black spot

[Doug]

I have a climbing rose bush and out back there is a red tip. Both have black spot. The poor rose bush didn't have it the first two years in the ground and it climbed and was healthy as anything could be. Now it can't sustain the roses and is failing miserably. How can black spot be destroyed permanently?

[Warren]

It can't be. Black spot is a fungus. The spores cannot be effectively destroyed, and even if you use a backhoe, you're bound to leave some behind.

Reducing black spot takes planning. If you must choose varieties that are susceptible to black spot problems, make sure that where you place them gets plenty of sun, especially in spring, and make sure that you prune to encourage an air flow that will dry the rain and dew quickly.

While you can't stop Mother Nature from raining on the plants, you can refrain from wetting the foliage when you water. Use drip irrigation or soaker hoses (not the ones that spray, but the ones that weep) when you water, and allow the surface to dry before watering again. Clean-up any leaves, prunings, dropped foliage, etc. Don't use prunings from roses or other plants with black spot in your compost -- or at least not if you plan to use that compost anywhere near plants susceptible to black spot.

If you know that a plant is susceptible to black spot, starting in early spring you can use a systemic treatment such as Bayer's 3 in 1 for Rose Care. (This is the liquid stuff you mix in a watering can, not the 2 in

1 granular stuff.) Retreat every 4 to 6 weeks until the dry season.

Once black spot appears, prune away any foliage that has black spot. Be careful while pruning, as the more you disturb the foliage, the more the spores will be set free, and settle in the soil. If you're removing a substantial amount of foliage, you may also want to remove any mulch around the plants, too. Like I said at the top, you won't be able to totally remove all the spores, but the fewer you leave behind, the easier time you'll have controlling them next year.

Once you remove all the black spot affected foliage, you can try using the Bayer 3 in 1 systemic, but continue to prune away any new black spot affected foliage at least twice a week -- daily if you can -- until things get better. And remember that part of why things will get better will be the generally drier weather of summer, and the hotter sun. Once conditions better suited for fungus growth comes back, so will your problem.

It may take you a year or two to get things under control. But if you've got the wrong plants in the wrong place, you may never see an improvement. Varieties susceptible to black spot located in a shady spot that has no air circulation will likely never get much better, and you'll be fighting a losing battle.