Elytroderma Deformans Tour HandoutOctober 4, 2013

Bill Layton, RPF

Purpose

To bring 100 Mile House professionals together to look at the impacts of Elytroderma deformans(DFE) in older pine plantations (30+ years) in the 100 Mile House TSA.

Problem

DFE impacts on older plantation pine in the IDFdk3 are significant and reducing growth on thetrees in older plantations that survived the Mountain Pine Beetle epidemic. These stands are acritical part of the mid term timber supply in the wake of the IBM epidemic.

Scope

DFE is particularly prevalent in the IDFdk3 subzone with severest impacts felt in pine­onlyplantations from 70 Mile House through to Gustafsen Lake. In the 70 Mile House area alone thereis between 6,000 and 10,000 hectares severely impacted. There could be as many as100,000ha of DFE­impacted stands in the 100MH TSA. The SBPS subzones are also impactedalthough more so the subzones to the west than the wetter subzone to the east (SBPSmk).

Discussion

DFE is significant because it has the ability to grow past the needles and into the cambium of thetree where it becomes systemic, atrophying the cambium. It can have a major impact on growthby infecting branches, and even greater impact if the infection reaches the bole.

DFE is common on pine trees older than 20 years within the drier subzones in the 100 Milehouse TSA but most commonly the disease is a simple foliar infection. In the IDFdk3, older pineplantations have rates as high as 30% of larger trees (layers 1, 2, 3) infected. This “infectionrate” refers to trees that are past the point of being acceptable as well­spaced acceptable croptrees.

In worst cases (e.g., Hanging Tree on 1000 Road), as many as 1050 pine per hectare or 41%were discounted as well spaced acceptable. It’s fair to say that many of the accepted crop treesin these plantations also had DFE infections that were systemic but only on some branches orpart of the crown.

We developed a rule for acceptability whereby trees that had at least 50% healthy crown andpositive leader growth could be considered WSA. It is common for a tree to have a badly infectedlower crown and reasonable looking upper crown. If the leader has stopped growing and the topis rounded then the infection is considered too great for acceptability.

Elytroderma Facts

From Management Guide for Elytroderma Needle Cast, By Jim Hoffman, US Forest ServiceForest; Health Protection and State Forestry Organizations, May 2004

Spores mature in small linear black fungal fruiting bodies during mid­ to late­ summer onneedles that were infected the previous year. Alternatively, fruiting bodies can also formon new needles that emerged from perennial infections on the buds and twigs.

Spores are disseminated by wind to the current­years needles and germinate if there israin or heavy dew.

After germination the fungus grows rapidly through the needle tissues and into the twigswithout initially killing the needle. Needles die the next spring, turn reddish­brown, developfungal fruiting bodies in the summer, and then are shed from the tree during fall rains.

From Hunt, R.S. 1978. Elytroderma Disease of Pines. Forestry Canada, Forest Insect andDisease Survey, Forest Pest Leaflet No. 27 4p.)

Once within the shoot, the fungus can grow in both directions, that is, it can keep up tothe host shoot growth and also grow back down the branch, invading other branches andthe tree trunk branches die (Roth, 1959).

Elytroderma deformans overwinters in three ways: in the cast needles, as new infections

in green current needles and in perennial infections in buds and twigs. The bright red of the previous year's needles is a good indication of Elytroderma

deformans infection, but experience is necessary to separate this from winter damage,or other needle cast fungi

The bright red needles gradually fade to a straw color (Fig) and on lodgepole pine theneedles may become gray.

The dwarf mistletoe also produces brooms and brown lesions in the inner bark oflodgepole pine shoots but is readily separated from E. deformans by observing theparasitic plants.

Severe infection results in so much needle casting that only the current needles remainover much of the crown, producing "lion's tail" symptoms.

Deformities: Needles and shoots are shorter and twigs may be thickened and curvedupward. On some trees there is loss of apical dominance so that lateral buds grow andthe whole tree resembles a broom.

The fungus damages the tree by decomposing areas of phloem (Waters, 1962), causingbrooms that act as nutrient sinks and causing dwarfing, deformations and vigor loss.

Severe infection can result in increment loss and predisposition to otheragents.,especially bark beetles and root rots. Thus, it is thus difficult to estimate mortalitydirectly from this fungus.

Once perennial (systemic) infection is established, the fungus can spreadvegetatively within the tree so that the impact continues for several years.

Childs (1968) found that the more severe the crown symptoms, the less the annualincrement, and this deleterious effect increases with time, especially on larger trees.

Volume reduction may be as great as 50%. Disease intensity on lodgepole pine in some areas of the Cariboo and Kootenay Forest

Districts is very high, but studies have not been made to measure its impact (that was in1978)

Practical control depends on silvicultural manipulations such as clear cuttings in maturestands and thinnings to promote vigorous growth in young stands.

Vigorously growing young stands can outgrow infections in the lower crown (Childs,1968).

On valuable trees, pruning out infections, especially brooms, which have potential togrow into the mainstem, is recommended.

(Hanging Tree) The two pine trees in the foreground are roughly the same age. Both have DFE,one severely:

Example of severely infected crown:

A badly infected branch

Example of fruiting bodies, note the black elliptical shapes on the brown needles:

Notice grey coloured needles with fruiting bodies vs. brown needles with none

Partial BibliographyElytroderma Needle Cast Elytroderma deformans (Weir) DarkerFIELD GUIDE TO INSECTS AND DISEASES OF ARIZONA AND NEW MEXICO FORESTSReferences

Boyce, J.S. 1961. Forest Pathology. 3rd ed. McGraw­Hill Co. Pub.

Childs, T.W. 1968. Elytroderma disease of ponderosa pine in the Pacific northwest.U.S.D.A. For. Serv. Res. Pap. PNW­69.

Hepting, G.H. 1971, Diseases of forest and shade trees of the United States. U.S.D.A. For.Serv. Handbook No. 386.

Lightle, P.C. 1954. The pathology of Elytroderma deformans on ponderosa pine.Phytopathology 44: 557­569.

Lightle, P.C. 1955. Experiments on control of Elytroderma needle blight of pines by sprays.U.S.D.A. For. Serv., Ca. For. & Range Exp. Sta. For. Res. Note No. 92.

Roth, L.F, 1959. Perennial infection of ponderosa pine by Elytroderma deformans. For. Sci.5: 182­191.

Waters, C.W. 1962, Significance of life history studies of Elytroderma deformans. For. Sci.8: 250­254.