Tag Archives: fungicides

Without Fungicides, Fungal Infections Would Render Celery Unmarketable

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Septoria late blight is a worldwide disease of celery plants. First reported in Italy in 1890, late blight was then reported in North America in 1921, leading to losses of 25-50%. The disease is explosive – a half billion spores can be produced on a single celery plant. Each spore can start an infection resembling a dark spot, which can grow large enough to cause leaf death. Celery growers spray fungicides to prevent septoria infections. Another option is to use laborers to trim off the infected parts of the celery; however, this is not practical.

“Septoria late blight is an important disease of celery worldwide. Yield loss ≤ 70% can occur. … Effective management of septoria late blight is essential for the production of a marketable crop of celery. The disease threshold for celery is effectively zero because plants with noticeable lesions on leaves and petioles [stalks] are unmarketable, so diseased petioles must be removed by hand. … Septoria late blight is difficult to control once present in a field, and celery growers must rely on application of foliar fungicides to manage this disease. The labour requirements to trim fresh-market celery with lesions are high, and loads of processing celery showing disease symptoms can be rejected entirely.”

Author: C.L. Trueman, et al.
Affiliation: Department of Plant Agriculture, University of Guelph, Ontario
Title: Evaluation of disease forecasting programs for management of septoria late blight (Septoria apiicola) on celery.
Publication: Canadian Journal of Plant Pathology. 2007. 29:330-339.

Climate Change Warms Up Finland – Increased Need for Fungicides Results

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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.

Japan’s Most Popular Green Tea Variety Depends on Fungicides

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In the 1970s, a new high-yielding green tea variety – Yabukita – was introduced in Japan and has been wildly popular because of quality attributes that Japanese tea drinkers favor, including the characteristic “umami” savory taste. This one-cultivar industry led to prevalent and frequent outbreaks of tea plant diseases which has resulted in a dependence on regular fungicide applications.

“Tea is one of the most important cash crops in the warm southwest areas of Japan. The green tea cultivar ‘Yabukita’ has been cultivated since the 1970s and grown in about 75% of all tea fields in Japan. Using a monoculture cultivation system, new Yabukita tea shoots can be harvested synchronously, producing green tea of consistent quality. However, this system has resulted in severe pest problems such as outbreaks of tea anthracnose … and tea gray blight … Therefore, repeated spraying of fungicides is needed to protect tea plants against both the diseases for each tea crop.”

Authors: K. Yoshida, A. Ogino, K. Yamada and R. Sonoda
Affiliation: National Institute of Vegetable and Tea Science
Title: Induction of disease resistance in tea (Camellia sinensis L.) by plant activators.
Publication: Japan Agricultural Research Quarterly. 44(4):391-398.

Fungicides Make Apple Growing Possible in South Korea

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Farmers in South Korea harvest about 900 million pounds of apples annually. This production is only possible because a large number of fungicide sprays are made to prevent fungal pathogens from rotting the apples. The most common disease of apples in Korea is white rot, a disease that starts on the apple peel, moves toward the core and turns the entire fruit into a soft, watery, pale rotten mess.

“In Korea, due to frequent rain during apple growing season, especially in one month of the rainy season, the disease problem is very serious. If fungicides are not used at all, more than 90% of the fruit may be rotten and almost all the leaves may drop before harvest. Most apple growers spray fungicides 14 to 16 times in each growing season. Among the diseases of economic importance, white rot is the most serious, as cv. Fuji that is highly susceptible to this disease accounts for more than 70% of apples produced.”

Authors: J.Y. Uhm, D.H. Lee, D.H. Kim and H. Woo
Affiliation: School of Applied Biology and Chemistry, Kyungpook National University, Daegu, Korea
Title: Development of a spray program for apple with reduced fungicide application in Korea.
Publication: Journal of Plant Pathology. 2009. 90(Supplement 2):S2.155.

Fungicides Necessary for Southeast Peanut Production

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In the U.S., fungicides are used in the field to control ten major diseases of peanuts. For decades, peanut harvesting started when the peanuts in a field were stripped of their leaves by one of these diseases. Peanut yields increased dramatically between 1969 and 1987 following the introduction of effective synthetic chemical fungicides. Fungicides continue to be needed to maintain high peanut yields.

