Author : Danlag, Expedito E.

Summary : White root disease is by far the most serious among the three root diseases of rubber. Current methods of control of the disease include re-planting control procedures, such as mechanical or hand clearing, sulphur amendment, use of covers and intercrops; post-planting control procedures, 1.e. disease detection, treatment with collar protectant dressing; the use of isolation trenches in mature rubber; and more recently the application of Calixin emulsion as soil drench. High costs of labour and chemicals, however, made these methods rather expensive, not to mention the serious hazard chemicals pose to the environment. This study explored some possible methods of white root disease control which minimize, if not completely avoid, dependency on chemicals. Such methods as introduction of antagonists, application of chemicals at minimal rate and antagonists, application of chemicals at minimal rate and addition of organic matter supplement applied either individually or in combiantion with each other were included in the study. Results demonstrated that chemically assisted biological control against white root disease could be achieved with combined application of the different treatments. It was also evident that the inclusion of antagonists and cow manure in the treatments further enhanced increase of population of the mycoflora. Fifty percent of the treatments with total population of mycoflora significantly higher than that of the control included both antagonists and cow manure. Sulfur is a single treatment likewise achieved good results in terms of enhancing population growth of the mycoflora, and consequently Trichoderma spp. Treatment 224 (Sulphur alone) had always resulted in a significantly higher (1 percent level) population over that of the control (T (subscript 0)). With the enhancement of the activity of the soil mycoflora, especially Trichoderma spp., by one or a combination of the different treatments, survival of propagative units and consequently, the activity of R. lignosus.