The incidence and management of white stem borer is the most talked about subject in the arabica coffee growers' circle in Karnataka at present. Though this serious pest of coffee is not unfamiliar to the arabica growers ever since they took up coffee planting, the present crisis with regards to its management is an unprecedented one in the recent time. Devastation of arabica plantations by stem borer was experienced during the earlier part of the twentieth century when there were no effective methods available for its management.

Judicious use of pesticides coupled with better plantation management practices kept this pest at low population levels, not affecting the general performance of plantations. However, the present high level incidence of this pest is a matter of concern and a detailed consideration of all the factors responsible is required to understand the situation and adopt remedial measures.

Growing arabica coffee in India is an agroforestry activity wherein coffee is cultivated under a well maintained tree canopy as shade for the coffee plants. Good overhead shade is a basic requirement for healthy growth of plants in view of the weather conditions prevailing in our coffee tracts. The most important reason why shade needs to be maintained is the build up of stem borer under unshaded conditions. This is due to the behaviour of the borer beetles, which are active during bright sunlight and prefer to lay eggs on the main stem of coffee plants more exposed to sunlight.

In a normal situation, many growers are not inclined to uproot the borer infested plants as and when noticed with the thought that at least some crop could be realised from such plants. Actually, borer infested plants do not contribute much to the production as evidenced from the fact that even after removing quite a number of borer infested plants, there would not be much reduction in the crop. This is due to the very low productivity of heavily borer infested plants. However, when the number of infested plants increases due to the steady increase of borer infestation and if such plants are not removed regularly the cumulative loss will be very high and attempts to remove borer infested plants at that time will have a telling effect on the crop production. It is a fact that many growers get frustrated at this stage and adoption of other control measures including pesticide application will not be helpful in salvaging the situation.

Let us look back at the history of arabica cultivation in India for the past few decades. During the 1950s, there were only about 67,600 ha of arabica coffee, which was cultivated under highly suitable conditions. Even in such conditions there were flare up of borer incidence during certain years and adopting control measures including use of pesticides could effectively contain the pest. Now the area under arabica is over 1,60,000 ha and the arabica production has also registered a significant increase from a mere quantity of 15,511 tonnes during the 1950s to a total of over 1,21,000 tonnes during 200102. It is evident from these facts that the productivity of arabica coffee could be increased from a level of 229 kg/ha. during the 50s to the 800 kg. ha by the beginning of this century. Effective management of white stem borer played a major role in the increase of arabica productivity over the years. After the advent of effective pesticides, the level of pest incidence could be maintained at low levels and this has resulted in the lesser adoption of other measures especially shade maintenance and regular borer tracing and destruction of infested plants.

Simultaneously, expansion of arabica area also occurred with adoption of intensive cultivation practices with targeted higher production levels. This was the situation during the 70s and 80s during which time a balance could be maintained in the management practices, borer incidence and production levels.

The 1990s witnessed a rapid expansion of arabica coffee especially with the variety Cauvery. This variety was preferred by growers for its compact nature, and potential for high yield levels even at early stages of its growth. During this phase, larger areas which were not very ideal for coffee cultivation by normal standards with regards to elevation and other ecological factors were converted into coffee farms. Cauvery also found a place even in low lands as an intercrop under coconut, arecanut etc. The performance of Cauvery for two to three crop years was very good and later on there was a decline in production levels due to over exploitation (as in many cases), exhaustion, higher build up of leaf rust and then stem borer incidence.

The maximum expansion of Cauvery occurred during the boom period when coffee prices were high. Many low lying areas especially adjacent to traditional coffee tracts were converted in to coffee farms with planting silver oak as mono shade. When the coffee prices were at high levels, the trend among the planters was to maximize the production levels so as to take advantage of the prevailing high prices. It is needless to say that the first causality in the event of crop maximization will be the shade and the same thing happened here too. The shade was drastically reduced and high levels of fertliser schedules were adopted, which definitely resulted in higher crop levels. Suddenly, the prices started falling unexpectedly and most of the growers were not able to maintain the standard of cultivation being followed. The plants, which were left unattended directly under the sunlight, could not withstand the pressure and started declining. Under this situation, the white stem borer gained a free entry into these farms and flared up into high population levels. The pest gained a firm stand in the so called marginal areas first and slowly migrated to the nearby plantations situated in the traditional areas. This was quite evident from the fact that the majority of the pest stages collected by growers under the incentive scheme were from the marginal areas. The availability of large number of stages from Cauvery plants and also the comparative ease in collecting them from the infested stems were attributed to this.

Even in the traditional areas, many growers had to compromise on the level of management practices including borer control operations due to the financial crisis faced by them and such estates also functioned as sources of inoculum. There were also many completely neglected estates amongst well-maintained estates in many areas, which posed great threats to the neighbouring plantations. The pest from these estates started migrating to reasonably well-maintained estates jeopardizing their borer management efforts.

