DALBERGIA SISSOO IN INDIA

M.K. Sharma, R.M. Singal and T.C. Pokhriyal
Indian Council of Forestry Research & Education, New Forest, Dehra Dun-248006, India

1. INTRODUCTION

Dalbergia sissoo (shisham, sissoo) is one of the most important timber species of India. Shisham grows naturally and also planted on alluvial soils and is widely distributed on riverain beds in sub-Himalayan tract from Indus to Assam and Himalayan valleys.

Dalbergia sissoo is widely distributed in many parts of India up to 900m in the sub- Himalayan tract and occasionally ascending to 1500m. It grows abundantly and forms a forest, either pure or mixed with other species on the new alluvium formed of deposits of sand, boulders etc., in the riverbeds of these regions. It grows on land-slips and other places where fresh soil is exposed but not on stiff clay. Sissoo trees from different localities have varied characteristics including growth, form, colour, grain, working and strength properties.

Sissoo is a primary coloniser on the new alluvial soils along the riverbanks. It is a large deciduous tree growing up to 8 feet in girth and 100 feet in height. The rotation of the natural crop in Uttar Pradesh is about 60 years though in irrigated plantations of west Punjab, it is much shorter being about 20 years (Bakshi & Singh 1954). It thrives well in sandy loam soil with good drainage. In India, it is found in Jammu & Kashmir, Himachal Pradesh, Punjab, Haryana, Rajasthan, Uttar Pradesh, Delhi, Bihar, Orissa, West Bengal, Sikkim, Arunachal Pradesh, Assam, Nagaland, Manipur, Mizoram, Meghalaya, Tripura, Madhya Pradesh, Gujarat, Maharashtra, Andhra Pradesh, Pondicherry, Tamil Nadu, Karnataka and Kerala. In the sub-Himalayan tract, it occurs along rivers and streams, gregariously growing on alluvial soil. The tree is a characteristic species of khair-sissoo (Acacia catechu - Dalbergia sissoo) primary serial type forests (Champion & Seth 1968). It has been widely used for afforestation in most parts of the country except in the very hot, cold and wet tracts.

Sissoo has been extensively planted along roadsides, canal banks and sometimes on the private vacant and agricultural lands, especially in Bihar, Haryana, Punjab, Uttar Pradesh and in many other parts of the country.

According to UP Forest Bulletin year 1997, the total plantation area of Dalbergia sissoo in Uttar Pradesh is about 5,5997 hectares in relation to other planted species (excluding miscellaneous and mixed species). However, the above mentioned area does not cover farmer's field, where this species has been planted for profitable economic return under agroforestry system.

Sissoo can successfully be grown in combination with a variety of other crops viz., grasses, agriculture and fruit crops. Cultivation of agricultural crops between the lines of sissoo can be carried out without any difficulty for at least two years. Such cultivation is carried out in Uttar Pradesh in Taungya plantations as well as in departmentally raised mechanised ones. The agricultural crops, which can be grown in combination with Sissoo, are maize, mustard, rapeseed, gram, peas, wheat, sugarcane and cotton etc. Over the years D. sissoo has been grown as scattered trees on field boundaries and also as windbreaks around fruit orchards.

The extent of sissoo mortality in the natural forests, plantations and agroforestry has not yet been enumerated seriously. However, an attempt to record the extent of sissoo mortality in natural forests, plantations (mono and mixed), road-canal sides and agricultural fields is being initiated with the help of respective State Forest Departments.

2. DIE-BACK IN DALBERGIA SISSOO – SYMPTOMS AND DESCRIPTION

2.1. Root diseases

Bakshi et al. (1957), during a survey of diseases in sissoo forests, observed that the wilt and other root diseases are absent in the riverbeds, where sissoo grows naturally. In some natural forests situated away from the river and also certain plantations, it suffers from root diseases due to all the three fungi i.e, Fusarium solani, Ganoderma lucidum and Phellinus givus in varying degrees. Bakshi (1955) reported F. solani is a ubiquitous soil saprophyte present in all soils including where sissoo grows well such as in riverine areas.

