Diseases and DefectsDiseases and Defects

Trees are living organisms Trees are living organisms so they are prone to so they are prone to diseases and defects. diseases and defects.

Diseases and defects affect Diseases and defects affect the strength and quality of the strength and quality of the wood however, it can the wood however, it can make the timber more make the timber more valuable because it looks valuable because it looks well.well.

Timber we get from trees Timber we get from trees can be subject to any of can be subject to any of the following:the following:

1.1. Natural Defects Natural Defects 2.2. Artificial Defects Artificial Defects 3.3. Fungal Attack Fungal Attack 4.4. Insect AttackInsect Attack

Natural defectsNatural defects

Natural defects are Natural defects are often pleasing to the often pleasing to the eye while others are eye while others are unwanted defects.unwanted defects.

Heart Rot-Heart Rot- caused by caused by a fungus that rots the a fungus that rots the pith or the heartwoodpith or the heartwood

Spike Rot-Spike Rot- reduces reduces the strength of the the strength of the woodwood

Spiral Grain-Spiral Grain- tree tree may twist when may twist when growinggrowing

Knots Knots

Knots form where branches of a tree are cut off or stop Knots form where branches of a tree are cut off or stop growinggrowing

Loose knots are called Dead Knots – branch has stopped Loose knots are called Dead Knots – branch has stopped growing before tree is felledgrowing before tree is felled

Other knots are called Live KnotsOther knots are called Live Knots All knots reduce the strength of the timber.All knots reduce the strength of the timber.

Resin PocketsResin PocketsMost common in conifersMost common in conifersForms in internal cracks/cavities in the woodForms in internal cracks/cavities in the woodCracks caused by high wind or extremes in Cracks caused by high wind or extremes in

temperaturetemperatureReduce the strength of the timberReduce the strength of the timber

Natural defectsNatural defects Shakes-Shakes- these are splits these are splits

in the end grain. They are in the end grain. They are either either Radial, Tangential or Radial, Tangential or Cross(thunder) shakesCross(thunder) shakes

Radial-Radial- along ray lines along ray lines include heart or star shakeinclude heart or star shake

Tangential-Tangential- in annual in annual rings at old age, seasoning rings at old age, seasoning or strong windsor strong winds

Cross-Cross- split across the split across the grain when tree is subject grain when tree is subject to shock in fellingto shock in felling

Artificial DefectsArtificial Defects

Artificial defects occur Artificial defects occur as as a result of a result of stresses stresses caused by poor caused by poor stacking or stacking or seasoningseasoning..

They include:They include: Cupping Cupping Bowing Bowing Twisting/Warping Twisting/Warping End splitting End splitting Case hardening Case hardening Honeycomb Honeycomb

checks checks

Artificial DefectsArtificial Defects

Cupping-Cupping-this form of this form of shrinkage forms a shrinkage forms a curvecurve if if you look at the plank from you look at the plank from either end. Caused by either end. Caused by incorrect stacking during incorrect stacking during seasoning.seasoning.

BowingBowing-where the timber is -where the timber is taking the form of a taking the form of a bend bend along the along the length of the length of the piecepiece. Like cupping,it is . Like cupping,it is caused by incorrect stacking caused by incorrect stacking during seasoning, often the during seasoning, often the incorrect positioning of the incorrect positioning of the stickers.stickers.

Artificial DefectsArtificial Defects Twisting or warpingTwisting or warping-the -the two two

ends of the pieceends of the piece have twisted in have twisted in opposite opposite directions while the directions while the sides of the piece have remained sides of the piece have remained straight.straight.

End splittingEnd splitting-this is caused by -this is caused by the the end of the piece end of the piece drying out drying out too quickly. too quickly. Most common in Most common in natural seasoning where there natural seasoning where there has been excessive exposure to has been excessive exposure to the heat or sun. Can be the heat or sun. Can be prevented by covering or treating prevented by covering or treating the ends during seasoning.the ends during seasoning.

Artificial DefectsArtificial Defects Case HardeningCase Hardening-t-this occurs his occurs

when the piece is when the piece is seasoned seasoned too quicklytoo quickly and moisture is and moisture is still trapped within the wood. still trapped within the wood. The surface and the centre The surface and the centre have different drying rates have different drying rates creating compression at the creating compression at the centre and tension at the centre and tension at the surface. surface.

Honeycomb checks-Honeycomb checks-the the inside of the wood splitsinside of the wood splits and and like case hardening the like case hardening the timber is seasoned too timber is seasoned too quickly for the centre to be quickly for the centre to be dried out. When it does there dried out. When it does there is shrinkage causing splits is shrinkage causing splits within the piece.within the piece.

