SHISHAM DIE-BACK IN PAKISTAN AND REMEDIAL MEASURES

M. H. Khan
Pakistan Forest Institute, Peshawar, Pakistan

1. INTRODUCTION

Dalbergia sissoo is known as shisham or tally in Pakistan. The species is found in India, Nepal, Bhutan, Bangladesh, Pakistan and Afghanistan. It is found under cultivation in tropical to subtropical Africa and Asia, viz. Java, Nigeria, Mauritius, Sri Lanka, Kenya, Northern Zimbabwe, Palestine and South Africa (Tewari 1994).

According to Troup (1921), it is very likely that sissoo is indigenous only to the sub- Himalayan tract and has been introduced by man elsewhere. D. Sissoo is considered to be native to TARAT situated in the subtropical and dry temperate foothills in Nepal growing at an altitude of 900 to 1500 m with an annual rainfall range of 900 to 1500 mm. In Pakistan, it is found along the foothills of the Himalayan mountains. As a species, it extends up the Indus valley to Attock, but does not dominate over any appreciable area (Champion et al. 1965). The species was introduced into Punjab (Changa Manga plantations in 1866) to produce coal for steam engines. The species is planted on private lands and also in the public plantations following demand for the tree for fuelwood and production of furniture. Community forests have been planted in Khanewal on quite a large area, and similar plantations exist in Bhagat, Bhakkar and Mianwali.

Private plantations along agriculture field banks have been set up by farmers in the districts of D.G. Khan, Faisalabad, Rahimyar Khan, Bhawalpur and Bahawal Nagar. Some other plantations include near the road sides and all along the canals, and water courses in Mardan, Bannu and Sawabi areas of NWFP.

2. DIE-BACK SYMPTOMS AND INCIDENCE

The die-back of sissoo (shisham) is a common occurrence among single tree or compact plantations growing in waterlogged and marshy tracts. It has also been noted that the die-back occurs in sissoo trees planted on marginal land in the cultivated fields, in the pockets or depressions bordering the highways, where soil is frequently dug up for repairs of the roads. In the agriculture fields, die-back is incident along water channels where land is ploughed, hoed, manured and irrigated. These are the conditions where sissoo frequently shows pathological symptoms or signs of ill health. The closely connected diseases of sissoo are wilt and die-back and their distinct symptoms are:

Wilt – The term "wilting" or "withering" is applied to cases where the whole plant dies suddenly from infection of fungus in the roots. The effects produced on trees are more or less of the same type as those produced by drought or frost, but are distinguished firstly by the absence of these causes, and secondly by their appearance in isolated plants or patches in the affected areas. The trees affected by pure physiological factors revive as soon as the causes are removed, while the crop suffering from pathological disease will never recover. This disease is identified by usual symptoms of flagging of leaves, pods and even tender twigs. But other symptoms which are associated with the early stages of die-back such as formation of thin crown, reduction and yellowing of leaves etc., are also present in wilt. The wilt is usually noted after the rains during September and October, but sometimes also in March and April after the flush rains as well. It may affect a single tree or a group of trees as in plantations, a few scattered trees in tilled lands, or growing on clayey soils in small depressions containing a pool of water. issoo trees of all ages have been found infected by the pathogen of wilt and die-back in the field, but the most susceptible appear to be saplings of 6-10 years age.
Die-back – The die-back disease has more specialised symptoms than wilt. The symptoms are thinning of leaves and crown, drying up of the ends of the branches, table topped conditions and stag-headedness in extreme cases. Small dry twigs keep on falling continuously and the tree looks like a blunt stub containing thick branches. The die-back in a tree takes place in successive stages and is characterised by progressive death of twigs, branches, shoots or roots starting at the tips. Staghead is a slow die-back of upper branches of a tree, and the dead, leafless limbs superficially resemble a stag's head. Die-back and staghead are caused by many fungi and a few bacteria that produce cankers, wilts and stem or root rots. The die-back usually affects mature trees.

