Introduction

Fungal Decay in Poplar Trees and Wood

N.S.K. HarshForest Pathology Division, Forest Research Institute, Dehradun - 248 006

Poplar (Populus deltoides) is an ideal tree for agroforestry and farm forestryin North India. Indigenous poplars grow in the Himalayas whereasP. deltoides have been introduced on the farm land in the plains of Punjab,

Haryana, Uttarakhand and Uttar Pradesh. The tree has become an integral partof the agri-ecosystem and play an important role in local, state and nationaleconomy. Initially, poplar farming was introduced to meet the demand of matchindustry but now poplar wood is extensively used in making plywood and manyother products. Presently, the plywood industry is the main consumer of poplarwood. Yamunanagar in Haryana is the main poplar wood trading and processingcentre in the country, where demand of about 300 plywood industrial unitsexceeds the supply. Farmers are the main growers of poplar to meet this demand.Poplars have changed the landscape of this region and also contributed in treecover of the country.

Besides plywood, poplar wood has uses in making packing cases,matchsticks, ice cream spoons, etc. Poplar wood is not used for making furnitureand doors and windows because of the mindset that it is soft and not durable.However, studies have revealed that the poplar wood has varying durability andnatural decay resistance and therefore, can be safely used for furniture anddoors and windows making (Harsh et al., 2009). Poplar trees and wood areattacked by wood decaying fungi in field and during storage. An account offungal decay in poplar (P. deltoides) and natural decay resistance is being givenbelow.

Fungal Decay in Living Trees

Root RotRoot rot in poplar trees is caused by Ganoderma lucidum (Curtis:Fr.) P.Karst. (Fig. 1a) The affected trees exhibit drying of branch tips when the rootsystem is decayed by the fungus. Young trees of 2-3 years die fast from topdownwards. The older trees may uproot during storms and heavy rains dueto rotting of anchoring roots. The fruiting bodies develop during the rainyseason at the base of the trees which are with a dark brown shiny stipe and

The poplar wood hasvarying durability and

natural decay resistance,however, poplar trees and

wood are attacked bywood decaying fungi in

field and during storage

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reddish brown laccate cap. G. lucidum has been reportedto cause 100 per cent mortality in poplar plantations inPhillaur, Punjab.

Heart Rot and Canker RotPhellinus pachyphloeus (Pat.) Pat. (=Fomes pachyphloeus(Pat.) Bres.) causes heart rot in older poplar trees (Fig. 1b).The trees become hollow within and the decay extends intosapwood making the trees vulnerable to wind breakage.The fungus enters the trees through wounds caused due totractor movement and sunscald injuries on the stem.The heartwood development seldom takes place in youngpoplar which is harvested early. However, when poplars areretained longer especially in avenues and for breedingprogrammes, P. pachyphloeus infection may take place.Singh and Singh (1986) have reported this infection inTarai region of Uttarakhand (in erstwhile UttarPradesh).

Fomes fomentarius (L.: Fr.) Fr. causes heart rot ofP. nigra trees on roadside in Kashmir (personal observationduring 2012 visit; Fig. 1c). The heart rotted trees snap duringstorms. Singh and Singh (1986) have reported F. fomentarius inPopulus yunnanensis and P. ciliata trees in Kumaun Hills ofUttarakhand.

Singh and Singh (1986) reported Earliella scabrosa(Pers.) Gilb. & Ryv. (=Trametes corrugata (Pers.) Bres.)causing heart rot in 10-yr old trees of P. x euramericana inTarai region of Uttarakhand. Harsh (2008) reported it fromLalkua (Nainital), Uttarakhand in P. deltoides (L-series;Fig. 1d).