Another major factor, which contributed to the aggravation of the problem, was the failure of monsoon for the past two to three years. The rainfall pattern has a major role to play in the population fluctuation of the white stem borer. As mentioned earlier, the beetles will be active under bright sunlight and absence of rain during the flight period of the beetles especially during October and December will have a telling effect on the pest build up. The pest enjoyed all the favourable factors viz., less shade, bright weather and non adoption of control measures during the past two-three years which ultimately resulted in the present situation of high build up of the pest even in estates with above average cultivation practices.

The underlying principle of Integrated Management of Pests is to create the most unfavourable conditions for the development of the pest so that the pest could be effectively controlled by adopting certain minimum practices. However, once the pest population builds up to very high levels under favourable conditions, even the best practices of control measures will not be successful in effectively controlling the pest. The last resort of pest management ie., application of pesticides also fails in such a situation.

Now, let us consider the management options available for the effective management of the pest. The components of IPM of coffee stem borer are maintenance of proper shade, regular borer tracing and destruction of infested plants, removal of loose scaly bark and need based application of pesticide on the main stem and thick primaries during the flight periods of beetles. Adoption of a single component (even application of pesticides as resorted to by many planters) will not be able to bring about the desired effect. The package of practices if adopted on time by majority of the growers in a particular area is effective in managing the pest satisfactorily. Many growers have demonstrated this over many years in all the coffee tracts. There were estates where the pest was being effectively controlled only by cultural operations with out resorting to any pesticide application. This was possible when the pest population was at low levels. However, the incidence of the pest is on an increasing trend now even in such estates, as reports come from different zones, due to the reasons already elaborated. This points out to one fact that the efforts on the control of white stem borer should be made on a community basis by all the growers in unison, which is sometimes very difficult to be put into practice due to various obvious reasons. Actually, the adoption of control measures should have been on a stronger footing when the conditions were highly favourable for the pest build up. However, this also could not be practiced due to the socioeconomic conditions prevailing in the coffee areas.

The effort on improving the management strategies against the stem borer is a continuous endeavour of the CCRI. The studies conducted so far have greatly helped to have a better understanding about the pest so that the control measures could be fine tuned to achieve better result. As there have been some apprehensions about the continuous use of pesticides like BHC and Lindane, the use of another pesticide chlorpyrifos, which was found effective against the pest, was recommended. With regards to the non-chemical measures, application of lime spray on the main stem and thick primaries was found to be effective against the pest in a normal situation. Studies conducted at the UAS Bangalore have shown that application of neem kernel extract affords good control of the pest. However, this measure has not been practiced in general due to the requirement of repeated applications, which will not be economical. The use of pheromones in pest monitoring / management is comparatively a new technique and studies on this aspect resulted in the identification and synthesis of the male sex pheromone of stem borer beetles. Extensive field trials with the synthesized pheromone have so far indicated that though the technology may not be very effective in the direct control the pest, it could be used as a monitoring tool to make other control measures more effective. Work on fine tuning the technology is in progress at present.

Use of biocontrol agents for the management of coffee stem borer was not found very promising mainly due to the concealed nature of the pest. However, search for better natural enemies like parasitoids, predators and pathogens was being continued and some natural enemies could be observed in the process. Many of these were of rare occurrences and found only when the pest population was very high. Recently, we were able to find out a candidate parasitoid which can be used as a biocontrol agent against stem borer. This parasitoid with the name Apenesia sp. is a wingless ant like insect which can enter into the borer infested stem and search for the larvae and parasitise it. This insect can be reared easily at estate using the stem borer grubs and release them on infested plants still remaining on the farm. This will be beneficial in building up the parasitoid population and exert some degree of natural control of the pest. Efforts are on now to popularize this method among the growers and the culture of the parasitoid and necessary technical help in rearing the parasitoid would be provided by the Research Stations. Currently, studies have been initiated on developing biocontrol methods especially by using fungal pathogens and entomophilic nematodes for the management of white stem borer in a long run. The immediate requirement to manage the stem borer is to remove the inoculum as soon as possible. This can be done, only by uprooting the severely infested plants. The gaps thus created by uprooting need to be covered so that open spaces in the plantations are reduced. The borer, for their activity, prefers open spaces and invariably the stem borer incidence spreads from such open areas. No doubt the gaps created are filled up by fresh planting of coffee seedlings but it requires three to four years for such gaps to be fully covered. The best option in such a situation is to plant stakes of temporary, fast growing shade trees like dadap and Gliricidia. Even closer planting of stakes should be adopted so that the open patch is fully covered within a reasonable time. The existing plants surrounding the spots from where the plants have been uprooted need special care. Scrubbing the stem and application of pesticide or lime has to be done on these plants to avoid the establishment of the pest.

