Here is what Herbs2000.com has to say about "Pests and Diseases of Hibiscus"

Pests and Diseases of Hibiscus


The organic philosophy
The aim of all organic practices -permaculture, biodynamics, natural farming is not just to reduce and ideally to eliminate the use of toxic chemicals that are harmful to humans, animals, plants and the planet, but to understand the processes of nature in order to participate, rather than to interfere.

This means a change in thinking. Instead of thinking monoculture on a massive scale, think biodiversity over a smaller area. Instead of thinking of insects as pests, think of them as part of the natural order, with the plant-damaging insects kept in check by predators. Instead of thinking of perfection in ornamental and edible plants as blemish-free, know that nature is not driven by glossy advertising. Think always of the way plants live without interference from humans.

Food for resistance
If you feed your hibiscus with compost-good-quality, balanced compost -you can never give them too much. Conversely, if you feed any plant with chemical fertilizers, you can easily give them too much. Too much can kill off all micro life. With edible plants, too much can contribute to cancer promoting nitrites, and the imbalance that can result from overfeeding with artificial fertilizers can create pest and disease problems. Nitrogenous fertilizers in particular can be harmful because they promote rapid soft growth that attracts sucking insects.
Just as mammalian predators pick off the runt of the herd, so insects will overcome the weakest of the crop. If you doubt that compost is resistance food, try an experiment using both organic and inorganic fertilizers by growing carrots or cabbage in two lots. Give one lot the best compost you can and the other lot a nitrogenous fertilizer, such as sulfate of ammonia. The latter will quickly be eaten by pests.
Another analogy is stress: stress in humans results in vulnerability to colds, flu and infectious diseases. Stress in plants makes them similarly susceptible.
A soil rich in organic matter not only provides nutrients but inhibits the growth of fungal and bacterial diseases, such as phytophthora, by encouraging the natural antibiotic activities of mycorrhizal fungi. And of course, the texture of such a medium provides hibiscus roots with that high air filled porosity they need. When they are healthy, well-fed hibiscus shrug off or outgrow pest damage.

Stability in the garden
Aim to provide all plants with the conditions they need. Aim for both lateral and vertical diversity, by matching plants with the conditions that suit them at every level, from ground-covering creepers through mid-high shrubs to the top of the canopy.
A stable garden does not contain impossibly difficult plants from quite different climates and conditions. Nor does it grow a huge number of similar plants in isolation from all others. And apart from the procedure of planting and transplanting, a stable garden is not routinely dug or hoed. Rather, layers are allowed to build up in the way a rainforest floor accumulates. Mulching and layering duplicate the processes of nature.
A stable garden in which natural pest control is practiced will always have a constant, but manageable, supply of pests providing food for a constant number of predators. Both are accepted as part of the ecosystem. Not all insects are bad -some are predators, some never cause plant damage, and others never build up their numbers.
Companion planting for insect control
Companion planting is a component of the stable garden, but it is not a cure-all. On its own it is ineffectual: it doesn't rid the garden of pests, but it does aid diversity and stability. Through releasing different scents, through utilizing different levels of soil, and by occupying different garden spaces in certain combinations, companion planting can attract, or repel, specific insects. For example, plants which attract aphids and are good companions for hibiscus include the annuals feverfew, coriander and nasturtium, and Hyssopus officinalis.

Hibiscus pests
Some hibiscus pests are worse than others. The larval grubs of garden butterflies can chomp their way through many a hibiscus leaf, but their harm is mostly visual. There are grubs which live off the foliage of shrubs and soft-wooded trees and other grubs which usually hatch out simultaneously. This means that if you find one, you'll find more. Watch closely for them, especially in the early morning, and if you discover them in the early stage, you may be able to pick off and destroy the whole batch.