In some early investigations, Parker (1918) reported that Fomes lucidum attacks the roots of living sissoo trees and speedily cause their death. Troup (1921) stated that the much more dangerous fungus is Fomos lucidus which is responsible for high mortality of sissoo trees in plantations and elsewhere. Bakshi (1956) showed that Fusarium solani is responsible for causing wilt and death of sissoo. The infection occurs through roots from where the fungus proceeds along the stem to some extent. It is evident that the pathogens are soil-borne. Khan and Bokhari (1970) conducted a study and concluded that amongst the commonest pathogens of sissoo is Fomes lucidum, a root and heart rot fungus that causes extensive damage once it is established. The other fungi which affect sissoo are Poria ambigua and Polyporus gilvus which cause die-back and canker. Wilt is quite serious in some localities and is due to Fusarium oxysporum.

In an overall assessment, the damage caused by fungi is not less than what is caused by insects. Khan and Bokhari (1970) carried out a survey in the irrigated plantations in Bhagat in Punjab. The results of the studies focussed attention on the serious nature and vast extent of losses due to die-back: the number of trees after the third thinning declined by half as compared to uninfected areas. Nearly 1 tree/acre was still found diseased out of the 74 standing trees. The total yield in all the fellings decreased by 21%. In financial terms, the loss was about 31 % of the total expected income. Out of the 8 % of diseased sissoo trees, the common pathogens were Ganoderma lucidum (7.85%) and Poria ambigua (0.45%). The cumulative rate of loss in 20 years came to be more than 28 %.

Recently, additional observations were made of the drying trees in various localities in Punjab (Gul & Mughal 1999). Trees were examined and samples of soil (12 – 25 cm depth), root and stem portions of infected trees were collected. Other morphological and ecological information were recorded. The infected sissoo trees in the farm lands and canal plantations of the following localities were examined: Dera Gahazi Khan, Rahim Yar Khan, Bahawalpur, and Bahawalpur. A total of 32 samples were collected for laboratory examination. Two trees in each locality were examined and two samples of each soil, root, stem and bark were collected.

The samples were determined and/or analysed in the following institutions: NWFP, Agriculture University of Peshawar, Department of Botany, University of Peshawar and Nuclear Institute for Food and Agriculture (NIFA). The results are as follows :

The bark samples yielded common saprophytic fungi, viz. Aspergillus flavis, Aspergillus niger and Rhizophus, while the soil material contained mostly Rhizoctonia and Fusanium spp.;
Die-back appears to be a new disease of sissoo for the pathologist in Pakistan. Twigs of infected trees were further required for confirmation of the pathogen;
The soil was tested for copper. This deficiency may have contributed to the problem of sissoo die-back, as has been noted in the case of apples;
Examination of the stem bark showed the presence of the fungus Collectotrichum sp. Which is also a die-back causing agent.

3. REMEDIAL MEASURES AND RECOMMENDATIONS

Earlier, Khan et al. (1965) advocated that mortality of sissoo is a physiological problem brought about by soil-cum-irrigation factors. The temperature and wind play an indirect role. Remedial measures suggested were more irrigation and change of plantation composition. An increase in water supply was recommended for areas where the trees had canker, brought about by compact soil which restricts deep root development and water percolation necessary to raise a medium crop.

Even though the cause of me die-back problem has not been clearly worked out, nevertheless a number of remedial measures can be taken to prevent or minimise the die-back problem. The following are the recommendations:

Avoid Injury – During studies carried out, it was observed that mostly trees grown along water channels were infected compared to the scattered trees in the agriculture field. It was revealed that during the cleaning of water channels, the roots of the trees were injured, which can allow the entry of the disease causing fungi. It is possible that frequent cultivation increases the chances of root injury and secondary infection from fungi. Cultivation therefore, should be restricted after establishment of trees.

However, soil flora is a complex world and pathogenicity of this fungus was not investigated to form a firm conclusion.

Mixed Cropping – In mixed cropping, the incidence of disease is usually low. Introduction of resistant plants such as Mours spp., Eucalyputs spp. And Acacia nilotica is recommended.

