Question
My roses are all very sick. We have a clay soil and after receiving 3months of heavy rain the entire 38 rose bushes have black spot and they leaves are yellow/green and all the new growth is very small thin leaves, not the usual rounded type leaf.  I have sprayed with Rogor (suggested by our local nurseryman) but this isn't helping the situation. I have given them seasol every month and added 5 in 1 manure mix to the soil as well as dynamic lifter.  Nothing is working.  In sheer desperation I cut them all back and they are now reshooting but the leaves are thin and they turn yellow on the outer edges.  Any suggestions would be appreciated.

Answer
Because you have worked with clay soil I don't need to tell you that 3 months of heavy rain is the worst type of weather for clay soil. First of all if you have amended your soil, it really doesn't need anything else to grow roses with. Clay has a lot of nutrients that roses need. Adding manure to the rose hole will certainly help brake down the clay. Seasol in North America is very expensive and is basically the same as a dead fish. It activate the micro organisms in the soil to do their job which is to break down the nutrients into a state where the rose roots can utilize them. Manure will do the same thing. You have done a lot of good things for your roses but the problem is because the roses are under stress the roots have shut down. Roses when dealing with any unusual weather conditions, will save them selves by simply stopping all growth. The next thing they have to do is get rid of the foliage which will turn yellow and die. The yellow-green colour of the leaves may mean two things, one that they are dying and the other could be that the soil is not acid enough. But you won't know until they start to grow again. The black spots n the leaves could be a fungal problem especially if it is normal in your region. But black spot can also indicate other disease which can attack a rose under stress. Again wait again until things are normal before you spray anything on them. No matter what the fungal problem, is any rose fungicide will do the job. Still keep an eye out for whether or not the soil is not acid enough. That is easy to fix but check with your locals because there are different types of clay soils.
Cutting them down was a good idea as your roses will come back, but the roots won't be able to support a large bush so a smaller bush is ideal. Honestly there is no reason to use anything on your roses when the weather gets back to normal. When a rose is under stress you compound the problem but giving them what may be good under normal circumstances but acts as an irritant under the unusual.
This is a waiting game because anything you do right now will not have an effect. Because roses shut down you won't lose them but when they start into growth they will take time to build up their strength. If possible this year, try not to use any insecticide sprays as some roses really re-act to them. There is a lot of good sound knowledge in regards to foliar spraying as a pick me up type of fertilizer. Fish is the one they say does a really good job. So any plain fish type made into 1 tablespoon to a gallon of water will definitely benefit the roses. I hope information this helps a little.