Hi all,
One of my roses has this white powdery looking stuff around base of only some of the new buds (photos attached). The affected buds droop like you can see in the second photo. I have about 12 rose plants in that area of my garden, and only this one plant is showing this symptom.
I thought it was powdery mildew so I sprayed the plant couple of weeks ago with Yates Roase Shield [https://www.yates.com.au/yates-200ml-rose-shield-concentrate/] but the powederyt stuff is still around.
Could someone please help me identify this problem and how to treat it?

It looks like powdery mildew, which is a common affliction of flowering stems and buds in susceptible varieties. The product you used states it should be repeated every fourteen days for control of pests and diseases. You wrote you "sprayed a couple of weeks ago". That variety of rose is either susceptible to powdery mildew or is growing in a spot which is conducive to the growth of the fungus. It appears what you are going to need to do is repeat spraying that particular rose, especially the developing flower buds, until the season ends to prevent the buds from mildewing. Or, you could remove that variety and either plant it elsewhere to see if it's the spot or the variety, and replace it with a rose promoted as "mildew resistant" or other plant type not afflicted by the disease. I would also check your watering of that rose. Water stress can easily force even resistant types to mildew. Perhaps increasing the water to the plant might help.

I would add removing the affected leaves and blooms so the mildew cannot spread.

That's been the thought for years, however, the spores are ever-present and they germinate when in contact with susceptible tissues in temperatures and humidity which promote their growth. If the plant is being appropriately sprayed with that product, it should prevent any spores from germinating and eventually kill the infection so no new ones will be added. If neighbors or nearby municipal plantings are infected, those spores will blow with the wind as well as travel in on birds, wild life, even people so removing mildewed buds from your rose likely won't prevent much and it will deprive you of the enjoyment and color of those flowers. Of course, the decision is yours.

Thanks @roseseek and @LittleAnne for your suggestions. Will try repeating the spraying every couple of weeks this season and note the results to see if it persists, warranting other suggestions like replanting it elsewhere or replacing it.