Bougainvillea

Introduction

The Bougainvillea is an immensely showy, floriferous and hardy plant. Virtually pest-free and disease resistant, it rewards its owner with an abundance of color and vitality when it is well looked after. The bougainvillea's versatility is legendary. It can be coaxed into a small manageable pot plant or a sizeable tree, to spread itself vertically on a wall, or climb up a trellis and form a luscious crown or burst forth into graceful arches. It makes one of the best hedges, bushes, and curb-liners. And as for bonsai or topiary purposes, it has few equals, lending its complex branching to the pruning shears, which promote even more unique and graceful forms. It is probably true to say that without the bougainvillea, our roads, parks, and private gardens would be a lot less colorful that what we see today. Almost everywhere we go, its brilliant hues and cheerful bursts punctuate the lush green mantle that cloaks our tropical environment. Other flowering plants certainly pale in comparison.

Along with palms, sunshine, and beaches, the cascading blooms of bougainvillea provide one of Florida's signature tropical images. As a profuse bloomer, bougainvillea is most striking during the winter, when it is at its peak and few other plants are able to provide color. Although it is frost-sensitive and hardy in zones 9b and 10, bougainvillea can be used as a houseplant or hanging basket in cooler climates. In the landscape, it makes an excellent hot season plant, and its drought tolerance makes bougainvillea ideal for warm climates year-round. Native to the coasts of Brazil, bougainvillea has a high salt tolerance, which makes it a natural choice for south Florida and other coastal regions. As a woody clambering vine, bougainvillea will stand alone and can be pruned into a standard, but it is perfect along fence lines, on walls, in containers and hanging baskets, and as a hedge or an accent plant. Its long arching branches are thorny, and bear heart-shaped leaves and masses of papery bracts in white, pink, orange, purple, and burgundy. Many cultivars, including double flowered and variegated, is available.

History

A native to coastal Brazil, the bougainvillea was discovered in 1768 in Rio de Janeiro by French naturalist Dr. Philibert Commerçon (also sometimes spelled Commerson). The plant is named after his close friend and ship's admiral Louis-Antoine de Bougainville, who commanded the ship La Boudeuse that sailed around the world between 1766-1769, and in which Commerçon was a passenger.

Twenty years after Commerçon's discovery, it was first published as 'Buginvillea' in Genera Plantarium by A.L. de Jusseau in 1789. The genus was subsequently split in several ways until it was finally corrected to 'Bougainvillea' in the Index Kewensis in the 1930s. Originally, B. spectabilis and B. glabra were hardly differentiated until the mid 1980s when botanists recognized them to be totally distinct species. In early 19th century, these two species were the first to be introduced into Europe, and soon, nurseries in France and England did a thriving trade providing specimens to Australia and other faraway countries. Meanwhile, Kew Gardens distributed plants it had propagated to British colonies throughout the world. Soon thereafter, an important event in the history of bougainvillea took place with the discovery of a crimson bougainvillea in Cartagena, a Spanish port in the Mediterranean, by Mrs. R.V. Butt. Originally thought to be a distinct species, it was named B. buttiana in her honour. However, it was later discovered to be a natural hybrid of a variety of B. glabra and possibly B. peruviana - a "local pink bougainvillea" from Peru. Natural hybrids were soon found to be common occurrences all over the world. For instance, around the 1930s, when the three species were grown together, many hybrid crosses were created almost spontaneously in East Africa, India, the Canary Islands, Australia, North America, and the Philippines.

Scientific  classification

Kingdom - Plantae
Division - Magnoliophyta
Class - Magnoliopsida
Order - Caryophyllales
Family - Nyctaginaceae
Genus - Bougainvillea
Species - Bougainvillea  spectabilis
       Bougainvillea glabra
       Bougainvillea peruviana
            Cultivar (or variety)

Note about Species: Many of today's bougainvillea are the result of interbreeding among only three out of the eighteen South American species recognized by botanists.

