A lecturer and a researcher at the Department of Plant Sciences, Microbiology and Biotechnology, Makerere University, Dr. Shahasi Yusuf Athman, says there are new microorganisms, called Potato cyst nematodes, that have attacked the Irish potato farms in Uganda.
Her worry is, most farmers are not aware of the presence of these potato cyst nematodes. “Even the few who have known about their existence, do not know how to prevent or deal with them.” She adds
NATURE OF THE POTATO CYST NEMATODES
Dr. Athman says they are microscopic. So, you can hardly see them with your necked eyes. “When they are still alive, they make a round yellow like structure, cling on the Irish potato roots and then start draining its nutrients with the water inclusive”. Dr. Athman explains the danger of the Potato cyst nematodes.
Due to the drained water and nutrients, the Irish potato plant cannot develop reasonable tubers.
She explains that this happens because the potato cyst nematodes interrupt the roots, yet they are the ones that are responsible for forming the tubers from where the Irish develop.
“At times, the Irish potato plant completely does not form any tubers from where the potatoes can develop. The plants can as well get stunted or dry up, and then the farmer experiences a patchy garden. This happens in case the potato cyst nematodes have highly accumulated.” Dr. Athman further describes the severe effects of these nematodes.
MOST FAVORABLE ENVIRONMENT FOR THE POTATO CYST NEMATODES
Cold environments like those in America and Europe, are the most hospitable for these potato cyst nematodes.
Even though they were discovered in Kenya, Dr. Athman says, for a long time, the nematodes have not been known to be in the Sub-Saharan part of Africa due to its hot temperatures.
They stay in the soil. According to Dr. Athman, they can keep their eggs in the soil for up to 20-25 years without any of them getting destroyed.
Towards the end of the season, the female nematodes form brown round-like structures called cysts. So it’s these brown cysts which can embody the eggs for all those years. “A single brown cyst contains over 400 eggs.” She adds.
Most times the brown cysts hatch the eggs when it senses exudes from host plants. Then, the hatched nematodes immediately go and cling on the host plant roots.
HOW THESE NEMATODES WERE DISCOVERED IN UGANDA
When the potato cyst nematodes were reported in Kenya in 2015, Dr. Athman says, she started preparing for the research to find out their state in Uganda.
In 2020, through its Research and innovation Fund, Makerere University funded her to conduct the research as per her proposals.
Together with her team, they focused on three regions, beginning with the key Irish potato producing areas. These include the Western region, East and the Central region.
In the Western Region, they looked at districts like Kisolo, Kabaale, and Kabarole. In the Eastern Region, they went to the districts of Kapchorwa, Namisindwa, Sironko, Bududa, Bulambuli, and Mbaale.
Yet in Central, they reached Irish potato farms in Mityana, Mubende, Masaka, Kyotera, Rakaayi, Lyantonde, Ggombe, Lwengo, Kasanda and Kiboga.
Dr. Athman says they picked soil samples from all the farms in the different districts. The samples were taken to Makerere University labs for examination.
They have completed examining samples from all these 3 Regions, and they are all 100% positive of the potato cyst nematodes.
SPREAD OF THE POTATO CYST NEMATODES
According to Dr. Athman, these potato nematodes do not penetrate into the potatoes. Though, she says, on digging the Irish potatoes from the ground, they come along with some soil. So it’s in this soil on the surface of the Irish, which harbors these nematodes.
Therefore, if someone buys Irish potatoes with the infected soil from one area to another, is how the nematodes come to attack farms in the new area where someone has taken them.
Since Uganda’s borders with Kenya are open, in addition to the existing trade in Irish potatoes between these two neighboring countries, Dr. Athman says this is how these potato nematodes might have crossed to Uganda.
“When you go to Food markets like Kalerwe, you find Irish potatoes purchased from Kenya. Yet some people use these very potatoes as seeds and they plant them in their gardens.” Dr. Athman emphasized how the nematodes crossed from Kenya into the famers’ gardens in Uganda.
When these nematodes land into one’s garden, they do not spread immediately. Dr. Athman explains that it’s the famer him or herself who spreads them.
She elaborates that a farmer can spread them slowly, especially when he uses hand hoes. However, she says, they can rapidly spread throughout the entire garden, when the famer is highly mechanized. For instance when he uses ox ploughs, or tractors during cultivation.
She notes that, since the nematodes are harbored in the soil, even people themselves can spread them from one area to another.
People can spread these Nematodes by carrying them under their shoes and gumboots, in case they visited an infected Irish potato farm before coming to one’s garden.
However much the Irish Potatoes are their main host crops, Dr. Athman says, these nematodes have other crops in the Solanaceae family which they can attack. These crops include Tomatoes, eggplants, peppers and indigenous vegetables like Nakati, katunkuma, among others.
HOW TO CONTAIN THE POTATO CYST NEMATODES
Dr Athman says, there is a need for the government to sensitize famers about the existence of the potato cyst nematodes, and how they affect them through losses in the form of reduced and poor quality yields.
She notes that it is better for the government to base on its borders and block the entry of Irish potatoes that come from neighboring countries with reported potato nematode cases.
The Government should as well put in place specialized areas from where farmers can get clean and uncontaminated Irish Potato seeds, such that they do not just buy them from anywhere.
Famers, can employ trap crops to kill and reduce the number of the nematodes in his piece of land. Trap crops, like Nakati, take less than 2-3 weeks to get ready, as opposed to the Irish potatoes. When trap crops are removed from the garden, the nematodes will starve to death. “By that time, the female nematodes, while not, have formed the brown cysts that can keep their eggs for a long period,” says. Dr. Athman.
