[muckyboots]

Hi ,I have a number of clematis ,but two growing up some some trees, small flowers late flowering(sorry don't know there names) and they are covered with a white mildew from top to bottom,I have sprayed them but they don't look very happy,shall I cut them off and wait to see if the come back next year.Thanks if you have any suggestions. 

[muckyboots]

HI just found the names if it helps,Texcensis Etoile Rose and Rooguchi .

[JayG]

Those are both "group 3 clematis" so can be hard pruned in February, although the mildewed leaves will be long gone by then:

RHS article HERE (and yes, they are prone to mildew!)

[muckyboots]

Thanks  JayG,I might opt to replace them with some other climbers rather than see them suffer the same every year.I'll give them one more chance then it's curtains.

[mumofstig]

It's been a dry summer, the trees probably take all the available moisture from the soil.

Try mulching them and give them a good watering if it's dry again next year 

[Trillium]

Most people think mildew comes from excessive moisture but often it's dry mildew. If your clematis are climbing up trees then they're competing for water and the tree will always win with it's bigger root spread.

Try to add some water twice a week, maybe a few jugfuls scooped out of a bath, or empty a dehumidifier pail on them, etc. With some direct watering they probably won't develop the mildew.

[muckyboots]

Thanks for the tips Mum and Trillium, you are spot on didn't know much about the causes of mildew,  they are on a south facing wall which is compounding the problem .I'll give them a good mulch and up the watering,thanks.

[JayG]

I agree with both of them too! 

Although I mentioned that clematis is susceptible to mildew that was a reference to the RHS article rather than my own experiences - I've had 5 different varieties for donkeys years and none of them has ever had mildew to any significant extent.