During recent surveys to different states i.e. Bihar, Haryana, Delhi, Punjab, Himachal Pradesh and Uttar Pradesh, sissoo mortality was observed to be prominent either in isolated trees or on the plants growing on agricultural bunds, roads and canal side. In the exposed roots of the stressed trees (dead or partially dead) it was observed that the feeding roots were blackish in colour and partially decomposed. In some cases, block plantations as well as mixed cropping, exhibited less mortality. However the trees growing on the fringes are being affected. An ocular estimation of the area has revealed about 20-30 percent mortality. The following diseases were reported to be associated with sissoo mortality.

Fusarium Wilt

The Fusarium wilt disease has been reported from Uttar Pradesh, Bihar and Punjab in plantations, raised on unsuitable sites i.e., stiff, clayey soils and water logged conditions. It does not occur in natural forests and in plantations raised on suitable sites.

The disease manifests during humid months from July to September. The characteristic symptoms of the disease are yellowing and deaths of leaves in acropetal succession up the tree. Eventually the entire tree appears chlorotic. In advanced stages of the disease, the leaves are shed rendering the branches bare. The affected trees die within a few months. Trees of advanced age are usually susceptible to the disease. The outer sapwood exhibits a characteristic pink to reddish stain. Though the stain is restricted in this region, it may rarely penetrate into the inner sapwood. The heartwood is free from the stain. The stain also progresses along the outer sapwood from the roots to the stem and, in the late stage of wilt, it may extend up the stem to about 3m from the ground (Bakshi 1954). The pathogen is mostly restricted to roots. The fungal hyphae and jelly like substances plug the vessels resulting in wilt symptoms. Unidentified toxins are produced in the culture filtrate, which may also be responsible for causing wilt (Bakshi & Singh 1959).

Elimination of the pathogen from the soil is not possible either chemically or by crop rotation (Bakshi 1955). Proper site selection with light textured soil, adequate soil moisture and good drainage is important for raising healthy plantations free from wilt disease.

Ganoderma Root Rot

Root rot of Sissoo due to Ganoderma lucidum (Leyss.) Karst. Is common both in natural forests and in plantations. However, a serious disease problem may arise when Sissoo is raised as a reforested pure crop without removing the stumps and roots of the original crop. The disease is prevalent in both light and heavy textured soils. In light soils, the pathogen spreads rapidly on roots and the trees are killed in a short period. However, in stiff soils, the fungus spreads slowly on roots. The pathogen is a root inhabitant and infects the roots through intact as well as injured surfaces. It causes white spongy rot in the sapwood. The affected trees exhibit a stag-headed appearance and are eventually killed. The symptoms of the disease appear when a large portion of the root system is damaged by the pathogen. Lateral spread of the disease in plantations is through root contact, which results in gaps in pure plantations.

Phellinus Root and Butt Rot

Root and butt rot of Sissoo caused by Phellinus gilvus (Schw.) Pat. Has been studied by Bakshi (1971). The fungus is primarily a wound parasite and is known to infect plantation trees. It occurs in association with Ganoderma lucidum or the wilt pathogen, Fusarium solani. Trees of advanced age are attacked and they exhibit stag- headed condition. The fungus causes restricted decay as white rot in the sapwood and to a limited extent in the heartwood. Sporophores of the fungus are developed on root and stem bases. They are annual, sessile, usually reflexed, rarely effuso-reflexed, leathery when fresh, drying hard, single or imbricate; upper surface with shades of yellow, brown and red and either coarsely hairy, sub-zonate in forma gilvoides or smooth with concentric zonations in forma licnoides; lower surface yellowish brown, bores round, dissepiments thick, margin, sterile (Bakshi 1971, 1976).

Root-Knot Nematode

Meloidogyne javanica has been recorded to form galls on roots of sissoo from Lachhiwala range nursery, Dehra Dun (Mehrotra & Sharma 1992). The nematode is polyphagus and has been found to attack several other tree species (Sharma & Mehrotra 1992). Heavy infestations of the nematode affect plant growth adversely.

