Maize

Land  preparation methods

In Rwanda, the majority of maize farmers use conventional methods of land preparation.

• Hand hoe

This is mainly used by small scale farmers. The method is slow, labour intensive but reliable.

• Conventional tractors

These are mainly used by large and medium scale farmers due to high purchase cost, lack of spare parts and expensive fuel consequently even the cost of hiring them is not affordable by most farmers.

• Walking tractors

An appropriate and proven technology for small and medium scale farmers; it is fuel efficient and cost effective though they might not be efficient on heavy soil. It is multi-purpose and easy to use. However, most farmers are not aware of the benefits of the tractors, probably because they are still new on the market.

• Animal traction

This involves the use of oxen to plough the land. With this method the farmer is able to open more land and plant more maize as compared to hand hoe. It is, however, not appropriate where soils are heavy and terrain is steep. It also requires the acquisition and management of the oxen.

After land preparation method, it is also necessary to consider erosion control measures so as to fight from erosion which may destroy the maize or reduce expected yield.

• Erosion control

Bench terraces

Erosion control devices

Planting Agroforestry scpecies

• First ploughing round and removal of weeds
• Second ploughing before planting

Fertilizer application

When you prepare to grow maize, you apply 20 tons per ha of organic manure while preparing the land. In case the soil is acidic, apply 2,5 to 5 tons per ha of lime two weeks before planting. This lime has residual effects for a period of 4 successive farming seasons. Add 250 kg of NPK 17.17.17 per ha in the seed holes while planting or 100kg of DAP per ha. Six weeks after planting, you add 100kg of urea per ha.

PLANTING

• Planting time

Planting time depends on the area:

For farming season A in low altitudes: planting maize takes place in the first half of September, or first half of October. In farming season B, maize planting is done in February.

In marshlands: for season A, planting takes place in October and February in Season B but some farmers may continue to plant up to March. In marshlands, maize planting is done in June when the marshlands start to dry up

Maize plantation management include two times weeding, pruning and ridging.

•  Weeding

The first weeding  takes place when the seedlings have reached 10 cm of height. This weeding is meant to remove the weeds which may compete for nutrients with maize as well as softening the soil to enable maize to grow faster and easily.

• Thinning

Thinning coincides with the second weeding. It consists of removing weak or sick seedlings which are not likely to grow well or reducing the number of seedlings per hole in case they are more than two.

• Ridging

Maize ridging is done when the seedlings have reached  30 cm of height. Ridging is meant to bring the earth closer to the seedlings in order to support them for proper growth with strong roots which enable the seedlings to resist the wind.

1.  Stem Borer (Busseola fusca, sesania colanistis, eldana sacharina). The insects are transmitted to the plants by butterflies, which lay eggs on corn in dry season. Damages inflicted to plants by these insects are remarkable from the holes they make in seeds, with leaves completely eaten up and galleries in stems, the whole surrounded by excrements of the insects.

Symptoms of maize stalk borer, Busseola fusca, damage on leaves:
(A). characteristic “window panes,” (B) shot holes where tissue has been eaten away, and (D) deadheart. Symptoms of damage to stems and cobs: (C) galleries filled with frass, (E) cobs showing frass, and (F) deposits and empty grains.

The following measures are recommended to fight against the disease: early planting, rotation of crops, pile up the stems in compost or apply Dursban 48%.1, 5l/Ha or beta-cyfluthrine 2,5% in 10 l of water /acre.

2. Maize streak virus; this disease

is transmitted by an insect called Cicadulina rubila. The disease is noticed by visible traces on leaves. The virus causes a white to yellowish streaking on the leaves. The streaks are very narrow, more or less broken and run parallel along the leaves. Eventually the leaves turn yellow with long lines of green patches. Plants infected at early stage usually do not produce any cobs.

To fighting against the disease, it is recommended to early plant the entire field, pull up possible infected seedlings, which could transmit the disease.

3.  Leaf spots: this disease is transmitted by a fungus called “Helmnthosporium turcicum “. This disease attacks the leaves of corn and it is seen by many large oval spots on them. It is frequent during rainy seasons

The following measure fight against the disease: early planting using resistant varieties and treated with Thiran and Benomyl before planting. It is recommended to compost the stems away from the field.

4. Fall Army worm

Fall armyworm (FAW) – Spodoptera frugiperda, is a pest that can cause significant damage and crop yield losses, if not well managed. Maize is its preferred host and a major staple crop for smallholders. In addition to maize, the pest has also been detected on an increasing number of other crops (e.g., sorghum and sugarcane).