“It’s one of the harsh realities of growing peanuts in the Southeast – you will have disease problems. ‘The same type of weather and climate that helps you grow peanuts so successfully in the Southeastern United States also makes it difficult to control diseases,’ says Bob Kemerait, University of Georgia Extension plant pathologist. Fungicide programs, he adds, constitute the single most expensive input a grower will have in peanut production. ‘It’s not seed, insecticides or herbicides. You spend more in fungicides than perhaps anything else – that’s the bad news. The good news is the tremendous value you receive from controlling diseases. We could not make the desired yields and grades without these programs,’ says Kemerait.”

Author: Paul L. Hollis
Title: Peanut fungicides valuable tools.
Publication: Southeast Farm Press. 2008. Vol. 35(12).

Modern Fungicides Continue Control of Potato Disease

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The disease of potatoes known as ‘early blight’ occurs earlier in the season than the well-known ‘late blight’ disease. Early blight is a significant problem in Wisconsin and Minnesota potato fields. Fungicides have been used for over 100 years to protect potatoes from early blight. Recent research in Wisconsin shows that modern fungicides continue to be most effective with newer chemistries expected to continue effective control into the future.

“Potato early blight is a perennial and potentially destructive disease caused by the fungus Alternaria solani. Appropriately-timed, effective fungicides are necessary to limit yield and quality loss. In 2010, we evaluated 38 fungicide programs for early blight control at the University of Wisconsin Hancock Agricultural Research Station on ‘Russet Burbank.’ Programs included an untreated control, conventional and organic grower standard programs, and newer chemistries.”

“The highest yielding program was the Wisconsin conventional grower standard. Organic treatments were ineffective. Several newer chemistries and modified standard programs were effective. At this time, and in the registration pipeline, there are excellent fungicides for the control of potato early blight that will contribute to good fungicide resistance management practices.”

Authors: Kenneth Cleveland, Jamie Dobbs, Rosemary Clark and Amanda Gevens
Affiliation: University of Wisconsin-Madison, Dept. of Plant Pathology
Title: Evaluating the efficacy of fungicide programs for the control of potato early blight in the Central Sands of Wisconsin.
Publication: American Journal of Potato Research (2012) 89:32.

Fungicide Use on UK Crop Acres Results in Significant Reductions in Greenhouse Gas Emissions

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Fungicides are used on more than 90% of the cereal acres in the UK resulting in yield increases of 16-20%. Without fungicide use, it would be necessary to bring about 20% more land into cereal production to meet demand. All of the operations needed to bring a parcel of land into crop production (tractor operations, fertilization, pesticide application) result in the emission of greenhouse gases. Since fungicide use reduces the number of acres that need to be in production, their use is credited with a significant reduction in greenhouse gas emissions.

“The GHG emissions produced by growing arable crops derive mainly from agricultural inputs, such as fertiliser applications, the use of field machinery and crop treatments including disease control measures such as fungicides. … Nevertheless, the largest contributors to barley emissions are fertilisers, which account for 71-76% of all emissions. … Field operations contributed 19-23% of total emissions. … Crop protection chemicals contributed less than 1% of the total emissions.”

“Fungicides were applied to 98 and 87% by area of UK winter and spring barley, respectively, in 2008. … If fungicide treatment had not been applied, an additional crop area of 165,000 ha (17%) on average would have been required each year to produce the same harvested yields of winter and spring barley in 2005-2009. Furthermore, an additional crop area of 638,000 ha (16%) on average would have been required to produce the same harvested yields of the four crops winter barley, spring barley, winter wheat and winter oilseed rape in 2005-2009.”

“Fungicide treatment of the major UK arable crops is estimated to have directly decreased UK GHG emissions by over 1.5 Mt CO2 eq. in 2009. … These results suggest that disease control in UK arable crops can have the positive environmental effect of reducing direct GHG emissions by making more efficient use of the inputs to agricultural production. …use of fungicides applied to control disease in UK barley contributed relatively little to GHGs while increasing yield and decreasing GHG emissions per tonne of crop.”

Authors: David Hughes et al.
Affiliation: Rothamsted Research, Harpenden, Herts, UK
Title: Effects of disease control by fungicides on greenhouse gas emissions by UK arable crop production.
Publication: Pest Management Science. 2011. 67:1082-1092.

