In a newly released study, the Crop Protection Research Institute says fungicide benefits to the United States are immense. The report, reviewed and endorsed by 38 commodity groups (including the National Cotton Council and United Soybean Board), says if left untreated, yields of most fruit and vegetable crops would plunge 50 to 95 percent.
“Fungicides are pesticides that kill fungi and bacteria,” said Leonard Gianessi, CropLife Foundation director and lead author of the report. “If they aren't killed, the fungi and bacteria cause plant diseases. There are 20,000 different species that release spores and bacteria. These spores float around and must infect plants to complete their life cycles.
“Once inside a plant … the fungus sucks nutrients and crushes cells. It has to do this in order to survive as a species. After all this damage inside the plant, the dead cells rot.”
When the fungicide study began 18 months ago, Gianessi and colleagues set out to answer three basic questions:
How widespread is fungicide use in the United States?
What value do farmers receive from using fungicides?
What portion of the food production in the country can be attributed to fungicide use?
“We wanted to quantify our answers. We focused on 50 crops — the major users of fungicides in the United States. We read thousands of plant pathology articles over the last 18 months. In the full report, there are 765 references. We learned there are 231 major diseases controlled in the United States with fungicides.”
A short history
In the years before widespread fungicide use, the United States suffered huge crop losses. In the 1850s when trying to grow peaches in Georgia, it was common to lose 50 to 70 percent of the crop.
“When they went to harvest, every other peach was rotted. They threw the bad one away and took the good one to market. The expectation was they'd lose half the crop. There was no defense.”
Potato late blight fungus is associated with the Irish potato famine in 1845 and 1846. But the potato blight problem actually began in North America.
“In the early 1840s, literature indicates potato growers on the east coast saw 40 to 90 percent of the crop turned to slime. There was nothing to control the fungus.”
Until a fungicide solution was found in the early 1900s, walnut blight prevented a vibrant walnut industry from taking root in California. Producers regularly lost 75 percent of their walnut crop to the blight.
Widespread use of fungicides in the United States began in the late 1800s and coincided with an increase in the commercial growing of vegetables and fruit. Gianessi said the first uses of fungicides were copper on potatoes for control of late blight and apples sprayed with sulfur.
“In the early 1900s, people stated it would be impossible to grow grapes in California if sulfur wasn't sprayed to control powdery mildew. The fungus was capable of destroying the entire crop.”
Synthetic chemicals came along in the 1930s and 1940s. With their arrival, growers began to switch from sulfur and copper.
“The synthetics were adopted because they improved control and did less damage to crops. Looking at yield charts, you can see the increase in yields tied to increased use of synthetic chemicals.
“Something else that happened with the introduction of synthetic chemicals is a significant reduction in use of fungicides. Copper and sulfur use was 10 to 60 pounds per acre while synthetic chemicals used 1 to 3 pounds per acre. With synthetic chemicals, there was a 200 million pound per year reduction from what was sprayed (prior to their introduction).”
The study also looked at the practices of organic growers. “We found organic growers are permitted the use of copper- and sulfur-based fungicides. They can be certified as organic growers using those controls.”
To what extent do organic growers use fungicides?
“Rutgers did a nice study of organic apple growing in the northeast part of the United States. What they reported is the typical organic apple grower sprays 12 pounds of sulfur per acre and 10 gallons of lime sulfur per acre. (Organic producers) face apple scab just like everyone else. They have to spray fungicides to bring scab-free apples in.”
Gianessi said the University of California has developed a series of studies on the typical practices of organic growers. Growers of organic grapes, strawberries and walnuts all make use of sulfur and/or copper.
Fungicides key to yields
Without fungicides, and based on literature review, “we conclude uncontrolled diseases would significantly lower U.S. crop production. Disease pathogens are widespread and before fungicides there were tremendous losses to diseases, a lot of rotted produce.
“The experimental data put out yearly by university plant pathologists continues to show significant crop yield reductions without fungicides.”
In the computational phase of the study, researchers estimated acres treated, pounds used, the number of applications and the costs of products and application.
“We have data for 45 active ingredients in 49 states. For much of the year it's too cold in Alaska for fungi to survive. But all other states are included.”
Of the 50 crops studied, estimates are that fungicides are sprayed annually on 18 million acres. There are 108 million pounds of fungicides sprayed and growers spend $880 million on the fungicides/application.
On the list, California is number one by a wide margin with 61 million pounds of fungicides used. Most of that is sulfur — 45 million pounds — used on grapes.
The states that rank lowest in fungicide use are typically “dry states where fungi don't do well. Fungi need moisture, humidity and rainfall. There aren't a lot fruit and vegetables grown in these states.”
To do benefit calculations, Gianessi and colleagues relied on a set of yield-loss estimates published by Farm Bureau and USDA. “These studies answer the question ‘What would happen to yields if fungicides weren't used?’ USDA got estimates from plant pathologists around the country.”
Without fungicides, Farm Bureau estimated California grape production would drop 97 percent. Other examples include 100 percent yield reductions in Georgia's peach crop and Kentucky's apples, 25 percent reductions in the soybean crops of Louisiana, Arkansas and Mississippi, and a 22 and 12 percent drop in Tennessee and Missouri cotton crops, respectively.
What about crop production increases attributable to fungicides?
“California ranked number one again with $5.5 billion worth of produce, nuts and berries due to fungicide use. Arizona comes in with high-value crops like lettuce and citrus. Texas is the same — another high-value crop loss state without the use of fungicides.”