Pest weeds
As with the livestock industries, the field crop, horticulture and viticulture industries were of significant importance to the state. Early legislation and programs dealt with:
- pests and diseases of vines
- eradication of weeds, particularly thistles and burrs.
By the later part of the 1800s, general acts were introduced covering noxious weeds, and in the early 1900s, pests and diseases of horticultural crops.
Surveillance for pests and diseases was increasingly important as travel between states and countries became more frequent. Quarantine arrangements were front of mind for much of the 20th century.
Various weeds and their effects on SA agriculture
- Branched Broomrape () – a parasitic weed of a wide range of plant hosts.
- Silverleaf Nightshade (or White Horse Nettle) – a summer growing perennial with a precise purple flower.
- Skeleton weed – a pest in the wheat field, competing with crops for nitrogen and soil moisture.
- Water hyacinth – an attractive water plant, but one of the world’s worst aquatic weeds.