Fungicides May Increase Health Benefits of Fruit Juice

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Fungicides are widely-used to control diseases of fruit. Some fungicides have been shown to alter antioxidant metabolism in plant tissues. UK researchers conducted an experiment to see if fungicide applications could increase the health benefits of blackcurrant juice, a fruit grown widely in Europe and New Zealand…

“[Blackcurrant] is well regarded and strongly marketed for its exceptional antioxidant capacity. …cultivars have not yet been released with complete resistance to a range of yield- and quality-reducing fungal diseases. These diseases therefore still require extensive chemical control within plantations. … Fungal diseases in blackcurrant have been demonstrated to be effectively controlled by a range of fungicide classes including the strobilurin group. … In addition to their antifungal activities, the strobilurin group of fungicides have been shown to modulate plant physiology and biochemistry, resulting in yield increases and improvements in crop quality.”

“The impact of fungicide treatment on fungal infection and blackcurrant juice quality was examined in a series of field experiments over the course of 2 years. … In conclusion, the work presented here demonstrates a clear benefit of fungicide application in the control of foliar disease. Furthermore, there is an indication that fungicide application could improve juice quality with respect to both sensory characteristics and potential health benefits of juice consumption.”

Authors: AJ Nwankno, SL Gordon, SR Verrall, RM Brennan and RD Hancock
Affiliation: The James Hutton Institute, Dundee, UK
Title: Treatment with fungicides influences phytochemical quality of blackcurrant juice
Publication: Annals of Applied Biology 2012 160:86-96.

Fungicides Prevent Wheat Losses in the Pacific Northwest – Organic Growers Can Only Pray

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Cool, wet weather causes explosions of the stripe rust fungus in wheat fields of the Pacific Northwest. Two articles by Matthew Weaver explain how most growers applied fungicides to prevent yield loss in 2011 while organic growers could only hope that they would not be hit by the disease.

From “Researchers say vigilance against stripe rust a must”:

“Even though there’s more stripe rust in Pacific Northwest wheat fields this year, researchers say the outlook is good -— as long as farmers spray their fields and keep an eye on them.”

“…most growers in Oregon are already on their second application of fungicide and many will make a third application, which is extremely unusual.”

“In most fields, the stripe rust is under control if sprayed. Very few fields haven’t been sprayed, Chen said. Farmers who haven’t should compare the cost of spraying to the potential for yield losses if they don’t, Chen [research plant pathologist with USDA’s ARS] said. ‘It can not only cause a problem in their fields, but also to their neighbors and potentially to the whole region,’ he said, noting rust spores can be carried by the wind.”

From “Rust resistance key to organic wheat survival”:

“Organic wheat growers in the Pacific Northwest are concerned about stripe rust, an epidemic for which they have few treatment options. … Oregon State University wheat breader Mike Flowers said most organic growers were hit by the stripe rust ‘pretty hard’ but losses vary depending on the variety of wheat they grew. … Corvallis, Ore., farmer Clinton Lindsey, farm manager of A2R Farms, said one of his best red wheat fields was ‘completely devastated’ by the rust.”

“There aren’t many options available to organic producers, researchers and farmers say. ‘Pray or not pray,’ said Owen Jorgensen, a Coulee City, Wash., farmer who is on the northern edge of the stripe rust region.” 

Author: Matthew Weaver
Titles:”Researchers say vigilance against stripe rust a must” 27 May, 2011 and “Rust resistance key to organic wheat survival” 8 July, 2011
Publication: Capitol Press

Crop Breeding Failure Led to Increase in Fungicides in CA Spinach Fields

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The breeding of crop varieties that are resistant to pest organisms is often touted as an effective means of replacing pesticide use. And yet, pest organisms mutate and overcome the plant’s resistance. According to the California Department of Pesticide Regulation, fungicide use in California spinach fields has doubled in the last decade. The reason for the increase has been the breakdown of the plant’s resistance to mildew (Peronospora farinosa f. sp. spinaciae).

“Downy mildew disease is the most important disease problem facing the extensive spinach industry in California. … While downy mildew has been around California spinach fields for decades, the last few years have seen the development of four or five new races. Each new race potentially overcomes the resistance factors in the cultivars being planted at that time, leaving the crop susceptible to severe damage.”

“Integrated management steps must be used. … Resistant cultivars will remain a foundational piece of such a program. Judicious use of effective fungicides will remain important.”

Authors: Steven Koike and Jim Correll
Affiliation: University of California and University of Arkansas, respectively
Title: Spinach Downy Mildew: Outlining the Challenges.
Publication: Crop Notes (University of California Cooperative Extension)