Lethal pest strikes tomato farms harder

Mutulu Amisi holds a tomato crop affected by Tuta absoluta at the Kwa Kya Irrigation Scheme in Makueni County. He says farmers in the region have nothing to celebrate as the highly destructive pest has wasted their efforts.

Photo credit: Pius Maundu | Nation Media Group

What you need to know:

  • Agriculturalists explain why growers across the country are witnessing a rise in Tuta absoluta attack, as the pest that multiplies faster during the dry weather seemingly becomes resistant to the many pesticides in the market
  • James Samo, an agriculture officer in Kisumu, says tomato farmers in nearly all the seven sub-counties of the region are reeling from the effects of the pest.
  • The high cost of managing the pest has rendered the farming of the crop a loss-making venture as prices of the produce fluctuate from a low of Sh1,500 per crate during high supply to Sh5,000 in low season.
  • Some agriculturalists blame the rapidly changing weather, which has seen day temperatures in some areas like Nairobi and its environs hit 29 degrees Celsius, to the increase in the pest.

The tomato crop inside the greenhouse, with fleshy red fruits dangling from the well-stalked plants, appears to be flourishing and appealing to the eye.

But as one moves closer and checks the plants, reality dawns. The crop is heavily infested with pest that has not only ravaged the leaves, turning them brown, but has also attacked the fruits, leaving most of them deformed.

Joshua Chianda, the owner of the farm in Mamboleo, Kisumu County, sighs.

“There is nothing I have not done to save my crop from Tuta absoluta,” he says of the pest ravaging his crop.

“I have sprayed the plants with all the recommended chemicals but the pest has not stopped destroying the plants,” he adds.

Chianda planted two tomato varieties, one in the greenhouse and the other in the open field. 

Inside the structure he has 300 Prostar variety plants and another 3,000 Zara variety in the open field. 

Dangerous at larvae stage

“I may not harvest anything from both farms because of this pest,” says the farmer.

His plight reverberates across hundreds of tomato farms in the country as the moth, which is also known as leaf miner, destroys the crop.

The current attack appears to be the gravest since 2014 when Tuta absoluta, which originated from South America, in particular, Peru, entered Kenya via Ethiopia.

Farmers’ accounts point to a pest that has become resistant to most of the pesticides that are in the market and had successfully contained it in the past.

“The pest is dangerous at larvae stage, as it destroys both the leaf and fruits. I would have harvested more than 20 crates of tomatoes were it not for the pest,” says Chianda, noting he would be lucky if he ends up with 10. Each crate goes for up to Sh5,000 depending on supply in the market.

James Samo, an agriculture officer in Kisumu, says tomato farmers in nearly all the seven sub-counties of the region are reeling from the effects of the pest.

“From the farmers we have talked to, many are complaining that the pest is resistant to recommended chemicals. The resistance comes when farmers misuse the pesticides," says Samo. 

High cost of pesticides

In Nakuru County, some farmers, especially those in Subukia, have lost their entire crop to the pest, with the moth attacking both crops in greenhouses and open fields.

Nicholas Kiplagat, a young farmer, says he lost his entire crop after it was attacked by the pest in a greenhouse even after applying the recommended pesticides. Kiplagat farmed in an 8m by 15m greenhouse, which hosts some 300 plants.

Nakuru Agriculture executive Immaculate Njuthe Maina says the county has been grappling with the Tuta absoluta challenge for long.

"We are supporting farmers by offering training on how to deal with the pest, including tips on doing proper crop rotation and use of recommended pesticides and application," says Dr Maina.

Mutulu Amisi, the chairman of Kwa Kyai Rural Cooperative Society, the largest tomato producer in Makueni County, observes that their farmers have nothing to celebrate as the highly destructive pest has wasted their efforts.

“The high cost of pesticides has made it harder for farmers smarting from the effects of Covid-19 pandemic to effectively fight Tuta absoluta,” says Amisi, noting being in dryer area has worsened the plight of farmers since the pest thrives in such regions.

The cooperative society promotes the use of integrated pest management (IPM) techniques that entail the use of pesticides and pheromone traps.

