Crop Protection Research Institute The Value of Fungicides In U.S. Crop Production September 2005 Leonard P. Gianessi Nathan Reigner CropLife Foundation 1156 15th Street, NW #400 Washington, DC 20005 Phone 202-296-1585 www.croplifefoundation.org Fax 202-463-0474 This study was funded by CropLife America. The following organizations have reviewed the report’s case studies and have indicated their support for the findings. Almond Board of California American Sugarbeet Growers Association Artichoke Research Association California Asparagus Commission California Citrus Mutual California Citrus Quality Council California Dried Plum Board California Fresh Carrot Advisory Board California Grape and Tree Fruit League California Kiwifruit Commission California Minor Crops Council California Pepper Commission California Pistachio Commission California Strawberry Commission California Tree Fruit Agreement Cranberry Institute Cherry Marketing Institute Florida Farm Bureau Federation Georgia Fruit and Vegetable Association Georgia Pecan Growers Association Michigan Asparagus Advisory Board Michigan Onion Committee Michigan Potato Industry Commission Minnesota Cultivated Wild Rice Council Mint Industry Research Council National Association of Wheat Growers National Cotton Council National Onion Association National Potato Council North American Blueberry Council Oregon Hazelnut Commission Texas Citrus Mutual Texas Vegetable Association U.S. Apple Association U.S. Hop Industry Plant Protection Committee United Soybean Board Washington Red Raspberry Commission Washington Asparagus Commission Cover Photograph Credits Top Left: Fungicide crystal : Charles Krause, USDA, ARS Top Center & Right: Living, untreated and dead, treated spores: Dow AgroSciences Bottom Left: Fungicide protected potatoes: DuPont Crop Protection Bottom Right: Untreated, late blight infected potatoes: DuPont Crop Protection Table of Contents 1.0 Overview 2.0 Introduction A. Plant Diseases B. History of Plant Pathology C. History of Fungicide Development 3.0 Crop Literature Review: Summary A. Target Diseases B. History of Fungicide Use in the United States C. Alternative Control Methods D. Experimental Results E. Organic Practices 4.0 Quantification of Fungicide Benefits A. Production Data B. Fungicide Use and Cost C. Fungicide Value Estimation D. Results E. Comparison to Previous Studies 5.0 Summary & Conclusions 6.0 Crop Literature Review 6.1 Almonds 6.18 Garlic 6.35 Pistachios 6.2 Apples 6.19 Grapes 6.36 Plums & Prunes 6.3 Artichokes 6.20 Green Beans 6.37 Potatoes 6.4 Asparagus 6.21 Hazelnuts 6.38 Raspberries 6.5 Bananas 6.22 Hops 6.39 Rice 6.6 Barley 6.23 Hot Peppers 6.40 Soybeans 6.7 Blueberries 6.24 Kiwi 6.41 Spinach 6.8 Cabbage 6.25 Lettuce 6.42 Strawberries 6.9 Cantaloupes 6.26 Mint 6.43 Sugarbeets 6.10 Carrots 6.27 Nectarines 6.44 Sweet Corn 6.11 Celery 6.28 Onions 6.45 Sweet Peppers 6.12 Cherries 6.29 Papaya 6.46 Tomatoes 6.13 Citrus 6.30 Parsley 6.47 Walnuts 6.14 Collards 6.31 Peaches 6.48 Watermelons 6.15 Cotton 6.32 Peanuts 6.49 Wheat 6.16 Cranberries 6.33 Pears 6.50 Wild Rice 6.17 Cucumbers 6.34 Pecans 7.0 Reference List Data Appendix (Separate Volume) 1.0 Overview This report estimates the value and benefits of the use of fungicides in United States crop production. A fungicide is a type of pesticide that controls fungal disease by inhibiting or killing the pathogen causing the disease. The study consists of three parts. First, a brief introduction to plant diseases, plant pathology, and fungicides is provided. Second, a literature review is summarized for the fifty crops included in the study. The literature review summarizes information on the diseases that affect each crop and details the historical record regarding control of the diseases in the U.S. with fungicides and other methods. The third part of the study consists of the quantification in dollars of the value of fungicides used in the growing of the fifty crops on a state by state basis. Foliar and in-furrow uses of fungicides are included; seed and postharvest treatments are not included. Fumigants that control plant diseases are not included. Plant diseases caused by fungi and bacteria are included; plant diseases caused by viruses and nematodes are not included. 2.0 Introduction A. Plant Diseases Most crop diseases are caused by fungi, which lack chlorophyll and therefore are unable to produce their own carbohydrate food.[144] Consequently, they must feed on other living plants or on dead organic matter. Of the 100,000 described species of fungi in the world, approximately 20,000 produce one or more diseases in various plants.[156] Many fungi produce spores in enormous numbers, which are found in the soil, air and on plant surfaces everywhere. Most fungi that cause plant disease are spread locally as a result of the dissemination of spores by wind or rain and are spread long distances in high altitude air currents.