Stem injection with selected systemic chemicals to control vascular disease of cocoa

Vascular Streak Dieback (VSD) disease caused by Oncobasidium theobromae (Talbot and Keane), is one of the common disease of cocoa in Malaysia. The disease is widespread throughout the country and cause considerable loss in cocoa production recently in Raub, Pahang. Infection can occur at all ages of cocoa growth and development and the outbreak and is more serious in areas with inadequate shade level. Furthermore, the seriousness of the disease depends on the weather pattern of the year (Bong, 1989). The pathogen enters the plant system and disturbs the uptake water and nutrients by cocoa plant. The disease can kill cocoa plant if remedial action and good cultural practices are not taken immediately. Usually systemic fungicides such as triadimenol and metalaxyl are sprayed on or drenched under the cocoa tree canopies to control the disease. Other alternative are by pruning the diseased twigs to remove the pathogen from the plant system and redu ce inoculums potential level (Tay et al., 1989; Keane and Prior, 1992). However, the fungicide applications to mature trees is not recommended because it is costly and easily wash off by the rain water since the disease infection occurs during rainy season (Bong and Seow, 1989). This paper reports the stem injection technique with three selected systemic chemicals to control VSD disease.