How to control striga and stemborer in maize Source Technical Centre for Agricultural and Rural Cooperation (CTA) Keywords Maize, plants, striga, stemborer, no pesticides Country of first practice Kenya ID and publishing year 7356 and 2011 Sustainbale Development Goals No poverty and life on land

Summary This practice explains how farmers can Some facts about Striga: control Striga and stemborer at the same • Striga seeds can lie in the soil for a long time, without using expensive chemicals. time up to 15 years germinating only when a cereal crop is planted. Description • Striga can only grow by attaching itself 1. Maize Production in Eastern Africa to the roots of a grass-like plant, most Maize is the most important staple food in commonly maize and sorghum. Eastern Africa. But yields on smallholder • It steals nutrients from your maize or farms are often very low, typically just one sorghum, making the plants smaller and quarter of what could be achieved. In a good weaker. year, using improved varieties with good • It can reduce the yield of your maize by management, recommended amounts of more than half and even cause complete fertilizer and effective control of pests and crop failure. diseases could increase yields from 10 to 1.2 What are stemborers? 50 bags per plot. Farmers report that three Stemborers are worm-like pests (the young main problems limit their maize yields: low stages of a flying insect - a moth). At first soil fertility, stemborer and particularly Striga the young stemborers feed on the surface (also called witchweed). A range of simple of maize leaves but soon they make a and appropriate technologies have been hole in the stem and feed inside the plant. developed to help overcome these problems. They can kill the growing tip of the maize 1.1 What is Striga? plant and also weaken the stem causing it to break. If your maize is attacked by Striga is a parasitic weed that affects cereal stemborers your yield will be reduced and crops, especially maize and sorghum, in in some cases the crop may fail completely. many parts of Africa. It can also affect other grass-like plants, such as finger millet, rice, 1.3 How does a “push-pull”system work? sugar cane, Sudan grass and Napier grass. ‘Push-pull’ involves planting Desmodium Two types of Striga are found in Africa: and Napier grass together with your maize • Striga hermonthica grows up to 1 m tall, to control Striga and stemborer. with pinkish flowers. • Desmodium produces a • Striga asiatica is shorter, growing to just smell that drives away TECA 30 cm height, with reddish flowers. stemborer adults and TECHNOLOGIES and PRACTICES for SMALL AGRICULTURAL 1/5 PRODUCERS Crop Production

also a chemical that prevents Striga from not the maize. When the eggs hatch, the attaching to maize roots. Napier grass produces a sticky glue that • Napier grass attracts stemborer adults - kills young stemborers. they lay their eggs on the Napier grass,

Table 1. Alternative ways of controlling Striga and stemborer

Source: CTA 2017

2/5 1.4 Establishing a “push-pull” plot • Plant rows of maize inside the Napier In order to establish a ‘push-pull’ plot, you grass hedge. Allow 75 cm between maize need: rows and 30 cm between seeds in a row. Ensure that the first row of maize is about • A plot not bigger than 50 m x 50 m and one metre away from the Napier grass. not smaller than 10 m x 10 m. In bigger • Using a pointed stick, make shallow plots, the Napier grass would be too far furrows, about 2 cm deep, in the middle away from the maize. In smaller plots, of the space between maize rows. there would not be enough room to grow • For a 50 m x 50 m plot you will need Napier grass, Desmodium and maize. about 600 gr of Desmodium seed. Mix • If you have more land available, make one handful of Desmodium seed with several such plots side by side. two handfuls of fertilizer. If you do not • Maize seeds, Desmodium seeds or have fertilizer, mix Desmodium seed with cuttings and healthy Napier grass canes or fine sand or soil. This helps ensure even root splits. sowing of the tiny seeds. • Ideally, fertilizer. • Sow the seed-fertilizer or seed-sand What to do: mixture thinly in the shallow furrows • Plant three rows of Napier grass all between the maize and cover with a thin around your plot. Allow 75 cm between layer of soil. rows and 50 cm between plants. • 6. If Desmodium seeds are not

Table 1. Alternative ways of controlling Striga and stemborer (continued)

Source: CTA 2017

3/5 Table 2. Stop the spread of striga

Source: CTA 2017 available, you can also use root splits or explains that it is the same maize variety cuttings. These should have at least two in both fields, planted on exactly the same internodes. day. • Plant Desmodium splits or cuttings during The difference between the two fields is the rains to ensure good establishment. striking. The first maize field was destroyed • Weed done about 3 weeks after sowing by stemborer and Striga, the two worst the maize and again after five weeks. pests of maize and sorghum in East Africa. • Trim the Desmodium so that it does not But what was different in the second field? overgrow your maize plants (about 6 weeks after sowing and then whenever Around the second field, Mrs Ouzo had necessary) and feed it to your livestock. planted three rows of Napier grass. “The 1.5 Case study beauty of this grass is that its odour is attractive to stemborer”, says ICIPE We are in western Kenya not far from Lake (International Centre of Insect Physiology Victoria. The small maize field in front of and Ecology) scientist Zeyaur R. Khan. “The us looks dreadful: the plants are only one- grass then produces a gummy substance metre-high, the leaves yellow and full of that traps the pests. holes, there are almost no cobs but there are plenty of plants with beautiful pinkish- Only about 10 percent of the stemborer purple flowers. larvae survive in the end”. Between the maize rows, Mrs Ouzo planted the Close by, Mrs Ouzo, the owner of this field, legume Desmodium, a groundcovering shows us another maize field. Here the plant whose odour repels stemborer. The plants are over two metres high, with dark stemborer is attracted to the Napier grass green leaves, healthy cobs and there are growing around the field and repelled by very few of the pink-flowered plants. She Desmodium from the inside of the field.

4/5 This “push-pull” system was originally damage and as well gave the opportunity to developed by ICIPE. What’s more, sell the Napier grass and Desmodium from Desmodium binds (fixes) nitrogen from the the push-pull plot as fodder, which generated air and so enriches the soil. As it covers the new income. ground, it also helps keep the soil moist and 3. Agro-ecological zones protects it from erosion. But that is not all: Desmodium is also very effective against • Tropics, warm Striga. With Desmodium inter-cropped with 4. Objectives fulfilled by the project the maize, very little Striga grows. • Women-friendly “Last year, I sold the Napier grass and Women can easily adopt this practice in their Desmodium from my push-pull plot as fields. fodder for about USD 100. With this money, • Resource use efficiency I could afford to pay school fees for my Costs can be saved since no chemical kids. This year, I am planning to produce pesticides are needed. Desmodium seed as well because all of my • Pro-poor technology neighbours want to go for this push-pull This practice help saving the maize system. Maybe, I can afford a cow then”, production from pests with simple adoption. says Mrs Ouzo. 2. Validation of the practice In western Kenya farmers had planted rows of Napier grass between maize pants, as a result only about 10 percent of the stemborer larvae survive. This helped farmers to secure their Maize product from

TECA TECHNOLOGIES and PRACTICES for SMALL AGRICULTURAL 5/5 PRODUCERS