Repeat of Irish Potato Famine Unlikely Thanks to Fungicides

The pathogen Phytophtera infestans causes a disease of potatoes called “late blight”. The pathogen grows in potato plants, breaking down cell walls so that it can use the nutrients found within them. Severely infected plants have an acrid odor which is the result of dying plant tissue. In the 1800s, Irish peasants subsisted almost entirely on potatoes. The late blight fungus arrived in 1845 and destroyed 40% of the Irish crop. In 1846, 100% of the crop was destroyed. Over 1.5 million Irish died of famine and a comparable number emigrated to America and other countries. Today, the fungus is still present in Ireland and would destroy the crop again if not for fungicides.

“Without the routine use of fungicides, large-scale commercial potato production in Ireland would be impossible. The cool, damp climate, which favours the cultivation of the potato and limits problems with virus diseases, is also ideal for the spread of blight. … In warm, wet weather when the humidity is high, P. infestans will lay waste an unprotected crop. … To prevent such devastating losses, the potato industry in Ireland has long been reliant on a substantial annual usage of fungicides.”

Author: L.R. Cooke
Affiliation: Plant Pathology Research Division, Department of Agriculture for Northern Ireland
Title: Potato blight control in Ireland: a challenging problem.
Publication: Pesticide Outlook. 1992. 13(4):28-31.

Fungicides “Vital” for Potato Production in Myanmar

Potato is a very popular vegetable crop in Myanmar and is essentially grown all year round. Phytophthora infestans, the fungus that caused the Irish Potato Famine in the 1840s, was first found in Southeast Asia in the late 1800s and has since been an annual widespread problem. Without fungicide protection, the disease spreads rapidly and can kill all the plants in a field within a few days.

“In Myanmar, late blight caused by Phytophthora infestans is the most destructive disease of potato. … High incidence and severity of potato late blight occur in this area because the crop can be found year-round at all stages of development, providing a constant source of primary inoculum.”

“At present, fungicide applications play a vital role in potato late blight control as resistant cultivars have not been widely available and adopted. … Fungicide is applied most frequently on post monsoon crops, which is when the weather conditions are ideal for late blight development.”

Author: M.M. Myint, Y.Y. Myint and H. Myint
Affiliation: Department of Plant Pathology, Yezin Agricultural University, Yezin, Myanmar
Title: Occurrence and growers’ perception of potato late blight in Kalaw Township, Myanmar.
Publication: Regional Workshop on Potato Late Blight for East and Southeast Asia and the Pacific Proceedings. 2004. 24-25 August, Yezin, Myanmar.

Climate Change Warms Up Finland – Increased Need for Fungicides Results

Finland is the northernmost country in the world with successful agriculture. Long harsh winters and low temperatures limit effective production of most crops. However, the cold climate also limits the proliferation of fungal pests. Now that the climate of Finland is heating up, the need for fungicides has grown.

“On average, since the 1960s there has been a trend of the growing season starting 2.1 days earlier per decade in the east and north of Finland, and 2.8 days earlier per decade in the west, with the pace of development accelerating since the 1980s.”

“With a longer growing season plant pathogens will thrive. For example, studies based on simulation models indicate that an increase of 1°C in mean temperature in southern Finland extends the period when potato late blight control (Phytophthora infestans) is necessary by 10-20 days, which means 1-2 more fungicide applications per season. The need for plant protection measures for potato late blight control has already increased following climate change, and the epidemiology of the pathogen has also changed substantially.”

Authors: K. Hakala, et al.
Affiliation: MTT Agrifood Research Finland, Plant Production Research, Jokioinen, Finland
Title: Pests and diseases in a changing climate: a major challenge for Finnish crop production.
Publication: Agriculture and Food Science. 2011. 20:3-14.