Shorea robusta or Sal is one of the important timber species of India. Sal forest ecosystems, which are found in MP, UP, Himachal Pradesh, Orissa , Bihar and other states of India are under threat from a pest beetle called the Sal Borer. Although the history of the Sal Borer attack in sal forests is not new and dates back to 1899, there has been wide spread destruction and felling of infected Sal trees in the last 2 years in various parts of India. The problem is serious enough for the Ministry of Environment and Forests to constitute a task force to monitor the problem.

Over the last two years, hundreds of infected trees have been felled which has led to significant concern amongst foresters, environmental activists and people. Remedial measures to control the beetle have not been different from what was being done in the early part of this century to control epidemics. These methods largely rely on physical destruction of the borer beetle. There are no effective chemical or biological control mechanisms in use.

This page provides detailed information about this problem, the beetle and its life history, history of incidents of infection and other issues related to this problem which threaten the Sal forests of India.

Suggestions from forest entomologists to solve this problem are welcome. You can write to Dr. C.S. Rathore.

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Shorea robusta, commonly known in India as Sal is one of the important commercial timber species of India. Sal is widely distributed in central and Northern India. The tree yields timber, which is used largely for construction works, railway sleepers and in mining operations. The timber is also used for beam, columns, bridges, piles, roofing door, and window frames, rafters, decking railing etc. , agricultural implements (plough, yokes, harrows), boat building (dug outs), carts, marine piles, motor lorry and bus bodies. Lops and tops of Sal are very good fuel wood.The caloric value of completely dried heartwood is 5433 calories. Sal tree also exudes an oleoresin, or ral that is valued as incense in religious ceremonies.  It is also used in paint and Varnishes. The presence of resin in the heartwood is responsible for higher calorific value. The Sal seed contains 12-19 percent fat.  The fat is used for soap manufacture.  After removal of certain ingredients, it is also used as substitute for borea fallow and cocoa butter in the manufacture of chocolates and confectionery.

Sal forests constitute an important ecosystem, which provides a cool and calm environment to many regions of India also being rich in bio diversity. Thus Sal is thus important both ecologically and economically. Sal forests in India occupies 105790 sq. Km area in two distinct regions, Northern and central region separated by gangetic plains. As regards the area under Sal forests, Orissa leads among the different states with about 38,300-sq.km area under Sal forest followed respectively by Madhya Pradesh 27,800 sq.km, Bihar 21,410 Uttar Pradesh 5,710, West Bengal 5,700, Assam 6500, Himachal Pradesh -330 and Haryana with 40 sq.km.

Though Sal and Teak constitute two distinct vegetation zones, both vegetation types also occur together in Madhya Pradesh constituting the rare ecosystem. Madhya Pradesh is the state with second largest area under Sal forests, distributed mainly in eastern part of the state forming 25 percent of the total Sal forest of the country.
 

This tree species belonging to family Depterocarpaceae is at the moment in the news for the massive attack by a woodborer insect in the central and eastern part of Madhya Pradesh and also Orissa. MP forest department has felled nearly 6 lakhs trees  as a remedial measures in year 1996-97.Till the end of the year 1999 almost 30 lakhs trees have been felled.  The beetles feed during day light on the fresh sap from the bark and the sapwood of the Sal trees.  This sap can attract insects from a distance of 400 meters.

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The Sal heartwood borer , Hoplocerambyx spinicornis , is an inhabitant (or is endemic) of the whole of the Sal tract of India ( and Indian Sub-continent) , ranging from Goalpara of Assam to Bhutan, Jalpaiguri and Kurseong Forest Divisions, Rajabhatkhawa (West Bengal), Chhotanagpur, Palamau, Singhbhumi (Bihar), Balaghat, Mandla, Hoshangabad and Dindori of Madhaya Pradesh, Thano, Phandowala and Timli in Dehradun Forest Division, and Lansdowne and Kalagarh Forest Divisions of Uttar Pradesh besides Nahan Forest Division in Himachal Pradesh.

The infestation of Sal borer is considered to be epidemic when the trees affected are more than 1.0 percent of the total growing stock of the trees. Several epidemics of this pest have been reported from different Sal growing areas of India existing from Himachal Pradesh to Assam and Orissa to Madhya Pradesh. The available records show that the infestation of this borer was reported in Apalchand range of Jalpaiguri Forest Division of West Bengal, Banjar valley reserve, Motinala, Dindori, Karanjira and Khanat ranges of South Mandala Forest Division of Madhya Pradesh etc., in 1905 - 06. After this, the borer remained endemic for many years again resulting in an epidemic in Amosoi of Nowgoan forest division and Mandala and Janali Hel blocks of Goalpara divison in Assam during 1961.