[144] When temperatures and moisture conditions in the soil or on the surface of the plant are favorable, a spore germinates producing a tube which enters the plant. The fungus grows through and between plant cells withdrawing nutrients. Some fungi produce toxins that kill plant cells. Usually, fungi produce spores on the surface of leaves, stems or fruit and these spores are then disseminated to healthy plants where the disease process is repeated. Infected cells and tissues of diseased plants are usually weakened or destroyed by fungi or bacteria. The ability of such cells to perform their normal physiological functions is reduced or completely eliminated; as a result, plant growth is reduced or the plant dies [163]. B. History of Plant Pathology Although the Old Testament contains many references to blights, blasts, rusts, and smuts, there seems to have been little or no effort to control them; such tribulations were accepted as an expression of God’s wrath.[156] The Romans relied on wheat as their primary crop and provided loaves of free bread to the populace. They noticed that when red spots appeared on the wheat plants, they harvested less grain. The Romans created a god of rust, Robigus, who was honored in an annual religious ceremony for over 1,700 years. A red dog was sacrificed to appease the rust god in an attempt to spare their grain. Climate change in the first century A.D. produced wetter and cooler conditions that led to frequent, severe outbreaks of wheat rust. Crop failures followed leading to famine, and social disruption that contributed to the downfall of the Roman Empire. During the following two thousand years, little was added to the knowledge of plant diseases although references to the ravages of plant diseases appeared in the writings of contemporary historians. The invention of the microscope in the 1600’s led to the discovery of fungi and bacteria. However, for two hundred years scientists concluded that the organisms were the result, rather than the cause, of disease, which was attributed to spontaneous generation. In 1807, Prevost proved that a crop disease was caused by a fungus. However, his findings were rejected by almost all his contemporaries. In 1844, a rot of potatoes caused the loss of 25-90% of potato production in the northeast U.S.[33][427] The rot was first reported in Europe in 1845 and it spread throughout the continent, reaching Ireland in August destroying 40% of the country’s potato crop.[425] Irish peasants were almost completely dependent on the potato for their diet and for feed for their farm animals. In 1846, the rot fungus destroyed 100% of the Irish potato crop, which led to the deaths of 1.5 million people and the emigration of a similar number of people, mainly to North America.[423] It would not be until 1861 that Anton de Bary, who is considered the father of modern plant pathology, would conclusively identified a fungus as the cause of the rotted potatoes and not until 1885 that a fungicide would be discovered that could kill the potato rot fungus.[516] C. History of Fungicide Development Sulfur is the oldest effective fungicide known. Elemental sulfur can be found near hot springs and volcanic regions in many parts of the world. At room temperature sulfur is a soft, bright yellow solid. Homer mentioned “pest-averting” sulfur in the 9th century BC. It was not until 1802 that sulfur, applied as a finely-ground dust, was used agriculturally to control mildew on fruit trees.[156] A major use of sulfur as a fungicide came about in France in the 1840’s to combat grape powdery mildew, which had been introduced from North America in 1845 and reduced French wine production by 80% by 1854.[601] The use of sulfur became generally widespread in vineyards, and by 1858 French wine grape production returned to its previous level.[602] The fungicidal action of sulfur is complex and functions primarily in the respiration process. When sulfur is applied to a plant, vapors are released. The powdery mildew fungus produces hydrogen, which reacts with the sulfur to form hydrogen sulfide, a gas toxic to the fungus. Attempts were made to control potato rots with sulfur, but it was not effective. In 1878, another pathogen of grapes, downy mildew, was introduced into French wine grapes from America and, once again, French wine grape production was greatly reduced. In 1885, an effective fungicide which controlled downy mildew was accidentally found. The story goes that a French botanist, Alexis Millardet, was walking down a lane observing the grapes infected with downy mildew when he noticed that some grapes were covered with a bluish-white wash. He also noted that the leaves on these plants were healthy whereas the neighboring plants were badly diseased. When he questioned the farmer to whom the grapes belonged, he was told that the grapes along the road had been sprayed with a mixture of lime and copper sulfate to discourage pilferers.