Slimy Molds:What are they?

     Slime molds in your yard. Ugh!

     The name alone makes you think of mucky, oozing blobs. Just the appearance of these slimy patches on grasses and yard mulches is alarming. This image has given slime molds a bad rap.

     Slime molds actually are more unsightly than harmful. They feed on bacteria and other microorganisms that grow on decaying organic matter.  Slime molds aren't parasitic and they don't cause diseases.

     At the very worst, slime molds temporarily shade grass leaves which weakens the plants, but this is a very minor effect and causes no permanent harm.

     Slime molds spores usually grow unseen in thatch and mulch from late spring to autumn. An abundance of wet weather stimulates the appearance of these fungi above ground.  Often, they quickly appear.

     Some slime molds become quite large, reaching the size of a dinner plate.

     As they begin the reproductive phase, patches of small purple, white or dark gray fruiting bodies appear on grass leaf surfaces, yard mulches, and shrub or tree branches that touch the

ground.  These serve as support structures from which spores are dislodged by movement from breezes, water, equipment, people, or animals.

     Slime molds look like a slimy blob before they turn into powdery reproductive masses.  They usually disappear in one to two weeks.  However, they tend to reproduce in the same area each

year.

     You can remove slime molds by brushing, mowing or hosing. I don't recommend using fungicide sprays because the fungi are not harmful.

Keeping the roses smelling like a rose

Prevent Rose Diseases

                 Spectacular blooms and diverse types and varieties make roses a favorite of many Kentucky gardeners.  However, our warm, humid growing conditions create an ideal environment for serious problems each year with black spot and powdery mildew.

                Gardeners can nip these fungal diseases in the bud by planting resistant or tolerant varieties and creating an unfavorable environment for disease development. It may be necessary to use fungicides throughout the summer, especially on susceptible varieties.

                The Hardin County Cooperative Extension Service has materials on resistant and tolerant varieties.  Nursery catalogues also publish this information.

                To reduce foliar diseases, try to avoid conditions where rose leaves remain wet for an extended period of time. Do not wet foliage when watering plants and allow sufficient time for leaves to dry before nighttime.  Prune out shading vegetation from overhanging trees and provide space between rose bushes to improve ventilation and sunlight penetration.

                Sanitation also is important for managing rose diseases. If you have not already removed and destroyed old leaves, winter-damaged canes and debris, do it as soon as possible. These items are a source of disease-causing organisms.

                Many fungicides are labeled to control rose diseases. Always check the label to be sure the product controls black spot and powdery mildew and read and follow application instructions.  To maintain disease suppression, repeat fungicide applications at 10 to 14-day intervals throughout the growing season.

                Black spot produces dark, circular spots with fringed borders on the top or bottom side of leaves. Infected leaves often turn yellow and drop, reducing flower numbers and quality.

                White, powdery fungal growth is a sign of powdery mildew. It is easy to locate on such plant surfaces as leaves, stems and flower buds.  Infected leaves may be small and deformed.

                Two other important, but less common, foliar diseases of roses are downy mildew and rust.  Downy mildew produces lesions that are an off-color, later turning purplish brown.  It leads to defoliation.  Rust-colored spots on leaves and stems indicate the disease, rust. Severely infected leaves may shrivel and turn brown.

Rose Rosette

                Another summertime disease is rose rosette, which affects roses throughout Kentucky.  It is not a fungal disease.

                This disease is spread by a microscopic mite.  The primary host is multi-flora rose, a thorny plant native to the Orient and introduced into the United States as a conservation plant and “living fence.”  The disease also affects cultivated roses.

                Early symptoms are increased growth of shoots, which appear more succulent than normal and develop excessive thorns, and distorted, dwarfed leaves. The affected shoots are not winter hardy and produce few blooms. Rose plants eventually die.

                Early disease detection is essential to keep rose rosette from spreading. Remove and destroy any infected roses to keep the disease from healthy plants that are nearby.  Carefully remove diseased plants to avoid scattering disease-carrying mites to other plants.  Since multi-flora roses might be a disease reservoir, remove and destroy any located within one-eighth of a mile from the rose bed.

                For more information on growing roses, contact the Hardin County Cooperative Extension Service at 270.765.4121, email:  Amy.Aldenderfer@uky.edu by webpage: www.hardinext.org and on Facebook.

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