By Bruce HaireWe talk a lot about invasive species

but what about our forests but most peo-ple think of lakes and not forests.

Ministry of Natural Resourcesforester John Osmok says our forests arenothing like what our ancestors saw andthe future may hold forests for ourgrandchildren that are nothing like whatwe see.

John has his own Top Ten list ofinsects and diseases that are threateningour forests.

Number one on his list is ChestnutBlight that took out the American SweetChestnut from forests across SouthernOntario.

John says the Chestnut was “a hugecomponent” maybe 50% of forestsacross Eastern North American with ahighly edible fruit and valuable wood.

This fungal disease came from Chinaand was first noticed in The Bronx Zooin 1904. It travelled 50 miles per yearand by 1940 there were only scatteredindividuals left. There has been someattempt to grow these trees in DufferinCounty outside of the normal range.

The second major disease is DutchElm disease which moved through theprovince in the 1950s and 1960s andstill lingers. The current front of the dis-ease is in Saskatchewan.

A few isolated trees have survived.The disease arrived from Holland in ashipment of logs.

Beech Bark disease is a slow mov-ing disease that arrived in the 1800s inNova Scotia. White scale insects createcankers and can girdle a tree. The frontof the disease is moving through SimcoeCounty right now.

Fourth on John’s list is the GypsyMoth which was imported intoMassachusetts by a man who wanted toestablish a silk industry.

It feeds on everything even poisonivy explains John. It arrived in Ontarioin the 1980s and 1990s and has a buildup of population that peaks every five to10 years. It can be sprayed with Bt.

Fifth on the list is the Pine ShootBeetle. It is native to Europe and wasfirst identified in Ohio in 1992. The nextyear it was in Ontario and arrived inSimcoe County about five years ago.

They are a difficult pest to controland can be first seen in the browning oftree tops. But the real worry is that thispest will reach the boreal forests of theNorth and devastate the Jack Pine.

Butternut Canker was first identi-fied in Wisconsin in 1967 and was iden-tified in Ontario in 1991 but might have

been here 15 years before that. This is ajelly like fungus and Butternut is thespecies at risk.

There are many wood wasps inOntario but the one of concern is theSirex Wood Wasp which has arrivedfrom Europe. It was first detected inNew York State in 2004 and trap sam-pling showed it was in Ontario the nextyear. It targets Scots, Red, Pitch andJack Pine but other Pines may be sus-ceptible.

Tree decline is associated with a fun-gus and toxic mucous associated withthe eggs.

John says while it has not yet beenfound, he is sure it is in Simcoe County.

Number eight on John’s list is theAsian-Long-horned Beetle which hasseen four outbreaks in North America.They include New York, Chicago, NewJersey and Vaughan on the north fringeof Toronto. The main concern here is theMaple tree. If it gets out, it could devas-tate our Maples.

Number nine is the Emerald AshBorer which as it name suggests targetsAsh trees.

This Asian species is already in fiveU.S. states — Michigan, Illinois,Indiana, Ohio and Maryland. It jumpedfrom Michigan into the neighbouring

Ontario counties where Ash trees makeup 90% of a very thin forest cover.

John says people play an “incrediblerole” in advance the pest by moving fire-wood and there are already outbreaks inNorthern Michigan where it can quicklyjump the border at Soo. Once again itkills quickly and could soon move intoLondon, Ontario (The City of Trees) andtake out its Ash trees.

Finally, number 10 is a new emergingthreat — Sudden Oak DeathSyndrome (SOD). This fungal diseasehas spread 300 kilometres along the cen-tral coast of California and into southernOregon with hundreds of thousands oftrees dieing or killed.

It was being exported by the largestnursery in the world in Californiabecause it easily spreads in other com-mon plants grown by the nursery indus-try. The SOD pathogen creates largenumbers of spores and will be transport-ed by humans also in vehicles.

This disease has a “very, very highlikelihood to spread to Eastern Canada”,explains John.

It is spread easily through variousplant species that have been shipped outof California nurseries. The most com-mon are — Rhododendron, Camellia,Vibernum, Pieris, Kalmia and Lilac.

“The rate of introduction (of newinvasive diseases) is what is new,” addsJohn. Ontario has over 860 confirmedinvasive species.

“It’s the downside of global trade,”says John and there are “probably hun-dreds of things we don’t even knowabout.”

Asked about the future of our forests.John says: “I don’t even want to answerthat because it is so depressing. Thatthey are going to look different, there isno question.”

If you have concerns about invasivespecies in your trees, the expert for thisarea of Ontario is Hugh Evans whoworks out of the Angus seed plant.

Threats to our forests: A Top 10 List

Sirex Wood Wasp

Sudden OakDeath

Syndrome

ChestnutBlight

Asian-Long-Horned Beetle

Emerald Ash Borer

Dutch Elm disease

BeechBark

disease

Gypsy Moth

Pine Shoot Beetle

Butternut Canker

24 August 22, 2007 Caledon Citizen