Wood Decay in Storage

Poplar wood decays fast by wood decaying fungi while instorage. Mostly it is attacked by white rot fungi. The commonwhite rot fungi reported by Harsh (2008) on stored poplar woodare: Daldinia concentrica (Bolt.) Ces. & De Not. (Fig. 1e),Lenzites acuta Berk., Pycnoporus sanguineus (L.: Fr.) Murr.(Fig. 1f) and Pleurotus spp. Singh and Singh (1986) havereported Oxyporus populinus (Fr.) Donk (=Fomes connatus(Weinm.) Gill. on stumps and roots of Populus spp. in Chakrataand Mussoorie in erstwhile Uttar Pradesh (now in Uttarakhand)and Polyporus squamosus Fr. on dead stem of Populus spp.in Manali, Himachal Pradesh.

Natural Decay Resistance of Poplar Wood

The information regarding the natural decay resistance incommercially grown poplar clones was first time brought out

in India by Harsh (2008). It is a misconception that poplarwood is not durable, however, the study conducted at ForestResearch Institute, Dehradun revealed otherwise. The studyrevealed that there is definite variation among the clones/source material of poplar for decay resistance; even withinsame clone of different locations and some clone exhibitednatural decay resistance.

Thirty-nine samples of 16 clones of P. deltoides werecollected from the states of Haryana, Punjab, Uttar Pradeshand Uttarakhand and subjected to accelerated laboratorytests (Bakshi et al., 1967) to assess natural decay resistancein them using one white rot test fungus Pycnoporussanguineus and one brown rot test fungus Gloeophyllumstriatum. The wood blocks were categorized on the basis ofweight loss in four resistant classes; i.e., highly resistant (0-10 per cent wt. loss), resistant (11- 25 per cent wt. loss),moderately resistant (26-44 per cent wt. loss) and non-resistant(above 45 per cent wt. loss; Table 1). Most of the testedpoplar clones showed resistance against brown rot fungus.Brown rot fungi are more confined to higher altitude temperateregions and from the findings, it can be suggested that poplar(P. deltoides) wood can be safely used for construction andfurniture making at high altitudes. It was also revealed thatunlike most traditional timber species, heartwood of poplar ismore susceptible to decay fungi than sapwood. This qualitycan be used while peelings are made for plywoodmanufacturing. Leaving a central core of inner-wood wouldgive a decay resistant material.

The materials assessed for natural decay resistancewere obtained from trees of different age groups startingfrom 4.5 years to 16 years, but age of trees was not found toshow any relation to decay resistance as the wood from 4.5years of tree was found in the same resistant class as fromthe tree of 16 years of age. Similarly, wood samples from thetrees of 5-7 yrs of age showed wide variation in decayresistance from Class I (highly-resistant) to Class IV (non-resistant).

Study showed that there were clear cut variations innatural decay resistance among different clones as well betweenthe same clones. While G-48 clone from Pind Khakli,Hoshiarpur (Punjab) showed Class I (highly resistant)resistance, G-48 clone from Haryana Bungha, Hoshiarpur andTajowal Mand, Kathgarh, Hoshiarpur were in Class IV (non-resistant). Similarly, G-3 clone from Brahman Majra, JagadhriTehsil, Yamunanagar (Haryana) showed Class II resistanceagainst decay but G-3 from Haryana Bungha, Hoshiarpur andPind Khakli, Hoshiarpu showed Class IV resistance (Table 1).

Clone G-48 from Pind Khakli, Hoshiarpur and S7C15from WIMCO, Rudrapur were found to be highly resistant

Forestry Bulletin, 12(1), 2012 101

b. Phellinus pachyphloeus

a. Ganoderma lucidum

c. Fomes fomentarius

d. Heart rot in poplar

f. Pycnoporus sanguineus

g. Accelerated laboratory test for natural decay resistance inpoplar wood

Fig. 1. Fungal decay in poplar trees and wood, a.-d. decay fungi of tree, e.-f. wood decay fungi of storage and g. test for naturaldecay resistance in poplar wood.

e. Daldinia concentrica

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Forestry Bulletin, 12(1), 2012 103

Table 1. Per cent weight loss in wood blocks of different clones of poplarPercent weight loss (Resistance class)

Sapwood (outer) Inner-wood (heartwood) S. no.