Chewing insects
Beetles too can be picked off. Apart from the flea-like bronze beetle (Eucolaspis brunnea), which leaps too quickly to be caught, most beetles can be hand removed if the bush is not first disturbed.
Snails and slugs, though voracious chewers, are a threat only to fresh new leaves, mainly on young plants. The best natural control is plentiful bird life. Other chewing pests include grasshoppers and katydids, those bright-green, well-camouflaged, flying bugs. Stick insects are also chewers, but fortunately don't often bother hibiscus. Excelling at camouflage on the bush, the females lay eggs which drop to the ground and emerge as nymphs in spring, climbing up the stem to feed on new leaves. A simple way to prevent them getting there is to band the base of the trunk or stem with a ring of grease -try Vaseline -that stops them in their tracks.

Sucking insects
Sucking insects may be less conspicuous. Although the green vegetable bug, Nezara viridula, and its immature form with the colorful mosaic back are often easy to spot, most sucking insects are a lot smaller. Scales are only 1/16 th in (1 mm) long; spider mites, pinprick-sized pests, can cover the undersides of leaves; powdery or fluffy mealy bugs are a menace, and there's always the common aphid. Be alert for these. Evidence of their presence is white spot or chlorosis of the leaves (spider mites), misshapen buds (aphids), or sooty mould (by-product of mealy bugs and aphids).
To avoid spraying other than a last resort, try first squashing these pests by hand or removing them with a strong-pressured hose. Squashing or hose-blasting mealy bugs will probably not work though, because they coat themselves and the surrounding surface with a waxy substance that resists dislodgment. For mealy bugs, try a paintbrush application of water mixed half-and-half with methylated spirits. Spot applications of this sort (i.e. using a paintbrush) are always environmentally safer than wide-coverage spraying.
Thrips can be difficult to deter as they are fast movers. They are worst in dry conditions, and are not usually a problem in moist areas. Frequent hosing and misting can eliminate them. Whitefly infestation most often occurs in heated glasshouses. It shouldn't be a problem for the home garden where hibiscus have good air circulation.

Other pests
A big problem is gall midge. It lays its eggs in the flower buds, which the larvae then damage. The buds eventually drop, and this bud-drop is the most obvious sign of the pest. To rid plants of this pest, remove all dropped buds or buds that begin to mold. Regularly apply orthene to the foliage and buds, and diazinon to the soil.
Another problem is Japanese beetle, Popillia japonica, fond of buds and flowers. Adult beetles can be controlled by spraying malathion, rotenone, sevin or methoxychlor.
There are other pests of course, most notably, perhaps, the dreaded hibiscus beetle (Macroura concolor) -scourge of hibiscus gardens in Queensland, Australia, to which it is fortunately confined.

Natural controls and non-toxic pesticides
For most of the above-mentioned insects, natural controls should be tried. Among natural predators are hoverflies, which can consume huge numbers of aphids and also eat mites and scale insects; praying mantis, which are fully carnivorous and eat aphids, leaf hoppers, caterpillars, beetles and sometimes moths; spiders, which besides consuming flies feed on the larvae of moths and whiteflies; and, best of all, the ever-friendly ladybug. Ladybugs should be encouraged everywhere. Upon hatching, their larvae start immediately to eat aphids, mealy bugs, woolly aphids, thrips and other sap suckers, and they continue into adulthood to clean up these menaces.
Non-toxic sprays should be used with caution, not because of harm to humans but because indiscriminate use can kill both the targeted insect and its predators. The non-toxic preparations described here are short-lived and break down quickly, so they should be used up quickly. Pyrethrum (make your own from Tanacetum cinerariifolium, or buy the ready-made produce from garden centers) is a broad-spectrum insecticide. Garlic spray (soak 3 oz (85 g) of whole unpeeled garlic in mineral oil for 24 hours and add 1 pint (600 ml) of water in which a bar of soap has been dissolved; strain, dilute by five times, and spray) will work if it is eaten -it is not a contact spray -and can kill stink, bugs and the mosaic-backed vegetable bug. Chile spray (1 cup of fresh chilli peppers pulped with 1/2 cup of dried chilli and 1 cup of water) controls caterpillars and loopers, which are also deterred by sprinkled cayenne pepper. Buttermilk spray (1/4 cup of buttermilk and 2 cups of flour mixed with 1 gallon (5 liters) of water) will control mites when applied to the undersides of leaves every two days. Onion spray can be good for scale, thrips, aphids and mites (pour 3/4 pint (500 ml) boiling water over 2 1/4 lbs (1 kg) of chopped unpeeled onions and strain; dilute 20 times with water for spraying). Applications of ash from the fireplace, provided it is wood ash and dry, can control leaf-eating earwigs, grasshoppers and katydids. Some gardeners recommend diluted antiseptic solution as a good general insecticide.
You can also try traps. Cut a piece of white or yellow cardboard the size of your hand, and coat it with Vaseline. Nail it to a stake or tie to a hibiscus branch. Insect pests, especially night-flying ones, will be lured to it, as they are to all light, and will stick fast. Such a simple device is good for assessing what is in your local insect population. A "trap" with a different purpose, that of catching aphids, can be made from a liquid containing sugar and yeast.
Another non-toxic suggestion is a diluted yeast- based spread laid around the garden in small quantities to attract predators such as hoverflies and lacewings, both of which feed on aphids.

