Pest Control Experience in the South African Citrus Industry Tim G Grout
Citrus Production Regions ZIMBABWE MOZAMBIQUE BOTSWANA NORTHERN LIMPOPO PROVINCE NORTH WEST GAUTENG GAUTENG MPUMALANGA MPUMALANGA SWAZILAND NAMIBIA FREE STATE KWAZULU-NATAL KWAZULU-NATAL NORTHERN CAPE LESOTHO EASTERN CAPE EASTERN CAPE ATLANTIC OCEAN WESTERN CAPE WESTERN CAPE INDIAN OCEAN
South African Citrus Production 2015 Local 6% Processed 27% Exports 67%
Approach to Citrus Pest Management Phytosanitary pests determine the approach to pest management False codling moth is throughout the country and is a phytosanitary pest for most markets, so that is the key pest Where black spot is present that will also determine what sprays are required In the first 6-8 wk after petal fall, thrips and mealybug must be controlled so impact from natural enemies is minimal From 8 wk post-petal fall to harvest, natural enemies must be conserved to prevent outbreaks that cannot be controlled late in the season
Pest Monitoring Growers will use some form of pest monitoring but the degree to which this is dependent on an action threshold will be variable Action thresholds are based purely on pest infestation levels and predator-prey relationships have never been formally incorporated into thresholds. However, parasitism levels and predator activity will be noted when scouting and chemical intervention delayed if it appears that the natural enemy activity is significant Just prior to harvest we recommend that growers inspect the fruit on the tree to record different cull factors and infestation levels. These can be used as a guide for the next season We recommend inspecting 5 trees/ha and recording presence of pest or natural enemy on 10 sampling units per tree.
Resistance Management Red scale resistance to OPs is stable and has remained so since development in 1975, perhaps due to continued use for other insects. We know little about imidacloprid resistance Resistance in citrus thrips fades with time but remains in the population so that if a product is applied twice within a season it will work the first time but not the second. Products include pyrethroids, carbamates and tartar emetic, with growing tolerance to OPs and abamectin CRI does not conduct research on resistance but tries to speed up the registration of new products from different IRAC groups We encourage growers to alternate products from different IRAC groups, but we have no legislation to force this
Spraying Most spray machines are PTO driven, with horizontal flow to reduce drift, and air oscillation to create turbulence Some are high wind volume, low velocity, others are high velocity with lower wind volume Most air-shear atomiser types like Cima do not have enough wind output to provide full coverage of large trees Most machines have the capability of spraying high volumes for dilute oil sprays Good2spray model: www.cri-phytrisk.co.za
Scale Insects Armoured scales: Aonidiella, Chrysomphalus, Lepidosaphes may require sprays Soft scales normally under biocontrol Wax scales normally under biocontrol Cottony cushion scale mostly controlled by Rodolia spp. beetles so neonicotinoid sprays or pyriproxyfen can cause repercussions
Thrips Scirtothrips aurantii SACT vs. Pezothrips kellyanus Soil fauna and microbes beneficial for PK PK is a pollen feeder and attracted to flowers, SACT damages fruit for 12 weeks but fruit less susceptible as it ages Alternate hosts and switching? Macadamias
Sucking Insects Mealybugs: biocontrol unless compromised Stink bugs? Psylloids: systemics essential if vectors Leafhoppers: may occur just before harvest; residues Whiteflies: problematic if poor biocontrol or no scalicides Aphids: normally controlled when spraying other pests minor importance if good CTV protection
Fullers Rose Beetle Cannot fly so trunk barriers effective Chemical sprays can cause drift and pest repercussions, even possible fruit residues Sticky barriers must be rejuvenated in dusty conditions Trees must be skirt-pruned and weeds controlled Impact of spinetoram used for other pests?
Lepidoptera Can Bacillus thuringiensis or viruses be used? Microbial control in the soil if pupate there Larval size and mass can be increased by imidacloprid and buprofezin applications; hormonal effects Internal (FCM) vs. external (LBAM) phytosanitary threat Postharvest treatments? Wang, I-H. et al. 2005. J. Econ. Entomol. 98: 1145-1149;. Yu, Y-S et al. 2007. J. Econ. Entomol. 100: 1188-1193.
Mites Abamectin plus oil used for citrus thrips suppresses mite populations, except for bud mite; Brevipalpus seldom seen Fenpyroximate one of the few acaricides still registered for the control of bud mite with PHI of 60 d Mites are expected to increase when farming under net due to higher RH and better egg survival.
Other Fruit fly Area-wide control? Home gardens? Baiting? Grasshoppers/katydids Ants Snails Biosecurity threats?
Thank You Further Questions?