Have you ever had roses or seen roses where all you have is roses on the end of the canes and very few leaves? 99.9% of the time, this is caused by the most common disease affecting roses called Black Spot.
Black Spot is actually a fungus disease that starts out as an obvious black spot on a green leaf. The leaf then turns yellow as the fungus spreads, causing the leaf to drop off.
The situation that causes severe problems with Black Spot is where moisture remains on the leaves for a long period of time.
Conditions that favor Black Spot are:
If the homeowner doesn't control Black Spot, it will not only denude the plant of leaves, it will severely reduce the quality of blooms and weaken the health of the plant. Stop and think about this, it only takes 4-5 days for a rose leaf to be infected and drop off. When you multiply this by dozens, you have a barren rose.
Here are some suggestions to manage Black Spot on roses:
As always, be sure to read the label before you use any pesticide.