Another epidemic was reported in Thano forest of Deharadun forest division in 1913. The epidemics of this borer in standing trees were however, recorded for the first time in 1916-17 in some compartments of this division. The trees of all sizes and ages were attacked in the epidemic, though, the preference was for trees of 60-120 cm. girth class. The number of sal trees attacked in 66 compartments of Thano forest were about 6772 in the year 1916-17 . This number rose to 10432 trees in December 1917 and subsequently 11440 trees during June 1919. These epidemics continued up to 1924 and spread to Kaulagarh and Lansdowne ranges of Dehradun division.

Continuous remedial methods adopted during this period brought this epidemic under control bringing the infestation below endemic levels by the year 1928. Later, the borer again multiplied to epidemic proportions slowly in Timli Range of Dehradun forest division in 1958 and continued to thrive upto 1960. The population was brought down to endemic levels after 1960 by continuously adopting the remedial methods after the epidemic was noticed.

In Lambirao compartment of Thano Range the incidence of borer attack again went above endemic level in 1964 when 8475 infested standing trees were enumerated and finally felled. This epidemic spread to 1185 acres and caused destruction of about 2213 infested Sal trees in Lambiaro Block and 166 trees in Ramnagar areas in 1965. Continuous trapping methods and felling of dead and dying trees lowered the epidemic. The infestation again increased in above blocks of Thano forest division in 1975-76 and continued up to 1976-77 but was suppressed by the use of remedial methods in time. More recently from 1994 till date (April 2000), there has been a gradual build up of the attack of sal borer in Thano range. This time, the infestation is reported in Lambirao, Ramnagar, Thano and Maidan blocks.

In Nahan forest division of Himachal Pradesh, the epidemic of the borer started from 1949 in Gorakhpur and Jamniwala sal areas. In May 1949, 211 trees were attacked. The number of trees attacked rose to 2225 trees in 1950-51. In this region during the early period of epidemic, the attack was apparently heavier on relatively smaller girths and spread more evenly to higher girths.

In Bihar the Sal heartwood borer infestation was recorded as early as in 1899 and again in 1906. The population build up was slow at that time. But during 1961 in Palamau and Singhabum districts, a large epidemic occurred covering a forest area of around 491 sq. kms. During this epidemic in the area, 60 Sal trees per hectare were found attacked by the borer.

From West Bengal, an epidemic was recorded during 1931-34 covering an area of 1850 acres and killing 3177 Sal trees in Sevok range of the Kurseong forest division. Again during 1974, an epidemic of Sal borer was recorded from Raja Bhatkhawa forest division covering an area of 1360 Ha. killing 23120 Sal trees.

In Madhya Pradesh, the first report of green Sal trees apparently dying under the attacks of an insect borer was recorded in 1905 from the Balaghat forests. Later, Sir George Hart, the then Chief Conservator of Forests, Madhya Pradesh noted the occurrence of this beetle in the Khannat forests of Mandla forest division in 1912. The borer is endemic to this area and ultimately increased to a considerable number in Banjar and Motinala ranges of Madhya Pradesh where 423 and 63 trees respectively were found to be attacked by the Sal borer. It was brought under control by felling the attacked trees. This infestation which was endemic between 1915-22 in Karanjia and Dindori was found to be suddenly reaching epidemic levels in1923-24. In the year 1924, the Chief Conservatorof Forests, the Silviculturist of Madhya Pradesh and divisional forest officer, South Mandla forest division inspected Banjar range and observed a heavy infestation of Sal borer in about 27 acres. The infestation in this range was severe in nearly half of the standing stock of Sal trees that were attacked by this borer. During the same year, the infestation was noticed in Motinala, Dindori and Karanjia ranges of South Mandla forest division. Felling of heavily attacked Sal trees was carried out from 1924 onwards. Nearly 2960 attacked trees were felled in 1924 from the above ranges, whose number raised to 28521 trees in 1925 and nearly 150000 trees in 1926-27. Of these, a few thousands were sold, nearly 40000 were debarked and stoved, and between 50000-60000 were burned to check its further spread.

