Thursday, March 04, 2010
Food Security and Crop Diseases
Science devoted the part of the February 12, 2010 issue to food security. They have a two page spread on plant diseases and other biological threats to crops. Here are the worse threats:
1. Rice blast (Magnaporthe grisea) fungus - Primarily affects rice, but infects 50 species of grasses and sedges. Can quickly kill whole paddies. Multiple strains of the fungus ensure that no cultivar stays resistant for more than 2-3 years. Estimated losses: $66 billion/yr. (enough to feed 60 million people).
2. Wheat Stem Rust (Puccinia graminis Ug99). fungus - New strain emerged in Uganda in 1998. It's now in Yemen and Iran. If it reaches Pakistan and India, famines will ensue because farmers are too poor to buy the fungicides which would slow the infections. Potential losses: 40% crop loss due to heavy infestations. Potential loss in Punjab, $3 billion/yr. If it reaches the U.S., $10 billion/yr.
3. Potato Blight (Phytophthora infestans) fungus - Affects potatoes and tomatoes. Cause of the Irish Potato famine of 1845-1851. Under the right conditions, the fungus can destroy an entire field in a week. Known losses: $2.75 billion/yr in developing nations.
4. Black Sigatoka (Mycospaerella fijiensis) fungus - Affects bananas and plantains. Discovered in Fiji in 1964, now in 100 countries globally. Potential losses: Can be up to 50% reduction in yield. No dollar amount given, but all commercial bananas are one sterile asexually propagated (cloned) cultivar named Cavendish which replaced the Gros Michel "Big Mike" banana cultivar which was susceptible to Panama disease. The Cavendish is now being phased out for a more disease resistant cultivar.
5. Witchweed (Striga hermonthica) weed - African parasitic plant that attaches to roots. Affected crops: corn, sorghum, sugarcane, millet, native grasses. Losses: 20-100% yield reduction. Monetary loss: Approximately $1 billion/yr.
6. Asian Soybean Rust (Phakopsora pachyrhizi) fungus - Primarily affects soybeans, but infects 31 other legume species. Losses: reduces yields 10-80%. No resistant cultivars exist yet. Fungicide use is advised.
7. Cassava Brown Steak Virus - Affects cassava. Losses: Up to 100% yield reduction. Economic losses were more than $100 million in 2003 in Africa.
While these diseases are on the rise, agricultural research funding has fallen in the last ten years. So, most rising crop commodity prices are due to lower yields due to disease and a rising population. This slow motion train wreck did not need to happen, but the Bush Administration cut back agricultural research funds starting in 2001. (The U.S. is a major donor for almost all of the major international crop research centers through USAID and USDA.) To be fair though, funding cutbacks started in 1986 and many developing nations were urged to buy their grain from primary producers instead of producing their own. But, the Bush cutbacks hurt the Centers of the Green Revolution where the plants are developed. Current projections suggest that food production will need to increase 70-100% by 2050 to feed the world's population (WDR 2008). At some point, beef will become too expensive to produce in terms of water and grain used for feed, then many meat lovers will be eating chicken. Also, organic farming cuts yields by 50% (no artificial fertilizers are used). Does this mean that poor farmers who can't afford modern fertilizers and pesticides are natural organic farmers? While eutrophication of fresh and salt water ecosystems is caused by fertilizer runoff due to farming, farmers are being taught how to mitigate the problem. No farmer wants to spray a crop and watch that money literally flow down a drain if they can avoid it.
1. Rice blast (Magnaporthe grisea) fungus - Primarily affects rice, but infects 50 species of grasses and sedges. Can quickly kill whole paddies. Multiple strains of the fungus ensure that no cultivar stays resistant for more than 2-3 years. Estimated losses: $66 billion/yr. (enough to feed 60 million people).
2. Wheat Stem Rust (Puccinia graminis Ug99). fungus - New strain emerged in Uganda in 1998. It's now in Yemen and Iran. If it reaches Pakistan and India, famines will ensue because farmers are too poor to buy the fungicides which would slow the infections. Potential losses: 40% crop loss due to heavy infestations. Potential loss in Punjab, $3 billion/yr. If it reaches the U.S., $10 billion/yr.
3. Potato Blight (Phytophthora infestans) fungus - Affects potatoes and tomatoes. Cause of the Irish Potato famine of 1845-1851. Under the right conditions, the fungus can destroy an entire field in a week. Known losses: $2.75 billion/yr in developing nations.
4. Black Sigatoka (Mycospaerella fijiensis) fungus - Affects bananas and plantains. Discovered in Fiji in 1964, now in 100 countries globally. Potential losses: Can be up to 50% reduction in yield. No dollar amount given, but all commercial bananas are one sterile asexually propagated (cloned) cultivar named Cavendish which replaced the Gros Michel "Big Mike" banana cultivar which was susceptible to Panama disease. The Cavendish is now being phased out for a more disease resistant cultivar.
5. Witchweed (Striga hermonthica) weed - African parasitic plant that attaches to roots. Affected crops: corn, sorghum, sugarcane, millet, native grasses. Losses: 20-100% yield reduction. Monetary loss: Approximately $1 billion/yr.
6. Asian Soybean Rust (Phakopsora pachyrhizi) fungus - Primarily affects soybeans, but infects 31 other legume species. Losses: reduces yields 10-80%. No resistant cultivars exist yet. Fungicide use is advised.
7. Cassava Brown Steak Virus - Affects cassava. Losses: Up to 100% yield reduction. Economic losses were more than $100 million in 2003 in Africa.
While these diseases are on the rise, agricultural research funding has fallen in the last ten years. So, most rising crop commodity prices are due to lower yields due to disease and a rising population. This slow motion train wreck did not need to happen, but the Bush Administration cut back agricultural research funds starting in 2001. (The U.S. is a major donor for almost all of the major international crop research centers through USAID and USDA.) To be fair though, funding cutbacks started in 1986 and many developing nations were urged to buy their grain from primary producers instead of producing their own. But, the Bush cutbacks hurt the Centers of the Green Revolution where the plants are developed. Current projections suggest that food production will need to increase 70-100% by 2050 to feed the world's population (WDR 2008). At some point, beef will become too expensive to produce in terms of water and grain used for feed, then many meat lovers will be eating chicken. Also, organic farming cuts yields by 50% (no artificial fertilizers are used). Does this mean that poor farmers who can't afford modern fertilizers and pesticides are natural organic farmers? While eutrophication of fresh and salt water ecosystems is caused by fertilizer runoff due to farming, farmers are being taught how to mitigate the problem. No farmer wants to spray a crop and watch that money literally flow down a drain if they can avoid it.
Labels: plant pathology famine