2.2. Entomological Studies

About 125 insect species have been reported to damage sissoo among them Plecoptra reflexa (Lepidoptra: Noctuidae) and Dichomeris eridantis (Lepidoptra: Gelechiidae) are the main defoliators. Plecoptra reflexa is a serious defoliator in nurseries and young plantations throughout the natural growing region of sissoo. For the first time, an epidemic of the defoliator was recorded from Changa-Manga area (Pakistan) in 1899 and afterwards in young plantations of Chichawati and Kanewal (Punjab). A serious epidemic was also reported in 1927, 1928 and 1932 and contributed to the final destruction of Moribund Compartment. The trees are completely stripped of the leaves and remain leafless for the greater part of growing seasons. The cumulative effects of repeated defoliations on the sissoo are disastrous.

2.3. Edaphic Conditions

The common experience that sissoo thrives well on loose sandy soils but suffers adversely from root diseases in stiff and clayey soils is substantiated by analysing the texture of soils maintaining healthy and diseased stands. The success of the species in loose sandy soils appears to be proper soil aeration with good drainage, which leads to healthy growth of roots (Bakshi 1957).

The soils with heavy texture and water logged condition; for a considerable period of time, cause asphyxiation of the roots. In the absence of oxygen, the tender roots are killed and a number of fungi colonise them. A common soil borne fungus, Fusarium solani has been isolated from the dead roots (Bagchee 1945, Bakshi 1954). The fungus colonises the vascular bundle of the roots and hinders the flow of water to the crown. As a result wilting takes place in terminal branches. The leaves turn yellow, wilt and in extreme cases the affected trees are killed. The outer sapwood of root exhibits characteristic pink discoloration. In advance stage of wilt the stain may extend to the stem.

In North Bihar, poor water drainage has created water-logged condition for a prolonged period. Excessive water can create as much stress on the plant as water deficiency. Symptoms of flooding are similar to those of drought including stomatal closure, yellowing of leaf and leaf scorching. Further, abnormal climatic condition such as prolonged foggy weather during winter (December.- March) and floods in the plains of North India during the rainy season also create unsuitable conditions for the growth of Dalbergia sissoo.

Failure of sissoo in plantations with a consequent outbreak of root diseases invariably occurs when the species is forced on a site unsuitable for healthy growth in unnatural environmental conditions. A typical example quoted by Bakshi et al. (1957) of such a plantations (Turnerpur Taungya, Lachiwala, Dehra Dun), where trees appear stag- headed and do not possess the loose spreading crown characteristic of healthy trees. Such trees dry from top downwards and eventually die. The incidence of wilt and other root diseases appears more and more every year and creates gaps in the plantations. However, there has been no correlation observed between soil pH and disease incidence in sissoo.

3. EXTENT OF DALBERGIA SISSOO DIE-BACK

Sissoo is very popular in north India with nearly 10-15% of total forest cover. Though the exact figures of the mortality rate could not be recorded, it was significantly high in some pockets. Mortality in sissoo occurs in trees between 10 to 25 years. Seedling and sapling stages were not found attacked by the disease. The disease was first observed by Bakshi (1954) both in the natural forests and plantations in Taungyas, in Dehra Dun and Saharanpur districts, Uttar Pradesh. Wilting starts during April-May after the new flush of leaves appears but is common between June and September during and immediately after the rains. The disease is systematic in that the entire tree shows symptoms of attack. In the early stages, an affected tree is characterised by drooping leaves and branches, due to loss of turgor. The leaflets turn yellow, dry up and eventually drop off rendering the branches increasingly bare. The entire tree becomes 'thin' in contrast to the adjoining dense green trees. Death of the affected trees is rapid and occurs within 4-6 months after the crown shows the symptoms of wilt.

