Gardening Plus...

We had a busy day on Gardening Plus on BBC Essex yesterday. I think the wet weather meant everyone was indoors catching up on their gardening advice – rather than outside actually doing it.

The morning started with some interesting pictures of an unidentified plant – Cannabis sativa or marijuana, the seed from which had come from a batch of bird food. The owner thought it probably was and was off to destroy the plant.

There were quite a few calls, texts and e-mails from people whose trees, shrubs and woody climbers had suddenly died this summer. Although difficult to do an exact diagnosis over the radio, the likely culprit is phytophthora root rot – a soil-borne disease that has become prevalent this year due to the wet weather and waterlogged soil.

One listener wanted to know how to control rust on pelargoniums that had spread from her hollyhocks. This sparked an interesting discussion that, although some diseases, such as botrytis, will spread from different plant species, others, such as rusts for instance, are specific to a particular plant or group or plants. So, rose rust only attacks roses, onion rust only attacks onions and other members of the allium family, pelargonium rust only pelargoniums and hollyhock rust only hollyhocks. Rusts are some of the most difficult diseases to control; carefully picking off affected leaves and spraying the rest of the plant with Dithane being just about all you can do – or assigning the plant to the dustbin if all else fails.

Another disease that provoked some interest is a new one in the UK – impatiens downy mildew, which appeared in 2003/2004 and kills busy Lizzie plants. Full details are available on the RHS website.

We had a call from someone who had taken over a neglected allotment and whose potatoes were riddled with wireworm and wanted to know how to control it. Sadly, there aren’t any cures, but wireworm are usually only present on undisturbed soil, and so tend to decline as the soil is cultivated – in a few years they should disappear altogether. We then had a text from a listener who said they controlled them by cutting old potatoes in half and part burying them in the soil. The wireworm start to feed on the potatoes and they can then be lifted and the wireworm removed – or fed to chickens, according to the texter.

Probably the most interesting call of the day was from a man who was trying to grow his own field mushrooms at home. He had cut an old mushroom into pieces and buried them under the turf of his lawn. He wanted to know when he’d start to get mushrooms. I answered it was more likely if rather than when as I doubted this would work. However, he was convinced it would and we asked him to keep us informed when he saw his first mushrooms – and to send us some!