Counts of citrus rust mite (Phyllocoptruta oleivora (Ashm.)) on leaves and fruit of citrus rose to a peak in the two dry seasons, the build up taking 4-5 weeks. It then decreased partly through infection by the entomogenous fungus Hirsutellathompsonii Fisher and partly through a decline in feed quality. The low counts in the wet seasons were associated with rain rather than humidity, temperature or infections by H. thompsonii. Spraying with suspensions of fragmented mycelium of H. thompsonii (mass concentration 0.5-1.0 g litre -1) prevented the build up of citrus rust mite.The severity of greasy spot (Stenella sp.) was positively correlated with counts of citrus rust mite. Defoliation of citrus trees after greasy spot infection was associated with high counts of mite.Control of citrus rust mite (with chlorobenzilate: mass concentration of a.i. 2 g litre -1at 500 litre ha -1) was warranted when 25% of fruit or 15% of leaves bore at least one mite per lens field (1.5 cm 2). Greasy spot could be controlled by preventing build-ups of citrus rust mite.