Saturday, March 26, 2016

Big, Bold Bougainvilleas

No matter where ever you go in the tropic's you'll always come across the vibrant sun loving presents of Bougainvillea's.   These drought tolerant sprawling climbers will thrive under neglect to shower you in a massively floriferous display of color throughout spring, summer or autumn.  Their resilience and color have gained them a place in many tropical gardens around the world.

Bougainvillea's were first discovered by a french naval commander, Louis-Antonie de Bougainville around the coastal areas of Rio de Janeiro, Brazil between 1766-1769.  By the early 19th century, Bougainvillea's had made their way to the nurseries of Europe where a thriving trade soon grew.  It was shortly discovered thereafter that the species naturally hybridized with colorful hybrids popping up spontaneously wherever Bougainvillea were grown.

Bougainvillea's comes from the Nyctaginaceae (Four-o-Clock) family which hosts 33 different related genera.  Within the genera Bougainvillea genera, there are 14 species, with only three that are considered horticulturally important; B. spectacles, B. glabra and B. peruviana.  They are a tropical to subtropical woody evergreen, shrubby vine typically with multi-trunked or clumping stems.  Left naturally, it has a spreading habit and forms a rounded plant with a height and spread of up to 20 feet.  However, with training the eventual size often is much greater.

The true flower is a small, tubular, white to yellow bloom that is surrounded by the brilliantly colored bracts, or modified leaves.  The same flower modification can be seen in Dogwoods and Poinsettias where the true flower is often over shadowed by the vibrantly colored bracts that surround it.  They come in various different colors from lilacs, oranges to yellows, pinks, purples, reds, violets and whites with various shades in-between.   Double braced forms and variegated foliage hybrids can be found for those looking for a little more interest.

Location: Bougainvilleas will grow best in full blazing sun or with at least 5 hours of direct afternoon light per day.  Not enough sun = not enough bloom.  They thrive best in outdoors in areas of low rainfall and intense heat with night temperatures that are above 60 degrees F.  This makes them ideal for year round cultivation in US hardiness zones of 9 and higher.  However, they can be grown during the summer months in colder zones as long as they are brought inside and protected from freezing weather.  Although a tough and durable plant, they don't tolerate strong prevailing winds.  It is best to secure your plants so they get shelter from high winds and don't rock around.

Feeding: Although Bougainvilleas grow like brutes in the garden, they are big babies when it comes to their roots.  They have delicate, thin roots which will easily burn if too much fertilizer to applied all at once.   The best approach to feeding is to apply the fertilizer weakly but with multiple applications out over a longer period.  A balanced, slow released fertilizer high in iron to prevent chlorosis, and plenty of micronutrients is all that is needed.  Liquid feeding with soluble fertilizer is also a good option but requires increased frequency of applications to achieve the desired results. They are heavy feeders during their flowering season and will benefit from a increase in feeding.  However, during  non-flowering periods the feeding can be reduced.  Fertilizer should never be applied to dry soil as this will burn their delicate feeder roots.

Soil and Watering: Bougainvilleas grow best when planted in a well draining loamy soil mixed with good amounts of organic matter to help nutrients and oxygen get down to those delicate roots.  A soil pH range of 5 to 7 is ideal.  Deep watering is always preferred as long as the soil drains with little trouble.  Once established, they're drought tolerant and prefer to on the dry side.  By keeping your plant a little under stress you'll improve the flowering show.

Planting or Re-potting:  As mentioned during the section on feeding, Boug's are big babies when it comes to root sensitivity.  When planting, try and not disturb the roots as you move the plant from its nursery pot to the final home.  Careless planting can send these plants into serious shock or in the worse case will lead the plant to die.  As such, many people chose to plant them with the nursery pot still on, but cut away the bottom to allow for the roots to push out and explore their new surroundings.  If growing in a container, Boug's love to be pot bound and should only be stepped up a single size without breaking of fiddling with the rootball.  Root pruning is not recommended.

Training and pruning: Bougainvilleas are extremely vigorous growers and don't mind a good whacking back to set their shape.  Start by training selected stems to make a good framework of branches and create a desired form.  Boug's don't have a natural ability to cling or attach themselves to structures so you will need to fasten them if you wish for it to climb.  Once the shape is achieved, lighter prunings after each flowering cycle and removal of water shoots is all that is need to keep the plant in check.  It is best to remove side shoots to about 2 inches from the old cane (just like climbing roses) to produce flowering spurs and maintain its shape. Bougainvilleas bloom in new wood. The more you pinch out and trim, the more flowers you'll encourage.

Growing in containers:  Of course not everyone has the space to allow these super-sized beast to take over or have the growing climate for it to live outside year round.  Fortunately, Bougainvilleas response well to container culture and actual prefers their roots to be a bit snug in a pot.  Start by using a container one size up from its nursery pot and use a planting mix moderate in peat moss with plenty of drainage.  Peat moss can retain to much moisture and may result in root rot issues.  Water soluble fertilizer is the best approach to feeding Bougainvilleas in pots with a application of slow release granular fertilizer given when potting on.  Also, consider some of the smaller cultivars (some of them thornless) like Helen Johnson, Flame, Silhouette, Miss Alice or the Ice series.  Click here for a chart of recommended cultivars.