Maximum damage has been observed in areas with exclusive artificial forests of sissoo. The basic norms of forestry prohibit monoculture, as trees become vulnerable to epidemics. In north Bihar, an area of 8400 sq km stretching from the fertile Gangetic plains to the terai grasslands bordering Nepal are severely affected by sissoo mortality. First the leaves of the trees turn brown, then they beak off, the sap dries up, until all that left is dead. More than 60 out of 100 trees were reported dead from farmer's field from Bettiah district in Bihar.

In Himachal Pradesh, 1200 sissoo trees dried in the last two years and 900 this year by 35 km Jawalamukhi- Kangra highway. In Dehra Gopipura area, according to SFDs sources, 656 dead sissoo trees were noticed in 1996, followed by 350 tree in 1997. Most of trees were between 30-35 years old. The combined infection by pathogenic fungi had infected thousands of sissoo trees in Bilaspur, Una, Hamirpur, Kangra and parts of Mandi district. In Kangra, Dehra and Nadaun sub-division alone more than 2000 tree have dried up.

In Haryana, an alarming 30% mortality in the major plantations i.e., Sirsa, Hissar, Rohtak and Gurgaon have been reported.

4. RESEARCH

Sissoo mortality in natural forests, plantations and agroforestry systems appears to be a complex phenomenon involving a combination of many environmental stresses. The factors responsible for tree mortality are poorly understood.

In the recent past, a large-scale mortality has been reported from the northern states of India, viz. Bihar, Delhi, Haryana, Punjab, Himachal Pradesh and Utter Pradesh. Being an important timber species, it has not only disrupted the economic targets of State Forest Departments but also incurred financial losses to big and marginal farmers.

Bakshi (1957) recorded complete failure of sissoo plantations raised in Tarai region of Uttar Pradesh. Unidentified toxins produced in the culture filtrate were responsible for causing wilt (Bakshi & Singh 1959). In Tarai, where the water table is high and may come up to the surface during rains, sissoo suffers from wilting. However, in Bhabhar tracts, with good rainfall and adequate drainage, sissoo grows healthily.

The fungus grows over a wide range of pH, but optimally at 4.6 pH. The pH of soil under sissoo trees at New Forest was between 6.3 – 7.8. Bakshi et al. (1959) reported that pH of sissoo tissues has no correlation with the H⁺ ion concentration of the soil in which they grow. The pH of the root of sissoo lies between 4.6-5.2, which is ideal for the infection of the pathogen. However, the plant tissues maintain an acidic pH in the range 4.6-5.2, even in highly alkaline soils, indicating that the roots possess a high buffering capacity.

Bakshi et al. (1957) studied the relation of pH and soil texture. They also correlated the incidence of wilt with soil texture and soil moisture. The disease was not found in soils containing a high proportion of sand and low in silt, provided the drainage was good and water-logging conditions did not exist. However, with the decrease in sand and proportionate increase in silt, there was manifestation of the disease.

The pathogen is mostly restricted to the roots. It produces jelly like substances, which plug the vessels. The fungus is a facultative parasite inhabiting soil and possesses a wide range of competitive saprophytic survival activity (Bakshi 1955). The fungus produces both micro- and macro-conidia besides terminal and intercalary chlamydospores, which are produced in culture.

Negi et al. (1999) studied the heavy mortality of sissoo in Haryana, Uttar Pradesh and Bihar. In Bihar the report indicates that northern districts like Gopalganj, Siwan and Muzaffarpur were badly affected. They observed that the pH of soil in the affected areas ranged between 7.5 to 9.7, as compared to near neutral pH in healthy localities. The chemical analysis of the plants in sick localities showed lower concentration of potassium and phosphorus in the leaves, as compared to healthy sites. They concluded poor uptake of nutrients by the roots in sick localities.