Clone/ material

Locality Age (yrs)

White rot Brown rot White rot Brown rot 1. S7C4 Sitapur, U.P. 39.09±1.89 (III) 7.61±1.89 (I) 23.69±1.69 (II) 8.29±0.67 (I) 2. S7C15 Bahraich, U.P. 29.41±3.29 (III) 2.82±0.55 (I) 32.03±2.99 (III) 1.75±0.52 (I) 3. G-48 Mohali, Punjab 31.22±4.80 (III) 2.52±0.40 (I) 25.59±3.86 (III) 2.44±0.15 (I) 4. WSL-39 Wimco Seedlings,

Rudrapur 6-7 16.99±3.08 (II) 4.13±0.97 (I) 41.39±5.25 (III) 2.82±0.19 (I)

5. L-34 (TC) - do - 6-7 19.57±1.31 (II) 3.37±0.43 (I) 25.88±2.82 (III) 3.33±0.27 (I) 6. G-3 (Female) - do - 6-7 22.84±2.99 (II) 3.82±0.96 (I) 21.75±6.32 (II) 3.26±0.36 (I) 7. Uday - do - 6-7 12.17±0.30 (II) 8.18±0.33 (I) 39.03±4.99 (III) 10.47±0.52 (I) 8. WSL-42 - do - 6-7 21.46±1.40 (II) 10.59±0.70 (II) 34.25±3.14 (III) 9.82±0.39 (I) 9. S7C8 - do - 6-7 45.16±1.59 (IV) 9.74±0.40 (I) NA NA 10. WSL A-26 - do - 6-7 26.72±1.53 (III) 3.77±0.91 (I) 34.05±7.95 (III) 6.13±2.61 (I) 11. G-48 - do - 6-7 24.93±1.51 (II) 2.29±0.30 (I) 37.05±6.47 (III) 3.44±0.46 (I) 12. S7C4 - do - 6-7 31.80±2.72 (III) 14.66±1.05 (II) 36.65±5.11 (III) 1.99±0.70 (I) 13. L-49 - do - 6-7 38.34±7.92 (III) 2.80±0.33 (I) 59.01±4.98 (IV) 2.67±0.24 (I) 14. WIMCO-81 - do - 6-7 27.68±3.49 (III) 3.99±0.94 (I) 43.33±4.80 (III) 3.66±0.95 (I) 15. G-48 Pavan Poplar Ltd.,

Rudrapur 35.40±2.26 (III) 9.87±1.71 (I) 22.71±14.95 (II) 2.49±3.15 (I)

16. S7C5 - do - 27.70±3.36 (III) 10.02±2.07 (I) 18.80±2.90 (II) 13.40±2.42 (II) 17. Uday - do - 19.39±2.40 (II) 7.16±1.67 (I) 27.55±2.90 (III) 14.80±1.10 (II) 18. S7C15 - do - 7.36±0.33 (I) 3.32±0.88 (I) 24.62±2.20 (II) 7.71±0.90 (I) 19. L Pandori Mindomind,

Punjab 16 41.63± 3.80(III) 4.01±1.29 (I) 41.86±3.56 (III) 3.58±0.45 (I)

20. PD-124 - do - 16 44.12±1.95 (IV) 3.57±1.51 (I) 41.75±4.51 (III) 3.73±0.98 (I) 21. G-48 - do - 16 34.80±1.06 (III) 7.60±0.44 (I) 43.23±2.09 (III) 2.83±0.62 (I) 22. G-3 Pind Khakli, Punjab 5-6 45.06±3.36 (IV) 5.61±1.09 (I) 43.93±3.26 (III) 3.83±0.36 (I) 23. G-48 - do - 5-6 5.35±0.14 (I) 3.04±0.49 (I) 43.85±3.65 (III) 2.81±0.55 (I) 24. G-48 Garhdewal, Punjab 5-6 27.97±2.20 (III) 4.50±0.19 (I) 49.36±2.15 (IV) 4.13±0.28 (I) 25. G-3 Hariana, Punjab 5-6 31.84±2.21 (III) 6.09±1.23 (I) 23.14±3.18 (II) 2.62±0.65 (I) 26. G-3 Hariana Bungha,

