The onion, scientifically known as Allium cepa, holds great significance as a widely consumed vegetable crop. It is cultivated on both large and small farms, encompassing greenhouses and open gardens. However, onions face challenges when it comes to competing with weeds. Consequently, they are susceptible to repeated waves of weed growth. Additionally, the onion plants have upright leaves that do not provide sufficient shade to inhibit the emergence of weeds within the crop rows. Weeds can be defined as plants that grow in undesirable locations, often hindering the growth of desired crops. These unwanted plants compete with the onion crop for essential growth resources such as nutrients, moisture, and space. If left uncontrolled, weeds can completely suppress the onion crop. Furthermore, they serve as hosts for pests and diseases, which can cause substantial yield reductions.

Common onion weeds

Numerous types of weeds thrive in onion fields. Some examples of these weeds are as follows:


Broadleaf weeds Grass weeds
Sow thistle (Sonchus oleraceae) Goose grass (Eleusine indica)
Purslane (Portulaca Oleraceae) Common wild oats (Avena fatua)
Double thorn (Oxygonum sinuatum) Barnyard grass (Echinochloa crusgalli)
Mexican marigold (Tagetes minuta) Star grass (Cynodon spp)
Devil’s thorn (Emex australis) Italian grass (Lolium multiflorum)
Thorn apple (Datura stramonium) Nutsedge (Cyperus spp)
Pig weed (Amaranthus spp) Winter grass (Poa annua)
Gallant soldier (Galinsoga parviflora) Guinea grass (Panicum spp)

Importance of proper weed management

  • Weeds pose direct competition to plants by vying for vital growth factors such as sunlight, water, nutrients, and space. This weakens the crop and makes it more vulnerable to pathogen attacks.
  • Weeds significantly diminish crop yield and overall performance.
  • Weeds serve as hosts for pests and diseases, further jeopardizing the health of the crop.
  • Certain weeds have parasitic properties, while others can be harmful if consumed by livestock and humans.
  • Some weeds can cause damage to the crop by producing toxic substances.
  • Weeds create difficulties during the harvesting process, particularly those that emerge late in the growing season.
  • In general, the presence of plants in inappropriate locations detracts from the aesthetic appeal.

Benefits of early/timely weed management

  • Preserves the crop’s yield potential by eliminating competition from weeds.
  • Safeguards the palatability and nutritional value of the crop.
  • Significantly reduces the chances of pests establishing themselves in the crop.
  • Young weeds are more manageable as they absorb and transport herbicides more effectively.
  • Weed control becomes less effective during periods of drought stress, which typically occur later in the season.

Management & Control

In order to achieve high-quality and abundant onion yields, effective weed management is necessary. Some commonly employed methods include:

Chemical Method:

This method involves the use of herbicides and is highly favored due to the following reasons:

  • It is a quick and easy application process.
  • There is no mechanical damage inflicted on the crop.
  • It is cost-effective.
  • It effectively controls weeds that share similar morphological characteristics with the onion crop.

The following herbicides are recommended for controlling weeds in onion cultivation:

  1. WEMBE 200 SL:

WEMBE 200 SL is a non-selective post-emergence herbicide that effectively controls annual and perennial grasses, as well as broad-leaved weeds. By applying WEMBE 200 SL during land preparation, you can effectively eradicate unwanted and resilient weeds.

Recommended application rate: 3.0 Liters per hectare (300ml in 20L).

  1. CATAPULT 480 SL:

CATAPULT 480 SL is a non-selective post-emergence herbicide that effectively controls annual and perennial grasses, as well as broad-leaved weeds. It is recommended to use CATAPULT 480 SL during land preparation to eliminate all types of weeds.

Recommended application rate: 2.0 Liters per hectare (200ml in 20L).

  1. COMMANDER 240 EC:

COMMANDER 240 EC is a selective early post-emergence or post-transplant herbicide (2-14 days after transplanting) used to control annual grasses and broad-leaved weeds.

Recommended application rate: 1.0 Liter per hectare (50ml in 20L).


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