The number of attacked trees also increased in other neighboring forest divisions. Baihar and Raigarh ranges of Balaghat and Lamni range of Bilaspur, Rewa state, Pendra etc were impacted. The total number of trees attacked over the whole infested Sal area before epidemic was checked, was estimated to be about 70 lakh (7 Million- 10 Lakh being 1 Million). The effect of adverse weather conditions in the replication of this borer together with remedial methods adopted resulted in marked decrease in the intensity of the borer attack in all the above ranges during the year 1927-28. Continuous use of this technique resulted in fall in the intensity of the borer attack in the year 1928-29 and finally an end of this epidemic in 1929-30.

Trap tree operations were continued in Banjar, Motinala and Didori ranges regularly with 1 or 2 interruptions in some ranges from 1931 onwards. As a result the population of borer could not increase to epidemic proportions. As soon as the population of borer was observed to increase in the year 1944-45 in Banjar range, it was immediately brought under control. The population of borer was again noticed to increase in a few compartments of Dindori forest range in 1961-62 that reached to epidemiclevels not only in Dindori but also in Bajag and Karanji forest ranges in 1962-63. Trap tree operations were carried out from June 1963 to the first week of September 1963 by using about 54208 trap trees to combat the epidemic which kept the problem under control in a few years.

The epidemic of Sal borer was again reported from Panchamarhi Hills in Hoshangabad forest division in 1976 . This epidemic considerably increased in 1978-79. Control remedies were initiated with the help of scientists of Regional Forest Research Centre of Forest research Institute, Dehradun from 1979 and were carried out continuously for 4 years. It was found that the population reached to endemic by the year 1982.

Recently , there have been reports of Sal borer infestations from the State of Orissa also.

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ABOUT THE SAL BORER

About 148 insect pests attack Sal. Of these, the major devastating insect pest is Sal Heartwood borer, Hoplocerambyx spinicornis belonging to the family Cerambyedeace. This beetle, popularly known as the longicorn beetle, is a dreaded woodborer.  It occurs extensively in Deharadun Sal forests, It also occurs in Haldwani, Ramnagar and Kalaghar forests of UP. It is quite abundant in Mandla, Balaghat and Bilashpur Sal forest of Madhya Pradesh. It has also been reported from Orissa , Assam, West Bengal and Nahan Sal forests of Himachal Pradesh.

 LIFE CYCLE OF THE SAL BORER

The life cycle of the Sal Borer consists of: the following stages :

1. Eggs.
2. Larvae or grubs
3. Pupae
4. Beetles

The life cycle can be summarized in four stages. The adult beetle lives for 1 month outside the Sal tree. Eggs are laid inside the tree and takes 7days to hatch. The Larva remains inside the tree between 6-10 months. The pupa remains inside the tree for 1-4 months before becoming an adult. The life cycle is summarized in the figure below:

Beetle
The beetle is dark brown beetle in color, is about 2-6.5 cm in size and has long antennae with spines at the corners. These insects are also called as longicorn beetles.  The beetles begin to appear annually with the start of Monsoon. Each shower of rain brings out a fresh lot of beetles.  The sexual dimorphism is distinct. The antennas of male are relatively longer than the body while the female is shorter than her body.  The emergence is largely complete when the cumulative rainfall from first June in any rainy season is about 900 mm.  The emergence period in Deharadun and Madhya Pradesh is from June to September, the greatest number emerging by the end of July.  In Assam and West Bengal the beetles commence emerging from the second half of May due to earlier start of rains.  The maximum life span of beetle is 4 - 5 weeks.

Eggs
Each female beetle lays 100-300 eggs, generally on the bark of the dead or dying trees after the emergence.  The eggs are white -creamed color. The egg laying is correlated with humidity.  At 55% relative humidity, there is no oviposition. Increase in relative humidity enhances the number of eggs laid.  The maximum eggs are laid at 91% humidity. (Beeson, 1941, Roonwal, 1978).
 
 

The hatching takes place in 3-7 days. The viability of the eggs varies between 75-100% depending on the weather conditions. The optimum humidity required for maximum number of eggs to hatch is 90-100%.

