In this section, we distinguish between soil problems and root problems. It is not always easy to decide what causing the problem, for root pests and diseases live in the soil for most or all of their life. Soil problems are normally nutrient imbalance or physical aspects of the soil makeup, such as heavy clay soils.
The difference has to be properly recognised for there is little to be gained by treating a root pest or disease problem with fertiliser!
Ask any vegetable gardener about 'root' problems and they will talk to you about a wide range of pests and diseases ranging from Carrot fly to Scabby potatoes, and Club Root to Root Eelworms. Ask any 'ornamental' gardener the same question, and you are unlikely to get any answer other than Vine Weevil Damage to Root systems.
The main reason for this difference, being that the vegetable grower sees a lot more roots (potatoes, turnips, swedes, carrots, onions, parsnips and the like) than does the shrub and perennial gardener.
The first visible sign of a root problem is likely to be seen above ground level. Plants wilt, leaves turn yellow, brown patches in the lawn, plants generally lack vigour. All can be attributed to some problem or other in the root system.
There are many 'pests' that attack root systems, and also a few diseases. Most of the pests are visible - once you have removed some soil or otherwise bared the roots.
Pests that live in the soil, causing damage to plant roots, are all slow moving, for they do not have to 'catch' their prey. An example of bad and good insects, being the slow moving Wireworms - vegetarians - and the quick moving Centipedes - carnivores. The Centipedes have has two pincer-like claws at the back end of the body packed venom with which to slow down its prey. It is not partial to potatoes or other vegetable, but is so to other soil-borne pests - like root aphids. It can be safely assumed that it is on our side. The Wireworm on the other hand is happy to feed on the vegetarian fare that we plant – such as potatoes and other juicy roots!
Aphids, which we normally associate with leaf and stem sucking, have also relatives that are happy to live in the soil - or compost - and feed upon the sap extracted from roots. They rarely kill off a plant entirely - providing we notice and act soon enough.
Some slugs live below ground exclusively and are partial to roots and underground stems. The same is true of Leatherjackets - the root eating larvae of the otherwise harmless Daddy longlegs Crane fly.
Vine Weevil Beetles - simply chew a few chunks out of leaves, but their larvae will strip a plant of roots in a few days. They are more apt to attack container grown plants - easy to lay eggs in the compost - and shallow rooted alpine plants.
Not all root pests are visible. Some are hidden away inside fleshy root systems. Others are small enough to necessitate a microscope.
Diseases of Plant Roots.