Note about Cultivars: Currently, there are over 300 varieties of bougainvillea around the world. Because many of the hybrids have been crossed over several generations, it's difficult to identify their respective origins. Natural mutations seem to occur spontaneously throughout the world; wherever large numbers of plants are being produced, bud-sports will occur. This had led to multiple names for the same cultivar (or variety) and has added to the confusion over the names of bougainvillea cultivars.

Species and Hybrids

Bougainvillea spectabilis is a large climber with distinctive curved thorns, and hair on stems and leaves. The bracts are crinkled, fairly large, egg-shaped, and possess colors in the rose, rusty-red, and purple. Flowers are cream in color, slender, with very hairy tubes. Leaves are large, ovate to rounded, leathery in texture and hairy underneath. The bark is pale and corky. Branching is close and short, giving rise to a very dense plant. The first species collected, it was described from dried specimens by Willdenow (1798).

Bougainvillea glabra has thinner branches that spread in many directions and have distinctive pointed triangle-shaped bracts that come in a range of whites, lilacs, mauves, and purples. Thorns are short, thin, and curved at the tips. Leaves are fairly evenly elliptical, widest about the middle. The small cream flowers are relatively big and tube-shaped. The also tend to flower virtually continuously, and often down the entire length of the branch. Originally described and named by Choisy (1849).

Bougainvillea peruviana has a branching habit that is looser and more open. This is a climbing, spiny, spreading shrub with greenish bark. Thorns (spines) are thin, straight in youth and curved when older. Leaves are thin and ovate to broadly ovate. The small roundish bracts, usually in light to dark magenta colors, are quite delicate to the touch, and are crinkly in appearance. Flowering is recurrent after strong vegetative growth in response to dry weather. This species was described and named by Humbold and Bonpland (1808).

Bougainvillea hybrids found today have been grouped into these three hybrid groups:

• B. x buttiana (glabra x peruviana)
• B. x spectoperuviana (spectabilis x peruviana)
• B. x spectoglabra (spectabilis x glabra)

Best Climate for Bougainvillea

Bougainvillea are tropical and must be protected from frost. In Zone 8 and cooler, you are almost limited to growing them in some kind of container unless you treat them as an Annual (plant a new plant outdoors each year) -- which works fine if you obtain a large plant in the spring. Bougainvillea thrives in full sun. At least 5 hours a day of full sunlight is the minimal light required for good bloom. More hours of direct sun are better. Less than 5 hours and the plant may not bloom very well. In shade or partial shade, you will have nice vegetative growth, but little or no bloom. A Bougainvillea just doesn't bloom well indoors. If possible, keep your plant outdoors (in the maximum sun available). If placed on a porch, patio or balcony, where the plant receives at least 5 hours of sun each day (afternoon sun is best), then it should bloom ok. A bougainvillea likes high humidity just before it comes into bloom. Once bloom has been initiated, then it will tolerate less humidity.

Production

Bougainvilleas' natural habitat is equatorial where day and night lengths are almost equal. Bougainvillea in these areas tend to bloom year round, but in North America, best blooming occurs when the night length and day length are almost equal (in spring or fall). In winter, blooming is better than in the dog days of August because of night length. Also, some cultivars are triggered to bloom after a rainy season followed by a dry season.

Light Levels

As a tropical plant, Bougainvillea requires full sun, or a light level of at least 4000 f.c.

Production Temperatures

Temperatures should be maintained somewhat high; a minimum of 65°F at night and 75° to 95°F during the day. Growth production will be delayed at cool temperatures, especially if the soil is also cool.