Larvae
The white grubs hatch forms the eggs and feed under the bark.  They soon enter the sapwood and finally the heartwood by the end of November.  The sapwood exudes a sap called ral or resins which, if flows in excess, kills the larvae entering inside.  If the resin is not in sufficient quantity the grubs survive successfully. The larvae feeds on sapwood throughout their life ravaging sapwood completely. It excretes a lot of wood dust that accumulates into heap near the base of the tree which ultimately leads the tree to girdle and dry up. By this time they have attained the full larval size of maximum length of 90 mm. Through the winter and ensuring hot weather the grubs bore tunnels in the heartwood. It then develops a pupae chamber, encloses it with calcium carbonate rich excreta, after linking it to an exit hole on the outer surface. In the final stage the larvae shuts itself in by a partition of calcium carbonate and long wood fibers loosely packed.

Pupae
Pupation occurs in pupal chamber. It depends on the weather conditions. It begins from February and continues till the month of April.  After 2-3 weeks of pupal period , immature beetles of Sal borer develop and wait inside the pupal chamber for the emergence till the monsoon arrives.  After the first heavy monsoon shower in the middle of June the moisture content or humidity in the air is increased.  The moisture also influence the calcareous operculum which guard the pupal chamber. This tiggers the emergence of beetles. The beetles make their way out by cleaning the wood fibers.  This borer has one generation in a year.

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ENDEMIC ATTACK

These insects are always present in the Sal forest in low densities. This is termed as the endemic stage technically.  The population of these insects sometimes explodes during favorable climatic conditions such as more humid conditions and temperature close to 27-28 degree during early monsoon. Thus although a tree may carry many eggs, only a few hatch during the unfavorable years. In contrasts, most eggs produce larvae when the climate is conductive. Apart from climate, several other factors enable the Sal borer to reach epidemic proportions. Homogenous, even aged, dense stands of Sal trees such as plantations, provides a fertile ground for the spread of the insects. Stressed trees are more susceptible to attack e.g. those experiencing nutrient deficiency or exposure to severe winds or climber load or reduced vigor due to compression or genetically lower natural resistance.

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The affected trees have been classified into following 7 categories (Beeson-1941) which is being followed by the  Forest Departments in India in marking the trees according to the extent :of damage:

Category I    : A tree is completely dead. Leafless crown; Leafless Epichormic branches; Wood dust in large heaps.

Category II   : Some portion of trunk alive, Crown dead and brown; almost all the epicormic branches dead and brown; wood dust in large heaps.

Category III : Crown dead and brown; epicormics of bark dead in upper parts; alive in lower part of the trunk; wood dust in heaps upto 7-8 cm high.

Category IV : Crown damaged severely. In most of the case no crown. Wood dust in large heaps.

Category V   : Crown partly green and partly brown; epicormics green; wood dust scattered.

Category VI : Crown green, one or two epicormics branches brown; Excessive resin oozing out of the tree as a part of defense mechanism; Stump with large heap of wood dust.

Category VII: Initiation of Borer attack.  Crown and epicormics entirely green; resin abundant or absent; wood dust scattered or scanty.

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Climate:
The year 1996 -1997 was  quite favorable for the beetles. Scientists are still wondering if the recent climatic  trends have begun to reflect this global climatic changes which is expected to make India hotter and moister. Such change, if any, might increase the risk of epidemic.

Ecological succession:
The species populations are regulated by many factors , predation being an important one. Such controls bring down the local population levels and provided other species great chances for competing with the affected species. Predation could therefore lead to maintenance or increase in the biodiversity. E.g. the sal act as a host to the borer, which in turn is preyed upon by the Alous beetle and wasp parasites, as a part of dynamic complex system. Usually, the host species  is found to recover once the predation  pressure reduces due to lowered host density and other factors, like the climatic or biotic regulation of the predator.

Evolutionary Succession:
One school of thought says that Sal ,a species belonging to family Depterocarpeceae, an evolutionary primitive family , is likely to be on the verge of its extinction, and hence prone to heavy losses. However, a famous red queen Hypothesis in ecology  tells us that extinction probability of a species is independent of its age. . Hence many species that came to inhabit earth have gone extinct like Dinosaurs while some much more primitive organisms are still flourishing but for human threat like turtles.
Moreover, Sal has neither shown any sighs of reproductive failure, nor the insect appears new to it. , For the Sal exude resin that entombs and kills many if not all larvae. The vigorous tree survives fully or for longer period while the less vigorous trees eventually succumb to death. The insects also preferentially attack the less vigorous, more stressed older trees. All these facts indicate that the insect attack on  Sal might be an ecological control mechanisms than signifying the evolutionary dead end.