Punjab 5-6 48.28±6.74 (IV) 6.51±0.21 (I) 44.74±3.14 (IV) 4.84±0.79 (I)

27. G-48 - do - 5-6 50.09±1.13 (IV) 4.82±1.09 (I) 38.97±2.12 (III) 3.17±0.43 (I) 28. G-48 Bela Tajowal,

Kathgarh, Hoshiyarpur

5-6 42.69±4.10 (III) 3.44±0.79 (I) 39.75±4.69 (III) 2.55±1.01 (I)

29. G-48 Tajowal Mand, Kathgarh, Hoshiyarpur

5 45.66±1.18 (IV) 4.41±0.96 (I) 55.19±4.58 (IV) 3.30±0.70 (I)

30. G-48 Santemajra, Hoshiyarpur

7 36.74±1.89 (III) 2.92±0.77 (I) 41.43±3.77 (III) 3.74±2.29

31. G-48 Khadri Village, Jagadhri Tehsil, Yamunanagar

7 25.66±2.92 (III) 5.50±0.98 (I) - 5.68±0.91 (I)

32. G-48 - do - 4.5 43.21±3.17 (III) 6.23±1.03 (I) 41.80±4.33 (III) 10.06±0.57 (I) 33. G-48 Brahman Majra,

Jagadhri Tehsil, Yamunanagar

6 23.04±3.38 (II) 5.22±0.41 (I) 16.61±0.28 (II) 4.16±0.36 (I)

34. G-3 - do - 8 16.37±0.84 (II) 5.18±0.58 (I) 18.38±1.09 (II) 2.33±0.41 (I) 35. G-48 Dakwala Village,

Near Darpur, Yamunanagar

7 35.78±3.53 (III) 4.72±0.67 (I) 37.93±2.38 (III) 4.39±0.49 (I)

36. G-48 Panjeto Village, near Chacharauli, Yamunanagar

7 39.02±1.68 (III) 4.16±0.34 (I) 40.74±5.13 (III) 3.90±0.60 (I)

37. G-3 Aligarh, U.P. 23.18±2.83 (II) 3.06±0.32 (I) 32.60±2.18 (III) 2.85±0.28 (I) 38. WIMCO-22 WIMCO Seedlings

Ltd., Rudrapur, U.K. 29.95±5.89 (III) 3.36±0.36 (I) 15.25±1.26 (II) 3.54±1.56 (I)

39. G-48 - do - 27.66±1.86 (III) 1.32±0.66 (I) 44.71±5.11 (III) 2.38±0.35 CD at 5% 4.28 1.07 4.13 1.21

 

clones against decay. These materials can be used for makingdecay resistant plywood as well as for construction andfurniture making. Decay resistance was found to vary withina tree from base to top, maximum resistance was observedat 2.5 m height, above and below, it decreased considerably(Table 2). Resistance was more at the base than at the top ofthe tree. This quality can be used for selecting logs onemeter above and below 2.5 meter from the base for selectingmaterial for manufacturing decay resistant plywood andpanels. Clones/source material showing resistance againstdecay will have potential for other uses, such as furnituremaking, construction, panelling, and will fetch good priceto the growers.

Management interventions could help poplar culturein delaying the decay of the wood. The field observations

recorded over the poplar growing region indicates that the slowgrowing poplar especially planted on forest land gets more decaythan that actively growing on farm fields. The decay furtherappears to be accelerated with termite infected fields whensome trees may be totally hollow from bottom to top, thoughthey may show some foliage on the crown. Wood decay instorage accelerates when logs get alternate wetting anddrying during rains which causes conducive environmentalcondition for fungus to multiply and infestation. Poplar haslargely developed a mechanism of fresh wood usage where it onharvest and conversion, is quickly transported to the marketing/processing sites and immediately used. The problem of wooddecay in storage is more common in government harvest andsupplies which take a lot of time in harvesting, storage in depotsbefore the logs are auctioned and, finally, used.