The following factors may have played a role in making sissoo more vulnerable to the pathogens Fusarium and others:

i) Water Stress: Bakshi et al. 1972 reported that in Karnal Forest Division (Haryana) 110 ha of sissoo plantation were raised in 1952-1960 and irrigated up to 1963. The irrigation was done by shallow channels, which lead to the formation of superficial root system. In nine out of eleven coupes the irrigation was stopped after 1963. Mortality started after three years in all the nine coupes where the irrigation was stopped. In the remaining two coupes where irrigation was continued no mortality was recorded. The trees had dried up due to lack of water, the superficial root system was unable to draw water from the low water table in deficit rainfall areas of Haryana. The leading cause for mortality appears to be water stress.

ii) Soil Texture: Bakshi and Singh (1954) reported D. sissoo mortality in Taungya plantations of Dehradun and Saharanpur District. The plants developed pale yellow foliage and died suddenly. Such mortality was also observed in Lachiwala Range of Dehradun Forest Division. Observations showed that the soil texture had a significant correlation with the disease incidence (Bakshi et al. 1957). The disease was not reported in sandy and sandy loam soils but began to manifest with increasing clay content. The stiff and clayey soils lead to asphyxiation of the feeding roots, and were subsequently colonised by wilt fungus Fusarium solani.

iii) High Water Table: Up to 30% mortality was recorded in sissoo plantations of Piplee Block of Bareilly Forest Division and 100% mortality in khair-sissoo mixed plantations of Ganganagar Patiain Tarai and Bhabar Forest Divisions. It was observed that the water table always remained between 2 – 3 m. The age at which mortality set in seemed to be related to the depth of the water table. In places where the water table was 2 – 3 m deep, mortality started at 10 – 12 years age; where the water table was slightly lower, mortality expressed at the age 12 – 14 years; and where it was within 2 m, mortality was at an early age of 5 – 6 years. It appears like when the roots come in contact with the water table, the plants become more susceptible to Fusarium solani infection, and ultimately die (Bakshi et al. 1972, Singh 1980).

5. SOLUTIONS TO SISSOO DIE-BACK

5.1. Findings from Surveys

The mechanism behind dieback disease in the various North Indian States i.e., Bihar, Haryana, Himachal Pradesh, Delhi and Uttar Pradesh can be explained thus. Foliage nutrient concentration is supposed to be an indicator of the physiological behaviour of the trees growing at different sites. It has been observed that the plants growing on fertile soil will have high nutrients in their foliage compared to those growing in infertile soil (Table 1). However, Dalbergia sissoo prefers to grow on highly leached sandy soil along the river belt. Hence, sites rich in nutrients, such as clayey soil with high moisture content may not be so favourable for sissoo. In Table 1, it can be seen that sissoo growing in normal sites stores higher concentrations of nutrients in its foliage, compared to sites which have higher mortality. In the latter sites, the plants have low nutrient concentrations (Table 1). This can be coupled with fact that the high moisture content and water logging create favourable conditions for pathogen activity resulting in root mortality, thus affecting nutrient uptake, which finally creates stress conditions for sissoo. Stress sites exhibit shortage of phosphorus and potassium in foliage. In addition, the higher pH (7.4- 8.5) observed at sites may be contributory to the higher mortality: the higher pH hinders phosphorus and potassium uptake. Potassium is known to be responsible for controlling stomatal transpiration and its deficiency disturbs the water balance of the plant thereby causing stress.

Table 1. Foliage Nutrient Concentration (%)

(Negi et al. 1999)

It is generally suspected that whenever a plant grows under stress it diverts more assimilates towards roots for storage, repair and maintenance. Negi et al. (1999) observed that sissoo growing in stressful sites allocated more carbon to its roots (60%) and less to foliage (40%), compared to those in normal sites (roots – 51%; foliage 49%). 

The earlier plantations were raised by sowing with seed, but replacements were done with cuttings. The water table at Bankatwa varied from 2-3 m. During the rainy season the roots start touching the water table, resulting in the death of the finer roots and thereby colonisation of wilt fungus. This seems to affect the crown development, and branches started drying from the top. This continued for several years, and ultimately the trees died. The pH value at the site ranged from 7.5 to 8.5. This can inhibit phosphorous and potassium uptake. Low phosphorous and potassium in foliage creates disturbance in nutrient cycling and water balance in the plants.

