Tuta Absoluta is wreaking havoc on tomato plantations in Morocco. "No grower has been spared, and everyone struggles to contain the problem". So reports Oussama Machi, an Agadir-based early vegetable grower.
Moroccan tomato growers have been cohabiting with Tuta Absoluta since 2008. It's a problem under control, but it does bring periods of widespread damage like the one in 2015, and it looks like this year will be another. Machi describes the situation: "Losses are of the order of 20% of the tonnage produced, rising to 35% if combined with Tobrfv, and can go as far as the complete uprooting of plants, a frequent scenario. And here I'm talking about farms with exemplary cultivation practices and major prevention efforts, for without them losses wouldn't fall below 70%. Damage also depends on the stage of production. If it's before the harvest, uprooting can reach 100%. We have seen a peak in damage since June.
The current widespread occurrence of Tuta Absoluta on Moroccan farms is due to changes in one of the components of integrated pest management, that is, pesticides. Machi explains: "The insect has developed considerable resistance to authorized pesticides such as chlorantraniliprole and abamectin. What's more, this year Europe allows only five active ingredients, and this number could be reduced to three in Germany. The exclusion of effective pesticides containing Spinosad complicates the situation. The spread has accelerated with this summer's heat and humidity".
Another factor contributing significantly to the current situation is the reluctance of growers to apply the other component of IPM, namely biological control using the insect Nesidiocoris tenuis. Machi explains: "Moroccan farmers often believe that biological control contributes to the spread of ToBRFV because the insects used are mechanical vectors of the virus. There is no firm scientific opinion on this, but it's an empirical observation that growers believe. Growers are therefore reluctant to apply integrated pest management, which remains the only effective means of controlling Tuta Absoluta".
Fortunately, the moth - Tuta Absoluta - spreads at the end of the Moroccan season, so the impact is minimal for the export campaign, and practically non-existent for the local Moroccan market. According to Machi, the insect is not aggressive in open fields, which are the main source of round tomatoes for the local market.
In the greenhouses, i.e. in the Agadir region, most growers have already finished their campaign, except those exporting to markets such as the UK or West Africa. In terms of varieties, given the calendar and the varieties produced in greenhouses, it is cherry and elongated tomatoes that are currently affected by the problem, much more so than round tomatoes. In terms of volume, the impact is negligible, reports Machi.
The effect on planting decisions, however, could be more significant for the coming season. To recall, the season got off to a very late and disruptive start due to the uncertainty caused by Tobrfv widespread last year and the previous summer's heat waves. Can we expect the same scenario next season because of Tuta Absoluta?
"I don't think there will be a delay in the start of the season," replies Machi. "Early tomatoes have been very profitable this season and remain very attractive despite the risk. I believe there will be no influence on the precocity of the campaign. You have to bear in mind that growers' opinions and decisions are very decentralized."
The impact of the current Tuta Absoluta episode remains to be seen, and two questions arise: will IPM cause Tobrfv to spread further - just as it is finally starting to weaken (according to professional sources)? Will this fear lead to delays in the launch of the next campaign? Given that planting decisions are being made right now, the next few weeks - between now and August - will provide answers and more clarity for the next season.
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