References

Bakshi, B.K.; Puri, Y.N. and Singh, S. 1967. Natural decayresistance of Indian timbers. I. Introduction andmethods. II. Decay resistance of sal and teak. IndianForester, 93: 305-328.

Harsh, N.S.K. 2008. Researches on natural decay resistanceof juvenile timbers like poplars. Project Completion

Report submitted to Department of Science andTechnology, Government of India. 25p.

Harsh, N.S.K.; Chandra, S.; Kumar, V. and Dhiman, R.C. 2009.Natural decay resistance of poplar wood in northIndia. In: National Forestry Conference, 4th,Dehradun, 9-11November 2009. Abstracts. p. 148.

Singh, P. and Singh, S. 1986. Insect pests and diseases ofpoplars. Dehradun, Forest Research Institute. p.74.

P er cent w eig ht loss S apw ood (ou ter) In ner-w ood (hea rtw ood)

H eig ht

W h ite rot B row n rot W hite rot B row n rot G -3 B ase 3 8 .2 7±4 .41 4 .60±0 .9 6 5 1 .77±5 .49 8 .27±1.0 6 1 .25 m 3 0 .2 6±1 .08 6 .05±0 .8 1 3 7 .46±2 .64 6 .73±0.7 7 2 .50 m 2 3 .1 8±2 .83 3 .06±0 .3 2 3 2 .60±2 .18 2 .85±0.2 8 3 .75 m 4 1 .3 1±1 .61 1 2 .5 0±1.29 3 3 .87±2 .65 7 .38±0.8 0 5 .00 m 4 2 .6 5±5 .69 1 0 .8 5±0.35 N M N M 6.25 m 4 8 .7 4±4 .09 1 1 .9 0±0.43 N M N M To p 4 9 .2 8±1 .15 1 2 .7 7±1.03 N M N M

W S L -2 2 B ase 1 6 .0 7±2 .65 1 .78±0 .4 4 4 5 .73±2 .99 3 .14±0.8 1 1 .25 m 9 .46±2 .7 0 2 .07±0 .2 2 2 9 .7 9±1 1 .0 0 3 .11±0.5 7 2 .50 m 3 .48±0 .4 8 1 .02±0 .2 8 3 .02±1 .0 6 3 .31±0.7 4 3 .75 m 4 .49±1 .1 1 2 .31±0 .4 2 1 4 .05±2 .08 2 .07±0.6 7 5 .00 m 2 9 .9 5±5 .89 3 .36±0 .3 6 1 5 .25±1 .26 3 .54±1.5 6 6 .25 m 3 1 .0 6±3 .59 4 .99±0 .9 4 3 1 .93±2 .27 5 .61±0.5 3 To p 3 1 .3 4±1 .62 5 .18±0 .3 6 N M N M

G -4 8 B ase 3 3 .7 2±4 .42 1 .31±0 .2 9 4 1 .73±5 .78 2 .47±0.1 7 1 .25 m 2 9 .1 1±6 .89 1 .28±0 .1 7 4 0 .96±6 .46 3 .07±0.2 0 2 .50 m 2 8 .1 8±1 .85 1 .19±0 .4 1 4 2 .33±3 .48 2 .38±0.3 5 3 .75 m 3 4 .7 5±6 .77 1 .57±0 .2 5 4 7 .09±4 .12 2 .74±0.2 0 5 .00 m 3 5 .4 7±2 .77 2 .77±0 .1 9 N M N M 6.25 m 3 8 .1 7±1 .85 4 .49±0 .2 2 N M N M To p 3 9 .2 2±1 .33 4 .75±0 .1 7 N M N M

Table 2. Natural decay resistance pattern within a tree (clone G-3, WSL-22 and G-48) at different heights

*Not measurable (heartwood).

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