Woodchip and fungi etc

[conkers]

When chipping trees with diseased branches or with wood decaying fungi, is there a chance of transfering the problem to other sites when tipping.

I realise the same could be said for timber but as woodchip usually is sourced from higher in the crown- unless you have a massive chipper- I wondered if we may be spreading problems further.

 

Anyone in the Know?

[Dean Lofthouse]

I've had one tree die from sooty bark but that was actually in the wood chip pile.

 

No other problems to report

[skyhuck]

I've had one tree die from sooty bark but that was actually in the wood chip pile.

 

No other problems to report

 

I could be wrong but,I think thats probably more to do with the amount of chip you put round that tree!!!!!:wave:

[Dean Lofthouse]

I could be wrong but,I think thats probably more to do with the amount of chip you put round that tree!!!!!:wave:

 

Do you think I over mulched??

 

I was told to mulch 7ft deep.... or was it 7 inches??

[treediver]

Heres some bedtime reading for you to mull over.

 

Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor,

Puyallup Research and Extension Center, Washington State University

 

The Myth of Pathogenic Wood Chips

“Uncomposted wood chips can spread pathogenic fungi and bacteria to healthy roots”

 

The Myth

Arborist wood chips are an increasingly popular choice for landscape mulching. Through research,

wood chips have been shown to moderate soil temperature and maintain soil moisture conditions to

optimize root growth and overall plant performance. Wood chips also provide a slow release of

nutrients to the soil, assisting not only plants but beneficial microbes and detritivores as well. Wood

chips are also instrumental in relieving soil compaction and improving soil health. Finally, many

studies have demonstrated the effectiveness of wood chip mulches in suppressing weed growth.

Recently there has been increased concern that wood chips made from diseased wood may spread

disease into healthy landscapes. This concern has led to the practice of allowing wood chips to

compost for several weeks before use, theoretically killing pathogens. Those without the time or

space to compost chips, however, may need to use green chips. Will green wood chips spread plant

pathogens into an otherwise healthy landscape?

 

 

The Reality

Though concern over pathogen-contaminated wood chips is increasing, there is little in the published

literature supporting this possibility. Although researchers at Colorado State University and the

University of Wisconsin have found that Cytospora, Thyronectria, and Verticillium survive on

uncomposted wood chips, they did not provide evidence that these pathogens would travel several

inches through the mulch to healthy roots below. In fact, other research has demonstrated that wood

chips made from infected maple trees and used as mulch failed to spread Verticillium to healthy trees.

One of the most pervasive root rots, Armillaria spp., will survive in the soil on root pieces of

susceptible hosts. This would caution one to thoroughly remove diseased roots from the soil, which

would be in much closer contact with healthy root systems than topdressings would be. It is a

different story, however, if one is foolish enough to amend backfill soil with wood chips. A

researcher working with Rhododendron spp. lost plant material to Phytophthora root rot after

amending the soil with 33% composted wood chips. Not only is this a poor practice for installing

woody plants, it also casts doubt on the efficacy of composting to remove pathogens from wood chips

Finally, it’s important to realize that many of these pathogens are both opportunistic and pervasive in

the environment. Armillaria, for instance, is widespread in many soils where it functions as a

decomposer but it can become pathogenic under unhealthy soil conditions. Healthy soil communities,

on the other hand, have diverse fungal and bacterial species, many of which are symbiotic partners of

plant root systems. These beneficial species can outcompete pathogens as long as soil conditions

remain optimal for root growth. When soils become compacted and anaerobic, plants decline and

become susceptible to opportunistic pathogenic microbes – always present but inactive in healthy

soils.

 

Given the distance between wood chips used as mulch and plant roots, it’s doubtful that pathogens

would travel far under healthy soil conditions. It does, however, point out the importance of keeping

wood chip mulches away from the trunks of trees and shrubs as moist trunk conditions are at risk of

pathogen infection.

 

 

The Bottom Line

 

• Fungal species in decomposing wood chips are generally decomposers, not plant pathogens

• Healthy soil communities include mycorrhizal species needed for optimum root health

• Under healthy (aerobic) soil conditions, beneficial and harmless fungi probably outcompete

pathogenic fungi

• Healthy plants are not susceptible to opportunistic fungal pathogens

• Do not amend soil with wood chips; use them only as a topdressing

• Keep mulch away from trunks of trees and shrubs to prevent opportunistic pathogen infection

For more information, please visit Dr. Chalker-Scott’s web page at http://ttp://www.theinformedgardener.com.

[Dean Lofthouse]

It has always amazed me how people panic at the mention of honey fungus.

 

I was called to price rwmoving a large Ash tree which had signs of Honey fungus at the base.

 

Some "Tree man" had taken a glance at the tree and condemded it.

 

I noticed that the rotting stub at the base of the tree was actually the stump of a shrub that had been cut down the year before and was being consumed by the honey fungus.

 

The ash was in a very healthy condition.

 

Now from my limited knowledge of the fungus, I was under the impression that it only attacked susceptable plants, with weakness or wounds and certain species of shrub which easily surcome.

 

As honey fungus is a natural cleanup fungus it plays it's part in the cycle of life and death and do most pathogens and only attack when an unhealthy situation arises.

 

As a rule, healthy plants, in healthy soil, shouldn't become infected. Thats my take on it anyway.

[Bundle 2]

Armillaria spp is an aggressive and successful fungus. It does not require an infection court to gain access to the root system of woody plants...this contributes to its success IMO. Thanx 4 the post treediver!

[conkers]

Thanks for that Treediver. :icon14:

[Dean Lofthouse]

Armillaria spp is an aggressive and successful fungus. It does not require an infection court to gain access to the root system of woody plants...this contributes to its success IMO. Thanx 4 the post treediver!

 

This is what I cannot understand. Honey fungus is a natural decomposer, it is absolutely everywhere where there is rotting wood, it cleans up the forest floor.

 

If Honey fungus is so bad and so aggressive, why are my 300 trees in my wood all still standing. I have deadwood in piles all over the place to encourage bugs etc. I can find honey fungus everywhere, but yet not one of my 300 trees have surcumbed to it.

 

Load of rubish IMO

 

That Ash I went to see and refused to take down is now a vibrant, healthy tree, all I did was pulled out the shrub root by hand and kept an eye on it.

The tree owner is chuffed because they didn't want to lose their tree.

[treediver]

Thanks for that Treediver. :icon14:

 

 

Out of the several species of honey fungus in the UK only 2 are really nasty infecting healthy plants 1 only infects stressed trees in poor growing conditions. The other 4 are saprophytic feeding off already dead wood/material. So just cause honey fungus rhizomorphs are present in soil it dosent mean theres necessarily a problem.

As for mulch infected with HF, the rate of passing the disease to healthy plants is very low and plants already infected with HF, mulch dosent have any impact on the infection process.

A brief account on the RHS research into HF and mulch can be found here

http://www.rhs.org.uk/Learning/Research/Projects/Armillaria.htm