Hibiscus, Chinese Hibiscus Hibiscus rosa-sinensis Propagation Hibiscus are normally propagated by softwood stem tip cuttings taken in late spring. Intermittent mist with soil temperatures of 70 degrees F should yield rooted cuttings in 4-6 weeks. Hibiscus may be propagated by seed also, although it will take 10-14 months for the plants to come to flowering. Seeds should be collected before they are ejected from the capsule in the spring and scarified, They can be germinated under high humidity, 50% shade and 80 degrees F in 1-4 weeks. Air layering in the summer will take 6-8 weeks to root or they may be cleft grafted in the spring. Pests and Diseases The current Insect Management Guide for Commercial Foliage and Woody Ornamentals can be found at http://edis.ifas.ufl.edu/ig012. The current Professional Disease Management Guide for Ornamental Plants can be found at http://edis.ifas.ufl.edu/pp123. Aphids Recognition: Aphids have small pear-shaped bodies with paired cornicles. They may or may not have wings. Aphids cluster and feed on new growth flowers, stems and leaves. Sooty mold grows on honeydew excreted by the aphids. Several kinds and colors of aphids feed on hibiscus. (Note: photo shows cotton aphids) Contributing factors: Aphids occur in the spring and throughout the growing season. Management recommendations: Aphid "mummies" are a sign that natural biological control is occurring. High aphid populations may be treated with insecticidal soaps, oils, or approved insecticides. 1
Parasitic wasp Scale (several types, including nigra, euonymus, and white peach scale) Recognition: Scales cause damage by sucking the juices from the plant. Feeding on the undersides may cause yellow spots to appear on the upper leaf surfaces, which become larger as the scales continue to feed. Scale feeding may result in leaf drop, reduced growth, and possible twig dieback. Scales are also found on twigs and stems. Mature scales are visible, although sometimes they are well hidden in crevices. Immatures, or crawlers, are tiny and require a hand lens to detect. The presence of sooty mold is also associated with soft scales. Contributing factors: Mature scales are present year round but crawlers hatch in spring and throughout the warm season, depending on species. Management recommendations: Round holes in the scale bodies indicate parasitic wasps have emerged and are helping control the pest population. Use oils or approved insecticides if parasitism is insufficient and the problem warrants. Contact insecticides should be timed to control crawlers, since matures are well-protected by a waxy covering. Systemic insecticides may be needed for severe infestations. Dead scales, however, will remain on the plant. Spider mites Aphid mummies White Peach Scale Nigra scale Recognition: Tiny (less than 1/50 inch) eight-legged mites are found most commonly on the undersides of leaves. Eggs, cast skins and silken webs are also signs of mites. Mites feed with piercing-sucking mouthparts, causing the upper sides of leaves to 2
Two-spotted mite Southern red mite exhibit a stippled or bronzed appearance. Common mite pests of azaleas include both southern red mites and twospotted spider mites. Two-spotted spider mites have dark spots on both sides of the abdomen. Southern red mites are named for their bright red color. Contributing factors: Southern red mites are most prevalent in cool, moist, conditions, whereas two-spotted spider mites prefer hot, dry weather. Management: Use a white piece of paper to monitor for mites. Check for predaceous mites as well, which are larger and move more quickly. Insecticidal soaps, horticultural oils, or approved miticides may be used to control mites when necessary. Whiteflies (Silverleaf, Citrus, and Giant) Recognition: The tops of the leaves become pale or spotted due to feeding by whiteflies; sooty mold also grows on the sugary substance excreted by the whiteflies. Whiteflies resemble tiny white moths, and the adults will fly when the plant is disturbed, then relight on the leaves. Their bodies are covered with a powdery wax. The silverleaf whitefly tends to fold its wings at an angle over its body, while the citrus whitefly Citrus Whitefly holds its wings flat over its back, but it is difficult to tell Silverleaf Whitefly Giant Whitefly them apart. Nymphs are translucent yellow ovals. They are mobile for the first part of their life, then insert their mouthparts into the leaves and remain stationary until they pupate. The giant whitefly is a new pest in Central Florida, and is larger (about 1/4" long) than the other whiteflies. Lots of waxy white filaments produced by the giant whitefly makes it very obvious on the plants. Contributing factors: There are three generations of citrus whiteflies per year, typically in late March, mid- June and late August. Management Recommendations: Parasitic wasps assist in keeping whitefly populations under control. Wasp parasitism can be recognized by round emergence holes in the pupae, rather than T-shaped holes made by emerging whiteflies. The silverleaf and giant whiteflies are more difficult to control than the citrus whitefly. Alternate classes of insecticides used. Check the IFAS Insect Management Guide for specific recommendations. 3
