By Charles Kimani & Dr Fathiya Khamis
Mango is the second most important fruit after banana in Kenya and its production is a major source of employment for farmers. Each year, mango production earns the country over US$ 1.6 million in foreign currency. There are about 32 mango varieties grown in Kenya. One of the major challenges mango farmers grapple with is pest infestation.
Common mango pests
There are over 400 species of insect pests that infest mangoes worldwide. The most devastating are fruit flies (Bactrocera spp., Ceratitis spp.) and mango seed weevils.
Other common pests include mealybugs, scales, mites, etc. These are mostly controlled using conventional pesticides, which have a negative impact on human health and beneficial insects. To increase the effectiveness of these chemicals, farmers resort to routine applications, which cause safety and health concerns, and high pesticide residues in the fruits, leading to rejection in export markets.
As buyers prefer to buy mangoes that are not laced with chemicals, farmers need to acquire knowledge on how they can produce their mangoes without applying chemicals.
Use of synthetic chemical pesticides interferes with the natural biological processes, which balance and keep pests below damaging levels. Farmers should aim to prevent the occurrence of pests by proper management of mango trees and the farms on which they grow.
Below are ways in which you can minimize pest occurrence in your mango farm:
1.) Use of plant extracts
As has been explained in previous articles on use of plant extracts to control pests, plants such as neem, basil, ginger, garlic and chili can be used to make microbial toxins that kill pests.
2. Use of lures or bait-loaded traps
One way of monitoring pests in your mango farm is by placing traps that attract fruit flies on strategic places on the mango trees. The trap consists of a plastic container and preferably yellow in colour. The yellow colour is attractive to fruit flies. In this container, you place a pheromone lure that attract the male fruit fly or foodbait that will attract mostly female. The lure or foodbait is normally laced with a killing agent to kill the flies that attracted and come to feed on the lure or bait.
This trap is cheap and easy to make. It is made of a cylindrical plastic container with 4 holes evenly spaced on its sides, a lid, a wire hanger and a bait basket (if it is to be used with a dry attractant). Similar traps can be made locally using ‘Kimbo’ or ‘Blue Band’ containers or similar plastic containers or plastic bottles.
They can also be used with food baits such as yeast, a piece of fruit (banana, mango) or vinegar.
3. Commercial biopesticides
Some companies such as Osho industries and Real IPM have collaborated with scientists to produce and sell biopesticides made from organic material. These biopesticides are free of synthetic chemicals as they are made from plant extracts or from microbes (bacteria, viruses, or fungi) found in air, soil or water. These biopesticides can either kill one or several targets, but they have no effect on human beings and beneficial organisms in the farm.
One of the biopesticide that you can use in your farm to control fruit fly and mealybugs is based on the use of the fungi Metarhizium anisopliae. Real IPM (Kenya) has been working in collaboration with the International Centre of Insect Physiology and Ecology (icipe) and has come up with products made from Metarhizium such as: Metarhizium 69, Metarhizium 78 and Metarhizium 62.
Metarhizium is a naturally occurring entomo-pathogenic fungi (a fungi that woks like a parasite ending up killing the pest). When applying it, follow instructions on usage of water as too much water affects its effectiveness. Metarhizium spores germinate and colonise the pest, killing it in 2 to 4 days.
4. orchard sanitation
If left unattended, pests can multiply in your mango farm and affect all the mangoes leaving you with nothing to harvest. Once you cite any affected mangoes (mangoes with dimples and oozing a clear sap) handpick them while they are still hanging. Waiting for them to fall on the ground has an increased risk as the maggots may have left the fruits to pupate. After picking the fruits, you can feed them to pigs or poultry, or keep them under a tent-like structure known as an augmentoria. This structure will allow out natural enemies back to the environment while trapping the fruit flies that eventually die inside.
5. Bagging fruits
Bagging prevents fruit flies from laying eggs on the fruits. Take papers such as newspapers and fold them in a way that they look like a balloon. You can use glue or any sticky material to make the shape. Blow into the bag to inflate it. Insert each mango fruit per bag and tie at the top firmly. Adjust the paper to ensure that the fruit is not in contact. When using plastic bags, open the bottom or cut a few small holes to allow moisture to dry up. Moisture trapped in the plastic bags damages and/or promotes fungal and bacterial growth that can cause diseases. Plastic also overheats the fruit. Bags made of dried plant leaves are good alternatives to plastic. For tall trees use a climbing ladder and bag all the fruits. Your bagged mangoes will be protected from pests and physical damage, and therefore have a quality appearance, for the market.
For more information on Integrated Pest Management contact us on feedback@biovisionafrica.or