The need for weed control

A weed is defined as any unwanted plant in a cultivated area. Calling a plant a weed is very subjective, e.g. blackberry is generally regarded as a weed, but in the USA, they can be encouraged, as they are the over-wintering host of the Anagrus wasp, that parasitises the grape leafhopper.

Advantages & disadvantages of weeds

Disadvantages Advantages
  • Compete with vines for soil water, space & nutrients. Dock can even block drainage pipes. Note that wild plants are usually better adapted to the soil conditions than crop
  • Smothering of aerial parts of vine, especially young ones
  • Hamper the passage of:
    • Machinery, e.g. harvesters & black nightshade
    • Manual labour – e.g. thistles, nettles, brambles
  • Increase frost risk by forming an insulating layer on soil surface
  • An act as hosts for pests and diseases, e.g.: broad-leaved species of ground cover will host eggs of ligthbrown apple moth in Australia
  • Look unattractive
  • Prevent soil erosion
  • Prevent nitrate leaching
  • Encourage biodiversity
  • Reduce excess vine vigour
  • Improve soil structure
  • Indicator weeds
  • Can look attractive
  • Possible crop

It is Important to understand wild plants:

  • Identify, particularly when young
  • Know whether ephemeral, annual, biennial, perennial, monocotyledon, dicotyledon
  • How they reproduce, spread and perennate

The main methods of weed control in vineyards are cultivation, ground cover, herbicides & mulching. It is important to know how to apply these techniques and understand their respective advantages and disadvantages.