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Impatiens downy mildew

Posted: Wednesday 15 May 2013
by Pippa Greenwood

It’s always great fun making Gardeners’ Question Time programmes. Sometimes it comes with an added bonus when we get to do a feature special...


Impatiens and downy mildew

It’s always great fun making Gardeners’ Question Time programmes. Sometimes it comes with an added bonus when we do a feature special, like when I took the opportunity to go and visit the labs at FERA (Food and Environment Research Agency) in York.

FERA carries out masses of environmental research, and their York site is filled to the gunnels with people I feel very at home with, including plant pathologists and entomologists. There are spores and bugs galore.

It was great to meet Phil Jennings, also known as ‘The Impatiens and Downy Mildew Man’ (well, that’s my name for him). Sadly, they’re still unable to come up with a miraculous solution to the downy mildew problems associated with busy Lizzies (Impatiens). But, believe me, they’re hard at work on it.

At the moment, they’re trying to formulate something to act as an early warning system, which will be used to identify any fungal infections showing resistance to the metalaxyl fungicides. They’re also working out the distribution of the sensitive strains of the fungus, i.e. those that can be controlled with metalaxyl fungicide, and the trouble-causing resistant strains, which can’t.

Last year, FERA was able to look at 10 mildew samples from eight different locations, including nurseries and private gardens. It was useful, but still more information is needed. In order gauge the extent of the problem and work out the speediest end to it, the scientists working on it need your help.

So, if you have any busy Lizzies (Impatiens) growing in your garden this year, and they’re showing signs of downy mildew infection, please help FERA and send samples in to: Dr Phil Jennings, The Food and Environment Research Agency, Plant Protection Programme, Sand Hutton, York. YO41 1LZ.

To make sure that the samples are in good condition please pack them as follows:

  • Keep the plant whole, but segregate the top growth from the roots by wrapping them in separate bags.

  • Label your sample with the name of the variety and the supplier.

  • Plants in plastic bags turn to (useless) slime very quickly, so wrap them in dry kitchen-paper before putting into polythene bags.

  • Send by first class post to arrive on a Thursday - that way the samples should be in perfect condition.


Thank you!





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Danny31 17/05/2013 at 08:28

I had just submitted suggestions for an area of damp shade, when I spotted the advice on the GW newsletter to: Read Pippa Greenwood's bog. Good idea.

Huntertony 17/05/2013 at 08:58

Ferns are my favourite plant for any shady spot! (Just thought I would throw that out there.)

olga84 20/05/2013 at 19:35

I have just purchased a buddleja globosa and would realy like to know when I can prune this please.