Salt Tolerance

Good salt tolerance.

pH Preference

Bougainvillea does best with a soil pH of 5.5-6.5

Media

Bougainvillea has an extremely fine root system, and should be planted in well-drained soils. Avoid soil mixes with high peat levels and water retention. These types of media retain too much water and will contribute to root rot; be sure to select a well-draining media. The best growing mixture is one that is soil-less. Soil-less media are free of any disease pathogens, insect pests, and weed seeds. They are also generally lightweight and porous, allowing for a well-drained yet moisture-retentive mix. Premixed growing media are available from garden centers. However, be careful not to use peat or peatlite mixes alone. By themselves, these media tend to become compacted, too lightweight, and hard to wet. The greatest problem with peat/peatlite mixes is when the soil dries completely, the root ball will pull away from the side of the pot, and it is almost impossible to completely wet the soil again -- the water simply runs down the side of the container and drains out the bottom. If your plant dries out and you use this type of mix, to rewet it, let the pot sit in a pail of water until the soil ball is completely wet. Before using your mix to repot plants, be sure it is damp. Totally dry soil mixture is difficult to handle and may damage tender roots before the plant is watered.

Fertilization

Bougainvillea are heavy feeders that require regular monthly fertilization. Nitrogen and phosphate are critical to flowering, but do not overfertilize with these two elements because it will add growth and inhibit blooming. This is the case when using generalized fertilizers like a 20-20-20 or 12-12-12. That’s why we’ve created a blooming fertilizer specifically for bougainvillea called BOUGAIN®. With Bougain’s 6-8-10 plus Minors formula, Nitrogen levels are just right for flowering, but low enough to limit excessive green growth. In addition, Bougain® contains 5% Iron -- and any professional grower will tell you that’s the secret for vibrant, beautiful color on bougainvillea.

Pruning & Pinching

Bougainvillea may be pruned at any time of the year. Bloom initiation does not depend upon pruning - a bougainvillea has a bloom cycle followed by a rest period whether pruned or not. A hard prune is recommended when you need to contain growth or when you are preparing to move your bougainvillea indoors for the winter. The ‘Soft Prune’ is recommended for bougainvillea only when trying to obtain a special form. A bougainvillea, like most vining-type plants, will continue to grow outward without sending out side branches from each leaf-bud point unless the stem is pinched. If you want one long stem, then don't pinch out the tip. By pinching out the tip, most bougainvillea cultivars will send out new stems from 2 to 3 leaf-buds below the cut. Some varieties do not send out any new stems, so their appearance is always stringy or bare. BGI only produces varieties that will send out 2-3 new shoots, so you don’t have to worry about a BGI® bougainvillea ever looking stringy – that is, unless you forget to pinch! So it is important when growing a bougainvillea, not to wait for the branches to grow very far beyond your desired size before you remove all the tips -- otherwise, the growth will be bare in the center of the plant, and the overall look will be misshapen.

Growth cycles

The bougainvillea has two distinct growth cycles:

1. A vegetative growth period for several weeks -- when new leaves and stems grow. If the plant receives enough sunlight, the plant will form buds during this time. If there is not enough sunlight, the plant will remain in vegetative cycle.

2. A blooming period of several weeks when little or no vegetative growth occurs. The length of time they will display color is dependent upon the health of the plant and the environment they are in; the more sun and heat, the better. However, long days and short nights (July and August in Florida) limit a bougainvillea's ability to bloom.

Photoperiod/Flowering

Blooms occur only on new growth, so new growth on plants is vital to the achievement of flowering. Bougainvillea normally flowers during the short days of winter, but blooms are highly dependent on temperature. Drought stress can also stimulate flowering even with long daylight exposure. Growers frequently allow plants to dry just to the point of wilting to induce flowering. However, excessive drying can cause leaf drop and dormancy; use care and be sure to water at first signs of wilt.

