Devastating New Potato Disease Has Growers Spraying at First Sign of Vector

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Potato psyllids in the Pacific Northwest are spreading a new disease, Zebra chip. Beginning in 2011, psyllid feeding has spread a virus that reduces potato yields and renders tubers unmarketable with bands that darken when fried. Immediate spraying to control the insect vector is required.

“Researchers say populations of potato psyllids – vectors of zebra chip, a crop disease new to the region – are growing dramatically in the Columbia Basin.”

“Despite the increasing psyllid pressure during the past couple of weeks, Phil Hamm, an Oregon State University plant pathologist, believes the disease shouldn’t cause major problems for growers who stick with insecticide programs. … ‘When the region has psyllids, you treat,’ Hamm said.”

Author: John O’Connell
Headline: Psyllid populations growing dramatically
Publication: Capital Press. August 31, 2012.

Repeat of Irish Potato Famine Unlikely Thanks to Fungicides

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The pathogen Phytophtera infestans causes a disease of potatoes called “late blight”. The pathogen grows in potato plants, breaking down cell walls so that it can use the nutrients found within them. Severely infected plants have an acrid odor which is the result of dying plant tissue. In the 1800s, Irish peasants subsisted almost entirely on potatoes. The late blight fungus arrived in 1845 and destroyed 40% of the Irish crop. In 1846, 100% of the crop was destroyed. Over 1.5 million Irish died of famine and a comparable number emigrated to America and other countries. Today, the fungus is still present in Ireland and would destroy the crop again if not for fungicides.

“Without the routine use of fungicides, large-scale commercial potato production in Ireland would be impossible. The cool, damp climate, which favours the cultivation of the potato and limits problems with virus diseases, is also ideal for the spread of blight. … In warm, wet weather when the humidity is high, P. infestans will lay waste an unprotected crop. … To prevent such devastating losses, the potato industry in Ireland has long been reliant on a substantial annual usage of fungicides.”

Author: L.R. Cooke
Affiliation: Plant Pathology Research Division, Department of Agriculture for Northern Ireland
Title: Potato blight control in Ireland: a challenging problem.
Publication: Pesticide Outlook. 1992. 13(4):28-31.

Leafhoppers Transmit Deadly Grapevine Disease in Italy

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The grapevine disease Flavescence dorée has been called “catastrophic.” Impacts include yield reductions, and reduced wine quality. The disease spreads rapidly and can affect 80-100% of the vines in a few years. The disease is spread by leafhoppers who acquire the organism while feeding on infected plants and then spread the disease when they feed on healthy plants. Spraying to control the leafhopper is mandatory in regions where the disease is known to exist.

“The leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is a serious pest of grapevines in Europe as it transmits the phytoplasmas of Flavenscence dorée (FD). … the eggs start to hatch in the middle of May, and nymphs can be found until the middle of July… The adults are present from the end of June until the middle of October.”

“Nymphs from the third instar onward acquire phytoplasmas by piercing the leaves and stems of infected grapevines. After a latency period of 4-5 weeks, during which time they become adults, they can transmit FD phytoplasmas to healthy grapevines. In Italy, insecticide treatment against S. titanus are mandatory in the districts where FD is present. The active ingredients include neonicotinoids and organophosphates; in vineyards subject to organic farming S. titanus is controlled with pyrethrum.”

Authors: F. Lessio, E.B. Mondino and A. Alma
Affiliations: University of Turin, Grugliasco, Italy
Title: Spatial patters of Scaphoideus titanus (Hemiptera: Cicadellidae): a geospatial and neural network approach.
Publication: International Journal of Pest Management. 2011. 57(3):205-216.

UK Consumers Would Need to Pay 40% More for Food…

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Most cropland in the UK is treated with pesticides to prevent diseases, insects and weeds from lowering crop yields. Without the use of pesticides, crop production would fall significantly resulting in higher prices for consumers. A 2010 study estimated the impact of the lower food production on consumer costs…

“This report estimates that without plant protection products, food security in the UK, and by implication in the EU and in most countries across the world, would be severely reduced and the cost of food would rise substantially. In the UK the cost of food would rise by about 40 per cent, increasing food and drink expenditures by some £70 billion per year and raised to the level of the EU this implies additional food expenditures of some £750 billion.”

Author: Séan Rickard
Publication: The Value of Crop Protection: An Assessment of the Full Benefits for the Food Chain and Living Standards. 2010 Report from the Crop Protection Association.

