Coffee is attacked by many pests, among which are green scales, brown scales, white waxy scales and star scales. Scales, together with Kenya mealy bugs, suck sap from coffee plant tissues, especially the soft and succulent ones. This leads to reduction in the quantity and quality of coffee that is produced.
Larvae of white stem borers cause ring barking as they feed on the bark at the base of the tree trunk and extrude wood shavings as they burrow into the stem. They cause great damage to the coffee stem.
Control of Green Scales, Mealy Bugs and Other Scales
The symptoms and damage caused by scales and mealy bugs
- Rows of flat oval green scales along main leaf veins and near tips of green succulent shoots
- Mealy white masses of insects (mealy bugs) between clusters of berries and/or flower buds
- Sticky honey dew and (black) sooty mould growing on leaves and the adjacent areas
- Attendant ants moving up and down on infested coffee trees
Management of the problem
- In case of severe infestation, spray the infested trees with a systemic and contact insecticide called PRESENTO 200 SP (Acetamiprid 200g/L) at a rate of 10g/20 Litres of water (100g/200L drum of water) or KINGCODE ELITE 50 EC (Acetamiprid+Labda Cyhalothrin) at a rate of 10ml/20 Litres of water (100ml/200L drum of water). Add a spreader, sticker and wetter called INTEGRA at 3ml/20 Litres of water to improve the effectiveness of the spray. These products are good for short to medium term control.
- For long term control, apply a 6 inch (15 cm) band at the base of the tree trunk with RANGER 48% EC (Chlorpyrifos 48%) at a rate of 700ml/20 Litres of water (35ml/Litre of water). Remove dirt and dead bark on the tree trunk before applying the insecticide. The chemical band helps prevent the attendant ants from climbing on the tree and therefore accords the opportunity for ladybird beetles to feed on the scales and mealy bugs uninterrupted, thus facilitating them to biologically clear the infestation. Repeat the banding after 1 year and then after every 2 years.
- Some key cultural control measures that are necessary to be undertaken are timely handling, de-suckering and removal or cutting back of branches touching the ground, as well as early weed control to avoid tall weeds becoming bridges to the attendant ants.
- To remove sooty mould, apply JAMBO CLEAN (Water soluble Phosphorous Pentoxide 8.2% + Total Nitrogen 10.0%) at a rate of 50ml/20 Litres of water (500ml/200L drum of water).
Control of White Stem Borers
Symptoms of attack
Symptoms of attack and damage are ring barking at the base of the stem, oblong holes on the trunks left by entering larvae, wood shavings extruded by larvae burrowing in the stem, round holes on trunks left by emerging adult white borer, yellowing of foliage and eventual death of trees
Management of white borers
Kill the larvae that is in the stem by inserting a wire/spoke into the tunnel or a cotton ball soaked in diluted RANGER 48% EC.
For long term control, smoothen the trunk by removing dirt and dead bark and paint or spray a 90 cm band with RANGER 48% EC diluted at a rate of 700ml/20 Litres of water (35ml/Litre of water). Repeat after 1 year and later after every 2 years.
Chemical stem banding with RANGER 48% EC at 700ml/20 Litres of water is the best long-term solution for control of scales, mealy bugs and white stem borers. For greater effectiveness, the chemical stem band should be applied during the dry season. In areas where coffee is susceptible to white borers, scales and mealy bugs, the chemical stem band should be upto 90 cm from the ground or to the lowest primary branches (whichever is lower) and in areas where coffee is only susceptible to scales and mealy bugs but not to white borers, the chemical band should be 15 cm round the stem near the ground.
Systemic and contact insecticides such Presento 200 SP and Kingcode Elite 50 EC will assist a lot in short and medium term control of scales and Kenya mealy bugs in coffee.