Pest and diseases: Bougainvilleas are fairly free of trouble.  For the most part, the usual culprits that cause damage are Aphids, Caterpillars (loopers), grasshoppers, mealybugs, mites and whiteflies.  Using a good wide spectrum insecticide at the first sign of damage will halt any problem from getting out of hand.  For diseases, leaf spots and root rots will be more of an issue on heavier soils or places where irrigation is frequently wetting the foliage.  Broad spectrum fungicides will help prevent the spread but a change in water management will reduced the problem over the longterm.

One common physiological problem faced by anyone growing Bougainvilleas is chlorosis, a lack of normal green pigmentation in the foliage.  This is often cause by a deficiency of iron or magnesium or a high soil pH that prevents the uptake of these nutrients into the plant.  Mixing 1-2 teaspoons of Epsom salts with 1 gallon of water and applying with a watering can will improve the situation.  Also, acidifying the soil with aluminum sulfate, chelated iron or elemental sulfur with help with the plants absorption of these elements.  If after this your plants systems don't improve, you could be seeing the effects of water logging or a nematode issue affecting those delicate feeder roots, where a change in cultivation will be needed to reverse the symptoms.

From vines, ground covers, hedges, containers, topiaries and bonsai, there is a Bougainvillea to fill you needs.  With very little needs, Bougainvilleas will provide eye-catching color over long periods in the garden.  Even if you don't live in the tropics, they adapt well to overwintering inside a house to provide a colorful display during the summer months.  So, isn't it time you planted a Bougainvillea for your garden?

For more information on Bougainvilleas follow these links:

Saturday, February 27, 2016

The case of the disappearing coconuts - A closer Look

In my last post I wrote about the mystery of disappearing coconuts from our shores and touched lightly on the causes leading to their decline.  Through my sleuthing on the internet I discovered something that may have a big impact not just on coconuts, but many other plants as well.

Without a doubt, coconut decline is a serious problem across the whole tropical region.  Many people depend on coconut palms not just for food but for oils, shelter, fuel and many other uses.  Should the decline of coconut palms become worldwide it could be compared to the Irish Potato famine in how it will effect many people reliant on the coconut industry.

Coconuts drying for Copra production

Lethal Yellowing syndrome (or complex) is a collection of different pathogens identified with todays crisis.  The main disease is a phytoplasma organism that is spread by a plant hopper (Myndus curdus) which feeds on the sweet sap of the palms fronds.  Thus far the only treatment has been to inject oxytetracycline HCI, an antibiotic into the trunks every four months.  However, shooting up trees with antibiotics is costly and the side effects of consuming any part of the palm can have a negative effect on protecting our own health from so called 'Mega-bugs'.

Injection sites for Oxytetracycline damages coconut trunks and leaves them unsightly.
LYS was first identified in 1830 running rampant through stands of coconuts in the Cayman Islands.  Since then it has spread across the Caribbean region and central America with cases being reported as far away as Africa.  There is no single symptom that can diagnose Lethal yellowing as many other stresses can turn a palm yellow.  Mineral deficiencies and pests like 'Red Ring', a nematode native to the Caribbean has lead to confusion and misdiagnosis of the disease.

Blacken, water soaked appearance at the stem
of the nut.
The first signs to appear on older, fruit bearing palms is the premature dropping of the nuts accompanied by flower necrosis.  However, coconut palms as young as 2 to 3 years have been know to contract the disease and often show foliar discoloration, starting at the lower fronds and extending upwards until the whole crown turns yellow. Eventually, the crown will turn brown and desiccate, hanging down for a few weeks before falling off to leave a solitary trunk.  Infected palms often die with in 3 to 5 months after showing the first symptoms.

Targeting the insect responsible for the spread is one approach, but it's so common and widespread that positive controls outside of infected areas is impossible to achieve.  Coconuts growing in areas of well maintained healthy grass like golf courses were the first to be impacted, while on dry sandy beaches the spread of LYS was far slower.  In fact, the juvenile insect cycle starts its life feeding on the roots of lawn grasses.  However, once the adults emerge they can jump long distances carrying the pathogen once infected from palm to palm as they feed.

So far, the best option has been to plant resistant cultivars of coconuts, but this isn't without its own set of problems.   In a 20 year field study conducted at the University of Florida a number of certified seed coconuts cultivars were grown and evaluated.  In a report published in 2002, 91% of Jamaica Talls, a common coconut for this region were lost.  However, the previously believed resistant strains like Malayan Dwarf, Maypan and Red Spicata suffered losses ranging from 50 to 83%.  The only cultivar that showed the greatest promise was Fiji Dwarf (Niu Leka) which had a loss rate of 0%.  This field study also demonstrated that 'off types' of Fiji Dwarfs were just as susceptible to infection with 50% loss.  Only clones or seed collected from controlled cross pollinations that produce 'true to type' can be considered 'resistant'.

