Vitis Cognitae

Have just noticed brown raised 'nodules' on some of this year's leaves on my Vitis Cognitae - see attached photo. (This young leaf measures about 8cm across.) The plant is well established and is about 4 years years old. Have checked the Shoot website for specific pests and diseases for this plant, but none of them appears to fit the bill. Grateful for any ideas. Regards, Brian.

Click image to enlarge

Vitis coignetiae

Reply from Katy Elton

Hi Brian,

This is a tricky one. The 'nodules' look to me like they may be galls caused by some sort of leaf mite - possibly in this case a grape leaf blister might. If this is the case then the damage to the plant is not usually serious, and the remedy is to simply remove damaged leaves.

This is no more than an educated guess though. It's very difficult to know what the problem is for definite. Are you a member of the RHS? If so they offer a free pest and disease identification service, which can be very handy in ambiguous situations such as this. http://www.rhs.org.uk/Gardening/Help-advice/RHS-Advisory-Service/How-to-send-samples-for-identification-and-examina

I do hope this helps.

Katy