Hibiscus diseases

Phytophthora
The soil-borne wilt disease associated with soils that dry out in summer and are wet in winter, can kill many ornamental shrubs, including hibiscus. It pays to avoid the kind of conditions favorable to phytophthora because affected plants usually do not recover. The problem rarely occurs where hibiscus are given good drainage and ample compost.

"Collar rot"
Visible as a browning discoloration, often slimy, at the root join, is prevalent where winters are cool and damp, and drainage poor. You can try a treatment of removing all affected stems and bark and painting the discolored area with Bordeaux paste. Clear the surrounding ground completely and spray with a strong garlic solution. Sclerotina rot affects stems at ground level.

Repeated applications of strong garlic or chamomile tea can help.

If your hibiscus has succumbed to tot and you want to replant in the same spot -inadvisable but sometimes unavoidable -you must first improve the site. Start by removing the affected plant and burning it, then dig up the whole area beyond root depth and spread, distributing the infected soil in an unimportant area, such as plugging a hole in the driveway. Some gardeners advocate lighting a fire and spreading it over the entire site before refilling, as fire will kill off any remaining pathogens. The next step is to infill for drainage by lining the cavity with a layer of pumice mixed with fine gravel or pumice over coarser stones, adding sand, then filling the cavity with new topsoil. To be extra-cautious, use sterilized potting mix.

Besides diseases of the soil, there are fungal diseases that can affect foliage. Leaf spot is the main one to watch for. Containered plants may be slightly more susceptible to it than in-ground plants, especially when positioned in places with less air circulation. Dark brown or black spots on leaves indicate the presence of pathogens which are most active in wet weather. Heavily infected leaves, where the individual spots have merged to discolor the entire leaf, will result in shedding, and shrubs so depleted can probably only be salvaged by the application of a fungicidal spray, such as Bordeaux. Liquid Bordeaux can be bought from garden retailers or made at home to an exacting recipe of copper sulfate and calcium hydroxide. Bordeaux paste uses the same two ingredients less diluted, with skim-milk powder for viscosity.

In general, compost and mulch are the best root-rot preventatives. Dolomite sprinkled on the area can also help. An all-purpose spray for fungal prevention can be made from a "weak tea" of nettles, comfrey, yarrow or horseradish. Even better, a weak liquid poured off from seaweed soaked in fresh water has a four-fold benefit: it is a foliar fertilizer, it promotes frost-resistance, it is an insect repellent and a fungicide, and the residual seaweed can be composted or used as a mulch.

Solutions to other problems

Sparse foliage
Apart from insect infestation or the general poor conditions that result from undernourishment, the most frequent cause of sparse foliage is insufficient sun. Site hibiscus in maximum sun.

Crinkled leaves
Check for aphids or leaf hoppers on the undersides of leaves. Large colonies of aphids can suck the life out of leaves before they are noticed. Remove the affected leaves along with the offending insects. If the infestation is severe, try spraying.

