Agricultural scientists in Uganda have found a solution for farmers across the country faced with the challenge of an invasive weed species ravaging farmer fields across the country.

The invasive famine weed with its scientific name Partherium hysterophorus locally known as congress weed attacks and competes aggressively with a broad range of vital priority crops such as banana, cassava, bean, Maize as well as vegetables and fruit trees thereby causing significant yield loss.

As a resulted scientists from the National Agricultural Research Laboratories (NaRL) jointly with researchers at Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA) have developed a technology of breeding biological beetles that will consume the weed.

Background

Experts note that the weed naturally inhabited areas around Mexico, Central America and South America.

It was first scientifically documented and identified on the island of Jamaica in 1753.

Over the 19th and 20th centuries, international trade, military movements and contaminated crop seeds carried the weed to roughly 43 to 46 countries globally including Uganda.

It spreads so aggressively with a single plant producing up to 15,000 seed that remains viable in the soil for a decade.

According to experts, the weed releases chemical toxins that supress and kill the surrounding native plants dominating the ecosystem and there has been no local insects that check on its population naturally.

Farmers face challenge and scientists develop solution

Dr. Kasifa Katono, a Senior Entomologist from NaRL explains that her team received reports from farmers in the districts of. Kayunga, Koboko and Palissa about the rate at which the weed is spreading in their farmers comprising of crops including Maize, Sorgum, banana, cassava, beans and vegetables such as tomatoes.

The farmers said the spread of the weed affects the yield of their crops with a good number harvesting completely nothing.

This prompted Dr Katono and his team to go ahead and conduct research where they identified the Zygogramma bicolorata beetle also known as Mexican beetle that breeds in the Ugandan environment but specifically feed on famine weed.

The scientists have been breeding these beetles under a three year project which started in 2022 running till end of this year. There is an extension of the project for two additional years funded by ASARECA.

It is implemented in with breeding sites in Koboko, Kayunga and Palisa and the insects have already been released in the environment.

The team is setting another breeding facility in Nakapiripirit to help farmers in the Karamoja region where farmers grow a lot of sorghum as their staple food.

The scientists are engaged in this initiative in collaboration with the ministry of agriculture and local governments in the concerned districts where farmers are being sensitized to be fully engaged in conserving the environment where the beetles have already been released.

Farmers are sensitized not to burn areas where the beetles are breeding including application of chemicals that will end up killing them. This is to enable the insects to multiply naturally in the environment.  

Farmers who prefer to weed their farmers must ensure that the weed is removed before flowering.

“Cropping communities in Uganda suffer many challenges one of which is managing weeds that compete for nutrients and space with crops. Farmers in across the country particularly in the districts of Kayunga, Koboko and Palissa districts have suffered similar challenges from massive growth and spread of famine weed. The farmers were troubled with the question of wether they can plant their crops to get better yields and the reached out to the scientists at NaRL,” Dr Kasita noted.

Koboko, Palisa and Kayunga were chosen because of the prolific spread of the weed in the three districts yet managing by use of chemical and through hand weeding have proved to be costly.

The researchers contend once the weed is mature and the seed spreads in the soil it is very difficult to control its spread since the seed can last 20 years remaining viable.

The better solution is to multiply the the Zygogramma bocalorata beetles which are the natural enemies are multiplied to increase their population in the wild.

Impact of the weed on farm produce

Dr Katono and a group of scientists carried out the economic impact famine weed can cause to a particular crop is a specific farm of various crop varieties which is quantified at 62.1% of yield loss and 83.3% of labour demand. Farmers using herbicide to eliminate the weed are estimated to be 6.7%

Dr. Katono explained that the weed affects agricultural production and the quality of food products since it contains chemicals that have harmful effects to other plant species.

Its presence can also have implications beyond the farm because agricultural products contaminated as a result of the weed may face restrictions in international markets.

She highlighted potential effects on livestock, including reduced milk production and changes in milk quality. Animals consuming the weed may also experience health problems, with implications for livestock productivity, meat and milk quality.

It also affects rangelands since its production rate is rapid, it can overpower growth of pasture for animals to feed on.

Farmers who get in contact with the weed face skin irritation and skin rush. Dust caused by its flowers aggravates respiratory challenges.

Using biological control is a more viable, cost effective and environmentally friendly option to its management.

A rearing facility was set up in Kangulumira sub-county in Kayunga. This unit has potential to serve the central region, another facility was set up in Koboko district to serve West-Nile region and two facilities in Pallisa and Pader to serve the Eastern and Northern region respectively. 

In Pallisa over 2000 beetles have already been released in 8 farmer fields and farmers are already witnessing how they feed and destroy the weed

Stakeholders at the district local governments pledge to sensitize the populations about the invasive weed that is also dangerous to livestock.

The Program officer in charge of Capacity building at ASARECA Ms. Blaise Amony observed that NARO has developed technologies that are now being taken up by farmers.

”Taking proven technologies to farmers is crucial because investments in Agricultural Research if well delivered to farmers translate into meaningful change for farmers. Research has already provided technologies that can help communities manage agricultural challenges sustainably. Our responsibility is to ensure that these solutions come out of the Research Institutions and taken to farmer communities,” Omonyi noted.

Ms. Anne Bulya the district Agricultural Officer for Kayunga district noted that the weed is widespread in farmers' fields and along roadsides. She observed that some farmers do not recognize it as a dangerous weed and many of them even appreciate its appearance and use it for decoration as flower bouquets which increases its dissemination.

Mr. Mawa Muktar, the Secretary for Production of Lobule Sub- County in Koboko district, explained that farmers in the district realized reduction in farm produce as a result of the weed.

He expressed hope that the new biological control initiative would provide the community with practical skills and additional support to address the challenge and the need to identify technical capacity building and skill development for farmers

He emphasized that the weed poses serious risks to agricultural production, livestock, wildlife and human health and encouraged communities to embrace the technology and ensure the beetles are protected.

Hon. Okiria Ben, the Local Council 5 Chairman Palisa district called upon the entire production department to adopt the technology and disseminate the information to farmers.