Sanitary Precautions – The stumps must be removed from the ground, or otherwise they will act as a potential source of infection from where disease will spread to healthy trees. In all areas used for sissoo planting, every effort must be made to free the ground completely of dead and decayed wooden posts or other woody fragments and fungal fruit bodies which are of course very conspicuous. Deep wounds may be dressed or sealed with grafting wax and rubber latex.

Deep Planting – In dry locations deep irrigation is recommended so trees can develop deep root systems which can draw water from the water table when irrigation is stopped. In addition, a deep planting hole and planting through seeds are recommended to develop long tap root, which may reach capillary zone of sub soil water within 2-4 years.

Ban on Debarking – Complete ban or debarking should be imposed. People use it for snuff preparation.

Site Selection – Elimination of the pathogen (Fusarium solani) from the soil is not possible either chemically or by crop rotation. Therefore, proper site selection, with light textured soil with adequate soil moisture and drainage conditions, is important for healthy plantations.

Removal of Over-aged Trees – Trees more than 45 years age which have been affected by the disease should be removed. It will reduce further spread of infection and termite problems.

Fungicides – Kanshik et al. (1996) stated that Bavistin (carbendazim) and captaf (captan) fungicides can be very effective against Fusarium solani.

4. CONCLUSIONS

Sissoo die-back is due to attack of root and stem rooting parasites, which may attack the aerial or under ground parts of the plant or both. It can be prevented by combining practices like the prevention of the root injury, maintenance of soil fertility, stoppage of haphazard use of pesticides and chemical fertilizers and proper cultivation management. A complete survey of the disease in different ecological zones is necessary to make an evaluation of the damage caused by the parasite in the natural, irrigated plantations and all along the canals and roads. Since the tree is an important tree crop in the northern region of South Asia, all these countries can collaborate on the research, exchange new findings, and develop a program for exchange of genetic material and testing them for performance and disease resistance.

5. REFERENCES

Anonymous, 1971. Ganoderma lucidum a destructive pathogen of Dalbergia sissoo, Biological Sciences Research Division leaflet No. 2. Pakistan Forest Institute, Peshawar.

Bakshi, B. K. 1995. Wilt disease of shisham (Dalbergia sissoo Roxb.). II-Behaviour of Fusarium solani, the wilt organism, in soil, Indian Forester 81: 276-281.

Champion, S. H., Seth, G. & Khattak, G. M. 1965. Forest Types of Pakistan, Pakistan Forest Institute, Peshawar, pp. 100.

Gul, H. & Mughal, M. S. 1999. Survey report on shisham die-back in Punjab (unpublished).

Kanshik, J. C., Ajit Singh, A., Nair, K. S. S., Sharma, J. K. & Varma, R.V. 1969.

Effect of soil texture and moisture on seedling root rot of Dalbergia sissoo and its control. Impact of diseases and insect pests in tropical forests. Proceeding of IUFRO Symposium, Peechi, India (23-26 November, 1993-1996).

Khan, A. H. 1993. Polyporus gilvus (Schw) Fr. And Pat. A suspected root parasite of shisham (Dalbergia sissoo), Indian Forester 23 (9): 503-506.

Khan, A. H., Asghar, A. G., Ghulam Rasul, Ch. & Hamid, A. 1965. Observation on the mortality of shisham (Dalbergia sissoo Roxb.) and other trees in Khanewal plantation. Part I, II and III, Pakistan Journal of Forestry 6 (2, 3, 4) : 109-120, 203-220 and 289-301.

Khan, A. H. & Bokhari, A. S. 1970. Damage due to fungus diseases in Bhagat

plantation, Lyallpur Forest Division. Pakistan Journal of Forestry 20(3): 293-311.

Parker, R. N. 1918. A Forest Flora for the Punjab with Hazara and Delhi. Printed by the Superintendent, Govt. Printing Press, Lahore.

Tewari, D. N. 1994. A monograph on Dalbergia sissoo. Intern. Book Distributors 9/3, Rajpur Road, Dun.

Troup, R. S. 1921. The Silviculture of Indian Trees 1, Oxford (Rev. Edition 1980).