Apple Production in the UK Made Viable by Pesticides

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UK apple growers produce about 400 million pounds of apples per year. About 18 insecticide and fungicide sprays are made yearly to control pests including scab, mildew, aphids and codling moth. By applying a full spray program, good growers have restricted losses due to pests and diseases to very low levels, usually no more than 1-2%. Below, an economic cost-benefit study determined the likely effect on UK apple production if growers did not use pesticides…

“Apples are the most important fruit crop in the UK in terms of area of production and require relatively high levels of pesticide inputs. … If pesticides were not used, apple production would thus not be commercially viable, and the market shortfall would be made up by imports at a similar price. With a negative gross margin apple producers would leave the industry and find other uses for their land.”

Authors: J.P.G. Webster and R.G. Bowles
Affiliation: Farm Business Unit, Wye College, University of London, Kent, UK
Title: Estimating the economic costs and benefits of pesticide use in apples.
Publication: Proceedings of the Brighton Crop Protection Conference, Pests and Diseases. 1996. 4B-1:325-330.

The Consumer is Always Right and That’s Why Farmers Use Pesticides

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More than 90% of US fresh produce (fruits and vegetables) is sprayed with insecticides and fungicides to prevent rots and yield loss. This spraying also assures that there are no scabs or insect-feeding marks on the produce. Although some consumers would prefer no pesticide residues, many are unwilling to accept any cosmetic damage. You can’t have it both ways—picture-perfect produce requires pesticide use.

“Over 300 shoppers entering supermarkets completed a questionnaire about purchasing certified pesticide residue-free (CPRF) fresh produce. One-half expressed concern about pesticide use on fresh produce. Two-thirds were willing to pay 5 to 10% higher prices to obtain CPRF fresh produce, but were unwilling to accept any cosmetic defects or insect damage.” 

Author: S.L. Ott
Affiliation: USDA Economics Research Service
Title: Supermarket shoppers’ pesticide concerns and willingness to purchase certified pesticide residue-free fresh produce.
Publication: Agribusiness. 1990. 6(6):593-602.

Fungicides “Vital” for Potato Production in Myanmar

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Potato is a very popular vegetable crop in Myanmar and is essentially grown all year round. Phytophthora infestans, the fungus that caused the Irish Potato Famine in the 1840s, was first found in Southeast Asia in the late 1800s and has since been an annual widespread problem. Without fungicide protection, the disease spreads rapidly and can kill all the plants in a field within a few days.

“In Myanmar, late blight caused by Phytophthora infestans is the most destructive disease of potato. … High incidence and severity of potato late blight occur in this area because the crop can be found year-round at all stages of development, providing a constant source of primary inoculum.”

“At present, fungicide applications play a vital role in potato late blight control as resistant cultivars have not been widely available and adopted. … Fungicide is applied most frequently on post monsoon crops, which is when the weather conditions are ideal for late blight development.”

Author: M.M. Myint, Y.Y. Myint and H. Myint
Affiliation: Department of Plant Pathology, Yezin Agricultural University, Yezin, Myanmar
Title: Occurrence and growers’ perception of potato late blight in Kalaw Township, Myanmar.
Publication: Regional Workshop on Potato Late Blight for East and Southeast Asia and the Pacific Proceedings. 2004. 24-25 August, Yezin, Myanmar.

Herbicides Have Helped Stabilize Wheat Production in Kazakhstan

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Kazakhstan ranks in the top 10-15 wheat-producing countries in the world depending on weather conditions (drought is a significant factor 2 out of 5 years). Kazakhstan is a major exporter of wheat with about 4 million tons exported annually. Weeds are a key limiting factor in Kazakhstan’s wheat production; however, recent increases in herbicide use have significantly reduced yield losses.

“Although weather remains the single most important determinant for grain yield in Kazakhstan, improvements in crop management practices fueled by the growing State subsidies have contributed to the recent increase and relative stabilization in wheat yield.”

“According to specialists at the Ministry of Agriculture, nearly half the total cultivated area in Kazakhstan is infested with weeds, including 2.5 million hectares infested with black oats. Between 1999 and 2002, farmers applied virtually no herbicides for the control of black oats on approximately 320,000 hectares. In 2003, treatment expanded to 1.0 million hectares thanks to government subsidies of about US$2 million which reduced farmers’ cost of chemicals by 30 to 40 percent. Herbicide subsidies increased to nearly US$3 million in 2004 and the treated area grew to about 1.4 million hectares. Specialists report that weed infestation has decreased by about 15 percent every year since the anti-black oat campaign was launched.”

Author: Mark Lindeman
Affiliation: USDA Foreign Agricultural Service
Title: Kazakhstan Wheat Production: An Overview
Available at: http://www.fas.usda.gov/pecad2/highlights/2005/03/Kazakh_Ag/index.htm

New Rice Planting Method Makes Herbicides Necessary in Pakistan

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Traditionally, rice has been planted manually in flooded fields in Pakistan. This method of planting requires large amounts of water and a high level of labor. The sustainability of this system is threatened by severe labor and water shortages. Research has focused on direct machine planting of rice seeds in non-flooded soil. However, weeds flourish when the soil is not flooded making herbicides a necessary component of the new planting system.

