To start with, I'm posting this link to a short article that I found on Internet about natural fungicides and insecticides.
https://homeguides.sfgate.com/...
I encourage you to do your own research on this topic however; there are several different " recipes " for these home-made , natural fungicides. For example, there is one made with water and skim milk, too. Also, the article doesn't caution enough about avoiding the use of oils when the sun is out and the temperature is high,so again I advise to to do some Google-ing on the topic. Likewise with the ideas about companion plants that help repel insects -supposedly pink geraniums are a big help. for example ,but I've heard of others. I did not know that borage was so good until I saw this article, nor that garlic helps ,not only by it's smell, but by adding sulphur to the soil,so that just goes to show how helpful it can be to hunt around a bit on Internet and read up on a matter that is of interest.Also, this article doesn't mention one of the easiest and best natural insecticides-soapy water spray. But. again, look it up to find the recommended dosage, and, as always when spraying ,don't do it when the sun is out.
The thing is that even 25 degrees is quite warm for roses, and the fact that they are in pots on a balcony is going to increase the plants' subjective experience of heat-by this I mean that,on a balcony, the light and heat are reflecting from the paved surfaces, whereas in the ground, surrounded by grass, plants are going to "feel" cooler. So they will need a lot of water, and might prefer some shade as well. Good cultivation is the most important thing to help control insects and disease.
