Weeds have a significant impact on vegetable production worldwide. These intensive cropping systems feature frequent tillage, fertilization and irrigation, providing ideal growing conditions for crops as well as certain weeds. Integrated weed management (IWM) can reduce reliance on herbicides by encouraging a systems approach to weed management. Using insights from global research and industry literature, we investigated the effectiveness of prevailing weed control methods, and evaluated emerging management practices and technologies for ongoing research and adoption. Weed control relies primarily on a relatively narrow range of herbicides as well as frequent tillage. Herbicides have negative impacts on soil, water and human health, while tillage impacts soil quality and function. Intensive cropping on smaller plots facilitates IWM, relying on multiple strategies including hand weeding, mulches, cover crops and cultural methods (e.g., crop rotations, timing). New herbicide options are suggested as an industry priority but are constrained by the lack of new chemistry and potential herbicide resistance. Refinement and adoption of non-herbicide and emerging precision control methods into farm IWM in vegetables is more likely to be sustainable. This review is relevant to advanced vegetable production systems globally, but also to smallholder vegetable production in developing economies.

Chickweed (Stellaria media) is a branched sprawling annual herb, native to Europe, with delicate stems up to 60 cm in length but usually 5-40 cm in length.

Leaves are between 1-3 cm in length, usually almost free of hairs, bright green, and oval to broadly elliptical in shape, with pointed tips. The numerous flowers are white, 3.0-6.5 mm in width when fully open, and comprised of five deeply divided petals (giving the appearance of ten petals), and are surrounded by longer hairy sepals.

Plants are diffusely branched from the plant base, with a distinct line of hairs visible between the stem joints (nodes). Roots are capable of forming from the lower nodes. The root system is shallow, dense and fibrous, and features a slender tap root.

Most vegetable farmers will be well aware of chickweed and how to identify it. However in some cases, depending on stage of growth and experience in identification, it may be possible to mis-identify chickweed as certain other Stellaria species, for example lesser chickweed (Stellaria pallida). Chickweed also closely resembles pimpernel (Lysimachia arvensis), a weed sometimes found on vegetable farms. However, pimpernel may be distinguished most readily by having either red or blue/purple flowers, and somewhat fleshier leaves.

Potato weed (Galinsoga parviflora) is a warm-season erect annual herbaceous plant, native to Central America. It grows up to 0.6 metres in height, but is usually about 0.3 metres in height.

Leaves are opposite, symmetrical, between 1.0-11.0 cm in length and 0.5- 7.0 cm in width, oval shaped, moderately hairy, with wavy margins. Cotyledon leaves are rounded with a slightly indented tip. Flowers are yellow with white to dull pink petals, 3.5-5.0 mm in length and 2.0-6.0 mm in height. There are two types of flowers: disc flowers, forming the central portion of the flower head; and ray flowers, giving the appearance of a single petal and forming a ring around the disc flower. Potato weed may also be known in parts of Australia as 'yellow weed'. It is named for its broad resemblance to potato plants.

Most vegetable farmers will be well aware of potato weed and how to identify it. It closely resembles 'hairy Galinsoga' (Galinsoga quadriradiata), though at the time of writing that species did not appear to be present in Australia. Depending on stage of growth and experience in identification, some other common annual heavy-seeding weeds of Australian vegetable production may be mis-identified as potato weed, including fat hen (Chenopodium album), amaranth (Amaranthus spp.), or blackberry nightshade (Solanum nigrum).

Common sowthistle (Sonchus oleraceus) is an annual herbaceous plant, growing between 0.2 m and 1.5 m in height.

Figure 1 includes a series of photos of common sowthistle at different life stages, from a young seedling through to a mature flowering plant, including images of the flowers and seed.

Common sowthistle initially forms as a rosette, up to 25 cm in diameter, before growing as an erect plant commonly 1 m in height. Stems are circular, green to purple, hollow, and produce a milky sap when cut. Lower leaves are smooth, thin, and lance-shaped, while upper leaves are generally smooth although can be hairy. Upper leaves can show considerable variation in shape, but are generally bluish-green with irregularly-toothed margins ending in small soft spines. Leaves can be between 6 cm and 35 cm in length. The plant has a long, slender pale taproot that is usually branched.

Flowers are light yellow in colour, 10 to 15 mm in diameter, with many narrow petals. Fruit (forming at the base of the flower) is wrinkled, tapers at the base, and produces fine white cottony hairs after flowering.

At its early growing stages, common sowthistle is almost indistinguishable from prickly sowthistle (Sonchus asper), a weed that is also common in Australian vegetable farms and has much the same impacts as common sowthistle. However, as a larger plant, prickly sowthistle is distinguishable from common sowthistle by its leaf form, which is thicker, more curled and with much more significant spines along the leaf margins (Figures 2 and 3). Management of the two species will largely be the same.