Deformed and sickly foliage
If it is possible or likely that your hibiscus has been exposed to systemic insecticides, it will quickly sicken. Hibiscus do not tolerate systemic chemicals, such as maldison, which are absorbed by the plant. Good feeding and watering may help it recover.

Yellow leaves
Yellowing of leaves at the base of branches and stems occurs naturally as the hibiscus sheds old foliage. If yellowing occurs higher up the stem, especially at the growing tips, it could indicate magnesium or iron deficiency -trace elements easily added to the soil. Alternatively, the discoloration could be a sign of over-watering or over-feeding with chemical fertilizers, in which case suspend both. Yellowing is another sign of exposure to systemic insecticides.

Yellow leaves with green veins
Yellow leaves with green veins are a clear indication of iron deficiency. Apply a good feeding of compost and manure, and scratch in kelp meal or seaweed. Iron chelate is often recommended specifically to target the deficiency. Dig this in lightly -never pack down tightly around the stem. Mulch, kept clear from the base of the stem, can also help.

Other leaf discoloration
Brown margins might be windburn, in which case watering and light feeding can restore health. Persistent and prolonged windburn, indicative of a windy climate to which hybrids may not be suited, is a problem that might be best solved by replacing hybrids with wind-tolerant coastal species.
Salt toxicity also shows up as brown leaf margins. Treat with generous watering. Leaves that turn brown at the tips, purple at the edges, and become brittle could indicate a lack of potassium.
Frost damage
Once frost has damaged your hibiscus, there's nothing you can do. If severe, the plant may not recover at all; if light, it will struggle back of its own accord to produce new growth in spring. Do not prune affected parts until the weather has warmed and new growth is established. If you live where frosts can be expected every winter, you may consider pot culture to enable you to move the plant to shelter each year.

Weeds
Any weeds growing around a hibiscus are competing with it for nutrients. Remove them. Remember that the feeding roots of hibiscus are very close to the surface, depending on the same top few inches of soil occupied by weeds. The easiest way to keep the area weed-free is to thoroughly clear it before covering with a layer of mulch; the mulch will keep the weeds at bay.

Lawn encroachment
When hibiscus are sited in a lawn, an area of about 3 square feet (1 square meter) should be kept clear of competing growth. Mulching will deter the grass from encroaching again.

Lichen
Gray, green or silver lichens occasionally establish themselves on old mature trees. They won't bother the hibiscus but may bother the gardener. It would have to cover and smother the whole shrub before harming it. However, if you want to remove the growth, scrub it off with a scrubbing brush or apply Bordeaux paste in winter.

Ants
Many ant species are valuable predators. They only invade hibiscus if there's something there for them to feed on, and although the odd ant may be attracted to nectar, ants in large numbers are usually after the honeydew excreted by aphids or mealy bugs. Deal with the aphids and the ants will go too. Moisture is an ant deterrent -they increase in dry places -as is pyrethrum spray. Banding the base of the hibiscus stem with Vaseline will prevent ants from traveling further up.

Poor flowering
Few flowers in an otherwise healthy plant may result from too much shade, or, if sun is adequate, from excessive nitrogenous feeding which promotes leaf growth at the expense of flower production. Bud damage may also be a cause.

Buds but no flowers
If your hibiscus are under attack from borers or beetles penetrating the buds before they open, the ground will show the evidence. The treatment of removing all buds, both from the bush (including the tips of branches) and from the ground below, and burning them, followed by insecticidal spraying, should reduce the problem, but may not eliminate it.
Bud drop can also result from lack of water during warm sunny weather; it is important not to let hibiscus dry out.

Flowers appear late in the season
The most likely cause of late blooming is sun and temperature -not enough sun and not warm- enough temperatures.