Loss-making venture

But farmers complain the approach is expensive as one is expected to install up to eight pheromone traps on an acre.

“IPM is a sure bet in containing the notorious pest but indiscipline among some of the farmers has impaired the roll-out of the approach,” says Amisi.

Each trap goes for Sh700. Thus,  if an acre needs eight, the cost comes to Sh5,600, which many cannot afford, as well as use pesticides at the same time, whose cost per acre averages Sh8,800.

The traps contain female pheromones that lure the male adult moths into them, especially when they are active at night since the pest is nocturnal. 

This, thus, leaves behind females that produce infertile eggs controlling their reproduction. 

The high cost of managing the pest has rendered the farming of the crop a loss-making venture as prices of the produce fluctuate from a low of Sh1,500 per crate during high supply to Sh5,000 in low season.

Alex Kibiwott, a tomato farmer from Moiben, Uasin Gishu County, says he sprays at least four times to control the pest.

Unauthorised pesticides

“You have to spray to control it. Initially, we used to spend Sh2,000 per acre an entire season but now we use chemicals worth at least Sh6,000 per acre,” says Kibiwott, who has planted the crop in the open field.

According to Kibiwott, the cost is lower if one grows hybrid seeds since they are a bit resistant to the pest. 

Benjamin Lagat, an agricultural officer in the county, notes the cold weather witnessed in the region this year has helped to suppress the growth and multiplication of pests. 

In Nyeri, John Wambugu, an agriculturalist, observes that the pest has wreaked havoc in the area but most farmers mistake it with blight, a cold weather disease.

“The pest has become resistant to pesticides due to its prolific production rate that has made it difficult for farmers to control. 

Joshua Chianda (right) and Otieno Otieno check their tomato crops, which have been attacked by tuta absoluta in Mamboleo, Kisumu County. The pest is dangerous at larvae stage, as it destroys both the leaf and fruits.

Photo credit: Elizabeth Ojina | Nation Media Group

“Some farmers have resorted to unauthorised pesticides that are not recommended for use on fruits and vegetables,” he says, noting the pest is a leaf miner and the chemicals used should penetrate into the leaf.

From an egg, the pest morphs into pupae that breed in the soil before it becomes a moth,  he explains.

“A female moth can lay up to 260 eggs during its 30 to 40 days’ lifetime. The caterpillar tunnels into leaves, eating the green part and causing them to dry out. They also underpass into the fruit causing deformities and rotting due to secondary infection.”

Develops resistance 

This problem has forced farmers to spray their crops frequently, resulting in high levels of pesticide residue on the tomatoes that reach the market, warns Wambugu, noting that excessive use of chemicals may lead to chronic diseases.

He isolates mulching as one of the natural methods to control the pest, saying it would take some time for the egg to get into the mulched soil.

Samo asks farmers to do regular scouting and monitoring of the tomato plants. Scouting entails looking for any abnormal signs on your crop on both sides of the leaves, stems and fruits.

“This should be done regularly and from one bed to another to detect any symptoms early enough. Look out for deformed or curling leaves and fruits developing abnormal shape. Check out for silvery tunnels on the leaves, which under severe cases causes the leaves to dry,” he says.

Some agriculturalists blame the rapidly changing weather, which has seen day temperatures in some areas like Nairobi and its environs hit 29 degrees Celsius, to the increase in the pest.

“The Tuta absoluta life cycle is short in high temperatures, hence the pest multiplies faster. The pest also develops resistance to chemicals if they are not well used with regard to rates and applications,” says Ann Macharia, an agronomist.

By Elizabeth Ojina, Francis Mureithi, Stanley Kimuge, Irene Mugo, Pius Maundu

satnation@ke.nationmedia.com


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Crucial tips

1. When using pesticides, it costs up to Sh8,800 per acre to spray against the pest.
2. One sprays the recommended chemicals at an interval of five days. 
3. There are two types of chemicals, one is in powder form and the other in liquid form. 
4. For effective application, the farmer is advised to mix the two chemicals to eliminate Tuta absoluta and other pests like white flies.