Pine needle diseases | NZ Government

Blight in Radiata pine

Blight is a type of plant disease commonly caused by fungi. There are different sorts of fungi that can cause blight, including mildews, rusts and smuts.

If your pine trees look like they may be suffering from blight, check the table to narrow down the likely cause.

	Cyclaneusma needle cast	Physiological needle blight	Red needle cast	Dothistroma needle blight
When	September to November	June to November	April to October	All year
Tree age	6 to 20 years	15 years +	Usually 3 years +	Planting to 15 years
Spread	No pattern Very severe	Small area affected More than 50% of trees within the affected area	Small to medium-sized area affected Almost all trees within affected area	Widespread Almost all trees within affected area Wide variation between trees
Needles	Yellow Gold Brown	Brown Red-brown Grey Olive (with or without black bands)	Yellow Red Olive (with or without black bands)	Brown Grey Red bands with black spots
Wilt	None	Only at later stages	None	Slight
Retention	Needles detach easily	Needles are retained	Needles detach easily	Needles are retained but die
Cambium & bark	No damage No lesions No resin	No damage No lesions No resin	No damage No lesions Some resin blobs may appear at base of affected trees	No damage No lesions No resin

If you're unsure what may be affecting your forest, NZ Farm Forestry has a step-by-step identification guide that may help.

Use Farm Forestry NZ's guide to identifying pine needle diseases

Detailed disease descriptions

The 4 main diseases present in New Zealand differ from each other in a number of small but important ways.

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Cyclaneusma needle cast (CNC)

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Symptoms

Needles:

turn mottled yellow then brown
often develop transverse (horizontal) bands during the later stages of disease development.
remain rigid and are very easily removed from branches.

After the needles are cast, the tree crown appears very thin.

Other identifying factors

The entire tree crown may be affected.
Disease is not uniform in a stand unless the trees are genetically identical – affected trees are scattered amongst unaffected trees.
Symptoms start September or October, with a second (usually less severe) cast occurring around April.
Trees aged between 6 and 20 years are most affected.

Spread

CNC is abundant in the Waikato and Taranaki regions and very common in Northland and on the east coasts of both the North and South islands.

It is uncommon in Otago and the greater Wellington-Wairarapa region.

No areas in New Zealand are known to be free of CNC.

Treatment

No treatment is believed to be economically viable.

Find out more – NZFFA website

Physiological needle blight (PNB)

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Symptoms

Needle colouring:

In the initial stages, needles have distinct olive or olive-with-black resinous bands.
In later stages, needles turn red-brown.
After one year, needles turn grey.

Needles droop and wilt and are not easily removed from branches.

Other identifying factors

Symptoms develop on foliage that flushed in the previous year.
The entire tree crown may be affected.
On affected branches, nearly all foliage shows symptoms.
Symptoms start between May and November.
Disease peaks between October and November.
Trees older than 14 years are most affected.

Spread

PNB is abundant in parts of the Waikato region and very common in Northland and on the east coast of the North Island.

It is uncommon in the greater Auckland region, Taranaki, the greater Wellington-Wairarapa region and all but the west coast of the South Island.

PNB is known to be absent in the areas surrounding the Abel Tasman National Park.

Treatment

Phosphite spray may be effective in treating PNB. Research is still being done to work out how much phosphite should be used and how frequently it should be applied.

Scion doesn't recommend spraying affected trees until at least 35% of the tree's leaves show signs of infection. This percentage can vary – more valuable trees should, in general, be treated more promptly.

Find out more – NZFFA website

Red needle cast (RNC)

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Symptoms

Needle colouring:

In initial stages, needles have distinct olive or olive-with-black resinous bands.
In later stages, needles turn yellow then red-brown.

Needles remain rigid but are easily removed from branches.

Other identifying factors

The entire tree crown may be affected.
Symptoms may start anytime between March and September but are rare during summer.
Peak disease occurs from July to September, depending on the region.
Needles are cast or blown off the branch within a few months of symptoms. After the needles are cast, the tree crown appears very thin.
Affects trees of all ages.

Spread

RNC is abundant in parts of the Waikato, Central Plateau and Gisborne regions and is very common in Northland, the upper South Island and the Bay of Plenty.

It is uncommon in the greater Auckland region, Taranaki, the greater Wellington-Wairarapa region, Hawkes Bay and the area surrounding Abel Tasman National Park.

PNB is known to be absent in most of the South Island.

Treatment

Phosphite spray may be effective in treating RNC. Research is still being done to work out how much phosphite should be used and how frequently it should be applied.

Find out more – NZFFA website

Dothistroma needle blight (DNB)

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Symptoms

Needles:

turn red-brown - there is a clear distinction between the red zone and the remainder of the needle
remain rigid, and are not easily removed from branch
remain on the tree after they have died.

The lower half of the crown is usually affected. In severe cases, the entire crown can turn red-brown.

Other identifying factors

Symptoms start on the new flush of needles around December or January.
Disease development continues through to winter – when it slows but doesn't stop.
Peak disease occurs about September.
Affects pines from planting age up to about 15 years.

Spread

DNB is abundant in parts of the Waikato and Central Plateau regions and is very common in the Bay of Plenty and upper South Island.

It is uncommon in the greater Auckland region, Taranaki, the greater Wellington-Wairarapa region, Hawkes Bay and the area surrounding Abel Tasman National Park.

No areas in New Zealand are known to be free of DNB.

Treatment

Plan your copper fungicide spraying for early summer for any trees with less than 15% of the crown affected (at the time of assessment during winter).

Find out more – NZFFA website

Blight in Radiata pine

When

Tree age

Spread

Needles

Wilt

Retention

Cambium & bark

Detailed disease descriptions

Cyclaneusma needle cast (CNC)

Symptoms

Other identifying factors

Spread

Treatment

Physiological needle blight (PNB)

Symptoms

Other identifying factors

Spread

Treatment

Red needle cast (RNC)

Symptoms

Other identifying factors

Spread

Treatment

Dothistroma needle blight (DNB)

Symptoms

Other identifying factors

Spread

Treatment

Find out more

Who to contact

MPI business units