Problem 1: Exposed roots
Although this may not seem much of a problem, it can lead to serious health issues. Roots can easily be scalped by mowers, or damaged in other ways. This can then allow rots, fungi or insects to attack the tree, leading to a host of nasty problems.

Solution: Carefully remove lawn growing up to the trunk and around the roots. Fill the voids between roots with a quality compost and then cover this with a mulch. Ensure the compost and mulch are not pushed up against the trunk.

Problem 2: Sap suckers
There is a huge range of bugs that can slowly weaken a tree by infesting the leaves, sucking out nutrients. The first hint your tree is being attacked may be black sooty material appearing on anything below it, such as smaller shrubs or garden furniture. The black material is a mould that grows on waste produced by the sap suckers.

Solution: To identify the pest and find the right treatment, take a sample to your local garden centre. In the first instance, the only solution may be to apply a spray that is systemic (travels through plant sap) such as Yates Confidor or Defender MaxGuard. For large trees this may not be an option, so try improving their general health.

Problem 3: Borers
These pests, ranging from tiny maggot-like critters to plump 'witchetty grubs', live under bark and burrow around, chewing out wood that transfers sap. The risk is they can ringbark a branch or the whole tree. The damage can also allow fungal pests to enter the tree.

Solution: Look for entry holes; they may be concealed by excreted chewed-up wood, called frass. Use fine wire to fish out and kill the grubs or mix up a solution of pyrethrum. Spray into hole and squash grubs when they fall out.

Problem 4: Bracket fungus
Unfortunately, when a bracket fungus (large solid shell-like growth) appears, the tree has been damaged beyond recovery. This is the visible fruiting body of a fungus that will have already rotted away heartwood and roots.

Solution: This will depend on the tree, its location and condition. The tree may survive for some time but there is an increasing risk of branches, or the whole tree, falling. Talk to a qualified arborist or tree specialist, but be aware they are likely to recommend removal.

A successful start
If you want healthy, happy trees, make sure you give them the best start in life.

• Before planting, soak the plant thoroughly in a solution of a liquid soil wetter and a seaweed tonic such as Seasol.
  Dig the planting hole at least twice the size of the tree's root ball.
  Water, but do not saturate, the planting hole with soil wetter and a seaweed tonic solution.
  If soil is poor, replace a portion of it by blending in a planting compost.
  Add pre-soaked water crystals if soil is dry, sandy or water repellent.
  Remove plant from pot and position in the hole so its soil level is the same as surrounding soil. Back-fill around roots and gently press down soil.
  Stake with at least two stakes, ensuring they do not go through root ball.
  Slightly mound soil to create a watering basin and water well.
  Mulch well, ensuring mulch is not pushed up against trunk.

Keeping trees healthy
It's an accepted fact that a healthy tree is rarely attacked by pests or diseases. To keep your tree in the best of health, here are a few simple tips:

• Every six months, gently aerate the soil with a garden fork to allow water and nutrients to penetrate.
  Fertilise annually using an appropriate slow-release fertiliser. Apply it after you have aerated the soil.
  During times of potential stress, such as extended dry periods or during the hot months, apply a solution of a tonic such as Seasol at the rates for trees.
  If branches are snapped off by wind or mechanical damage, use a quality pruning saw to tidy up the damaged area. This lets the tree heal quickly. Don't cut the remains off flush with the trunk; leave a small 2-3cm stump.
  Remove crossing branches when young, leaving a small stump.
  Don't let aggressive climbers scramble up trees.