SADC tomato production under threat

> Mpho Tebele

GABORONE- BOTSWANA’S ban on the importation of tomatoes continues, as the country battles tomato leaf miner or Tuta absoluta, which broke out at the end of last year.

The highly destructive tomato pest, with its origin from South America, has invaded both greenhouse and open field tomato crops in North East, Central, Chobe and North West districts in the past two months.

Minister of Agricultural Development and Food Security, Patrick Ralotsia, says the pest has also reached Kgalagadi district in the western part of the country.

Ralotsia, who this past week launched digital signage machines used to transmit bio-security messages to different border posts, has warned other Southern African countries to be vigilant of Tuta absoluta.

Ralotsia observed that there is need for everyone in the country and the region to be alert of this pest, as it is not only a problem for the relevant ministries but the nation at large.

He added that already the impact of the tomato leaf miner is evident with prices now high and shelves sometimes empty in retail stores.

The minister emphasised that at the moment the ministry has closed down all imports of these vegetables in an effort to control and contain the pest.

He expressed concern over the tomato leaf miner outbreak, as is jeopardised international market and local distribution.

Ralotsia revealed that the newly structured and revived ministry he heads will put all necessary measures from raising awareness, border control, seedling movement restrictions and so forth.

He said his ministry, in partnership with the immigration department, has adopted the system in an effort to improve border control compliance.

According to officials at the ministry, the installation of the machine came along with raising awareness to all stakeholders including consumers, agricultural product users and traders.

The signage machine installation project included the aspect of creating communication system of monitors, which will transmit any new or relevant information to customer’s nation at borders with regard to movement of agriculture products going in and out of the country.

According to Ralotsia, these diseases and pests do not necessarily originate from Botswana while some are brought in by travellers unintentionally and some brought in intentionally by individuals.

Ralotsia said that the pest aftermaths are felt countrywide and the Tuta absoluta seems to have spread to all parts of the country.

Therefore, he said, there was need to control and contain the pest that was already in the country urging Batswana to cooperate in ensuring that the pest was not allowed any further.

According to the press release, the pest comes from eggs which are oval-cylindrical, usually laid on the underside of leaves, on buds or on the calyxes of green fruit. They are cream-coloured and very small, being about 0.2 mm in diameter and less than 0.4 mm on the longest axis. Larvae are white or cream in early instars, with a black head. As they grow older, they turn pink or green with a brown head. The prothoracic shield just behind the head has paler patches in later instars, though the exact markings are variable.

There are no other distinctive markings. Larval identification can be made from leaf mines, as few other larva mine tomato leaves. Pupae are brown, and less than 6 mm long.

The adult moths are small, with a body length of around 7mm. They are a brown or silver colour with black spots on the narrow wings. The antennae are long, and the legs and palps are ringed with black and brown.

The release also noted that that the Tuta absoluta can produce 10-12 generations per year with females laying up to 260 eggs in each generation with a total life cycle completed within 30-35 days. Adults are nocturnal and hide between leaves during the day time.

Further, it says the larval period is the most damaging, usually lasting 12-15 days.

However, since the larvae can delay maturity as long as food sources are available, they may be active feeders for the entire crop cycle.

The pest attacks tomato leaves, stems, flowers and fruits. It also attacks potato, eggplant and bean crops. Most feeding damage is done to the leaves and stems of tomatoes creating blotch leaf mines that are visible on both sides of the leaf.

There can be several mines on a single leaf. The mines have dark frass (excrement) attacked if the infestation of Tuta absoluta is heavy, but even small amounts of damage mean that the fruit will not be suitable for market. Secondary rot can occur in the wounds, rendering the fruit unfit for consumption.

January 2017
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