This document discusses the Silver Oak plant. It provides details about its scientific name, natural habitat, physical description including leaves, flowers and trunk, uses including as fuel, gum and in furniture, and common diseases such as anthracnose, oak leaf blister, oak wilt, bacterial leaf scorch and armillaria root rot. Key symptoms and management strategies are outlined for each disease.

1. Sliver Oak
Submitted by :
Muhammad Ataullah
Registration no :
20-arid-2048
D E P A R T M E N T O F P L A N T
P A T H O L O G Y . ( P M A S A A U R )

2. Sliver Oak
 It is a native of eastern coastal Australia.
 Scientific name of this plant is Grevillea robusta.
 Silver Oak is a flowering plant in the family Proteaceae.
 Grevillea robusta is a fast-growing evergreen tree with a single main
trunk.
 The flowers are arranged in one-sided, "toothbrush"-like groups,
sometimes branched, 12–15 cm long.
 Its leaves are fern-like, 10–34 cm long, 9–15 cm wide and divided
with between 11 and 31 main lobes.
 Its trunk are 5–40 m (20–100 ft) tall and the bark is dark grey and
furrowed.

3. Sliver Oak
 The carpel of each flower has a stalk
21–28 mm (0.8–1 in) long.
 The flowers are glabrous and mostly
yellowish orange, or sometimes reddish.
Flowering occurs from September to
November and the fruit that follows is a
glabrous follicle.
Flower's rich in vitamin C. Leaves and
twigs reported to be high in aluminum.
Studies have suggested scavenging
activity, leishmanicidal, L-DOPA
inhibitory properties

4. Natural habitation
Silver oak occurs naturally on the coast
 It grows in subtropical rainforests, dry rainforests and wet forests.
 In its natural habitat, it is now relatively rare, but it has been widely
cultivated all over the world.
 It has become naturalized in many places, including on the Atherton
Tableland in Australia and and Florida.
 It is regarded as a weed in parts of New South Wales and Victoria, as
"invasive" in Hawaii.

5. Importance
 For exterior window joinery, its timber was commonly used before the introduction of
aluminium,
 It has been used in furniture, cabinetry, and fence production. Due to a drop in G.
Felling has been limited by robusta species.
 robusta was used on guitars produced by Larrivée and others for side and back woods.
 It provides shade and support for the growth of weak creepers like black pepper.
 Flowers are a rich source of nectar which can be directly sucked from the flower,
shaken into a bowl or washed out in a small amount of water..

6.  In Kenya, natives of the Kakamega Forest use the plant to treat sore throats,
earache, chest problems, flu and toothache.
 In North Garo Hills, Meghalaya, NE India, bark and leaves used for headaches
and dizziness.
 Study yielded seven phenolic compounds from the methanolic extract of
leaves – Grevirobstol A, B, C and Robustaside A, B, C and D.

7. USES OF
PLANT
Dye: Yellow and green dye from the leaves; used for
dyeing silk..
Fuel: Wood makes a good charcoal. Used to fuel
locomotives and river steamers, power boilers
and small industries. Sapwood has calorific value
of 4800 kcal/kg; the heartwood yields 4950
kcal/kg.
Gum: Natural gum has potential as adhesive.
Wood Used for joinery, cabinetry and paneling
Ornamental: Grown for its attractive foliage. Leaves used in
flower arrangements.
Poison: Flower buds, fruit and seeds
Apiculture: Golden flowers are an attractant for bees, making
it an important honey plant.

8. Diseases of Oak
Anthracnose Anthracnose
Oak leaf blister
Oak wilt
Bacterial leaf scorch
Armillaria root rot

9. Anthracnose
Causal organism: Apiognomonia
Symptoms:
 Winter twig dieback may occur.
 young leaves are blighted as bud break occurs
 large dead areas form between the leaf veins
 Slightly raised, brown dots on the lower surface of leaves and on dead twigs.
Management:
highly valued trees should be treated with a fungicide to protect new twigs
pruning and destroying dead twigs and branches during dormancy.
Apply a fungicide to protect new leaves and twigs.

10. Oak leaf blister
Causal organism: Taphrina caerulescens
Symptoms:
Raised blister-like buckling of the leaf .
The leaves usually do not fall prematurely.
Spots ¼ to ½ inch in diameter turn light green as young leaves expand.
Leaves surface covered with a buff white coating of fungus that later turns brown.
Management:
Fungicide application is not necessary at maturity
 because the leaves are seldom severely spotted and do not fall prematurely.
In the nursery, a fungicide must be applied late in dormancy prior to bud break.
Once bud break has occurred and symptoms are visible, it is too late to spray.

11. Oak wilt
Causal organism: Ceratocystis fagacearum
Symptoms:
 Twigs and branches die.
 Leaves at the top of the tree turn brown along the tips and margins.
 And soon leaves begin to fall while there is still some green color left in them.
 Brown streaks often observed in the outer sapwood are sometimes difficult to find.

12. Oak wilt
Management:
 Remove infected trees as soon as the diagnosis is made.
 Do not stack the wood since insects in it may leave and carry the fungus to neighboring trees.
 Cut root grafts first and then inject a mildly infected tree and neighboring oaks with a
fungicide.
 This will not eliminate the fungus from root systems but will inhibit the fungus in twigs and
branches.

13. Bacterial leaf scorch
Causal organism: Xylella fastidiosa
Symptoms:
 Browning of the oldest leaves along their margins on few branches
 A wavy, reddish-brown band develops between the brown and green tissue of the leaf.
 The browning of leaves progresses to include more leaves toward the ends of branches.
 Branches and eventually entire trees die.
Management:
 Leafhoppers and spittle bugs carry the bacteria from tree to tree.
 Promote plant vigor by protecting the tree from stresses.
 xytetracyclin injections alleviate symptoms but this does not cure infected tree.
 Symptoms will reappear years in which no injection is done.

14. Armillaria root rot
Pathogen: Armillaria
Symptoms:
 Branches die back.
 A fleshy, firm, honey-colored mushroom forms annually in a cluster at the tree base.
 The cap of the mushroom is 1½ to 6 inches in diameter with a slightly depressed center
 Cap have brown, scale-like spots. cap is usually dry, but it may be slimy after a rain.
 The spores are formed on flat, plate-like structures (gills) on the underside of the cap.
 A white fan of fungus is often found under the bark at the base of the infected tree.
 Dark-brown rhizomorphs may be found under the bark or on the surface of the roots or trunk.

15. Management:
 Remove infected trees.
 Protect healthy trees in the area from stresses, especially those that cause defoliation, such as
insect feeding

16. END