Landscape Culture

Bougainvillea is a wonderful addition to any landscape, whether it's used as a permanent fixture, a container plant or hanging basket in a semi-tropical landscape, or an annual in cooler climates. For the best performance out of your Bougainvillea, follow these guidelines:

• Keep Bougainvillea on the dry side, especially if you want lots of blooms. Too much water will promote root rot and cause leaves to drop. Don't water on cool nights.
• Use a high-bloom fertilizer.
• Plant or place Bougainvillea in full sun. As a potted plant, flowers will last for up to eight weeks if kept in a sunny location.
• Winter dieback may be a problem if the weather gets too cool, so if you're growing Bougainvillea in a frost-prone area, plant in a protected location or cover in case of frost.

Frost Tolerance

Bougainvillea require winter protection. It may be killed if the temperature remains below freezing for more than 4 hours. A light frost will not kill a mature bougainvillea, but may for a young planting. Within a day after the frost, all the leaves and bracts will fall off. If they remain on the plant, they may have a “singed” or “burnt” look to the edges. In this case, the plant will regrow, but only if not subjected to further frosts for longer durations.

Winter Protection

It is not unusual for a bougainvillea to be full of bloom when it comes time to move it indoors for winter. Almost immediately after bringing a plant like this (full of bloom) inside, all the bracts will fall off and most of the leaves will eventually fall off as well.
It’s recommend that you do a hard prune before moving it indoors:

Bougainvillea is a vine and new growth (after a prune) starts one or more leafbuds below the cut and not up and down the entire branch. By doing a "hard" prune, next spring, when the plant regrows it will be fuller from the base up. Most reference to pruning bougainvillea I have found on the web is applicable more to nonvining plants where new branches grow up and down the stem after a pinch -- vines or climbing plants tend to grow only one or two branches from the leafbuds just below the cut after pruning. If you like the shape of your plant now, then you may not even want to prune before moving it indoors. Next spring it will hold the same shape, just grow larger. But, if is not quite the shape you desire or is overgrown, the best thing to do would be to perform a hard prune.

Bringing Indoors for the Winter

If you have planted your bougainvillea in the soil outdoors and want to dig it up and move it indoors for the winter, expect the plant to go into dormancy sooner than if it had been in a container -- the root damage as a result of digging will be the cause rather than the cool weather -- but the plant should survive this kind of transplanting. Make sure to dig as far away from the root system as you possibly can. It’s important not to sever the roots; take care to dig up the entire root ball and especially in one piece.

Any space which doesn't freeze will be fine for your bougainvillea while indoors. If you put your plant in a high light area which remains warm during the winter nights, it may not go into dormancy and will be in better shape once Spring comes. If the spot you have doesn't have much light and stays cool during the day, then expect the plant to go into dormancy. After a few weeks indoors bougainvillea may go into dormancy and all the leaves will fall off. While indoors, water very little, and just keep the soil slightly damp.

Planting In Containers

Generally, bougainvillea can be grown in anything that will hold soil and allow proper drainage. Some of the more traditionally used containers include terra cotta (clay) pots, plastic pots, hanging baskets, wire baskets lined with sphagnum moss or fibrous liners, concrete planters, planter boxes, and bushel baskets. When BGI was on a bougainvillea exploration trip through Southeast Asia, we saw beautiful bougainvillea growing out from old laundry baskets and tires! Just remember that the container MUST have proper drainage. If you place your pot directly on the ground, the roots may emerge from drainage holes and find their way into the earth. To prevent this, place wooden slats or four bricks (in a T-design) under the pot. The air will naturally prune the roots that are exposed.

It’s very important to remember that a bougainvillea does not tolerate standing in water. Whatever container you choose, consider these tips:

• Drainage: Bougainvillea must have it.
• Insulation: Avoid using black containers in full sun.
• Large enough: The container must be large enough to hold the minimum amount of soil required for mature plants to grow in.
• Weight: Will it be too heavy to move? Styrofoam peanuts can be used in the bottom of the container rather than filling it fully with soil mix. This should also help with drainage and keeping drainage holes clear of debris.

