The day is bright, the sky clear and the sun is scorching as more than 150 mango farmers from various counties in Ukambani meet at a farm in Kathiani, Makueni County.
The farmers from Kitui, Makueni and Machakos had gathered on the farm in Mukunuku to update their skills on how they can farm their mangoes organically – for the export market.
With concerns over chemical residue in farm produce rising in the export market, organic farming of mangoes and other fruits like oranges and avocados is the way to go for a discerning who wants to access premium market.
The model farm hosts 340 trees of grafted apple mango variety (which exporters prefer) and belongs to Peter Ngovi, a successful organic grower of the fruit.
His orchard was chosen by the International Centre of Insect Physiology and Entomology (Icipe) as a learning centre for mango farmers from Ukambani.
Kitui, Makueni and Machakos counties, which make the Lower Eastern mango and citrus growing zones, have for ages battled notorious fruit flies, which account for their huge losses.
Consequently, most farmers sell their produce to local buyers at throw away prices due to high presence of chemical residues as the farmers rely on pesticides to curb the pests.
Before turning organic early last year, Ngovi would spent at least Sh40,000 every season purchasing pesticides trying to control fruit flies.
His plight worsened when buyers rejected his fruits noting they were unfit for export market.
“One buyer told me I was producing fruits meant for dumping, a term used by traders for buying bulky low quality mangoes at throw away prices,” Ngovi explains.
TARGETED AT SPECIFIC SPOTS
His saving grace came when he was introduced to organic mango farming, which involves biological control of pests.
“I only spray to fight the fruit flies during pruning, which is before the mangoes begin to flower, and the spraying is not haphazard but targeted at specific spots,” says Ngovi, knowledge he was passing to other growers on his farm.
The exercise involves use of spot sprays, where a protein food bait is applied on the tree canopy to attract the female fruit flies, which are always in search of proteins to mature their eggs.
“When the flies feed on the bait, they die,” he explains, noting he now spends only Sh7,000 to curb pests a season.
The spray contains ingredients like Metarhizium anisopliae, a fungus occurring naturally in the soil and is used to kill the pupae.
“The spray is available in agrovet shops and goes at Sh2,200 for 200ml. One litre of water is mixed with 50ml of the food bait. A knapsack which contains 20 litres of water can spray 400 trees,” says Ngovi, adding that one should maintain high sanitation in the orchard to interrupt the development of the fly by removing the dropped fruits every day.
A farmer should also kill maggots by burning the produce, burying at least 2ft in the ground to prevent emerging adult flies from reaching the soil surface or enclosing them in black plastic bags and then exposing in the sun for a few hours to kill the maggots.
Bio-pesticides like pyrethrum and neem solutions can also be sprayed to kill the flies, and even False Codling Moth, another deadly pest.
Bactrocera dorsalis, a destructive species of mango fruit fly, which originated from Asia, destroys between 60 to 100 per cent of fruits on a farm, but the extent of damage depends on the locality, cultivar and season.
Horticultural Crops Development Authority (HCDA) estimates that export restriction losses due to fruit fly stand at Sh564 million annually.
Fruit flies, according to industry data, account for an annual loss of up to 2 billion US dollars to fruit farmers across the continent.
BIOLOGICAL PEST CONTROL
Countries such as the US have placed a ban on horticultural produce from African countries where bactrocera dorsalis inversions has been reported.
Ngovi and other farmers at the training use an integration of at least two out of six biological pest control measures.
Besides sprays, another method the farmers are using is traps containing pheromones to kill male fruit flies leaving behind a female population that cannot lay fertilised eggs leading to a decline in general population of the flies.
The male flies, according to scientists, are lured into the trap thinking they are heading to females for mating.
Unknown to them, the scented trap is laced with chemicals that kill them, meaning the more they die, the lower chances of fertilisation. A female fruit fly lays 300 eggs in her lifetime, and are usually in their thousands on the farm.
Dr Ivan Rwomushana, the scientist leading the fruit fly integrated pest management programme at Icipe, says there are six different biological methods farmers can use in organic farming to access the export market.
“Once you eliminate the male flies with the traps, the females can be controlled by a method known as protein food bait technology. In this mechanism, farmers spray the bait on the tree canopy but not on the fruits. The bait, which has a pesticide mainly attracts females.”
Use of parasitoid wasps, which feed on the eggs of the fruit flies killing them is another method.
The wasps have been released in specific farms in Ukambani and farmers advised against using chemical sprays as it kills the parasitoids.
“Chemical pesticides are harmful to the environment, the users and consumers and the pests also develop resistance to them over time,” Dr Rwomushana says, adding that orchard sanitation is the other key biological method.
Dr Sunday Ekesi, the acting director of research and partnership at Icipe says that they are currently working with over 5,000 growers in three counties, but they are targeting at least 10,000 by 2018.
HOT WATER TREATMENT
“To access premium market like US and Britain, farmers should have high quality produce. We are currently working on area-wide management where farmers collectively apply the interventions on the farms,” says Dr Ekesi, adding it is possible to eradicate the pests if farmers join hands.
If the interventions are consistently and effectively used for eight weeks, the population of the flies will be brought down by 90 per cent, the scientist says.
Currently, Icipe is developing organic post-harvest treatment parameters for farmers to curb wastage.
“The remedy is based on hot water treatment whereby the mango fruit is immersed in warm water of 46.1 degrees Celsius for 45 minutes to kill any other remaining fruit fly. This method cannot affect the quality of the mangoes.”
After effectively utilising the organic mango farming techniques, the market is literally going after the farmers in Ukambani.
“Our farms are now being monitored by the Ministry of Agriculture through HCDA and Icipe. Most exporters go to the Ministry of Agriculture, which then directs them to farmers who produce chemical-free mangoes,” Ngovi points out, noting he is now selling a kilo of fruits at Sh15 to traders who are exporting, up from Sh5 to Sh10 to local traders.
“A week ago, a buyer visited my farm, took fruit samples for laboratory test to check their pest residue level and it turned out they were chemical-free. He will now start buying my fruits for export.”
MADE LOSES BEFORE
Regina Sumbu, a mango farmer from Makueni, says she used to record a lot of waste before she employed the new techniques.
“Right now I am assured of harvesting over 10,000 mango fruits from my orchard of 100 trees in a season. Back then, a considerable number would be wasted due to fruit flies infection.”
Kassim Mustafa, a mango exporter, says before they buy fruits, they look at its physical appearance and the methods used by the farmer to control pests on the farm.
“To find out which farmers use organic or biological pest control methods, I normally go to the Horticultural Crops Development Authority which directs me to farmers they have cleared,” says Kassim, noting he exports the produce to Asia.
While the Bactrocera fruit flies species prefer mangoes, they also attack melons, cucurbits, bananas, guava, loquats, matomoko, avocados and wild fruits, which act as hosts.
- For quality mangoes, prune immediately after harvesting to allow the tree to grow horizontal.
- Pruning is done both from the inside and outside to expose a larger surface area to sunshine which helps improve the quality of mangoes. Lack of pruning makes fruits acquire a different shade with some having sporty black marks that make them unmarketable. Consumers prefer fruits with a ripening colour.
- Manuring should be done immediately after pruning, following the tree’s canopy as that’s where the roots are. Though after manuring, the plant looks like its straining, thus, no watering should be done as this will be like helping a chick out of the eggshell a thing that weakens it eventually causing its death.
- Watering should be done after flowering to avoid making the plant look healthy by flashing lots of leaves but in the long run yield little.
- Once the fruits mature and acquire a ripening colour, the mangoes should be hand-picked. There should be no shaking of trees to collect later.