Fear of a rice ‘Covid’ in Tanzania

First modification: 07/06/2023 – 17:32

By Alexis Bedou

Some already call it the “Covid” of rice. This Xoo bacterium (Xanthomonas oryzae pathovar oryzae) burrows into the leaves, attacks the plant and dries it out. As a consequence, the rice grain does not fill up, which affects the yield.

According to several Tanzanian experts contacted, a fifth of the production is affected. “The farmers we met on the ground told us that last year they had twice as many bags of rice per plot as this year. But this year, the epidemic has exploded, and that is very worrying,” explains Boris Szurek, IRD plant pathologist, the French Development Research Institute, who has just returned from monitoring the epidemic in Tanzania.

Seeds carrying the disease?

These bacterial pests have been observed in Morogoro, the main rice growing region, but also in the Muenza and Arusha regions. Scientists have even detected the disease near Mombasa in Kenya.

According to Ibrahim Hashim of the Tanzania Research Institute for Agriculture, the epidemic is spreading and is affecting a large proportion of fields: “In all irrigated areas, half of the fields are affected. The challenge is to supply healthy seeds to these regions, because my fear is that if farmers continue to receive seeds that carry the bacteria, the problem will persist for a long time.”

According to the authorities, the origin of this epidemic is being investigated. The seeds themselves could carry the bacteria, which would explain the spread over such great distances. The IRD is leading the investigation. What we do know for sure is that the first burns of rice plants were observed in 2019 near Dakawa in the Morogoro region. There is also a Tanzanian research center there – the Tanzania Agricultural Research Institute (TARI) – which started working closely with China almost 10 years ago.

Various tests and research on high-yield seeds are being carried out. However, it was an Asian strain of the bacterium that was found in Tanzania, and it had never been seen in East Africa before, hence the hypothesis developed by a team of international researchers including Boris Szurek from the IRD: ” We know that the Chinese introduced hybrid rice seeds by planting them on an experimental farm to show the public, local breeders, and farmers that their varieties work well and produce high yields. Which is absolutely true. The problem is that they also introduced this germ. which is a ticking time bomb for East Africa.”

Concern for the country’s food security

Tanzania is the second largest rice producer in sub-Saharan Africa. It imports a small amount from Pakistan, and exports some rice, mainly to East Africa. The country is practically self-sufficient, but with a 20% drop in the harvest, “it could find itself in a difficult situation, and end up depending on the foreign market,” according to an economist specializing in the rice sector.

The price of local rice has already risen, and the situation is becoming worrying. “This could become a serious problem for food security here. Tanzania depends on the production of rice, which is the second most important crop in the country after maize. The government is struggling to control this epidemic. Supplies must be secured.” says Jason Jonathan Kanan, a consultant at Dar Es Salaam’s College of Agriculture and Natural Resources.

There are solutions. The international research consortium “Healthy Crops”, led by Professor Wolf B. Frommer of the Heinrich-Heine University (HHU) Düsseldorf, is developing disease-resistant rice varieties. According to Boris Szurek, “it is necessary to introduce resistance genes into Tanzanian rice varieties to counteract these bacterial strains.” The Tanzanian authorities did not respond to our interview requests.