Syngenta trains stockists and lead famers on tuta absoluta disease

By Bob Aston

Syngenta Kenya on March 27, 2015 trained 20 stockists and lead farmers on tuta absoluta disease also referred to as leaf miner at Coconut Hotel in Wiyumiririe, Laikipia East Sub County. The training was held to help the stockists and lead farmers to understand pests and diseases and particularly tuta absoluta.

Speaking during the training, Mr. Daniel Njoroge from Syngenta Kenya informed the stockists and lead farmers that they need to understand how the pests and diseases feed, when they feed, their growth stage, breeding cycle, life cycle and blood circulation as well as the correct dosage of insecticides.

Infected tomato leaves

He noted that tuta absoluta is a devastating pest affecting tomatoes and is considered to be a serious threat to tomato production. He said that the pest is easily found on tomato plants because it prefers the apical buds, flowers or new fruits where the black frass is visible. The pest which originated from South America is said to breed between 10-12 generations a year. Each female can lay 250-300 eggs in her life time.

“Stockists are and are still the first level of contact by farmers thus it is important to have enough knowledge about the pest so that you are able to advice farmers accordingly when they seek information about the pest,” said Mr. Njoroge.

He said that prevention and proper management of the pest is crucial thus farmers need to adopt an integrated pest management strategy to control the pest. He noted that the pest usually develop resistance to insecticides when used more than three times. The infestation of Tuta absoluta has also been reported on potato, watermelon and common beans.

There are 4 instars. Early instars are white or cream with a black head, later they turn pink or green. Fully grown larvae drop to the ground in a silken thread and pupate in soil.  Pupation takes place in soil on plant parts such as dried leaves and stems. Adult female lives 10-15 days while adult male lives between 6-7 days. Seventy (70) percent of its eggs are on the leaf.

He said that the larvae usually feeds voraciously upon tomato plants, producing large galleries in leaves, burrowing in stalks and consuming apical buds and green and ripe fruits.

Infected tomato fruit

“The pest usually affects both tomatoes in green houses and open fields. They are most destructive at larvae stage. Without proper care a farmer can experience 100 percent yield loss due to tuta absoluta,” said Mr. Njoroge.

Signs and symptoms include; puncture marks on the surface where the larvae has entered, abnormal shape, exit holes, rot due to secondary infective agents and frass produced at stem nodes where larvae have bored into the stem.

Control of tuta absoluta

Tuta absoluta has proved very challengin to control. Effectiveness of chemical control is limited due to insect's nature of damage as well as its rapid capability of development of insecticide resistant strains.

The use of biological factors is still largely under development and not ready to combat this pest effectively and in a cost effective way. Sex pheromone trap (TUTRACK) that has been developed by Kenya Biologics limited has been an effective tool for early detection of the pest.

Mass trapping and lure which contains pheromone has been found to be effective to control Tuta absoluta by attracting and trapping the male Tuta absoluta moth.

Tomato farmers are also advised to exercise hygiene in their farms to reduce the effect of tuta absoluta, uprooting and burning suspected crops and also avoiding throwing tomatoes remains near their farms.

According to the International Plant Protection Convention (IPPC) the government of Kenya has put in place elaborate trapping program and pest management that includes: integrated pest management, use of traps, introduction of biological control agents and imposition of quarantine in affected areas.