Factors associated with occurrence of crown disease in oil palm (Elaeis guineensis Jacq.) and its effect on growth and yield

Summary Crown disease was investigated in oil palm families derived from four sources of (Deli) dura female and three sources of pisifera male parents. These families were planted both at Bah Lias (after rubber) and Gunung Melayu (after oil palm) in North Sumatra.We observed the first symptoms on emerging leaves at 8 months after planting; severity reached a peak at 12 months and diminished gradually until virtually no new leaves were affected in palms older than 35 months. At Gunung Melayu crown disease, in terms of severity score on newly emerged leaves and percentage affected palms, was about double that at Bah Lias. At both locations it was highest in material exclusively bred in Indonesia. In this material crown disease significantly retarded vegetative growth, and reduced cumulative yield of oil for the first 6 years of production by about 4.5% with the highest loss in the first year.The relation between crown disease and nutritional status was inconsistent, but a crop rotation effect on crown disease merits further research.The contribution of the dura parents to crown disease was more evident than that of the pisifera. Screening of genotypes appears to be the most effective method of control of crown disease.