Research in 2018, found that 97.9% of 400 respondents in Kenya and 99% of 426 respondents in Zambia reported Tuta absoluta as the main problem in tomato farming with mean seasonal production loss based on farmers’ estimates being 114K tonnes in Kenya and 10.7k tones for Zambia which is equivalent to US$ 59.3 and US$8.7M in economic loss respectively.
Tuta absoluta has 4 stages; egg, larva, pupa and insect. Application of prevention measures on egg and larva stages often occurs in the first month preventing these massive losses.
It is good at this point to make a disclaimer that there I have not yet found a silver bullet for Tuta absoluta. These prevention measures if applied well and at the right time go a far way in preventing these massive losses.
Early Scouting
Early farm monitoring to determine the threshold level and the start of the application.
Chemical application
Early spraying from the first day of planting with strong insecticides will kill its eggs which are usually laid underside of the leaves, buds, stems and calyx of the ripe fruits ensuring proper leaf coverage on both the upper and undersides of the leaves by the chemicals.
Do not forget to spray the soil surface below the tomato plant as pupation tends to take place on the soil where pupas turn into full insects.
Spraying programme
Spraying a combination of Dynamec 10ml + (alternating,25ml of Match or 4ml of Belt [flubendiamide 450g/l] or 8ml of Tihan [spirotetramat 75g/l + Flubendiamide 100g/L]) Once every week in the first one and a half month and once after every 2 weeks in the rest of the period until harvesting. Please avoid the use of one single chemical for a long time as it may lead to resistance.
The efficiency of Match, Belt or Tihan depends on Dynamec as it has the ability to penetrate the leaf’s mesophyll enabling them to kill the larvas.
Spray late evening or night as they hide between the leaves during the day, making it hard to control them. Consider adding a sticker to the mixture to prevent the chemical from being washed away in heavy rainy seasons.
Biological and physical control
Use of pheromone traps and removal of crops residues with aggressive de-leafing of the infected leaves and burn will help as Tuta absoluta eggs are laid on the leaves and may stay for up to 3-6 weeks to complete the leaf cycle depending on the temperature. Read Also: how to farm tomatoes successfully
Where you go wrong
- Late spraying when the population is too high. It is not easy to destroy eggs, larvae and pupa from flying insects.
- The use of one chemical leads to Tuta absoluta developing resistance.
- Poor leaf coverage by the chemical during spraying.
- Failure of spraying the earth’s surface.
- Inconsistency in Spraying.
- Spraying the wrong chemicals that cannot penetrate the leaf mesophyll and the wrong time of the day-
- Crop rotation with solanaceous crops such as peppers
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