Bacterial wilt on potatoes

By Jade Alfie Sale

Potato is the fourth-largest food crop in the world just next to wheat, rice and maize. It is popularly known for its products like fries, chips, and a variety of local dishes. But just like any other crops it is also susceptible to diseases which could greatly affect its production process.

A major disease which threatens the production process of potato especially in the Province of Bukidnon has become alarming. Bacterial wilt which is caused by a bacterium pathogen called Ralstonia solanacearum is an extremely destructive plant disease in tropical and subtropical regions. This organism is known to inhabit in soil which is carried away through water irrigation and farm floods. The bacterium can also be transmitted by a simple root to root contact.

Extensive researches and studies were already done in the past hundred of years to combat such plant disease. However, results were not effectively distributed among the affected regions as well as its target client, the potato farmers, which caused the continuity of plant sickness.

Certain local and international organizations were already doing its best to come up with a perfect disease management control; one of it is the International Potato Center (CIP). This organization has been evaluating and defining disease management measures which were done to help potato farmers in a specific locality.

Another organization which is located in Dalwangan, Bukidnon is also conducting research for the disease; it is called the Northern Mindanao Integrated Agricultural Research Center (NOMIARC) which is associated with the Department of Agriculture in Region X. It already conducted investigatory measures in potato producing places in Bukidnon like Lirongan, Miarayon, and San Miguel.

They found out that despite of the thousand of hectares in Bukidnon which are feasible for potato planting attuned with a perfect climatic condition, limited lands were still planted because of the incidence of this disease. In 1985 survey, the average yield of white potato was only 7-8 t/ha (Kloos and Fernandez, 1986). The increasing incidence of Bacterial wilt disease is said to cause the decreasing yield of potatoes.

Disease indication and control

The dreaded plant disease shows symptoms in the hottest part of the day which caused plants to slightly wilt, nonetheless, ill-stricken plants can slowly recover during nighttime but the continuous wilting can still cause the death of the plants. It is also observed that the center part of the stem is color brown when cut which then oozes grayish white droplets of bacterial slime when the cut stem is suspended in a glass of water. The grayish white droplets are also said to give off foul smell.

Certain control measures were already done to combat the spread of Bacterial wilt in potatoes, it includes:

• The use of certified seeds in non-infected soils.

• Rotating potato with non-solanaceous plants like cereals, legumes, etc.

• Eliminating solanaceous and volunteer weeds which serve as alternate hosts of the disease.

Spread of disease in Bukidnon

In the 1960’s Igorots from the Mountain Province in Northern Luzon introduced potato crops in Bukidnon (CIP, 1985). The potato crops introduced were said to be grown as “garden plots” from their province. Since the growing of potato crops from Mountain Province, the dreaded plant disease was already been prevalently occurring and had been affecting Northern Luzon with crop losses reaching up to 100 percent. From the time when potato was introduced in Bukidnon the prevalence of disease was experience in 1983 by 88 percent of the potato farmers.

The disease through the years was constantly affecting the farmers in Bukidnon for the following reasons:

• In 1980’s farmers still continued to plant potato using infected seeds.

• They don’t have enough knowledge to stop and prevent the spread of the disease.

• They don’t have proper sanitation. Decaying wastes of the potatoes were just left on farms.

• The infected farms and wastes were left after harvesting which was then inhabited by bacteria.

• Selling of infected seeds to the neighboring places.

Bukidnon farmers coped up by abandoning infected lands after 1-2 cropping cycles depending on the level of present bacteria, leaving it fallow thus converting new land to plant by “Kaingin system”. However, this strategy is obviously non-sustainable and is environmentally hazardous which also paved way in the unmet demands of potatoes for fries, chips and other varieties of local dishes of businesses.

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As of the moment the infection is partly managed by planting non-infected seeds from Luzon specifically in Baguio City, NOMIARC also imported seeds from foreign countries like Netherlands, Australia, and the United States. They also started planting potato crops in Bacteria wilt free soils. Suitable cultural practices were also observed by making “plot” or “raised beds” to prevent potatoes from submerging to water during rainy seasons. Proper sanitation was also followed by using disinfected farming tools (which were previously used in infected crops) and burying of infected plants.

Sources:

http://www.rtb.cgiar.org/seed-degeneration-of-roots-tubers-and-bananas/overview/

Department of Agriculture Crop Production Series- Leaflet No. 2

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