“An increasing water crisis, as well as the unavailability and high cost of labor, in Pakistan has forced rice-growers to plant rice directly into the field. However, severe weed infestation causes disastrous effects on the productivity of this rice system. In this study, three herbicides were evaluated for weed control in direct-planted rice on a sandy loam soil. Weedy check and weed-free plots were established for comparison. Weed infestation decreased the rice yield by 75.2%. However, the application of herbicides suppressed the weed infestation, with a simultaneous increase in the rice yield.” 

Author: Khawar Jabran, et al.
Affiliation: Ayub Agricultural Research Institute, Faisalabad, Pakistan
Title: Application of bispyribac-sodium provides effective weed control in direct-planted rice on a sandy loam soil.
Publication: Weed Biology and Management. 2012. 12:136-145.

Mr Bittman, Reducing Herbicide Use on Farms is Not Simple

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The New York Times writer Mark Bittman writes glowingly about a recent study¹ that reported on an Iowa experiment in which crop yields were maintained while herbicides to control weed populations were reduced (“A Simple Fix for Farming,” NYT,10-21-2012)². Bittman concludes that, “there was only upside—and no downside at all” in this study.  Rhetorically, Bittman asks, “Why wouldn’t a farmer go this route?”. That question was studied by rural sociologists from the University of Missouri and their findings³ show that it’s not so simple to reduce herbicide use—there are serious downsides. The study that Bittman cites reduced herbicide use by switching from spraying the entire field (broadcast spraying) to spraying just down the row of plants (banded spraying) and using cultivation to kill weeds between the rows. This technique of “banding” the herbicide spray in combination with tillage was widely-used several decades ago, but farmers changed to spraying the entire field without the need to cultivate. The sociologists asked farmers why they abandoned the practice and if they would consider using it again. The answer was…

“Operators are not rejecting the practice due to a perceived lack of knowledge of how the practice works or dissatisfaction with reductions of pesticide use or of water quality risks. … The reasons for discontinuing banding related to difficulties of implementing and maintaining the practice and consequently, potential negative impacts on yields and profits. Banding requires two major tasks—the initial banding and the subsequent two (or sometimes three) cultivations between the rows. In effect, it substitutes time, labor, and equipment for out-of-pocket pesticide costs and thus has important ripple effects in terms of time, labor, management, flexibility, and individual control.”

“Banding tasks need to be done on a timely basis; a shortage of labor during windows of cultivation opportunity can mean the growth of weeds to the point where they inhibit crop progress and effective cultivation, and thus decrease yields. Some operators report inabilities to find labor. We have ample evidence of the decline of availability of hired labor in most rural communities… Those people willing to custom cultivate are usually farmers themselves. And home farm demands, overextended commitments, and bad weather and machinery breakdowns can easily combine to delay or postpone custom cultivation beyond optimal periods.”

“Cultivation of large banding acreages requires continuous weeks of effort. Although such commitments were common practice before the broadcast use of herbicides, farmers who rejected banding criticize cultivation as too time-consuming, intrusive into other needed work, ineffective, and certainly one of those jobs they were not eager to resume.”

“Some farmers have purchased banding-related machinery or attempted to experiment with the practice only to find it too difficult to incorporate into tight farming schedules. … Effective cultivation also creates dependency on other external factors. In years with a particularly wet spring and early summer, for example, cultivation has to be postponed.”

“In summary, operators who abandon banding do so not because of water quality issues or lack of knowledge or even additional costs; they drop it because of time and labor requirements, custom labor constraints, loss of control over operations, and potential risks to yield and profitability. … In essence, while banding may work for water quality, it is not working for most farmers.”

¹Authors: A.S. Davis*, J.D. Hillª, C.A. Chaseº, A.M. Johannsº and M. Liebmanº.
Affiliations: *USDA ARS; ªUniversity of Minnesota; ºIowa State University
Title: Increasing cropping system diversity balances productivity, profitability and environmental health.
Publication: PLoS ONE. 2012. 7(10): e47149.

²Author: Mark Bittman
Headline: A Simple Fix For Farming
Publication: The New York Times. October 21, 2012.

³Authors: J.S. Rikoon, R. Vickers and D. Constance
Affiliation: Department of Rural Sociology, University of Missouri-Columbia.
Title: Factors affecting initial use and decisions to abandon banded pesticide applications.
Publication: Agricultural Research to Protect Water Quality Conference Proceedings. 1993. February 21-24, Minneapolis, Minnesota.