As mentioned earlier, shade is the most important component in the management of stem borer. If shade is less, the yield would be more, but plants would get exhausted if enough care is not taken and less shade is always going to be an initiation to the borer. If more shade is available, the plants may yield less, but survive for a longer period. Hence when we think about sustainability, the role of shade cannot be ignored. But the situation in most of the arabica plantations at present is far from desirable in this regard. There is practically no second tier of shade in most of the plantations. In most of the cases, the permanent shade trees have been trimmed to a height of almost 60-70 feet, mainly to train pepper. Such a shade pattern will not be of any use as far as stem borer management is concerned and in this situation maintenance of the second tier of temporary shade becomes compulsory. There is lot of advantages in having temporary shade. They can be regulated at regular interval as per requirement. As the weather pattern changes are unpredictable, cultivation of coffee in India without adequate shade has become a loss-making venture. The lower canopy of shade is actually responsible for controlling the microclimate. Once humidity around the coffee plants is enhanced, the activity of the stem borer is reduced. Further, many other natural enemies like fungal pathogens can flourish if good microclimate is provided around the plant, which in turn would have a negative impact on the pest survival.

When taking about shade with regards to stem borer management, the shade provided by the coffee leaves to the main stem of the plant is also of much significance. Hence, our aim should be to see that the coffee plants retain their full complement of leaves so that the main stem is not exposed. However many causes like leaf rust incidence, overbearing etc., results in loss of foliage which will have an indirect effect on stem borer incidence. Hence management leaf rust incidence and proper nutrition also play important roles in the effective management of stem borer.

Regarding borer tracing and uprooting, the concept of behind this approach has to be fully understood to achieve success in managing the pest. The real purpose of removing infested plants from the field is to see that the borer will not develop into adults in the infested stem, escape back in the field and infest new plants. For this to be achieved, the infested plants should be removed before the flight period. Hence, though tracing can be done throughout the year uprooting should be completed in the months of March for the summer flight period and in September for the winter flight period. If this is practiced meticulously, the incidence can be kept very much in check. The uprooted infested stems should be destroyed immediately by burning. If the wood has to be used as firewood, then it should be immersed under water for at least 10 days. Some planters are apprehensive about this method. But this has been rechecked at the CCRI and it is confirmed that 10 days of immersion under water is sufficient to kill all the stages present within the stem.

BHC 50 WP was the pesticide of choice for stem borer control over many years, not only because it was very effective but because of its low cost, strong smell and ability to leave a white trace on the swabbed plants, thus making it easy for the planter to observe the fields where swabbing operations was done. Along with BHC, Lindane 20 EC was also recommended, but no body was using it due to the higher cost. The claim that BHC was more effective than Lindane in coffee planting circle is more psychological than scientific. Recent evaluation tests conducted for three years at CCRI have revealed that Lindane is as effective as BHC and since Lindane is available in liquid form it is easy to spray the solution directly on to the main stem and thick primaries with some amount of pressure using a backpack sprayer which facilitates penetration of the pesticide solution into the cracks and crevices on the coffee bark. Lindane 20 EC at the Brain Storming Session on Coffee White Stem Borer Coffee Board organized a Brain Storming Session on Coffee White Stem Borer at the Board's Conference Room on 23rd July 2004 at Bangalore on the premise that there was a communication gap with regard to the management of the stem borer and the coffee growing community needs to convinced about the research efforts being made and also about appropriate management strategies to be adopted to mitigate the situation. The short term and long term measures needed to tackle the stem borer menace as well as prioritization of research areas keeping in view the changing weather parameters formed the main focus of the Brain Storming Session.

The Brain storming session was attended by the Chief officers of the Board, Sri K.R. Keshava and Sri S.K. Soundara Pandian, Members of the Coffee Board. Dr. S. Jayaraj, Chairman, Sustainable Farm and Development Centre, Chennai and Consultant, Farmer Participatory Research (FPR) Programme, Scientists and Extension Officers of the Board.

The gist of the deliberations are presented below:

Research efforts shall be focused to develop sustainable management strategies by taking into consideration the changes in the environmental conditions.

Research studies to be pursued on Pheromones and Kairomones in collaboration with National Institutes where expertise is available in the field of Pheromone Research.

Provide parasitoid culture of Apensesia sp. in the form of a kit to the growers for on farm rearing, especially to the Women Self Help Groups to encourage mass rearing and field release.

The work on entomophilic nematodes and parasitic nematodes to be intensified by the Entomologists.

Studies to be initiated on resistance breeding to generate data base on the relative resistance of different coffee cultivars to coffee stem borer for which studies on marker assisted breeding are to be pursued at the Tissue Culture and Bio-technology centre at Mysore.