Blooms change color
The hybrids sold today are the result of years of intensive hybridizing, of crossing one with another, and often backcrossing again to achieve desirable attributes. As with many such "manmade" garden plants, dominant features of parent plants or earlier ancestry occasionally appear after they have been bred out. Sometimes hibiscus revert to colors of an earlier form; sometimes they'll revert from double to single, from ruffled to unruffled, or from overlapped or windmill single to plain single. This happens most often out of season, while true-to-type blooms can be expected in summer and fall.

Words of advice from the University of Florida

Hibiscus in Florida

D. L. Ingram and L. Rabinowitz

The Chinese hibiscus, Hibiscus rosa-sinensis L., is probably the most popular and widely planted shrub of the tropics. This colorful shrub has been grown in Florida for many years, but it is believed to be native to China and was introduced to Florida by way of the South Pacific and Hawaii.

Little is known about the early history of tropical hibiscus. Early Chinese hibiscus may have been hybrids involving two or more species from areas adjacent to the Indian Ocean. Today, most of the varieties that are commonly grown in Florida and known as Hibiscus rosa-sinensis L. are probably hybrids. Other Hibiscus species such as H. schizopetalus and H. tiliaceus are used limitedly in south Florida. The Florida Exotic Pest Council has reported H. tiliaceus to be an invasive plant.

Most hibiscus varieties have one-day flowers; the blossoms open early in the morning and wilt late that afternoon. Flowers of a few varieties remain open for two days. Although individual flowers do not last long, the flowering season is nearly all year in southern Florida. Most hibiscus are odorless, but a few varieties are slightly fragrant.


Selection of Varieties
Hibiscus varieties are selected on the basis of plant growth habit and size, the form and color of the flowers, and adaptability to specific environmental conditions. Plants range from low, spreading forms to upright varieties reaching 20 feet (6 meters) in height. Some are compact and dense while others are open and thin.
Tremendous flower variations exist between varieties. Although the six basic colors are red, orange, yellow, white, lavender, and brown, there is a broad range of color combinations, color shades, and flower forms. Hibiscus flowers are basically characterized as single or double forms with variations in the number and arrangement of petals.

Hibiscus flowers are often used in flower arrangements. Picked flowers do not have to be placed in water but should be kept in a reasonably cool place. Hibiscus flowers may be saved for evening use if picked just after they have opened in the morning and refrigerated until needed.

Hibiscus are used in the landscape as informal hedges or screens, foundation plants, or background for other garden plants. They do not perform well as formal sheared hedges. The repeated use of a single variety in hedges and other mass plantings is usually more effective than a mixture of several varieties. Selected varieties may be trained to grow with a single trunk and are called "standards." Standards make attractive specimen plants for patios, terraces, and flower gardens.

Hibiscus breeders are still active in Florida as evidenced by the hundreds of named varieties found today. In general, the older varieties that grow well on their own roots are the most desirable for use in the landscape. Many of the newer varieties grow well only as grafted plants and are not widely available. All varieties can not be listed in this publication, but a few common varieties are presented in Table 1 .


General Culture
The use of hibiscus as an evergreen shrub in Florida is limited to the southern half of the peninsula. The limiting factor for growing hibiscus in north Florida is low temperatures. Plants will be killed to the ground by 28 to 30°F (2 to 1°C) temperatures, but established plants may come out in the spring and bloom on new growth that summer. Hibiscus should be protected from cold northern winds by fences, buildings, screens, or trees. Hibiscus are not tolerant of salt spray or saline irrigation water.
The amount of sun required for optimal hibiscus growth and flowering differs with variety. Generally, half a day of direct sunlight is the minimum requirement.


Soils
A wide range of well-drained soils is suitable for hibiscus if proper fertilization is provided. A soil pH of 5.5 to 6.5 is preferred. Hibiscus grown on alkaline soils may suffer from micronutrient deficiencies and these are discussed in the fertilization section.

Planting and Transplanting
Container-grown hibiscus can be planted any time during the year, but transplanting in the yard is best done during the cooler months.
The planting hole should be one foot (30 cm) wider than the root ball and as deep as the root ball is tall. Hibiscus should be planted at the same depth as they were in the container or field. Staking may be necessary.