Fungal AttackFungal Attack Fungi attack causes damage by Fungi attack causes damage by

feeding on the cells of the feeding on the cells of the woodwood. The wood becomes soft . The wood becomes soft and eventually decays.and eventually decays.

A fungus is made up of cells A fungus is made up of cells called hyphae. A large number called hyphae. A large number of hyphae together will form a of hyphae together will form a mycelium. These hyphae mycelium. These hyphae penetrate the wood to feed and penetrate the wood to feed and get moisture. They will then get moisture. They will then produce food bodies called produce food bodies called sporophores. The cycle will now sporophores. The cycle will now repeat itself when the spores repeat itself when the spores produced are blown on to new produced are blown on to new wood.wood.

The following conditions are The following conditions are required:required: MoistureMoisture Food supplyFood supply OxygenOxygen WarmthWarmth

Fungal AttackFungal Attack Wet Rot (white rot)-Wet Rot (white rot)-Usually Usually

occurs outdoors where it will rot occurs outdoors where it will rot fence posts, window frames, logs, fence posts, window frames, logs, doors, etc. The affected wood will doors, etc. The affected wood will become very moist and slimy and become very moist and slimy and will produce a white residue.will produce a white residue.

Dry rot (brown rot)-Dry rot (brown rot)-This type is This type is usually found indoors, eg under usually found indoors, eg under wooden floors. This fungi attacks wooden floors. This fungi attacks wood and eats the cellulose wood and eats the cellulose found in the wood. Wood will found in the wood. Wood will appear dry and contain appear dry and contain rectangular cracks in it. rectangular cracks in it. Treatment of this type of rot must Treatment of this type of rot must be immediate and severe as the be immediate and severe as the rot can cause extensive damage. rot can cause extensive damage.

Fungal AttackFungal Attack

Treatment processTreatment process

1.1. All infected wood needs to be removed All infected wood needs to be removed as well as uninfected wood 500mm as well as uninfected wood 500mm around the area. around the area.

2.2. All surrounding brickwork and materials All surrounding brickwork and materials must be scorched or treated to kill must be scorched or treated to kill remaining fungicide remaining fungicide

3.3. The cause of the dry rot must be The cause of the dry rot must be remedied before new preserved timber is remedied before new preserved timber is put in place. put in place.

Insect AttackInsect Attack Some insects will attack Some insects will attack

and feed on timber much and feed on timber much like fungal attack. like fungal attack.

1.1. The adult lays the egg in The adult lays the egg in an old insect hole an old insect hole

2.2. The egg hatches and the The egg hatches and the larva/grub will feed on the larva/grub will feed on the starch in the wood – this starch in the wood – this creates the tunnels creates the tunnels

3.3. The larva makes a cocoon-The larva makes a cocoon-like shell around itself like shell around itself before it settles for a before it settles for a period of time to change period of time to change into an adult bettle. into an adult bettle.

4.4. The adult then emerges The adult then emerges and breaks out to the and breaks out to the surface to begin the cycle surface to begin the cycle again. again.

Insect AttackInsect Attack

Furniture Beetle Furniture Beetle (woodworm)- t(woodworm)- this his common beetle, more common beetle, more often known as often known as ‘woodworm’ is ‘woodworm’ is probably the most probably the most common in Ireland. common in Ireland. Woodworm will attack Woodworm will attack both softwoods and both softwoods and hardwoods, mostly hardwoods, mostly just the sapwood of just the sapwood of these timbers.these timbers.

Insect AttackInsect Attack

Treating timber with woodwormTreating timber with woodworm

1.1. Apply coats of insecticide following Apply coats of insecticide following the instructions on the container.the instructions on the container.

2.2. Ensure that all surfaces and cracks Ensure that all surfaces and cracks are coated with the chemicalare coated with the chemical

3.3. Use an applicator to insert Use an applicator to insert insecticide to the exit holes of the insecticide to the exit holes of the woodworm.woodworm.

Insect AttackInsect Attack

Deathwatch Beetle-Deathwatch Beetle- t this his beetle is not so common in beetle is not so common in Ireland, but will be found in Ireland, but will be found in Southern England. It will Southern England. It will attack damp timber, usually attack damp timber, usually where it is embedded into where it is embedded into walls. If timber is painted it walls. If timber is painted it will greatly reduce attack will greatly reduce attack

Powder Post Beetle-Powder Post Beetle-It is It is reddish brown in colour and reddish brown in colour and generally attacks the generally attacks the sapwood of new hardwoods sapwood of new hardwoods particularly during or after particularly during or after seasoning.seasoning.