What's a home remedy for killing the disease on my roses?

It depends on the disease. This link should help:

https://gardenerspath.com/how-to/disease-and-pests/common-rose-diseases/

Hello. Is it black spot, rust or another discoloration leaf issue or insect problem? A photograph or more information would be helpful.

This link might be helpful

https://extension.psu.edu/rose-diseases-outdoors

Can you describe the disease or share a photo?

Here's a helpful link with rose diseases and treatments:

https://hgic.clemson.edu/factsheet/rose-diseases/#:~:text=Rose%20Diseases%201%20Black%20Spot.%20Black%20spot%20is,8%20Rose%20Mosaic.%20...%209%20Crown%20Gall.%20

Since you didn't stipulate the disease, not sure but here's a DIY for black spot:

1 tbsp baking soda

1/4 tsp dish soap

1 gallon water

This is an anti-fungal to keep the spread and reduce the issue.

Depends on the type of pest.

https://homeguides.sfgate.com/homemade-pesticides-roses-37091.html

You did not say what the "disease" it. It could be a multitude of things including powdery mildew, rust, thrips, aphids etc.

Hello J M hope this link helps you out, it has a listing of diseases and cures

https://hgic.clemson.edu/factsheet/rose-diseases/

If it’s mildew or rust, be sure to not water them at night. Only in the morning.

Hi,

Might I suggest you buy a book on Roses - you can buy them cheaply, then you will always have it to hand for when you need it!

Hi there, do you perhaps have a picture of your ailing roses? It helps us come up with something that will work for that specific condition.

This is what I use on mine - https://amzn.to/2TvLEwA