Guest Author - Charity Armstrong
Rose gardeners everywhere hate the dreaded fungus known as black spot. Many gardeners have already discovered the impossibility of eradicating this annoying fungal pest from their garden. However, proper landscape planning and rose garden maintenance will help keep black spot under control.
The first and most important step to preventing black spot is to locate your roses where they’ll receive full morning sun. Black spot needs only seven hours to begin developing. If your roses don’t receive full sun until 10:00 a.m. they’ll be damp with evening dew for at least twelve hours. Plant your roses so they’ll be hit with the first full sun of the day, this will help keep them within the seven hour time frame.
Keep your rose leaves dry! Roses don’t like wet leaves. If you’re going to water your roses from overhead, only do so in the early morning. Early morning watering will ensure your roses can quickly dry their leaves in the sun. Watering your roses overhead late in the day or evening is asking for a black spot problem. Drip irrigation or a soaker hose is ideal method for watering roses. If you hand water your roses, hold the sprayer down by the soil to keep the rose’s leaves dry. You can purchase an extension wand to make this method of hand watering easier on your back.
Proper pruning has a tremendous effect on the level of black spot and other diseases your roses suffer from. Black spot first forms where your roses don’t receive adequate air circulation. This is why black spot commonly gets its start at the bottom or inside of the rose plant. Every time you prune a cane back on your rose plant you should prune back to an outer facing bud. Never prune back to an inner facing bud. Training your roses to grow outward will open up the rose plant, increasing air circulation and light in the center, where black spot gets its start.
If you’re just getting started planting and haven’t developed your rose beds yet, give extra attention to plant selection. The decision to forgo hybrid teas for “Knock Out” roses, Old World, or Rugosa roses can give your more blooms with less garden maintenance. If you don’t plan to show your roses consider adding just a few hybrid teas or perhaps none at all. Including various types of disease resistant roses in your garden will help reduce maintenance and create interest.
If you’ve taking care to implement the steps above and are still having black spot issues, to the extent the affected leaves can’t just be removed and thrown in the trash, there are a variety of fungicides on the market that help control black spot. Many researchers have had excellent luck mixing insecticidal soap with a small amount of baking soda that is applied weekly. This would be the least toxic method. A variety of rose fungicides can also be found at all “big box” home improvement centers as well as local garden centers. If you’re looking for more potent products they can generally be found online. Always take care to thoroughly read the entire product label. Follow all product instructions for safe application exactly as stated on the label. Be sure to check the temperature requirements as well, since spraying during hot weather or under full sun can severely burn your roses.
Black spot is the annoying bane of the rose gardening world, both amateur and professional. The best method of control is to implement proper rose garden maintenance practices. These simple steps will give you healthier roses, while saving you time and money on fungicides. I’ve yet to meet a rose gardener who actually loves spraying.