Silvicultural Genetic Erosion:
It is well known world wide that the pests that preferably attack old and dying trees in natural forests manage to easily sweep through the plantations, especially the even aged and dense monocultures. This may be due to many reasons.  Most of the trees in plantations are derived from seeds of only a few trees  -often from those called the plus trees in forestry.  Although such trees are vigorous and robust, their progeny have a more narrow genetic base than if the saplings were borne to different trees, hence a suitable strain of pest find it easier to infest all the genetic homologous that make up the plantation, no matter how healthy they look.  In many cases, realizing the economic importance of Sal, people in past had adopted a Silvicultural practices for the removal of other species. Thus the dominance of Sal in the forests is largely due to the human influence, especially the forestry operations. Such populations often have limited genetic variation. Sal also multiplies through coppices springing up from the rootstock and those might have lesser genetic variation than the saplings grown from the seed.

Further, increasing physical distance between the neighboring trees of the same species retards the rate at which the pest spreads. Indeed, the worst affected Sal area include its pure and dense stands while areas where its proportion is low the degree of infestation is less or negligible.

Environmental stress:
The Sal borer is seen attack many more trees in the hill tops than slopes. The hill tops, especially those along the edges and ridges are more exposed to wind stress than those on the slopes. Hilltops also may have less soil than the slopes.  The Borer attack is more severe on less fertile soils than the nutrient rich soils. The Sal borer attack  is more pronounced  in the areas closer to human habitation, than the remote area. The trees loaded with heavy climbers, having crooked stem are infested more. All these conditions  suggest that the trees growing under stress are more prone to attack. The soils near human habitation are often compact  and could have lower water retention capacity.  The people store infested fuel wood during monsoon in their houses and insects emerge from such fuel wood, and mainly attack the trees nearer to the human habitation.

Fires:
Many heavily attacked area were brought under joint forest management and the village forest committees had successfully stopped fires in those forests for the last few years, Local people wonder if that might have helped the build insect populations. Light fires might be limiting the number of saplings while retaining stronger individuals. Besides, light fires burn the wood laying on the forest floor, there by reducing the chances of infestation. Light fires might also kill the larvae contained in the stems of fallen logs. The fire might therefore be an important factor restraining the insect populations and merit further research.

Forest Hygiene:
The forestry management prescribes that the trash that remains on the forest floor after the commercial extraction should be burnt.  For, It serves the fertile breeding ground for pests. However, normally these operations are not conducted. Even though the litter, including small branches and fallen trees, the potential habitats for egg laying) usually occurs on the floor of all the forests, its proportion is much more in the forest areas subjected to logging.

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Trap tree operation
Forestry management, especially the working plans of   Sal dominated areas, prescribed that a few medium sized trees from each hectare should be felled every year during the monsoon( especially June- July) and their bark should be smashed. The resultants smell attracts the borer insects from the distance of upto 2 kms. These insects which form a large proportion of the local population, should be collected and killed. In Mandala district, such tree trap operations are prescribed provided there is a noticeable increase in the abundance of the insects.

Collection and Killing of insects
The trap trees operations discontinued from 1976-1995, were again undertaken in 1996 because of the increase in insect abundance. In Mandala alone, more than 21 lakhs insects were reportedly caught and killed during the monsoon of 1996.The incentives given to the people or catching borer insects and submitting their heads to the forest department was raised from 50 paisa to 75 paisa.  Records show that in 1997 monsoon, 1.2 corer borers were caught and killed. However the no of trees found to be infected has crossed more than 14 lakhs in the Mandala district alone.

Some of the forest entomologist's say that the trap trees can attract up to 90% of the borer beetles in a given area. Further, they say that an infested tree may contain 300 to 600 larvae, most of which may metamorphose into beetles. By this logic, from 2 lakhs trees that were infested by 1996 monsoon, at least 6 corer insects might have emerged, besides those emerging from the trees growing on the private lands.

Cutting affected tree
The trees affected by the wood borer can be identified on account of the large amount of yellow resin oozing out of the bark and heap of wood dust piled on the ground by the side of trunk. The working plans have prescribed classification of the affected trees into 7 categories. Indicating the severity of attack.. Category I indicate the dead tree while category VII indicates the least infested trees i.e., the first stage of attack.  A given tree may belong to different categories of attack at different periods, depending upon the intensity of attack and the vigor of the tree.

