Push and Pull technology

We don’t need pesticides or herbicides

You try to kill the pests but you kill the good ones as well, like the bees and bumble bees.

 

What can be done in the garden ?

For the potager try to rotate the crops. I was amazed to see some French people grow potatoes year after year in the same field, the result : thousands of colorado beetles.

Look after your soil and attract the wildlife to create a natural balance between pests and predators .

 

The article following is about a method of controlling pests and weeds on a specific crop like maize in Africa. The way of control used before would have been neonicotinoides pesticides, like the cruiser which are famous for causing the death of millions of bees. The bees have got enough problems already with the varroa and the asiatic hornet.

 

Pests of cereal crops

Stemborers, parasitic striga weeds and poor soil fertility are the three main constraints to efficient production of cereals in sub-Saharan Africa. Losses caused by stemborers can reach as high as 80% in some areas and an average of about 15-40% in others. Losses attributed to striga weeds, on the other hand, range between 30% and 100% in most areas, and are often exacerbated by the low soil fertility prevalent in the region. The soils are highly degraded due to continuous cropping with limited or no external inputs to improve soil fertility. When the two pests occur together, farmers often lose their entire crops. Crop losses caused by stemborers and striga weeds amount to about US$ 7 billion annually, affecting mostly the resource-poor subsistence farmers.

Control of stemborers using pesticides is not only expensive and harmful to the environment, but also usually ineffective, as the chemicals cannot reach deep inside the plant stems where stemborer larvae reside. Similarly, the use of herbicides against striga is neither effective nor feasible among smallholders in the region for both biological and socioeconomic reasons. Preventing crop losses from stemborers and striga weeds, and improving soil fertility in eastern Africa alone could increase cereal harvests enough to feed an additional 27 million people in the region

The pull

The approach relies on a combination of companion crops to be planted around and among maize or sorghum. Both domestic and wild grasses can help to protect the crops by attracting and trapping the stemborers. The grasses are planted in the border around the maize and sorghum fields where invading adult moths become attracted to chemicals emitted by the grasses themselves. Instead of landing on the maize or sorghum plants, the insects head for what appears to be a tastier meal. These grasses provide the “pull” in the “push–pull” strategy. They also serve as a haven for the borers’ natural enemies. Good trap crops include well-known grasses such as Napier grass (Pennisetum purpureum) and Sudan grass (Sorghum vulgare sudanense). Napier grass has a particularly effective way of defending itself against the pests: once attacked by a borer larva, it secretes a sticky substance which physically traps the pest and limits its damage.

The push

The “push” in the intercropping scheme is provided by the plants that emit chemicals (kairomones) which repel stemborer moths and drive them away from the main crop (maize or sorghum). The best candidates discovered so far with the repellent properties are species of leguminous genus Desmodium. Desmodium is planted in between the rows of maize or sorghum. Being a low-growing plant, it does not interfere with the crops’ growth and, furthermore, has the advantage of maintaining soil stability, improving soil fertility through enhanced soil organic matter content and nitrogen fixation. It also serves as a highly nutritious animal feed and effectively suppresses striga weeds. Another plant showing good repellent properties is molasses grass (Melinis minutiflora), a nutritious animal feed with tick-repelling and stemborer larval parasitoid attractive properties.

 

 

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