Repotting Bougainvillea

A bougainvillea blooms best when pot-bound so do not be tempted to re-pot unless you must. It is best to leave the plant in its original container until the roots have replaced all of the soil and you can't keep the plant well watered. For example, it is not unusual to grow a bougainvillea in a 1 gallon pot for three or more years. When it is necessary to re-pot remember that a bougainvillea has a very delicate root system and a fragile root to stem connection. Handle bougainvillea with care. Root pruning is not recommended when re-potting bougainvillea - in fact, disturb the roots as little as possible because the plant might go into shock and take weeks to recover. Bougainvillea love to be pot-bound, so pot in the smallest container available for the purpose you desire. Re-pot into larger pot sizes gradually. For example, move a plant in a 6" pot into a 9" or 10" pot. Several years later, you can then move up to a 14" pot. The root system needs time to grow into each new pot.

Common Pests & Diseases

A part of the bougainvillea’s appeal is that they are relatively disease and pest-free plants. It is NOT common for your bougainvillea to be affected by these pests and diseases if you follow BGI’s Rules for Care, and fertilize with Bougain® which contain a significant amount of micronutrients – vital for healthy, blooming bougainvillea. This page contains most (but not all) common pests/diseases that may affect your bougainvillea.

On the rare occurrences that your bougainvillea experiences pest problems or disease, always try the least toxic method of pest control as your first step. If you use chemical pesticides to control insect pests, you will also kill natural predators. If you choose a chemical control, follow directions and guidelines closely and always wear protective clothing and safety gear including a long-sleeved shirt, long pants, neoprene gloves, goggles and a respirator. Chemical pesticides are not recommended for use inside the home.

Aphids

Known also as greenfly, blackfly or plant lice, aphids are minute plant-feeding insects. Important natural enemies include the predatory ladybugs/ladybirds/ladybeetles, and lacewings. Aphids are tiny, pear-shaped, sap-sucking pests, appearing in the spring to feast on your plants' tender new leaves. They leave behind a secretion that attracts ants and promotes mold growth. Not to fear; you don't have to resort to toxic chemicals to save your bougainvillea.

Natural Control

1. Examine your garden regularly for signs of aphids. Look for clusters of the little bugs on new growth as well as on the curled and twisted leaves.
2. While wearing gloves, remove the aphids by hand, or use a sharp stream of water to knock them off the plant.
3. Cut away and dispose of infested foliage.
4. Capture flying aphids by placing yellow sticky traps near infected plants.
5. Make a nontoxic pesticide by mixing 1 cup vegetable oil with 1 tablespoon liquid dish-washing soap. Add 1½ teaspoon solution per cup of warm water to a handheld spray bottle.
6. Hit the aphids directly with above mixture and spray entire plant thoroughly.
7. Introduce beneficial insects, such as ladybugs/ladybirds/ladybeetles, or green lacewings to your garden to feed on the aphids. Both can be bought from garden stores or online.
8. Avoid planting bougainvillea near aphid-attracting plants, such as birch trees, and instead grow plants such as white sweet clover, spearmint, sweet fennel and Queen Anne's lace, which attract and house the lacewings, ladybugs and other insects that feed on aphids.
9. Rid your garden of ants. Ants love to eat the sugary sap (honeydew) secreted by aphids, and will “farm” the aphids, protecting them on the plant they eat.

Caterpillars; namely the Bougainvillea Looper Caterpillar

The bougainvillea looper is a green or brown caterpillar about 1 inch long. It is also called inchworm or measuring worm. The looper larva mimics stems and branches very well and feeds primarily at night, which is why you may see the damage but fail to find the culprit on the plant. The adult is a moth, a very fast flyer with a wingspan of about 1 inch. The moth does not feed on the foliage. Like the larva, it also is active at night, when it is believed to lay its eggs on the underside of bougainvillea leaves. Go out scouting very early in the morning or at night if you have a good strong flashlight. The bougainvillea looper feeds from the edges of the leaves, which results in severe scalloping of the foliage. Attacks begin on the young tender shoots and leaves before progressing down the stem. The insect will cause significant visual damage to bougainvillea, although this does not apparently result in the death of the plants.