Fiji Dwarf Coconut
Another study, published in 'The Journal of the Mexican Chemical Society' has put a different light on the fight against LYS with an article published on 'Cuticular Wax Composition of Coconut Palms and the Susceptibility to Lethal yellowing Disease'.   The study was to measure the wax coating on the fronds of coconuts to see if there was correlation between thickness of this wax layer had any effect to the palms contracting LYS.  As it turned out, those palms that had a thicker layer were less prone to LYS.  This natural barrier prevents sap sucking insects from penetrating the leaf layer and introducing a pathogen.  This might explain why in infected areas you can still find stands of coconuts seemingly unaffected by LYS.

On reading up on cuticle wax I discovered that environmental stresses like drought, excessive heat, exposure to strong wind and even acid rain can all dissolve this protective layer leaving the plant vulnerable to attack.  However, all these stresses are a result of climate change, which is progressively changing what crops can grown where.

So what can be done to protect our existing coconuts?

The answer may lie in a study conducted at a Canadian agricultural research station in Ontario concerning ways to combat Tomato Spotted Wilt Virus (TSWV).  In the study, they compared various film-forming products like Wilt-pruf, a anti-transpirant product and Horticultural Oil on the feeding habits of Thrips connected to the spread of TSWV.  What was discovered was Wilt-pruf significantly reduced the virus transmissions and feeding damage from thrips.  It was also suggested that 'TSWV transmission may occur more readily during brief and shallow probing which is associated with thrip salivation and discharge of the virus'.

With this knowledge in hand, it seems highly possible that by applying an extra layer of persistent, clear flexible film to many plants will help in deterring the feeding habits of many virus spreading insects.  By coincidence, we noticed that spraying our Plumeria's to protect the foliage from the burning damage caused by salt-laiden winds we saw a drop in Plumeria rust and scale as a result.  If this reduced a plants pathogen load, then spraying coconuts might also help in reducing attacks from Red Palm Mite and other insects too.

In summary, knowing how important cuticle wax is on a plants defense and how easy it is for this to be reduced, it is only logical to believe that applying film forming sprays can have a positive benefit to a plants health.  This is something that we will be experimenting with over the course of a year to see how positive it is on the health of our coconuts.  At the same time, the application of film forming products could be used in a much wider spectrum to protect highly susceptible plants like Roses from all the damage they sustain.

For further reading on LYS, please click on these links;

Wednesday, January 27, 2016

Nevis needs more Nuts!

Most of you non-tropical mainlanders may be unaware that our iconic symbol of Caribbean islands is in deep crisis.  The symbol I'm referring too is our beloved Coconut Palm or Cocos nucifera a palm featured so many times on the pages of travel magazines, has been disappearing from our beaches at an alarming rate.

So what has happened?  Simply put, these palms face the same crisis as Bananas, too many of the same genetic types with little diversity.  These mono-culture's of nearly identical types can't resist diseases when outbreaks occur.  Although the main disease I'm referring too is 'Lethal Yellowing Disease', two other pathogens, 'Bud Rot' and 'Red Palm Mite' have run rampant through the population.  In a future post I will get into the details of all three issues, but collectively they have been termed 'Coconut palm complex' as they can all be found at the same time on declining trees.

Pinney's Beach before Lethal Yellow Disease
When I first came to Nevis a longtime ago, the beaches were lined as far as you could see with Coconut palms that stretch deep into the interior of the island.  Locals will tell stories of never taking any supplies with them to the beach as natures bounty was ripe for harvest.  Jelly water (a local term for coconut water) was drunk to refresh the body and Coconut flesh was eaten to fill your bellies.  Nowadays, there's not even enough palms to meet the needs of everyone as over 70% of coconut palms were estimated to of died, although the number is mostly likely higher.

Effects of Lethal Yellowing Disease
This week I was sent on a mission to find some jelly waters for guest staying at the place where I work.  It should of been a simple walk along the beach, but every stand of palms I found was devoid of their nuts.  Instead, the ground was littered with opened husks left behind from harvesting.  So rare now is it to find jelly waters, entrepreneurial people have seen a market willing to pay good prices for what was once ample.

Fortunately, efforts are being made to replant these iconic symbols of Tropic islands. Various government ministries have committed themselves in a scheme to replant resistant coconut strains across both islands of St Kitts and Nevis, but is this enough?  No one really knows the true amount of coconut palms lost to this 'complex' but its impact is evident.  Although bring in resistant types would in the long run help, its those trees that survived that leave me to ponder why?  Do these survivors have a natural ability to fend off attack.  If they do in fact come from better genetic stock, then the constant harvesting for jellies is only adding to the complex of coconut decline.

Nut grabber in action
Maybe a better approach to re-nutting Nevis is through educating the nut collectors in sustainable harvesting.   After all, they are the benefactors of the harvest and profit from what remains, so its in their best interest to secure their chosen crop for future profits.  If for every two nuts they collect, one is planted in gratitude, we can reclaim the bounty that Nevis once relied on.  Because at the end of the day Nevis wouldn't be Nevis without its Nuts!