Giant Whitefly Giant Whitefly Parasitized pupae Parasitic wasp next to pupae Bacterial Leaf Spot (Xanthomonas and Pseudomonas spp.) Recognition: Symptoms of bacterial leaf spot are water-soaked spots on the leaves. Both pathogens cause angular spots with dark margins and yellow halos. Infected leaves turn bright yellow and drop from the plant. Contributing factors: Overhead irrigation or long periods of leaf wetness along with warm temperatures are favorable for the development and spread of this disease. Management Recommendations: Avoid overhead irrigation, especially at night. Provide good air circulation around the plants. Root knot nematodes Recognition: Poor growth, plant decline, yellowing leaves and thinning of the canopy may be symptoms of nematode infestation. Infected roots have obvious galls and may be brown and stunted. 4
Contributing factors: The highest populations of nematodes occur in well-drained sandy soils where previous crops have supported high levels of nematodes. Management recommendations: Keep plants as healthy as possible with adequate water and fertilizer to support new roots. No chemical controls are available for use on existing plants. When replacing plants, remove all roots and replace soil. Avoid replanting with susceptible species, or fumigate before replanting. Environmental Stress Recognition: Environmental or cultural stresses may cause hibiscus to react by dropping flower buds or leaves, developing leaf chlorosis, and/or shoot injury or necrosis. Contributing factors: Bud drop can be a response to root injury, excessive water or fertilizer, insects (thrips or midges), nematodes, or temperature changes. Cold injury may cause bud drop or leaf chlorosis, or a freeze may kill the above-ground portion of the plant. Management Recommendations: Reduce cultural stresses associated with the respective factors. Provide cold protection if desired. Some leaf drop can be tolerated Cold damaged plants can be cut back and allowed to regrow once spring arrives. Cold Temperature damage 5
Sources 1. Neal, Cathy, Celeste White and Eleanor Foerste. Key Plant and Key Pests in Central Florida Landscapes. University of Florida Extension slide set. 2. University of Florida Landscape Plant Propagation Information. http://hort.ufl.edu/lppi/ Prepared by: Juanita Popenoe, PhD, Extension Faculty, Regional Commercial Horticulture Lake County Extension, 1951 Woodlea Rd., Tavares, FL 32778-4052 Tel.: (352) 343-4101, FAX: (352) 343-2767 June 2008 The Institute of Food and Agricultural Science (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. DEPARTMENT OF AGRICULTURE, COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, IFAS, FLORIDA A. & M. UNIVERSITY COOPERATIVE EXTENSION PROGRAM, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING 6
WEEKLY IPM REPORTING FORM FOR HIBISCUS Date: County: Site Code: Scout: Aphids Green peach aphids (GPA) or Cotton aphids (CA) Beneficials present (check): Plant #1 (cultivar:_) Terminal GPA CA Terminal Plant #2 Plant #3 (cultivar:_) (cultivar:) GPA CA Terminal 1 1 1 2 2 2 3 3 3 Total Total Total GPA % parasitized: % parasitized: % parasitized: CA Friendly fungus PFR fungus lacewing adult lacewing larvae lady beetle adult lady beetle larvae parasitic wasp predatory mites praying mantid spiders syriphid fly larva tachinidfly wasps J Whitefly Type(silverleaf whitefly or citrus whitefly): Plant #1 Plant #2 Plant #3 Leaf Adults Imma tures Leaf Adults Imma tures 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 Leaf Adults Imma tures Environmental Conditions: Temperature range (days): 60-70 70-80 80-90 90-100 Temperature range (nights): 40-50 50-60 60-70 70-80 Irrigated Unirrigated Rainfall since last sampling date: inches Note any extreme weather: Total Total Total % parasitized: % parasitized: % parasitized: Sail trap (adults): Sail trap (adults): Sail trap (adults): 7
Hibiscus Mites Type of mite, if known: Site Code: Plant #1 Plant #2 Plant #3 Leaf No. Eggs No. mites (+ or -) Leaf No. Eggs No. mites (+ or -) Leaf No. 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 10 10 10 Total Total Total Niger Scale No. Eggs mites (+ or -) Plant #1 Plant #2 Plant #3 Branch Mature scale Eggs (+or-) Branch Mature scale Eggs (+or-) Branch Mature scale Eggs (+or-) 1 1 1 2 2 2 3 3 3 Total Total Total % parasitized: % parasitized: % parasitized: Please note any insecticides applied since last sampling date: Any other pests/problems observed: Scouting procedure for hibiscus: Choose three plants to scout weekly. Count the number of aphids and scale on each of 3 terminals per plant. Count adult and immature whiteflies on 5 leaves per plant. If mites are present, count the number of mites on 10 leaves per plant. Note presence (+) or absence (-) of eggs. 8