THE STATUS OF CITRUS IPM IN SOUTH AFRICA

Four years ago citrus IPM in South Africa was largely defined by the use of biorational control strategies such as microbial control, sterile insect release, mating disruption, attract-and-kill and soil- and stem-applied systemics. This is still the case but pressure from export markets on quarantine pests and diseases has increased, together with further residue restrictions. Due to concerns about citrus black spot, Guignardia citricarpa, mancozeb applications have increased in the Eastern Cape province and are likely responsible for a decline in numbers of the phytoseiid mite Euseius addoensis. This has resulted in greater populations of citrus thrips, Scirtothrips aurantii, early in the season and led to the use of longer residual thripicides such as chlorfenapyr. This product is harmful to both phytoseiids and hymenopterous parasitoids of quarantine pests such as certain mealybug species and false codling moth (FCM), Thaumatotibia leucotreta. Attempts to redress these imbalances are sometimes made by releasing the FCM parasitoid Trichogrammatoidea cryptophlebiae and Coccidoxenoides perminutus for mealybug, but the latter is not very effective against other mealybug species. Although California red scale (CRS), Aonidiella aurantii, is not a quarantine pest for most export markets, it must be controlled preventively where biological control is compromised by disruptive thripicides. This requirement, coupled with the increased price of spray oil, has resulted in widespread use of generic imidacloprid formulations as soil drenches. Although spirotetramat was recently registered in South Africa for the control of CRS and it appears to be IPM-compatible, its cost is high relative to other scalicides. The only new citrus pest that has become established in the last four years is the woolly whitefly, Aleurothrixus floccosus. The fruit fly Bactrocera invadens has spread throughout the rest of Africa south of the Sahara but is not yet established in South Africa.