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.


Hi John

Given the volume of comments on GM following yours at you might have created a niche issue.

The prickly pear was particularly bad in Australia.

Warning: This is a bit rambling.


Australia is the poster child for ecological damage. Rabbits, mice, foxes, feral cats, cane toads, and prickly pear are just some of the unintended damages from people that didn't know any better. My point was as stated, here we have countries pouring enormous amounts of funds into thermonuclear weapons while they may let their people inadvertently starve down the road. What good is it to have a nuclear umbrella if you are starving to death? Seen in this light, Pakistan might be the next North Korea. If I hadn't have seen your article, I wouldn't have had the epiphany. All economies are inefficient due to misallocation of funding and inappropriate subsidies. Governments plowed money into agriculture research in the 1950s and 1960s all the way up to 1986 or so to help countries grow their own food. Then agribusiness arose in the 1970's and 80's and agriculture became a type of political leverage (Russian grain shipments) for governments as well as income. Priorities shifted from self-sustaining growth to food exports from producers to developing nations, but populations continue to grow. That is politically and economically unwise since whoever controls the food supply controls you and your government indirectly and you are causing your government's fortunes to rise and fall on your people's stomachs. That agriculture is subsidized heavily in the U.S. is not in dispute, and that these subsidies are in part to blame for this shift in international affairs is not in dispute, but there are other problems. Agriculture is resource wasteful (especially with water) if not properly managed and destroys habitat. Agriculture depends upon the weather and other environmental factors (no plant diseases and pests) for good yields. Throw in a drought or good old plague and you have famine, followed by disease, war, and death. The main causes of political and economic instability in the past were due to food shortages and/or disease. Poor farmers can't afford fertilizers and fungicides. What happens when Ug99 hits Pakistan and India? Why aren't they growing "golden rice" cultivars with vitamin A? it's a GM crop. Humanity has been changing domesticated species genomes for over 10,000 years or longer (witness dogs). We've just gotten better at fine-tuning the technique. But people don't think of conventional breeding as bad, while they fear genetic engineering. But conventional breeding was the old way of genetic engineering.

There will always be blowback. More food may mean more obese people or more people without reproduction education. But curing tropical diseases has the same effect. As more people survive, there are more mouths to feed. Nuclear power is peaceful and nuclear reactors destroy the same ingredient that can make nuclear bombs. Agriculture rather than destroying more wilderness might be able to increase the productivity of the current lands, feed more people, and take some of the pressure off of the wilderness that is left. But our commons are being degraded. Fisheries are collapsing, the air is more polluted, wilderness is vanishing and species are going extinct. Top predators are in an ecosystem for a reason. Remove them at your peril. Either obey Nature's balance or be balanced by Nature. The problem with Nature is that it doesn't listen to fancy arguments. Nature obeys laws whether we know those laws or not. But ignorance of Nature's laws generally leads to death. If you defecate and don't wash your hands afterwards, the guy you shake hands with or who takes your money gets dysentery or diarrhea. (

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