Cassava is grown on over 15 million hectares and over 550 million people depend on cassava in the continent of Africa. Cassava is a perennial root crop that is grown as a long-term crop annually in over 90 tropical countries. Cassava has serving as a staple crop providing essential dietary nutrients to a large portion of the population in countries where it is grown. Cassava not only provides direct dietary needs of a large portion of the world’s population but it increasingly generate revenues to many farmers, a large portion of whom would be considered small-holder farmers. A number of initiatives are developing industrial scale use of cassava, including in food processing, baking and brewing, biofuel, feed for animals, leading to increased demand. There is increasing research to explore value addition for new cassava products increasing its economic value. However, many challenges face producers of cassava that must be addressed for sustainable production and income security including soil and nutrient management, availability of improved germplasm and pest management, the most prevalent and common are weeds. For example, Nigeria grows over 50% of the world’s cassava with about 4.5 million farmers involved who grow cassava on 3.8 million hectares.

WEEDS AND CASSAVA
Weeds, which grow incessantly throughout the 10-12 month growing cycle makes it difficult to manage annual and perennial species. Weeds not only reduce yields, but weeding, which is mostly done by hand hoeing, takes 50-80% of the total labour budget of the average farmer. In Nigeria, in particular and Africa as a whole, cassava yield per hectare has not been encouraging compare to other continent like Asia and Latin America. This is because of weeds that compete with the crop for essential growth and also reduce because of poor weed management practices and poor timing of removal. Improved weed management techniques including more systematic integrated weed control tactics are needed, not only in Nigeria, but in other countries in sub-Saharan Africa that would reduce the menace of weeds and increase yields and minimize the drudgery of hand weeding by labourers, thus freeing the labour force to pursue more productive farming practices that result in greater economic opportunities for each.

Cassava production is mainly concentrated in the tropical regions of the world with three major areas producing the majority of the crop. Africa grows about 50% of the world cassava with the leading countries being Nigeria, Congo D.R., Ghana, Tanzania, Mozambique, Uganda and Madagascar, Southeast Asia which grows 30% of the world cassava where Thailand and Indonesia are major producers and Brazil in Latin America which grows about 20% of the world cassava.

In Nigeria, the primary herbicides used are atrazine, metolachlor, glyphosate and paraquat and within the farming community, less than 50% of them use herbicides routinely, instead they manage weeds by hand hoeing. The problem is even more serious when considering how farmers prepare their fields. Field preparation and removal of problem weeds, especially perennial grasses and broadleaves, is poor. Fields are mostly cultivated with hand hoes and field preparation often does not include removal of existing perennial weeds. Research by IITA in Nigeria has shown that proper field preparation including application of glyphosate to existing weeds followed by plowing, harrowing, ridging and removal of existing perennial weed propagules leads to lowered weed presence in the cassava field. If proper field preparation and roguing are coupled with use of pre-emergence herbicides and follow-up application of post-emergence herbicides and/or use of mechanical weeding, cassava can become more productive for smallholders. There is also the potential for mechanization on larger farms resulting in higher yields and a reduction in the drudgery. In other parts of the cassava growing world, outside of Africa, a few more herbicides exist and some improved use of mechanical tillers is more common but even in these regions, the need for improved herbicide availability is needed.

6 STEPS TO CASSAVA WEED MANAGEMENT
Weed management include techniques the following;

1. Select a site that is fertile with the presence of biological activities such as worm casts.

2. Slash the vegetative cover and allow for regrowth after a week interval. If using tractor, carry out the first plough and allow regrowth after 14days.

for more info on cassava management technique
www.http://armi.com.ng/cassava-weed-management-technique-to-increase-yield/