n 



bronzing is damage to the surface of citrus fruit when little additional 

 fruit growth will occur. P^. oleivora feeding causes epidermal cells to 

 die and turn brown, but the cuticle does not crack. These fruit will 

 take a polish because the cutin and waxy layers remain intact (McCoy 

 and Albrigo, 1974). 



Methods of sampling . The square method of sampling was described 

 by Yothers and Miller (1934) as a piece of paper with a half inch square 

 hole cut in it. The paper was placed over the surface of the citrus 

 leaf and mites counted by viewing through a lOX hand lens. A linen 

 tester with a defined field of 0.5 in. x 0.5 in. was used to establish 

 P^. oleivora infestation by Osburn and Mathis (1944). Pratt (1957), 

 Johnson (1960), and Simanton (1960) used lOX hand lens to count citrus 

 rust mites per field of view. A stereoscopic microscope at 18X 

 magnification was used to count mite populations on leaf samples (Dean, 

 1959). Later that year, a brushing machine was used to gently brush the 

 mite population off the surface of leaves by Dean and Sleeth (1959), 

 then by Bailey and Dean (1962). 



A method of removal of all citrus rust mites from the fruit 

 surface was described by Muma (1965). He washed the fruit in an alcohol 

 bath while still on the tree. Another method of rust mite sampling was 

 described by McCoy et al. (1971). An index for the number of mites 

 per leaf was determined by counting the mites within four microscope 

 fields, two on the upper and two on the lower leaf surface, at lOOX 

 magnification. 



Allen (1976) has recently developed an attachment which fits a 



2 

 lOX hand lens and defines a 1 cm field. 