Chemical Control

Bacillus thuringiensis (BT, or Dipel®) and neem-based biological insecticide products should are a good solution and should be effective on the loopers without harming other insects that may biologically control them. Insectical oils and soaps will not control caterpillars such as the looper. Most synthetic insecticides with labels permitting use against caterpillars on landscape ornamentals, such as carbaryl (Sevin®), will likely kill the bougainvillea looper, although these products are often destructive to beneficial insects as well. Spraying insecticides late in the evening is recommended. This is when the bougainvillea looper caterpillars and adult moths are active, and also when the beneficial insects are not likely to be active.

Leafminers: Moths, Flies, Beetles, Wasps

The vast majority of leaf-mining insects are moths (Lepidoptera) and flies (Diptera), though some beetles and wasps also exhibit this behavior. Although the types of insects differ, the damage they cause is very similar. Because of this, the larval stages of all insects which leaf mine are collectively and generically called “leaf miners”. All leaf miners will cause the leaves to look skeletonized, and to fall from the plant. Eventually they can kill the plant.

Natural Control

Cleaning around the plant is your best solution. Like wood borers, leaf miners are difficult to control as they are protected from insecticide sprays and plant defenses by feeding within the tissues of the leaves themselves. Some leaf miners can be killed by systemic pesticides (a type of pesticide that moves inside a plant following absorption by the plant), but many breeds are still immune to the effects of pesticide.

1. Cleaning around the plants. Debris tends to collect at the base of plants, and this is where the adults of the leaf miner larvae lay their eggs. Some leaf mining larva may also “winter over” in this debris. Removing leaves and other debris from around plants is an excellent method for controlling them.
2. Weeding provides an alternate food source for leaf miners, so areas around plants should be weeded and mulched.
3. Do not use contact pesticides. Since the leaf miner is inside the leaf, contact poisons cannot reach it, and therefore cannot kill it. Additionally, leaf mining insect larvae quickly become resistant to contact pesticides.

Scale Insects: Parasites, Mealybugs

Most scale insects are parasites of plants, feeding on sap drawn directly from the plant's vascular system. Scale insects vary dramatically in their appearance from very small organisms (1-2 mm) that occur under wax covers (some look like oyster shells), to shiny pearl-like objects (about 5 mm), to creatures covered with mealy wax. Scale insects' waxy covering makes them quite resistant to pesticides, which are only effective against the juvenile crawler stage. Over time, scales and mealybugs turn leaves black with “sooty mold”.

Natural Control

1. Identify scale insects by looking on the undersides of leaves and around leaf joints. Scale-damaged plants look withered and sickly and may have sticky sap or a black fungus on the leaves and stems.
2. Move an infested plant to isolate it from the rest of your collection. Scale insects are invasive and will infest other plants.
3. Remove scale insects with a twig or scraping tool. They will scrape off of plant tissue easily.
4. Wash infested plants with a soap/oil mixture if scraping alone doesn't do the job. Mix ½ tsp. insecticidal soap, ¼ tsp. horticultural oil into 1 quart of warm water. Wash the leaves individually with the soap/oil mixture. Rinse well. There are also numerous chemical products available for the control of mealybugs.
5. Purchase and release a natural predator called Chilocorus nigritus or Lindorus lophanthae for serious infestations. Place the insects directly on the infested plant. Once they have consumed the scale, the predators will simply die from lack of food in the indoor environment.
6. Spray with pyrethrin as a last resort. Pyrethrin is an organic pesticide made from chrysanthemums.
7. Be diligent - examine infested plants for evidence of new scale every day. It may take some time, but your bougainvillea will thank you!

Snails & Slugs

Photo Credit: Weidners' Gardens. Encinitas, California, Jeffrey Lotz; FDACS-DPI and David Robinson.

