria from Cowes in the Isle of Wight sent me a sample of a leaf which has long yellow streaks and the edges of the leaves are turning brown.
This is called Streak Virus. You need to dig the plant out and take it to the recycling centre.
If left it will spread to cannas in neighbouring gardens as aphids could fly from your garden to others.
I’ve also been asked if cannas can be split up to provide more plants and can this be done now?
The answer is yes.Water the containers two hours before splitting the clumps. Remove the plants from the containers and gently roll the roots on a table so the foliage won’t be damaged.
With a sharp knife, cut through the thick roots where they join and then repot each one into fresh compost. Keep the pots in the shade for seven days and don’t over water.