The Himalayan Rose is a vigorous climber that is often used to cover an arbor or pergola. In ideal conditions, it can grow to take over an area.
Himalayan roses are as susceptible to insect and disease issues as most other roses. Their growth habit may even bring about more disease problems from the potential lack of air movement through the plant.
Prevent these diseases from developing on the rose by pruning it so that air and light can reach the majority of the plants foliage.
Roses suffer from three fungi, Powdery Mildew, Rust and Black Spot. Bayer Advanced Rose and Flower Care is a treatment for these diseases. It also helps to control insects on ornamental plants.
I find it interesting that you refer to the disease as "black leaf" rather than black spot. If the entire leaf is black, rather than black spotted, it might be the result of mildew that is growing on the leaf. Black spot is a fungus that eventually makes holes through the leaves. If you have no holes, it's mildew or mold, and that is a sign of an insect problem.
Aphids create a sticky substance that helps them to adhere to the underside of the leaf and branches of the host plant. Airborne spores collect in the "honeydew" and begin to grow. Enough of the mold and mildew can prevent the leaves from utilizing the sun's light to grow.
The insecticide that the Ortho and Bayer products use will control the aphids as well as other bugs that damage your roses.
The Home Depot offers organic alternatives to control insects and diseases, but they will need to be reapplied after significant rainfall since they will wash off.