The novice hibiscus gardener often plants the hibiscus too close together. Plants should be spaced on the basis of their mature size. A three and one-half to four feet (one meter) spacing is recommended for a hedge, but four and one-half to five feet (one and one-half meters) is appropriate in garden areas and foundation plantings.

Plants should be watered thoroughly immediately after planting and frequently enough to prevent wilting until they are well established. However, the soil should not be kept continuously wet. The proper frequency will depend upon soil characteristics, rainfall, air temperature, and degree of cloud cover.

An organic mulch will conserve water, reduce weed problems, and help control nematodes. Good mulches include cypress or pine bark, oak leaves, or pine needles. Do not place mulch in contact with the hibiscus stem.


Watering
Hibiscus require well-drained soils and do not tolerate saturated soils or "wet feet." However, they do require adequate water and will need regular irrigation during periods of drought. Hibiscus should be watered heavily about once a week during dry periods. Apply enough water to wet the soil to a depth of 12 to 18 inches (30 to 45 cm).

Fertilization
Regular fertilization of hibiscus is essential to maintain healthy and vigorous plants. Hibiscus bloom best when fertilized lightly and often. Three or four applications per year have proven satisfactory: 1) early spring, 2) after first growth flush, 3) midsummer, and 4) early winter. The amount of fertilizer per application depends on frequency of fertilization and size of the plants.
The rate may range from one-half ounce of 15510 or 15515 fertilizer for a small plant, up to one-half or one pound (225 to 450 grams) for a mature plant per application. Some hibiscus growers fertilize once a month all year round, applying from a small handful to one-half cup of fertilizer per plant, depending upon the size of the plants. Spread the fertilizer beneath the canopy to slightly beyond the branches and avoid fertilizer placement on or near the stem. Irrigation after fertilizer application will help prevent fertilizer burn.

An ample supply of micronutrients is essential for proper growth of hibiscus. Iron and manganese are often limiting on alkaline soils. Manganese sulfate at a rate of one to two ounces (28 to 57 grams) per plant has proven helpful. Some iron chelates, such as Sequestrene 138®, are designed for alkaline soils and will often correct iron deficiencies. Commercial mixtures (Perk, Stem, Esmigram) containing many micronutrients have proven to be effective and convenient for the home gardener. Extreme soil conditions, such as the lime-rock soils of the Miami-Homestead area, may limit the effect of soil applications of micronutrients. Foliar sprays of micronutrients applied two or three times per year may be the only way to reduce symptoms in these conditions.


Pruning
Heavy pruning is best done in the early spring (February or March) and should not be done late in the fall or in the winter. Light maintenance pruning may be done any time of the year to remove diseased or dead wood, rubbing branches, and weak or droopy growth.
Hibiscus blooms are produced on new growth, so blooming is delayed and reduced if the plants are pruned heavily during the active growing season. Plants can be pruned to maintain a desired size and shape without disrupting their blooming or appearance by cutting only the longest one-third of the branches at one time. The next longest third of the branches may be cut 30 days later, and the remaining third cut 30 days after that. Light, periodic pruning avoids the need for heavy pruning.


Propagation
Hibiscus can be propagated from seed or cuttings, or by air layering, budding, or grafting. Seedlings are quite variable and are never identical to the parent plants, so seedlings are grown primarily by hibiscus breeders.
Cuttings are taken from softwood or new growth in the spring and summer and placed in a well-drained medium, such as equal volumes of fibrous peat and coarse builders' sand. These cuttings will usually root in about six weeks and the plants produced will begin to flower in about nine months. When hibiscus are propagated commercially, the cuttings are usually treated with a rooting hormone and rooted under a mist system. Intermittent mist is the best method for maintaining cuttings in high humidity during rooting.

Some varieties do not root readily from cuttings and air layering becomes a useful alternative. Branches one-half inch or larger are girdled by removing a one-half-inch-wide to one-inch-wide band of bark (1.3 to 2.5 cm). Moist sphagnum moss is placed around the wound, sealed with a plastic wrapper, and secured with rubber bands, tape, or string. Newspaper or aluminum foil can be wrapped around the plastic to shade the newly formed roots and prevent birds from pecking through the plastic.

