Interrelations between citrus rust mite, Hirsutella thompsonii and greasy spot on citrus in Surinam

Counts of citrus rust mite <em>(Phyllocoptruta oleivora</em> (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 <em>Hirsutella</em><em>thompsonii</em> 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 <em>H. thompsonii.</em> Spraying with suspensions of fragmented mycelium of <em>H. thompsonii</em> (mass concentration 0.5-1.0 g litre <sup><font size="-1">-1</font></SUP>) prevented the build up of citrus rust mite.<p/>The severity of greasy spot <em>(Stenella</em> 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.<p/>Control of citrus rust mite (with chlorobenzilate: mass concentration of a.i. 2 g litre <sup><font size="-1">-1</font></SUP>at 500 litre ha <sup><font size="-1">-1</font></SUP>) was warranted when 25% of fruit or 15% of leaves bore at least one mite per lens field (1.5 cm <sup><font size="-1">2</font></SUP>). Greasy spot could be controlled by preventing build-ups of citrus rust mite