Cassavas Weed Management and Control

Cassavas weed management and control

As weeds, we consider-treat plants that grow in laces and in time that is not desirable. Many different types of weeds occur in cassava farms and cause considerable losses to the farmer. Weed management means preventing weeds encroachment from overturning the farm. Weed encroachment of fields is a significant constraint in cassava production in Nigeria. Weeds are notorious constraints to the development of cassava in the area. This is because weeds compete with the cassava crop for nutrients, sunlight, and space. Weeds can be a shelter for pests and diseases causing physical damage to cassava plants. This undermines the efforts of farmers to grow a healthy crop and obtain high cassava yields. The presence of weeds limits the productivity of cassava and negatively impacts farming families. Hoe weeding is a common practice among farmers. Weeding frequency and timing depend on climate, cultural practices, crop growth, fertility, and weed species [2].

The effect of weeds is apparent on cassava during two periods. The first is the first two to three weeks after planting. This period is characterized by a slower growth rate, and the third month is the second phase when the roots are already forming. It is therefore recommended that the weeding schedule be made at four, eight, and 12 weeks after planting. However, the issue of weeds persist because weeding is expensive and the nature of hand hoe weeding deployed by farmers in Nigeria. A delay in clearing the weeds leads to reduced yields [1].

Weeds are big problems in cassava farms that hamper productivity. In Nigeria, weeding takes about 50% to 80% of the total labor budget of cassava growers. Women contribute about 90% of the hand-weeding labor. More effective ways to remove or suppress weeds are needed [2].

While Nigeria is one of the largest cassava producers globally, weed control is not as well developed and weeds are still a threat to cassava yield. This affects the livelihoods of farmers in Nigeria compared to other countries in South America or Asia. To prevent weed infestation, adequate measures are needed to be taken in this respect. One key measure that must be considered before cassava is propagated is land preparation. 

Common weeds in Cassava farmlands

Three major common weeds compete with cassava plants for space, nutrients, and water.

• Grasses are usually slender, erect, or creeping plants. Their stems can be oval, and the leaves of the grasses are much longer with broad leaves. Examples of grass weeds commonly found in cassava farms include spear grass, Imperata cylindrica, bermuda grass Cynodon dactylon, guinea grass panicum maximum, and the feathery Pennisetum, Pennisetum polystachion.
• Segdes resemble grasses but are always erect and usually have solid and triangular-shaped stems. Examples of the Segdes include  Mariscus alternifollus, purple nutsedge, and Cyperus rotundus. 
• Broadleaf weeds: Broadleaf weeds are herbs, creepers, climbers, and shrubs whose stems are solid and irregular. Examples of these weeds commonly found in cassava farms include Siam weeds, Chromolaena odorata, wild poinsettia, Euphorbia heterophylla, giant sensitive weed tridax, and goat weed water leaf,

Farmers can control weeds by:

Land preparation: If adequate measures are considered in land preparation, it can help to suppress weeds. Some measures that must be considered before cultivating cassava are plowing, harrowing, and ridging.

Plowing is the process of making the soil loos and turning it over. It is one of the essential ways to prepare the soil before planting and improve soil aeration and weed management (uprooting perennial weeds, exposing their seeds and stolons, etc.). Harrowing levels any mole hills and removes any unwanted materials that may affect crop cultivation. This allows air movement and root aeration and improves water infiltration. It reduces the disease problems in the pasture by exposing fungi and bacteria to sunlight. This is crucial for the health of the pasture. Ridging is a technique that permits to cover of the base of the plants with soil. This increases the productivity of the crop and grants better protection for cassava plants from weeds. If farmers make ridges, they are likely more to control weeds than if they plant cassava on a flat surface. If these techniques are applied to the preparation of farmland, they could suppress weeds compared to growing cassava on a flat surface without proper soil tillage.

Planting methods:

Cassava spacing is very critical to weed control. Research shows that if farmers can plant cassava at 12500 stands per hectare at a spacing of 1 meter by 0.8m, it gives a better result, and they are likely to control weeds than planting at 10,000 stands per hectare at a spacing of 1m by 1m. This is imperative because the cassava plants can easily form a canopy and therefore smother the weeds.

Approaches to weed control and management in Nigeria.

• Mechanical approach weed control refers to using farm equipment to control weeds, for instance, testing gas power machines to replace hand hoeing. This is a common practice in Nigeria and is characterized by a lot of bodily implications [3].
• Chemical approaches: Chemical weed involves the application of a chemical (herbicide) to inhibit weed growth, and appropriate application of herbicides can reduce the manual labor required. This improves the livelihoods of women and children, who are used as laborers. Herbicides show some promising results in terms of the pre-emergence herbicides that can be sprayed at the same time one is planting cassava. This can suppress weed growth for almost two months, which is quite a blessing for the farmers. Research has shown that pre-emergence herbicides decreased the need for manual weeding in cassava in Nigeria. The common herbicides used by farmers in Nigeria are atrazine, s-metolachlor + atrazine, glyphosate, and paraquat. Farmers apply s-metolachlor + atrazine immediately after planting and before the crop and weeds emerge.
• Cultural weed control involves any technique applied in the field to maintain the growth of weeds. Crop rotation, avoiding overgrazing of pastures, and maintaining good soil fertility are some of the examples in this category [3]. This technique may help to reduce how weeds may thrive in cassava farmlands.

References

1. https://forages.oregonstate.edu/nfgc/eo/onlineforagecurriculum/instructormaterials/availabletopics/weeds/control
2. https://www.premiumtimesng.com/agriculture/agric-news/396433-iita-recommends-efficient-herbicides-for-cassava-weed-control.html?tztc=1
3. Ekeleme, F., Dixon, A., Atser, G., Hauser, Stefan et 2021. Increasing cassava root yield on farmers’ fields in Nigeria through appropriate weed management. Crop Protection Volume 150, December 2021, 105810 https://www.sciencedirect.com/science/article/pii/S0261219421002805

• Cassava: History, Nutritional Value, and Plant Information
• Cassava Climate and Soil Requirements
• Cassava Varieties
• Cassava Propagation and Planting
• Cassavas Weed Management and Control
• Cassava crop Water Needs and irrigation Systems
• Cassava Fertilization Requirements
• Pruning of Cassava plants
• Major Pests and Diseases of Cassava
• Cassava Harvest, Yield per hectare and Storage