Mites

The pineapple tarsonemid mite, S. ananas, only infests pineapple plants (see Fig. 9.11; Jeppson et al., 1975). It occurs universally on

Fig. 9.22. Cross-section of Penicillium funiculosum-infected flower showing rotting of internal flower parts and beginning of leathery pocket in locules (arrows).

the growing plant, developing inflorescence, fruit and crown. The pineapple tarsonemid mite is most abundant from just prior to flower induction (forcing) through the 12.7 mm and 25.4 mm open-heart stages of inflorescence development (see Fig. 9.21) and flowering. It is grey in colour and the body of the adult mite is oblong, 0.125 X 0.25 mm and flat. The life cycle is 7-14 days, depending on temperature. Pineapple tarsonemid mites feed on developing trichomes on the white basal-leaf tissue and flower bracts and sepals, causing light brown necrotic areas. Mites may also enter the infected flower and feed on internal flower parts. The young developing inflorescence cone seems to be the preferred feeding site (Petty, 1975, 1978c; Rohrbach and Schmitt, 1994).

Very high populations of pineapple red mite, D. floridanus, are always associated with epidemics of Fusarium fruitlet core rot in Hawaii (see Fig. 9.10; K.G. Rohrbach, personal observation). The association between the pineapple red mite and F. subglutinans FCR is not understood. No cause-and-effect association has been demonstrated.

Control of the pineapple tarsonemid mite is important to the control of P. funiculosum-induced FCR, LP and IFC. Endosulphan (ThiodanĀ®) applications at 3 weeks prior to and 1-5 weeks following forcing have resulted in the best control of P. funiculosum-induced diseases (Le Grice and Proudman, 1968; Le Grice and Marr, 1970; Rohrbach et al., 1981). Petty (1990) also reported reductions in the incidence of disease symptoms (leathery pocket) caused by P. funiculosum following applications of the miticide endo-sulphan, which suppressed the pineapple tarsonemid mite in South African pineapple plantings. Jeppson et al. (1975) observed that species in the genus Steneotarsonemus are not typically controlled by sulphur but show great susceptibility to organophosphate aca-ricides or the halogenated thioether group.

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