Chompoo Paan plumeria
Plumerias are generally easy to grow and relatively care free.   In the growing field,
however, plumerias can be susceptible to a number of diseases, insect pests and
pathogens, some of which can be serious threats to the plants' health.  Below is the
list of garden pests, pathogens and diseases associated with plumerias that I have
encountered over a number of years within my grove and around Thailand.
Spider mites:  They thrive in warm and dry conditions --especially a
lack of rainfall for an extended period of time.  The mites feed on plant
juices and cause leaf yellowing and bronzing on upper leaf surface.  
Spray of water directly to the leaves helps to keep their population
down.  In severe case, Miticites should be used.

Left: Leaves infected with spider mites
Right: Webbing between the midrib
Suggested Reading:
Click here.
Mealybugs coaggulate in large number on undersides of young and
mature leaves (esp. midrib and veins), leaf axils, stem tip and flower
inflorescence.  Nymphs (male and female) and adult females feed on
plant sap and excrete honeydew which serves as a growing medium for
sooty mold fungi.  The insects cause leaf yellowing, leaf stunting,
(young) leaf malformation and inforescence distortion.
Left: Mealybug feeding on mature leaves and cause leaf yellowing and
malnutrition on infested branches.
Right: Black ants feed on honeydew
Mealybugs feedling injury (leaves and inflorescence):

Left: Mealybug feeding on stem tip and young leaves
Right: Deformed inforescence


Infested leaves and inforescence should be removed and/or applied with
insecticides such as Chlorpyrifos and/or white mineral oils.
Mealybugs feeding injury (young leaves):
Left: Mealybugs infested leaves at early stages and their feeding results
in leaf distortion (wrinkled/warped leaves) and growth stunting.
Top right: Light yellow spots seen on upperside of young leaf are the
indication of mealybug feeding on the opposite site of leaf (underside).
Bottom right: Mealybugs on the underside of warped deformed leaf

Suggested Reading:
Click here
Broad mites (Polyphagotarsonemus latus) feed on underside of newly
formed leaf (left picture).  As they feed, they inject their toxin saliva and
damage meristematic tissue stunting the growth of growing tip (right
picture).  They also feed on flower buds damaging the inflorescence
and flowers.

Broad mites are microscopic and difficult to see even with a good hand
lens.  They thrive in warm and humid condition especially in rainy
season.
Broad mites:

Damage to young expanding leaves (left and middle picture) by broad
mites causing the leaves to brittle, distort and curl (sideways)(right
picture).

Dicofol and Abamectin are the most effective chemicals to control
broad mites.
Suggested Reading:
Click here.
Scale insects on underside of mature leaf (left picture), stalk and seed
pod (right picture).


(under construction)
Thrips are so tiny in size (each specie varies in size) and are difficult to
see since they feed in unopened flowers and in the sheaths of new
leaves.  They use rasping, sucking mouthparts to take sap from
emerging and new leaves, young stems, and flower buds and petals.  
Thrip feeding leaves tiny scars or streaks (turn silvery when the leaf
matures) on young foliage and causes them to distort and curl
(sideways).
Left: Streaks on young expanding leaf
Right: Silvery streaks, and distorted/sideways curled leaves
Under construction
Thrips can cause flower buds to turn brown, distort the flowers'
growth, and leave discoloring spots or streaks on flower petals or keep
them from opening and fall off.
Damage on plumeria by thrips is generally limited.  In severe case,
Imidacloprid or Abamectin may be applied to control their poppulation.

Left: Flower buds fell off.
Right: Petals exhibit pale discoloring of petal tissue caused by thrips
feeding before buds opened.
Leafminer females (after emerging from underground and mating) lay
eggs on underside of leaves, and hatching larvae tunnel through the
mid-leaf tissue, feeding as they go and leaving tell-tale wavy lines that
are visible on the surface.  They leave the leaf and drop to the soil to
pupate.

In plumeria, leafminers are not a major problem and their damages are
very limited.
Plumeria stem borer injury casued by an identified long-horned bettle
(likely Lagocheirus undatus).  This beetle deposits their eggs
underneath plumeria bark, and larvae penetrate further inside, feed on
the core tissue of stem and cause it to rot.  The rotten stem softens,
hollows and finally collapses.  Full adults emerge from the stem, feed
on other foods and search for new host.

Left: Holes on stem with black ooze dripping out
Right: Larvae feed on stem's tissue and leave frass behind
Plumeria stem borer injury:  The insects mainly attack tree under
stress (e.g. an extended drought) especially unhealthy or shriveled
branches in the shade (e.g. interior of the plumeria canopy).  Beetles
may attack the whole trees grown in dense shade and lead to tree death.
Insecticides are infective once they ensconced in plant tissue.  The
infested branches should be pruned and destroyed.

Left: Stem decay (bottom) and hollow stem (top)
Right: Stem collapse
Pinhole bark beetle or common ambrosia beetle (Euplatypus sp.)
does not ingest the wood tissue but excavates a tunnel to build gallery
inside plumeria tree's trunk by pushing the sawdust out and releases
spores of its fungal symbiont.  Beetles feed on fungus growth in
galleries.  Fungus kill plant xylem and phloem cells and eventually kill
the infested branches or the whole tree if being attacked at main trunk
by large number of beetles.
Left: Holes with sawdust on tree's trunk attacked by ambrosia beetles
Right: Sawdust fell down to the ground near tree's trunk
Pinhole bark beetle:

Left: Leaf yellowing, and stem decay and collapse.  The infested tree
declines quickly and dies within a short period of time after the attack.
Right: Male ambrosia beetle (Euplatypus sp.; size: 1.0 mm body wide,
3.0 mm long)

Suggested reading:
Click here 1
Suggested reading: Click here 2
Twig borer injury?: under investigation
Damage on plumeria by this borer is rare and limited.  Its larvae feed on
the cambium and bark tissues of two or three year old branches, and
leave the remaining thin layer of bark's outer parts to die off. The
infested area of branch does not rotten but weaken and prones to
break.  With time, callus tends to develop to cover the wound.

Left: Borer injury on plumeria twigs
Right: Twig injury with small circular emergence holes
Twig borer injury?: under investigation


Left: Sawdust like frass under dead outer layer of bark

Right: Borer larva and sawdust like frass
Under construction
Termite injury



Left: Termites feed on the core tissue of plumeria trunk
Right: Termites feed on the bark tissue of plumeria trunk
Leaves and flowers damaged by beetles at night.  Spraying with Sevin
(Carbaryl) helps to keep the insects away from the plants.
under construction
White fly feeding on underside of mature leaf.
Spiralling whitefly (
Aleurodicus dispersus)
under construction
Aphid
Table 1 Pests, Pathogens and Diseases in Plumeria in Thailand
Frangipani rust (bright yellow or orange pustules) on the underside of
mainly mature leaves caused by the fungus
Coleosporium plumeriae.  
The disease thrives in moist and humid conditions.



Suggested Reading:
Click here.
Frangipani rust:
Leaves damaged by Frangipani rust turn yellow/brown that leads to
early drop.  Spraying the tree with Triadimefon (Bayleton) helps to
provide preventive control for Frangipani rust.  It is not effective if the
leaves are severely infected with the rust.


Rust resistant plumerias:
Pink San Germain, Super Moon
Under construction
Powdery Mildew
Under construction
Black tip
Lichen
Under construction
 
   
   
Table 3 Others associated with Plumerias in Thailand
Table 2 Fungal Diseases in Plumerias in Thailand
Plumeria Pests, Pathogens and Diseases in Thailand