LSU AgCenter Ornamental Horticulture E-News & Trial Garden Notes Mid-August 2014 Nursery, Landscape & Garden Center Updates Compiled by Allen Owings, Professor (Horticulture), Hammond Research Station, LSU AgCenter Edited by Rick Bogren, Professor (Communications), LSU AgCenter Phone 985-543-4125; Email aowings@agcenter.lsu.edu; www.lsuagcenter.com/hammond Landscape News Articles (from Allen Owings and Rick Bogren) Care Now Improves Fall Roses August 8 http://www.lsuagcenter.com/news_archive/2014/august/headline_news/care-now-willimprove-fall-roses-.htm AgCenter Research Gardens Study New Trees and Shrubs August 15 http://www.lsuagcenter.com/news_archive/2014/august/headline_news/agcenterresearch-gardens-feature-new-trees-shrubs-.htm Louisiana Super Plants Fall 2014 The Louisiana Super Plant Selection and Advisory Committee, in cooperation with the LSU AgCenter, announces the Louisiana Super Plant selections for fall 2014: Mesa series gaillardia Rabbiteye blueberry Louisiana Super Plants 2015 Fireworks pennisetum (spring) Henna coleus (spring) Homestead Purple verbena (fall) Leslie Ann camellia (fall) Ornamental Plants of the Week for August 2014 (from Allen Owings and Rick Bogren) Delta Jazz Crape Myrtles August 1 The burgundy foliaged crape myrtle, Delta Jazz, would make a great landscape addition. Trees reach a mature height of 10-12 feet and have brilliant pink blooms from early June
through Labor Day. This variety is part of the Southern Living Plant Collection series of Delta crape myrtles. Crape myrtles do best in full sun locations. Plants can be added to the landscape year-round. Soil should be slightly acid and well drained. Crape myrtles are very drought tolerant and flower best in dry, hot summers. Pawpaw August 8 A popular native fruit tree sometimes hard to find at garden centers is the pawpaw. Pawpaws need some shade to get established but can tolerate full sun after the first couple years. Flowers are maroon and appear in mid-march in South Louisiana. Fruit ripen in August and early September. They are tannish-yellow with white, creamy flesh that is custardy in texture. Pawpaws prefer a well drained soil. Pawpaws will attract zebra swallowtail butterflies to the garden. Firebush August 15 Firebush, also called firecracker plant, goes by the scientific name Hamelia patens. This is one of the top five plants for butterflies and hummingbirds in Louisiana. Starting to bloom in mid summer, flowers will continue through the fall. Plants are typically perennial statewide. Plant in full sun and in well drained soil. Plants do well in containers. Irrigation demand is low once establishment is completed in the landscape. Celebration Pennisetum (Sky Rocket, Cherry Sparkler, Fireworks) August 22 The Celebration series of purple fountain grass includes the well-known red-foliaged variety Fireworks and the lesser-known green-and-white variegated form (called Sky Rocket), along with the white, green and pink variegated Cherry Sparkler. These are annuals in north and central Louisiana but can be perennials in south Louisiana.
These grasses need full sun and will be 4 feet tall in the landscape by fall. Plant in clumps of three to five. Use as a vertical focal plant in flower beds. Irrigation required is minimal. Flower plumes start midsummer and continue until first frost. There are no insect and pest issues with these new unique fountain grasses. Big Leaf Tibouchina August 29 Princess flowers include several species. One of the lesser-known species is glory flower (Tibouchina grandifolia), also known as big leaf tibouchina. It has much larger foliage and larger flowers than the other commonly grown princess flowers. Considered a tropical or tender perennial, the plant is winter-hardy most years in USDA hardiness zone 9A, which is generally south of I-10/I-12. Purple flowers start in late summer and continue through fall. Plants can be easily rooted using softwood cuttings. A few garden centers in Louisiana sell this plant, which needs to be used more. Plants need full sun to perform best. Prune once or twice during the growing season prior to blooming to control size and make a better-branched plant. Cuttings root easily.