The working plan prescribe cutting of all infested trees including the dead ones, except those from category 7, i.e. those with least infection, as evident from their fully intact green crown. In 1996-97 6 lakhs  out of the 18 lakhs trees were identified and marked as infested belong to the category 7. These were marked for observation and were decided that those would not be felled until they pass onto other categories of infestation, by the time of other survey. Of the remaining 14 lakhs trees , the department had cut nearly 6 lakhs trees by 15 January 1998 and by the end of 1999 about 30 lakhs trees have been felled.

Biochemical control
Chemicals similar to those derived from the bark and sap wood of the trap trees have failed to attract insects unlike the trap trees themselves say the forest entomologists. Hence it is not possible to use the chemicals to attract insects and kill them. There are very few experimental trees in a few places under some biological or chemical treatment.  The students of IIFM studying the borer attack found a pupa of the borer from the tree given a chemical treatment during the month of January 2000. They could also observe the rotten bark of the same tree, in the compartment no 556 of Motinala range, from where the chemical was supplied. About 45 trees were given treatment in this compartment. The observation based  on the small sample may not be representative, however, the biochemical control is very costly and tedious as it requires every infected tree to be injected with the control chemical.

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Scientific issue
A  major difficulty in offering management prescription and weighing ecological options against the economic ones has been inadequacy of revelant data. Very little information is available on how quickly and what proportion of trees pass through various categories of infestation.  The reliability of estimates of proportion of  insects removed by the trap trees operation is limited.  There has been little work  on predator control of the borer population, and much  of it is laboratory based than under the natural conditions.  The forest department has not maintained forest area with different treatments such as differential removal of affected trees to evaluate their implications.   These gap in forestry research might appear inexplicable given that known history of the borer spans 8 decades and is full of massive losses.  The  glaring research gap however does not seem to be surprising given the strong economic orientation of the forest department and their political bosses  right from the British period  who took satisfaction in removing and selling all the infested timber rather trying to find out other options.

Socio economic issue:
The forest department cannot be blamed for its revenue oriented mind set.  The Sal borer attack has boosted the local economy of the affected areas in many ways.    When people deposit the heads of these insect with the forest  department, they get reward of Rs.75 paise  per insect head.  This has helped some people especially tribal to earn up to Rs. 20,000/-. Additionally,  a large number of local people are employed as labourers in the operations like tree felling , logging  and transportation.  People who benefited from this economic boom are therefore not entirely happy about the ban on felling of infested trees.

Political issues
The growing social concern also reflects the likely political ramifications. Incidences of local politicians meeting the task force members and requesting them to continue the tree felling operations, as it would benefits their vote bank owing immediate economic gains and apparently a secured bright future.

Policy Issues
Not withstanding the diversity and importance of the socio economic and political issues the task committee was asked to look into only the scientific aspects involved. Members of the task force were not provided with any background information such as data, reports, literature, on the pretext that it might influence the member on the pre text that it might influence the members  the members.

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The Sal Borer problem has in the recent times come up a major problem plaguing Indian Sal forests. Although attacks have been known to occur for a long time, there is still no control of this pest except for what has been mentioned in the current remedies section. As a result, there continues to be a large-scale damage to the Sal forests in various parts of India. In April 2000, there has been a massive infestation in the Sal forests of Orissa . A more effective method like some form of chemical or biological control breaking the life cycle of the pest is required to combat this very destructive pest infestation.

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1. TROUP'S SILVICULTURE OF INDIAN TREES;VOL II- DIPTEROCARPACEAE (1980) ; Revised and Enlarged by H.B. Joshi, IFS, Editor, FRI press ,Forest Research Institute and Colleges, Dehra Dun, India .
2. Ghate Utkarsh (1998) : THE SAL BORER EPIDEMIC ON MADHYA PRADESH QUESTIONS IN ECOLOGY AND POLITICS; DISCUSSION , Centre for Ecological Sciences, Indian Institute of Science, Banglore, India .
3. Diwedi, A.P. (998) MADHYA PRADESH ME SAL BORER KI SAMASYA NIYANTRAN KE PRAYAS. MP Forest Department, Satpura Bhavan , Bhopal , India (Text In Hindi with tables in English)

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Material on this page has been written by Kabita Ghimre and Amitabh Dongre, PGDFM Class of 1999-2001, IIFM Bhopal. If you wish to contribute matter on this page, please send a mail to Dr. Chinmaya S. Rathore

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