It's caused by Botrytis cinerea (a fungus) Michelle which is stimulted by cool,moist conditions.There are effective fungicides for curative control but with roses this is just not practical (unless your growing in a greenhouse).
We use Rovral for greenhouse control of botrytis.In crazy weather we get balling on some of our garden roses too eg.Boule de Neige.Alexander Hill Grey.I just dead head them and threaten them with removal if they don't do better next season.This must surely be the best way around the problem as there are many rose varieties which resist this fungus problem almost entirely, while some others are spoiled on a monotonous basis.
Thrip

Thankyou Thrip.
Your advice was wonderful before on another issue so I will go with you on this.
I have been removing the affected buds hoping the bush will produce more buds.I think with the mad weather we have been having its the best thing to do.
Thanks again
cheers
Michelle

Michelle, I'll give you the most likely scenario. This answer was given a lady some time ago.

Luise, You should never neglect Malmaison in Spring. It is not the fault of the rose that blooms can rot, but rather our neglect. Problem is thrips, which damage petal edges, causing petals not to reflex. So they sit closed and the damaged petals begin to rot.

Be aware that early Summer is thrips time. They can be controlled to some extent by spraying with Orthene every 3 or 4 days. Don't spray directly onto the blooms, it also is not good for petals. The idea is to eradicate the thrips in the general area. In addition, and do this anyway to help the blooms, whether you use Orthene or not, take the bloom in both hands and ease the petals downwards slightly, thus breaking the seal caused by bleeding petal edges sticking to each other.

To explain in more detail - the process goes like this. Spread your fingers under the bloom, and with the thumbs above, and on either side of the bloom, touch the outer petals with the thumbs and ease the petals downwards. For petals further inside the outer ones, press a little firmer and ease them down (you'll definitely hear the "crack" as the seal is broken). This separates the petals, spreads them, and allows one to spray the water between the petals, washing the thrips into the base of the petals. If you check next day, you'll find plenty of dead thrips down below, and for exhibition, remove with a fine paint brush.

Then with your hand spray, flush the bloom out with water. Try and wash thrips down into the base of the flower where they will drown. That's really the only effective way to deal with thrips, and after Xmas (in Australia) they are largely gone anyway, and that's also why we get such great blooms of Malmaison into Winter, in the dampest conditions. The rose can handle that, but we must help it when it comes to thrips damage. The same practice works tor all rose blooms at that time of year (early Summer).

It seems to be the rain that causes the problem - makes the petals stick together so they are unable to open. I just trim the balled buds off, so the bush can get on with making new ones. Papa Meilland and Kentucky Derby seem to be the worst affected in my garden - the balls were so big and heavy that it felt like I was cutting apples off the bush!

Thanks everyone
Its a great help,I thought there was something more serious. It is thrip--little black bugs....uurrggghhh
came out when I cut some for a vase.
Its raining here now but I will follow your advise
Thanks a lot its very helpful.
cheers
Michelle

Yes thrips prevent flowers from opening properly but whether thrips are present or not the cause of the petal rot/brown patches is botrytis.Excessive rain/irrigation leads to a lowering of calcium concentrations in the flowering tops which increases botrytis susceptibility remarkably.It's also present all year round just waiting for those dewy nights or rainy days to come by.If your going to show your flowers however then treating thrips with sprays may be necessary but it still leaves us with a secondary botrytis infection to clean up.Be careful with the orthene Michelle and be aware that thrips like two-spotted mites are now resistant(in varying degrees) to almost every chemical available to Australian growers/gardeners. This leaves us with no choice but to rely on the speedy development of Integrated Pest Management, ie the use of beneficial/predator organisms and existing or new chemistry sprays, which have either less or no impact on them.
Thrip

Thanks everyone
very helpful
cheers
Michelle

Hi everyone

Well I have followed your advice Thrip.
I went around the blooms ,water in each one.
I cracked open the buds peeled them back.Its amazing you really can hear a crack.After folding down the outer petals poured the water in.
Later in the day I gave them all a spray with Rose Gun.
The next day(yesterday)--the buds were opening (which I would have lost to balling) and NO thrips!!!!
Now I have lots of blooms without thrip and opening blooms that I would have lost to balling.A success story.
Thankyou for the help .I am telling my friends about this because it works and the results are immediate!
Thanks again.
cheers
Michelle

Yeah, thanks for the benefit of your experience Thrip??

You'll have to thank lozza for that one Michelle, he was spot on.I just thought you must have been having heavy rains down there by the sound of things. I think my username Thrip must be confusing you.
PS If you see me inside one of those balling flowers please don't drown me.I'll just move next door to a different plant...I promise.
Thrip

Oh sorry!
Did I give the credit to the wrong person....apologies:))
Anyway the advice from everyone was very much appreciated.
cheers
Michelle

Good lad Thrip.

Aw shucks Loz. I feel all gooey inside now.
Young Thrip

The link is now published for those who want to know about thrips.

Here is a link that might be useful: Thrips

Thanks lozza
cheers
Michelle