Blackspot

Hi @Sandy Ground for the last 3 years I have always underplanted my Roses with a host of different flowers,especially with Tagetes,with the final height of tomatoes its not a method I would try as blackspot is a a fungus, disease (Diplocarpon rosae) can travel through the air,I have not found tomatoes in any way help prevent blackspot on my Roses

 

I don't think I would use the method, Sandy, as while some garden myths work a lot of them don't However, the upside of that method is even if it doesn't prevent Blackspot you should get plenty of Tomatoes!!

 

Good morning Spores are easily spread by water splash and infections take hold when the water remains on the leaf for about 6-7 hours. Areas with high summer rainfall and high humidity usually have the highest incidence of black spot. Treatment of the disease is year round as the fungus overwinters on stems and leaf litter. All diseased leaves should be raked up and disposed of.