Why is my Vitis coignetiae going yellow?

It started off the year as usual, but then the new shoots got burned by a cold spell in April. Then a large section of it died back (you'll see some evidence of the dieback in the last photo.)

And now I'm seeing a strange yellowing of the leaves.

It's been there for about 20 years, thriving until now!

 

I'm going to bump this.

Could it be some sort of mildew?

 

I don't think mildew, but more likely a deficiency, perhaps nitrogen or magnesium.
Have you tried foliar feeding, it might help, also a hose dribbling for an hour or so at the roots if it looks dry.

 

hi it could be a number of reasons although they are hardy but as pete said
it important that their planting site is well drained. Soil that excessary moist can cause leaves to yellow Water the plants in a way to avoid wetting the leaves also leaves can yellow If you add too much or not enough fertilization. This can cause the plant to become stressed and stressed plants are more susceptible to disease. For eg like leaf spot and root rot fungal infections, if you think it might be diseased make sure to remove and destroy yellow plant.leaves. This will reduce the spread and occurrence of pathogens in the garden.

 

Can you recommend (or just find) a foliar feed? Amazon prime would be good!

 

Lots on Amazon I think, some of the seaweed ones are supposed to be good but I cant actually recommend any as its not something I use.
I just thought in your case you need to get the nutrient as quickly as possible to the leaves, and it wont do any harm.

Some fertiliser around the root area might help also, when you are watering it.

 

I used couple of months ago coffee grounds for the garden as it is a slow-release source of nitrogeN if used asfertilizer it adds organic material to the soil, which many say it improves drainage, water retention, and aeration in the soil.
The used coffee grounds will also help microorganisms beneficial to plant growth thrive as well as attract earthworms. I have noticed a difference Either apply some directly, around the soil or in compost But not all plants like coffee so if you plan to use coffee you would be best to.look up how to use it. And what plants not to use it on etc
Another use I found was put used coffee grounds in bins to keep flies out it keep bins fresher as flies hate coffee so less chance they enter the bin so I tryed it and so far worked I read it can deter slugs as they hate coffee but unfortunately it dont deter squirrels wish it did
I prefer to use things that I have in my pantry for my garden so I couldn't recommend anything either

 

A couple of images of my problematic Vitis coingnetiae, in case anyone has any ideas about what’s going on. As you can see, from one side of the trellis it looks as though it’s gone into its normal autumnal behaviour early, and on the other side it looks more poorly.

It’s been fed and watered, well and truly mollycoddled.

Anyway I’m bracing myself for it’s imminent death, and wondering what to replace it with - probably another, but any other suggestions wouldn’t go amiss. Preferably something which will look wonderful in my lifetime.