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COLUMBUS — If the leaves of an ornamental pear, apple, or crabapple were covered with rusty orange spots last summer, the time to prevent this fungal disease for this summer is arriving.
Rust colored spots on leaves are caused by the fungal diseases cedar-apple and cedar-pear rust.
Neither will kill an ornamental pear, apple or crabapple so homeowners can choose not to treat their trees.
For those who wish to control rust disease, we are in the time when fungicides need to be applied. Once an infection occurs on leaves, fungicides are not effective. Fungicides need to be applied to trees that had rust disease last season prior to the fungus infecting leaves this spring.
The first fungicide application needs to be made just as a tree begins to leaf in spring and repeated according to label.
Two applications are usually sufficient in reducing cedar apple or cedar pear rust. The best way to manage rust disease is to plant resistant cultivars.
Dividing perennial flowers like black-eyed Susan and ornamental grasses is an important management practice for many herbaceous plants. Plant division encourages vigorous growth and increases blooming. Signs a plant needs division are dead centers, especially with ornamental grasses, and reduced blooming in flowering perennials.
Many perennials benefit from division every three to five years. As a rule, divide summer and fall blooming perennials during spring just before or as new growth begins; and divide spring blooming perennials in late summer.
Dividing plants is also a good way to propagate perennials for your garden or to share with others; particularly if it’s a specific cultivar that outperforms others or is difficult to find. Divide perennials by digging them up and then cutting or gently pulling them apart. Each division needs to have healthy roots attached when replanted.
In lawns, powdery mildew disease appears as a grayish-white growth on the surface of grass blades that cannot be rubbed off. When heavy, it may lead to some yellowing and browning of grass blades. Mildew is common in shady areas with poor air circulation but is rarely more than an aesthetic concern for lawns. Cloudy, overcast weather and high humidity promote infection and spread of the fungus. Powdery mildew is best managed by reducing shade and increasing air circulation to reduce leaf wetness. If this is not feasible, replace Kentucky bluegrass with tall fescue which is more shade tolerant. Powdery mildew typically disappears with dry summer weather and fungicide treatment is not needed. Under heavy disease pressure, fungicides are an option. Treatments need to begin prior to significant powdery mildew development, and applications repeated according to label directions.
Most roses are pruned in late April after the threat of very cold weather has passed. Pruning roses in the fall or in winter can lead to an increase in winter damage on roses. With most roses, the main pruning done is to remove winter killed wood which will be dark brown to black in color. If rose growers wait until just as new growth is emerging, it is even easier to determine what wood has been winter killed and needs to be removed. Remove all winter killed wood back to healthy tissue, making the pruning cut just above on outward facing leaf or leaf bud. If tender roses, like hybrid teas, were killed nearly to the ground, after removing dead wood, watch for regrowth that occurs from below the graft or underground. If this is the only growth that occurs, it is best to remove the entire rose.
The growth is coming from the root stock rather than the desirable grafted portion and is typically not desirable in the rose garden.
We continue to lose trees from storm damage and pests like emerald ash borer. When a large tree needs to be removed, the stump is typically ground out or treated with a treatment to prevent resprouting.
When stumps are treated, rather than chipped out, carefully read label directions for products sold for stump treatment. For example, Tordon is a herbicide labeled for use in treating stumps; however, it should not be used in home landscapes or areas where there are nearby trees. Tordon has a fairly long soil residual and can kill nearby trees, shrubs or other plants whose roots are growing in the same area.
Keep in mind plant roots, especially trees, grow outward not downward and can grow up to two or more times the height of the tree outward from the trunk.
If the label of a herbicide used for stump treatment says not to use it near other plants, avoid using it in landscapes or near other living trees.