Snails usually eat from the middle of the leaf, but they can take bites out the edges as well. All this biting and chomping will make the leaf look scalloped. Putting down barriers that slugs can't cross is, perhaps, the best way to protect your garden from these common pests. Keep them from entering and you won't have to use pesticides.

Natural Control

1. Water your garden only in the early morning, or use an underground irrigation pipe. This will keep the top of the soil dry and uninviting to slugs and snails.
2. Spread dry soot, dry ashes, dry lime, sharp cinders and dry chalk around plants or beds. Any one of these or several in combination should do the trick.
3. Rough, sharp sand is another option. Use it the same way as the materials in Step 2.
4. Try calcified seaweed or crushed eggshells as a barrier.
5. Another barrier material is clippings from thorny roses or holly leaves. Rosa rugosa (Japanese rose) clippings are good.
6. Spread pine needles in your garden (these are also good mulch for strawberries).
7. Spread chopped hair (human hair is fine) in your garden.
8. Try using oak leaves as a barrier. Slugs and snails don't like the tannin in the leaves.

Chemical Control

Any brand of slug/snail killer will do the job. Sluggo is good because it can be used around pets and people.

Mites; namely Spider Mites

The webspinning two-spotted spider mite occasionally makes their home on bougainvillea. To the naked eye, spider mites look like tiny moving dots. Adult females, the largest forms, are less than 1/20 inch long. Spider mites live in colonies, mostly on the under-surfaces of leaves. The names "spider mite" and "webspinning mite" come from the silk webbing most species produce on infested leaves. The presence of webbing is an easy way to distinguish them from all other types of mites. Mites cause damage by sucking cell contents from leaves. A small number of mites is not usually reason for concern, but very high populations—levels high enough to show visible damage to leaves—can be damaging to plants. At first, the damage shows up as a stippling of light dots on the leaves; sometimes the leaves take on a bronze color. As feeding continues, the leaves turn yellow and drop off. Often leaves, twigs, and fruit are covered with large amounts of webbing. Damage is usually worse when compounded by water stress. Check the undersides of leaves for mites, their eggs, and webbing; you will need a hand lens to identify them. To observe them more closely, shake a few off the leaf surface onto a white sheet of paper. Once disturbed, they will move around rapidly. Be sure mites are present before you treat. Sometimes the mites will be gone by the time you notice the damage; plants will often recover after mites have left.

Natural Control

If a treatment for mites is necessary, use selective materials, preferably insecticidal soap or insecticidal oil. Petroleum-based horticultural oils or neem oils are both acceptable. Oils and soaps must contact mites to kill them so excellent coverage, especially on the undersides of leaves, is essential and repeat applications may be required. Mid-season washing with water to remove dust may help prevent serious late-season mite infestations. Regular, forceful spraying of plants with water will often reduce spider mite numbers adequately. Be sure to get good coverage, especially on the undersides of leaves.

Chemical Contol

Spider mites frequently become a problem after the application of insecticides. Such outbreaks are commonly a result of the insecticide killing off the natural enemies of the mites, but also occur when certain insecticides stimulate mite reproduction. Naturally controlling mites is the best method.

Thrips

Thrips are tiny, slender insects with fringed wings that cause discoloration and deformities on bougainvillea and other plants. Other common names for thrips include thunderflies, thunderbugs, storm flies and corn lice. Thrips are generally tiny (1 mm long or less) and are not good flyers, although they can be carried long distances by the wind. Thrips feed by piercing plant cells with their paired maxillary stylets, which form a feeding tube. Due to their small size, cryptophilic behavior, and high rate of reproduction, thrips are difficult to control using classical biological control. Only two families of parasitoid hymenoptera are known to hunt them, the Eulophidae and the Trichogrammatidae.

