Step-by-Step Project
How to beat borers…

Nothing ruins trees and shrubs faster than an attack of borers, the big, bad, bugs of the garden world.
1. Keep a lookout for:

• the presence of frass or sawdust. This is the expelled wood ‘chewings’ of the borer or caterpillar.
• a depression or sunken zone around the borer’s entry point.
• ‘droppings’ around the branch forks or on the ground around the base of the plant.
• borer holes or strike points on the bark.

2. If you discover any of the above signs, determine the extent of the damage. If you are concerned about a large tree, call in experts, as the damage may have rendered the tree dangerous. If you’re dealing with a smaller problem:

• take a sharp knife and carefully cut away the depressed bark.

• poke some old copper fuse wire into the hole and squash the borer with it (there is no insecticide registered for injection into borer holes by home gardeners).

3. Prevent moisture and disease from entering the wound you have created by painting the entire area with a slurry made from a fungicide such as Mancozeb Plus, Bordeaux or Copper Oxychloride. Once dry, paint over with tree wound dressing paint. Fill remaining holes with candle wax or commercial wood or builder’s glue.

4. Improve the plant’s ability to fight off any damage the pest has caused by fertilising and deep irrigating.

• Take a crowbar and make 30cm deep holes 30cm apart around the drip line.
• Into each hole, place five grams of a complete fertiliser.
• This should then be thoroughly watered with a seaweed solution and liquid wetting agent added to the water. Re-water weekly for a two-month period.
• After first watering, mulch under the tree or shrub canopy with a cow-manure enriched mulch of sugar cane, lucerne or straw.
• To avoid collar-rot problems, don’t mound the mulch around the trunk.