Hibiscus can also be propagated vegetatively by grafting or budding. The techniques result in plants that combine two different varieties, the entire top portion being one variety and the root stock another. Grafting or budding is used primarily to propagate varieties that are highly susceptible to nematodes or do not produce strong plants on their own roots.


Pests and Problems
Pests
Several types of chewing pests feed on hibiscus leaves, buds, or flowers at one time or another. These include caterpillars, grasshoppers, snails and slugs, beetles, cutworms, and leaf miners.
Pests that damage hibiscus by sucking plant juices can also be a problem. These include scale, mealybugs, spider mites, aphids, whiteflies, and thrips. These pests are generally more of a problem in areas with poor air circulation. Control of these pests can be difficult if large populations are allowed to develop. Thrips generally feed on flower buds and may produce distorted flowers or cause flower bud drop.

Generally, pests can be controlled with applications of contact or systemic pesticides. Routine inspections instead of routine spray schedules may reduce the quantity of pesticides required. Hibiscus are sensitive to many pesticides and this sensitivity can be increased by improper use. The safest time to spray is early morning and not in the middle of a hot sunny day. Specific recommendations for control of a given insect on hibiscus can be obtained from your local county extension office. Always read the label before applying a pesticide.

Common diseases of hibiscus include leaf spot, canker, and mushroom root rot. Canker is a fungus disease which causes twigs and branches to die back and sometimes the entire plant is killed. Reddish-orange fruiting bodies can often be found on diseased bark. The best control is to prune off and destroy all diseased wood.

Hibiscus infected with mushroom root rot usually wilt suddenly and die a short time later. Poorly drained soils and buried tree stumps or roots encourage this disease. Dead or dying plants should be removed with as much of the root system as possible, and the soil should be replaced or sterilized before replanting.

Leaf spots caused by various fungi and bacteria can occur on hibiscus. These diseases may cause the death of affected leaves, but usually the spotting is minor and little cause for alarm. The primary control of these diseases is to pick off or rake up diseased leaves and destroy them.

Nematodes are microscopic round worms that feed on plant roots and can cause severe plant injury. Sometimes the only symptom is a decrease in plant vigor. Visual symptoms also include frequent wilting, poor growth, small leaves, and nutritional deficiencies. Soils can be sterilized before planting, but no chemical control measures are available to treat established plants. Mulching can reduce nematode damage by encouraging their natural enemies.


Problems
Premature flower bud drop is often a problem with hibiscus. Some varieties, especially some doubles, are characterized by premature bud drop. Some varieties bloom well during one period of the year and consistently drop their buds at other times. The importance of variety selection is illustrated by this point.
Bud drop can be caused by insects such as thrips or caterpillars. Nematodes, nutritional deficiencies, overfertilization, and environmental factors such as poor drainage and excessive water, drought, or salt spray can cause flower buds to drop.

Introduction to Unbelievable Hibiscus

Unbelievable Hibiscus has been a family business for almost ten years. We have been involved in the American Hibiscus Society (AHS) for the whole time through the Sunset Chapter located in St. Petersburg Florida. We started this business as a hobby with a handful of plants that instantly grew on us and blossomed into the business we have today. We started by purchasing Fifth Dimension and a few others from a AHS show at Westshore Mall in Tampa Florida. In all the years we have done this Fifth Dimension is still one of the best selling of our entire nursery because of the way the bloom changes color over time. We started with a few tables in a makeshift greenhouse in the backyard and ended up buying ten acres to put greenhouses on before we even built our home. Hope you enjoy our labor of love because we love to labor for the joy of these hibiscus.

Don Mixon

Get that wax out of your ears

Here Is a grafting party we had at a Sunset Chapter meeting a few years ago. It goes to show that you don't need the expencive wax to get the job done. The following bloom is Barry Schlueter.

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