Whitefly

Whiteflies typically feed on the underside of plant leaves. Whiteflies feed by tapping into the phloem of plants, exposing plants to the whiteflies' toxic saliva and decreasing the plant's overall turgor pressure. The damage is quickly elevated as whiteflies congregate in large numbers, quickly overwhelming susceptible plants. Damage is further exacerbated as whiteflies, like aphids, excrete honeydew as a waste product, which promotes mold growth. Whitefly control is difficult and complex, as they rapidly gain resistance to chemical pesticides. A major problem is the fact that the whiteflies and the viruses they carry can infect many different host plants. Use of yellow sticky traps to monitor infestations and only selective use of insecticides is advised.

Common Diseases & Problems

Fungal and Bacterial Leaf Spot (Pseudomonas and ropogonis)

The early symptoms are small reddish-brown leaf spots which usually occur on younger foliage, and cause the leaves to look "rusty". These enlarge into circular or irregular dark necrotic spots. When environmental conditions are drier and less favorable, leaf spots are slower to develop. Lesions have a tan center surrounded by a dark redbrown margin, and are sometimes bordered by a chlorotic halo. In time, leaf edges may become ragged as the necrotic tissue turns dry and papery. Under conditions of high rainfall or relative humidity the lesions develop quickly and are often black and vein delimited. Infection of developing leaves and bracts results in puckered, distorted growth.

Defoliation will occur when leaf spotting, blighting or marginal necrosis becomes severe.

Natural Control

Maintaining dry foliage is the primary control measure. Prune branches back and away from each other or, if just starting to grow, allow a large amount of space between them. Branches that are overlapping can't dry quickly and become more susceptible to leaf spot disease. Remove infected leaves and/or plants from the growing area.

Dispose of them immediately to reduce the spreading of infection.

Chemical Control

Spray fungicide in the spring if necessary. It will not cure infection that is already there, but it can control the spread of it. In frost-free climates where bougainvillea is perennial, disease incidence drops during cool and/or dry weather.

Black, Sooty Mold

See “Aphids”, “Scale Insects: Parasites, Mealybugs”, and “Whiteflies”

Leaf drop

Problem as a result of over-watering, under-watering, low light levels, or cold temperatures.

Leaf spots

Yellow or tan spots appear on older leaves may be sign of Magnesium deficiency (common with yellow bougainvillea varieties), or from over-watering.

Root rot

Plants that are over-watered or subjected to water logged conditions can develop root or stem rot. It’s easily prevented by careful handling and by the application of a broad spectrum fungicide drench during transplanting or planting in the landscape.

Scalloped Leaves a.k.a. “Help, Something’s Eating My Bougainvillea!”

See "Snails & Slugs" and "Bougainvillea Looper Caterpillar"

Yellowing or chlorosis on new growth

Often a result of a magnesium or iron deficiency, and an application of a complete micronutrient blend should help, but use caution--too much of either Mn or Fe will result in a secondary deficiency, as the plant is unable to absorb one when the other is present at high levels.

Yellowing or chlorosis on old growth

Often a result of a magnesium or iron deficiency. Apply Epsom salts at 1-2 tsp/gal as a drench or foliar spray.

Deficiency signs

Recommended remedy for any of the deficiencies below is the application of a complete micronutrient blend such as BOUGAIN® 6-8-10 Plus Minors.

Nitrogen deficiency: Older leaves turn a pale green and the veins are usually a reddish color. New growth will be stunted.

Phosphorus deficiency: The veins will turn red to purple and the plant as a whole will look purplish.

Potassium deficiency: Causes the edges of older the leaves to be a purple color and the leaf tips will be a brownish color.

Magnesium deficiency: First appears on older leaves where they turn a spotted yellow or tan color.

Zinc deficiency (rare): Will look almost like magnesium but here the leaf will be twisted.

Iron deficiency: Young growth is stunted and pale -- you'll know its iron if the veins on the leaf remain green.

Calcium deficiency: Dead areas appear in young growth and the tips soon die.