In the Hasanpur, North Gonda district, pure sissoo plantations were raised under the Taungya system in 1951. These plantations appear to be undergoing a vegetation succession process, however. After 50 years, the new vegetation comprised of 60% Mallotus phillipenses, 18% Dalbergia sissoo, 9% Trewia nudiflora, 3% Eugenia jambolonia, with scattered Holoptelia integrifolia and Cassia fistula. (Negi et al. 1999). The girth class distribution varied between 50-170 cm. For Dalbergia sissoo and 20-70 cm. For Mallotus phillipenses. This suggests sites with high moisture and clayey soils are not favourable for D. sissoo, and other mesic species colonised the site over time.

Table 2. Soil Texture and pH

The high mortality of sissoo in Delhi may be attributed to the water stress, soil compaction and high solar radiation. It is interesting to note that the block plantations and mixed cropping have not exhibited any serious mortality except for a few individuals in the fringes. This can be due to the fact that mixed cropping/block plantations may create the appropriate microclimatic conditions for survival of sissoo (Negi et al. 1999).

Sissoo mortality on road and canal sides in Bihar, Haryana and Himachal Pradesh can be correlated with prolonged water logged conditions during rainy season and seepage of canal water. The symptoms such as stomatal closure, yellowing, scorching and reduction in leaf size appeared to be similar to those of drought conditions. Prolonged water logging creates anaerobic conditions for root growth, causing root infections, and inhibits nutrient uptake especially of P, K and Ca, and ultimately leads to death.

In 1998, surveys were done in Haryana. In Ginnaur a pure stand of sissoo along the canal bank recorded very high mortality – 400 trees in a block were found suffering from wilt disease (pers. Obsns.). The area was water logged and the site was silty. But in a near-by block where a mixed stand of neem, jamun, Pongamia pinnata, sissoo, Albizzia lebbeck and Eucalyptus were established, sissoo suffered much mortality but not the others. The other sissoo plantations surveyed were in Yamuna Nagar and Bhiwani. Here too the growth was poor, probably due to stiff soil in the former and 'Kanker-' pan in the latter.

The mortality is generally noticed along roadside, canal banks, agriculture field bunds, and even in areas between rivers particularly Ganga, Yamuna and its tributaries. However, no mortality has been observed in the natural sissoo growing areas on the banks of the river Ganga near Rishikesh, Nandprayag and few sporadic upper parts of the Himalaya.

5.2. Ongoing Remedial Measures

Mortality has been so far, reported primarily due to pathogens (i.e. Fusarium, Ganoderma, Phellinus, Meloidogyne etc.). Other contributing factors include water logging, non-judicious irrigation schedules, imbalances in soil physical properties (soil, air, moisture, texture etc.) and monoculture plantations. Elimination of the pathogen from the soil is not possible either chemically or by crop rotation (Bakshi 1955). Proper selection of site with light textured soil, adequate soil moisture and good drainage, is important for raising healthy plantations.

Edaphic conditions such as soil physical properties (viz., soil air - water balance), and nutrient deficiencies may also contribute to sissoo parching. Adverse hydrological conditions, primarily water-logging leads to lengthy soil moisture regimes at saturation and sub saturation levels which, in turn, lead to the death of sissoo.

Despite the accumulation of knowledge, it is still not precisely possible to isolate the cause of sissoo mortality. As such it is difficult to propose exact remedial measures. However, proper drainage, suitable site for planting, mixed plantation, extraction of dead and diseased plants, and controlling human interference in the forest areas appear to be the appropriate way to go.

The new plantations must ideally be located in suitable sites. Silvicultural practices such as uprooting and removal of infected trees should be immediately observed. Periodic monitoring and assessment of the mortality and pests is desirable.