Providing replanting incentive to coffee growers in whose estates more than 50% of the stem borer infested plants and moribund plants have been removed to be explored by the Board and seedlings to be provided from Self Help Groups or Departmental nurseries for replanting.

Implementation of Pest Act on Coffee White Stem Borer to be taken up with all seriousness with the District Agriculture/ Horticulture officers. Mass Communication Programme (MCP) both in the field and through electronic media to be given added thrust in the coming months.

Alternatively, chlorpyrifos 20 EC at the rate of 600ml/barrel along with 200m1 of any wetting agent is also as effective as Lindane. One most crucial point that is to be kept in mind is that the pesticide purchased for spraying purpose should be from a reputed company confirming to the standards set up by the Government of India. Pesticides offered at low prices than that of the standard products are of spurious nature and using such pesticides is more risky than not using any pesticide. Even banned pesticides like BHC of spurious quality are available in the market exploiting the false belief of the planters that only BHC is effective against the borer. The coffee planters may please take note of these facts and ensure that only quality products are used whenever they take up spraying operations.

The Application of pesticide has to be timed well. It should never be done too early or late. The purpose of spraying the pesticide is that it stays on the coffee bark and when the stem borer female walks on the stem to deposit her eggs, she comes in contact with the sprayed surface and is poisoned. Even the eggs or the larvae, which hatch from the eggs, are poisoned and killed. For this to happen, the coffee stems should have the insecticide deposits during the flight period of the stem borer. Hence if insecticide application is resorted, it should be done by middle of April for the summer flight and by middle of October for the winter flight. Due to erratic and insufficient rainfall during the winter flight period between October to December, a second round of pesticide application may be necessitated. In order to motivate the growers to uproot and destroy the borer infested stems, the Coffee Board is implementing a programme of providing financial incentive to the growers based on the borer stages collected from the uprooted infested plants. Under this programme about one crore borer stages (larvae, pupae and adults) were collected and destroyed by growers during JuneAugust 2003 and another 65 lakhs during April-May 2004. This has definitely helped in removing a significant quantum of pest inoculum from the severely affected areas. This programme will be continued during September 2004 and it is hoped that more coffee growers will utilizes this opportunity to replace the borer-infested plants and rejuvenate the plantations. The growers can make use of the financial incentive provided for planting new seedlings in place of the uprooted plants. If the number of borer infested plants to be uprooted are more than 50% of the population and also in case of severe borer infestation, the growers can also avail the facility of replanting loan from Coffee Board to establish healthy plant population. Another activity connected with the supply of planting material especially for gap filling resulting from borer infestation is the production and supply of good quality coffee seedlings by self help groups supported by the Coffee Board operating in all the coffee areas. All these efforts are being made to establish healthy arabica plantations for future exploitation.

The most heartening news at present is the copious rains received during April-May period and also by the end of July and early August. There was good rainfall during April-May during which time the borer beetles were on flight and these rains would definitely had adverse effect on the beetle activity. As such, the egg laying and survival of eggs and early instar larvae during April -May could be lesser which may result in a set back in the build up of the pest. The continuous heavy rains received during the end of July and first week of August also have a negative impact on the survival of larval stages within the stem as considerable percentage of mortality of larval stages has been observed. In this situation, some more efforts by all the arabica coffee growers during the next flight period will be definitely effective in managing the pest. If good rainfall is received during North East monsoon period also will be advantageous in the management of stem borer. All the growers need to complete borer tracing and destruction by September end especially by making use of the incentive provided by the Coffee Board. Application of pesticide during October second half/ early November in fields with higher levels of incidence would become necessary to provide protection to the healthy plants. An intensive programme to establish shade, especially at middle level, also our enemy, the white stem borer or loose our heart when borer is taking an upper hand under favourable conditions. Any complacency or inactiveness on our part will only be advantageous to the pest and hence let us work together and save the arabica coffee from the ravages of white stem borer.

Mass Communication Programme on Management of Coffee White Stem Borer

The Coffee White Stem Borer on Arabica during the recent years has accentuated due to favourable macro/ micro climatic conditions in the coffee growing tracts coupled with less attention being paid to manage the pest in the wake of steep fall in coffee prices. The pest, it is believed, could best be managed through community approach.

The Coffee Board is conducting Mass Communication Programme (MCP) in the hot spots ofArabica growing areas of Karnataka and Tamil Nadu States to reach out to the coffee growing community and identify chronic stem borer endemic areas and carry out intensive work in such areas to bring down the incidence to below threshold levels through systematic demonstration, interaction and dissemination of information through extension folders.

The MCP will be initially conducted in Karnataka during the second.fortnight of August 2004 and first week of September 2004 to coincide with the major flight period of White Stem Borer.