Prevention

1. 1. • Deeply ploughing the soil with the aim of discovering, removing or burying the fall armyworms,
      • Always weeding the plantation whenever weeds have emerged and keeping clean the plantation contours,
   2. • Removing the plants residues in the field after the harvest,
      • Boosting the plants resistance by applying well decomposed manure, recommended inorganic fertilizers and irrigation,
      • Crop rotation of cereals with legumes (beans, soybeans,..) or tubers (potatoes, sweet potatoes),
      • Regular surveillance of the plantation (at least three times a week) and check whether there is no Fall armyworm outbreak. Once you realize that there Fall armyworms are available, you should inform the concerned people (farmer promoters, facilitators and extension workers at Cell, Sector, District and RAB…)

Control

1. 1. • Collecting fall armyworms and killing them,
      • Using pesticides like:
   2. • Cypermethrin 4%+profenofos 40% (example: roket, target, cypro, jaket,…)   at 1-2 ml of pesticide in1l of water,
      • Lambda-Cyhalothrin 50g/l, at 1-2 ml in 1l of water,
      • Pyrethrum 5% EWC, at 8ml in 1l of water,
      • Acetamiprid 20g/l + Lambda-Cyhalothrin 16g/l, 4-6ml in 1l of water,
      • Imidacloprid 200g/l at 1ml in 1l of water.

5. Maize Lethal Necrosis Disease

Maize lethal necrosis disease is caused by co-infection of maize by Maize chlorotic mottle virus (Machlomovirus: Tombusviridae) and Sugarcane mosaic virus (Potyvirus: Potyviridae) or sometimes another cereal virus of the Potyviridae group.

Symptoms

Maize chlorotic mottle virus (MCMV) causes a variety of symptoms in maize depending upon genotype, age of infection and environmental conditions. They range from a relatively mild chlorotic mottle to severe stunting, leaf necrosis, premature plant death, shortened male inflorescences with few spikes, and/or shortened, malformed, partially filled ears (Castillo and Herbert, 1974; Castillo Loayza, 1977; Niblett and Caflin, 1978; Uyemoto et al., 1981).

Prevention and Control

1. 1. • • Seed should not be recycled; farmers should plant certified seed only. Those seeds are available in agrodealers’ shops;
        • The best approach for the management of MLND is to employ integrated pest management practices encompassing cultural control such as closed season, crop rotation and crop diversification, appropriate spacing, fertilizer application, weeding etc…
        • Uprooting infected plants and bury them in 1m deep hole,
        • Do not grow maize nearby an infected maize plantation,
        • Crop rotating maize with other non cereal crops,
        • Grain and cobs that are rotten should not be fed to humans or animals. These should be destroyed by burning,
        • Domestic regulation can be put in place to prevent the movement of maize products from affected areas to disease-free regions.

Harvesting

• Harvest your maize when it is completely ripe and dried
• The leaves and husks starts to dry out
• The part of the kernel where it is attached to the cob starts to turn brownish or blackish in 90% of the kernels of the cob. This is called black layer formation
• The cobs are no longer appreciated for roasting
• Upon breaking a kernel the inside of it is no longer milky
• At least a quarter of the cobs have started to droop
• Moisture content is about 35%.

Cutting, stooking and dehusking

It can be done manually by removing cob by cob or by cutting the stocks together with the cobs and stooking in the field to dry further.

Drying, Shelling

In-field drying can be supplemented by drying the cobs in improved drying structures (well ventilated cribs) and this reduces the risk of development of moulds.

The cobs can be brought out the cribs spread on mats or trays and exposed to solar radiation to ensure complete drying to the required moisture content for shelling.

Shelling should be done when the maize has a moisture content of 13-14%. Shelling by hand is the most common method. Other types of hand tools and machines are used to making shelling easier and increase capacity.

Maize is shelled for the following reasons:

• Mixing with insecticide is easier and more efficient
• More accurate application rates of insecticide is attained
• Prolonged Shelf life of the Shelled grain
• Less space is required to store shelled grain (volume is reduced by 25-40%)
• It is easier to control and inspect the produce
• Rodents may burrow in cob maize but cant cause significant damage below a surface grain

Once shelled, the maize should be cleaned by winnowing and then treated with the recommended chemical insecticides like Actellic Super (100g of acteric per 100 kg bag)

Storage

• Dried maize can be stored either in cobs or shelled.
• It can be stored in bins, silos, cribs, or in sacks. Sacks should be raised off the ground to allow air circulation.