Florida Wax Scale (from Dennis Ring) The Florida wax scale, Ceroplastes floridensis Comstock (Homoptera: Coccidae) is a soft scale occurring from Florida to New York westward to California. Its severity as a pest of ornamentals is increasing in Louisiana. Wax scales have a globular shape and are coated with a wet-looking grayish, beige, white, pinkish-white or grayish wax. They appear rectangular from above and are lobed or oval at the base. The body of the scale is red and is covered by the wax cap. Reddish-orange eggs are oval and found under the bodies of grown or dead females. Crawlers, first-stage nymphs, emerge from eggs over two to three weeks. They then crawl to stems, twigs, and leaves of hosts, where the settle. Nymphs begin feeding by inserting their mouthparts into the plant and sucking plant juices. At this point the nymphs secrete wax around their body, giving them a star-like appearance. The nymphs often move, and scales that are more mature will move to the top of the plant onto new growth. Wax scale females grow through three instars before becoming adults and then producing eggs and dying. There may be hundreds of eggs in the body cavity of one female scale. There are two generations per year, and nymphs emerge in late April continuing through May followed by a second emergence from late July continuing through August. Additionally, some nymphs may emerge in other months. The overwintering stage is the female, and males have not been observed. The host range of the Florida wax scale includes trees, shrubs and some herbaceous plants. These
include hardwoods, softwoods, elephant ear, Virginia creeper, pomegranate, crape myrtles, elm, honeysuckle, holly, deodar cedar, golden Euonymus, loblolly pine and oaks. Most Florida wax scales colonize the upper surface of the leaf of holly. In this location heavy rain may kill some scales, and the scales are easily reached with foliar insecticides. However, some of the scales colonize branches, twigs and the underside of the leaves, where they are harder to observe and kill. These scales suck plant sap from the plant. High densities of scales may result in dieback and leaf discoloration and sometimes kill the plant. Honeydew may be secreted in large volumes, covering the plant. Sooty mold fungus will grow on the honeydew, turning the plant black and blocking sunlight from reaching the leaves. Some bark lice, ants, bees, hornets and wasps are attracted to honeydew. Biological control using predators, pathogens or parasites has not been observed for this insect. Heavily infested plants may be replaced with non-host plants such as wax myrtle, sea grapes, boxwood, junipers (except Blue Point), bottle brush, ligustrum, privet, oleander or pittosporum. Limitations of these plants should also be considered when selecting plants for the landscape. When hollies are purchased, they should be thoroughly inspected for Florida wax scale. Provide optimal fertilization and watering to promote the health of the plant. Look for infestations by regularly inspecting plants. Foliage that is heavily infested should be pruned and removed. This will make it easier to get good coverage with sprays and reduce numbers of scales. It is very important to prevent crawlers from infesting new growth. Systemic or foliar insecticides may be applied for management of Florida wax scale. Usually, all scales will not be killed using systemic insecticides as some scales on twigs or branches will survive. Thus, foliar applications will also be needed to kill all the scales. Apply systemic insecticides (imidacloprid) before crawlers emerge from eggs. This allows time for the insecticide to move from the soil to the leaves of the plant. Apply foliar insecticides after emergence of the crawler stage as nymphs start to settle on the plants. Inspect leaves for scales either weekly of biweekly beginning in late April and mid-august. The appearance of the nymphs that have recently settled is star-like, small, and white. Foliar insecticides should be applied on a seven-to-ten-day interval throughout the period of crawler emergence. Horticultural oil and insecticidal soap have a very short residual. The residual of acephate is longer. LSU AgCenter Landscape Horticulture Field Day THURSDAY, OCTOBER 9 8:30 am Registration 9 am until 12 noon Research Tours!2 noon 1 pm Lunch Followed by Southeast Louisiana Nursery Association Trade Show ALL LOCATED at LSU AgCenter HAMMOND RESEARCH STATION
LSU AgCenter Plant Diagnostic Clinic LSU AgCenter Soil Testing and Plant Analysis Lab