5.3. Suggested Remedial Measures

If we want to grow sissoo profitably in the mortality-affected areas in North India, the following issues need to be considered:

1. Land use patterns should be developed to check the topsoil erosion in the Himalayan areas;
2. While constructing roads, canals, railway tracks and other development activities, proper drainage systems have to be developed to avoid water logging. Sissoo prefers to grow on the well-drained porous and sandy soils, instead of waterlogged and clayey soils;
3. Seedlings should be used for setting up plantations, planting should be done in blocks, preferably in mixed cropping. Monoculture of sissoo should be avoided to prevent the root rot from G. lucidum as a result of root contact; and
4. Recommended silvicultural practices should be strictly followed, starting with site and provenance selection.

6. FUTURE STRATEGIES

The basic cause for sissoo mortality has still not been isolated. A small multi- disciplinary team should be set up to investigate further the problem, which should come up with suitable remedial measures. A collaborative study may be set up between ICFRE Institutes, Universities, State Forest departments and neighbouring countries and International agencies. The outline of the studies can be as follows:

1. Status of the mortality in relation to natural forests, plantations (mono- and mixed- crops), agroforestry system and variations in the agro-climatic factors;
2. Pathogens and their behaviour in relation to environmental factors;
3. Root behaviour studies in natural forests, monoculture, mixed, road and canal-side plantations and agroforestry systems;
4. Changes in physiological and biochemical parameters in relation to incidences of mortality in natural forests, plantations and agroforestry systems;
5. Genetic base studies – DNA markers – for disease resistant germplasms;
6. Standardisation of nursery practices and propagation techniques; and
7. Plantation management – drainage, soil amendments, density, thinning and other silvicultural practices.

Sissoo is now planted all over India as well as the neighbouring countries like Nepal, Bhutan, Bangladesh, Sri Lanka, Myanmar, Pakistan, Afghanistan and other tropical and subtropical countries in Africa. Therefore, a strong network linking all these countries would be very valuable in terms of sharing of data and planting techniques, and exchange of new genetic material.

7. REFERENCES

Bagchee, K. D. 1945. Pathological notes No. 2 – Wilt and dieback of Shisham, Babul and Khair in the artificial regeneration under agriculture-cum-forestry management. Indian Forester 71(1): 20-24.

Bakshi, B. K. 1954. Wilt of shisham (Dalbergia sissoo Roxb.) due to Fusarium solani Sensu Snyder and Hansen. Nature 174-4423: 278-91.

Bakshi, B. K. 1955. Wilt disease of shisham (Dalbergia sissoo Roxb .). II. Behaviour of Fusarium solani, the wilt organism in soil. Indian Forester 81(4): 276-281.

Bakshi, B. K. 1957. Wilt disease of shisham (Dalbergia sissoo Roxb.). IV. The effect of soil moisture on the growth and survival of Fusarium solani in laboratory. Indian Forester 83(8): 505-512.

Bakshi, B. K. 1974. Control of root disease in plantation in reforested stands (with special reference to Khair, Sissoo, Eucalyptus etc.). Indian Forester 100(1):77- 78.

Bakshi, B. K. 1976. Forest Pathology – Principles in practice in Forestry. FRI Press, PLO, FRI, Dehra Dun., India.

Bakshi, B. K., Arora, K. K. & Singh, S. 1957. Root disease of shisham (Dalbergia sissoo). V. Incidence of disease in relation to soil pH and soil texture. Indian Forester 83(9): 555-558.

Bakshi, B. K. & Singh, S. L. 1959. Root disease of shisham (Dalbergia sissoo). VIII Inoculation studies on wilt. Indian Forester 85(7): 415-421.

Champion, H. G. & Seth, S. K. 1968. A revised survey of forest types of India. Manager of publications Delhi, Govt. of India Press.

Mehrotra, M. D. & Sharama, V. 1992. Some new host record of root knot nematodes. Indian Forester 118:856-57.

Negi, J. D. S., Pokhriyal, T. C., Sharma, S. D. & Bhandari, R. S. 1999. Shisham mortality in India – A case study. Unpublished report.

Sharama, V. & Sharama, V. 1992. Meloidogyna species cause of root knot of important forestry tree species in nursery. Indian Forester 118: 961-962.