A weed is any plant growing in a wrong place, usually considered undesirable. Uncontrolled weeds compete with the crop of interest for nutrients, moisture and space, and may completely suppress the crop if uncontrolled. They also harbour pests and diseases. Young maize seedlings can easily be overwhelmed by weeds. Weeds take full advantage of the wide rows and upright growth of maize, colonizing the bare soil beneath.
Any plant growing in a wrong or undesired place is considered a weed. Uncontrolled weeds compete with the crop of interest for growth factors like nutrients, moisture, and space, and may completely suppress the crop leading to low or no yields. They also harbor destructive crop pests and diseases. Cabbage crop does not compete well with weeds and is easily overwhelmed by their attack.
The common bean (Phaseolus vulgaris) is the most widely grown of the cultivated species of Phaseolus which is extremely important as food. However, the crop does not compete well with weeds because it grows slower compared to most weeds and can thus suffer from successive flushes of weeds, causing significant yield losses.
Weeds are plants growing in the wrong place, which compete with the trees of interest for growth factors like moisture and nutrients. Some weeds are also alternate hosts of diseases, nematodes or insects pests. With this, it is therefore very important to keep the area under the canopy free of weeds.
Since onion crops are not competitive against weeds, many species may grow in the garden, resulting into significant yield losses.
Carrot crop is a poor competitor with weeds, and if not controlled, yields can be reduced by more than 90%, because the weeds can quickly overtake the crop.
Wandering Jew (Tradescantia and Wandering Willie) is a ground cover weed. This weed invades quickly, shades out and strangles other plants.
Star grass (Cynodon aethiopicus) is a warm climate noxious weed with an extensive system of creeping rhizomes and stolons. It belongs to the poaceae family.
Sowthistle (Sonchus oleraceus), which is also known as milk thistle is one of the key weeds in Kenya whose control is of great concern. It is an erect and fleshy plant that possess hollow, smooth stems that exude milky latex when damaged.
Smooth Pigweed are herbaceous annuals belonging to family Amarantaceae. They are tall, erect to bushy plants with simple oval, diamond shaped with alternate leaves