The weather conditions during the current South-West monsoon have been inclement to the development of the coffee white stem borer. Now that the rainfall has ceased, with intermittent rainfall during the month of October, there will be emergence of the adults. Hence, the growers are advised to complete measures like uprooting and destruction of the infested plants, bark scrubbing and lime application etc.

The borer has two peak flight periods, one during the summer (April-May) and the other during the winter (October-December). It is appropriate to emphasize that the beetle population that emerges during the winter flight is the most crucial, as all the adult borers are outside the stem during this period. A new generation starts during this period. From the eggs laid during this period, some complete development and emerge as adults during the ensuing summer flight and the rest continue to develop and emerge as adults during the next winter. New batches of eggs are laid by the adults that emerge during the summer and they complete development and emerge as adults during the ensuing winter flight. Thus, there are two broods of the stem borer; one completing its life cycle in six months and the other completing development in twelve months. As the beetles emerging during the winter are the major contributors to the next generation, it is very crucial that this population is tackled on a war footing. This is the weak link in the life cycle of the stem borer and all the arabica coffee growers need to tackle the winter population of the borer in a concerted manner to effectively manage the borer problem.

Now that the monsoon has subsided and soil moisture levels are depleting, the borer affected plants can be easily traced. The borer affected plants, during this period, show wilting symptoms, especially the drooping of the first pair of leaves on the branches. Such plants need to be uprooted immediately and destroyed by burning on the same day. The stems that are uprooted now should not be stored even for a day as it is the flight period and almost all the borers have completed their development and are ready to emerge, if they have not done so. It is best to complete the tracing now, if not done earlier, as it would be difficult to identify borer affected plants later that show only slight wilting as the dry conditions continue. As the moisture stress increases, healthy plants also would show slight symptoms of wilting and the difference between healthy and borer infested plant would not be that obvious unless the infestation is severe.

The stem borer prefers bright sunny weather conditions for its activities like flight, mate searching and egg laying. Hence, it is very important that the microclimate around the coffee plant is made as unsuitable to the borer as possible. This can be achieved only if the canopy of temporary shade trees can provide the required shade which would keep the ambient temperature around the plants low and also maintain high relative humidity. Being a diurnal insect, low temperature coupled with high humidity reduces the activity of the stem borer adults. Hence, the growers need to develop the stand of temporary shade trees as a lasting solution for the management of the borer.

If the North-East monsoon becomes active during this period, the borer would be further affected as the activity of the borer would be less and many of the eggs being laid now would not hatch due to the wet conditions. But we can not take any chance now as the rainfall is unpredictable.

The growers with plots having heavy incidence are advised to install the pheromone traps at the rate of 10 traps per acre in the heavily infested plots so that the adults are trapped. It will help in restricting migration of the beetles to low incidence areas.