Lavender turning black

I was bought some lavender plants for mothers day which have been thriving in the late march sun shine with highly scented purple 'bumble bee' flowers. However this weekend I noticed the plants are turning black and look like they are dying. I'm thinking either my dog had suddenly started cokcing his leg against them or that the heavy rain we've had lately is too much for the lavender.

Any ideas?

They are planted in open ground next to a patio i have at the end corner of my garden..Its a sunny spot and the soil is usually quite well drained, just not so at the moment!

Turning black seems strange-could you take a photo and post it in here.

Are they turning black from the top or from groundlevel?

from the top!

I think this is Fusarium wilt and that it is caused by two things: too much moisture and bad drainage.It is a common soil fungus. What you can do is re-plant in a dryer spot or you could lift them, dig the holes a bit deeper, add a layer of grit (and some soil on top ) and re-plant.

Either way you cut the Lavender back to healthy growth and remove all the clippings.  Remember to disinfect your secateurs.

Thats brilliant- thank you! I think given that May is also supposed to be a wet month, I might just replant into pots. At least then I can bring them into my run room if its a bit too wet and cold for the lavender outside.

Do i have to use special garden disinfectant or can i just use household brand?

Nothing special, I use a bottle with 70% methylated spirits solution.

...and finally, can i plant again in that area without re-infecting new plants?