April 2005

Pesticide Potpourri

  • wpdoc16.gifWhat starts as a problem in Brazil often winds up in Florida, as soybean rust has demonstrated. Now, a potentially crippling citrus disease has been reported in that country. Huanglongbing, or citrus greening (CG) was first detected in Brazil in March 2004 and has spread to 46 districts in Sao Paulo state. The disease has already killed millions of trees in Thailand and South Africa, and the only way to control it once established is to uproot trees. The Brazilian Agriculture Ministry issued an Executive Order (EO) that requires growers to pull up any infected orange trees and hedgerows, and also requires removal of certain ornamental plants in urban areas. The EO also ordered that saplings be grown only in roofed greenhouses, has prohibited transportation of saplings without certification, and introduced mandatory annual inspection of healthy groves and twice-yearly inspection of infected groves. Growers are obliged to notify authorities on discovering the disease and have 15 days to pull up plants. Should they not comply with the EO, local authorities will do it for them. In extreme cases where growers obstruct eradication, prison sentences as long as five years exist. Citrus greening is currently concentrated in the Araraquara region of Sao Paulo state but has spread north and south. The incidence of CG remains very low but is rising. Trees infected with CG become stunted and produce small, inedible fruit. In 2005, the Sao Paulo state orange crop will total 354.3 million 41-kg boxes, down slightly from the year before. (Promed-plant, 3/23/05).
  • Dioxin levels in meat have decreased over the past decade. In pork, the dioxin level fell by 80 percent, from 1.47 parts per trillion (ppt) to 0.28 ppt. In beef, residues dropped by a third, from 1.38 to 0.93 ppt. The consultant working on behalf of the Food Industry Dioxin Working Group also stated that none of the levels in food exceed the international standard for these contaminants. At this same meeting, research was presented that demonstrated humans are less susceptible to the effects of dioxin than are rodents. (Chemical Regulation Reporter, 3/28/05).
  • wpdoc17.gifNew tThe rapidly growing greenhouse tomato industry has become an important part of the North American fresh tomato industry. Greenhouse tomatoes now represent an estimated 17 percent of U.S. fresh tomato supply. Even though greenhouse tomatoes still constitute a minority share of the U.S. fresh tomato market, their influence is concentrated and growing in retail channels, which represent about half of U.S. tomato consumption. Around 37 percent of all fresh tomatoes sold in U.S. retail stores are now greenhouse, compared with negligible amounts in the early 1990s.ypes of tomatoes, improved varieties and handling, and positive health benefits associated with eating tomatoes have all contributed to a 30-percent rise in U.S. consumption of fresh tomatoes since 1985, with estimated 2003 annual per capita consumption level around 20 pounds. Growth in the greenhouse industry has challenged growers of fresh field tomatoes. With rising consumption of all tomatoes, field tomato sales in the U.S. retail market increased through 2001, in part due to new products, such as grape tomatoes. But in 2002, the combined retail sales volume of all field tomato types began to slip. Field tomatoes still dominate the growing foodservice market (restaurants, schools, hospitals, etc.) and foodservice sales are increasingly essential to the health of the field tomato industry. (USDA Amber Waves, April 2005).
  • wpdoc18.gifThe University of Florida reported on March 1, that scientists have found highly contagious soybean rust disease in a field in Pasco County, the first detection of the disease this year, adding, "The most recent detection of soybean rust in Florida is a find February 23 on overwintered foliage of kudzu in Dade City, Pasco County. That is the most southerly find so far in Florida." A spokesman for the American Soybean Association, was quoted as saying, "We anticipated rust was going to be in the South all winter. We knew there would be areas where it would not freeze enough to kill the rust spores." Traders at the Chicago Board of Trade brushed off Florida's finding, saying it was too early to worry about the spread of soybean rust. Planting season for soybeans does not start until May. (Reuters, 3/1/05).
  • wpdoc19.gifAs early as this year, China could start commercial production of a new breed of genetically engineered rice, which some say would provide an environmentally friendly answer to the food problems of the world's poor. The Xa21 strain, which was developed through publicly funded international research, is resistant to bacterial blight - one of the most serious crop diseases in Africa and Asia. It is derived from wild rice, and has emerged as the front-runner in the race to be the first GMO rice crop, ahead of insect- resistant Bt-rice. (Reuters, 3/9/05).
  • Renate Künast, German minister for Agriculture and Consumer Protection, is facing allegations of exerting undue political influence on science after it emerged that she instructed government researchers to cancel at least two projects into genetically modified crops. Künast is a member of the Green Party, which forms a coalition government with Chancellor Gerhard Schröder's Social Democrats, and the party strongly opposes agro-biotechnology, arguing that it is unsafe and that risks cannot be properly assessed. On March 9, the German parliamentary opposition is scheduled to put a series of questions to the government about revelations that first came to light on February 18, when the monthly newsletter Laborjournal reported that in September of last year, two researchers had received letters from Künast's office requiring them to stop specific research projects and not comment publicly on them. Joachim Schiemann from the Federal Biological Institute for Agriculture and Forestry and Reinhard Töpfer at the Federal Research Institute for Breeding of Cultivated Plants (BAFZ) had been working on methods to eliminate antibiotic resistance genes from genetically modified potatoes, canola, and wine. When contacted by The Scientist, neither Schiemann nor Töpfer wanted to comment publicly on the controversy, but Jörg Hinrich Hacker, vice president of the German Research Society, was cited as telling The Scientist that Künast's edict reflected the Green Party's political position on genetically modified crops, adding, "They do not want this technology as a whole. Any research eliminating the risk would destroy their argument." (The Scientist, March, 2005)
  • wpdoc20.gifIn California, 360 metric tons of pyrethroid pesticides are used annually. University of California-Berkeley researchers have conducted a study to determine the harmful effects of this class of pesticides on aquatic organisms through sediment residues. What they have found is a trend toward using newer compounds that can be more toxic to aquatic life. Increased monitoring of organophosphates resulted in a call for decreased use of these once popular pesticides. This may have only allowed for them to be replaced with pyrethroids. Peaking in 1993, pyrethroid use in the state’s agricultural system declined in the later 1990s but has shown a 25 percent increase in the past few years. Of the five pyrethroids used in 1993, permethrin accounted for 60 percent. In 2002, the number of pyrethroid compounds in use doubled to 10, but permethrin declined to 45% of the total. Newer compounds were found to be 20 times more toxic than permethrin. The team of researchers studied six pyrethroids in three sediments taken from California’s Central Valley, where two-thirds of the state’s cropland is found. Study results showed acute toxicity and growth impairment in the amphipod Hyalella azteca, a sensitive test species. Except for permethrin, most pyrethroids would be acutely toxic to H. azteca at concentrations only slightly above detection limits. The six compounds tested in order of decreasing toxicity were bifenthrin, lambda-cyhalothrin, deltamethrin, esfenvalerate, cyfluthrin and permethrin. Little research exists on the toxicity and prevalence of pyrethroids in sediments despite the finding that sediments are likely the primary reservoir for residues - not the dissolved phase as in previous studies. (Alliance Communication Group, 3/14/05).
  • wpdoc21.gifThe Iowa House voted on March 14 to block local governments from regulating the use of certain agricultural seeds. Rep. Sandra Greiner, R-Keota, who sponsored the bill, was cited as saying it established the state as the ultimate authority over agricultural seed, adding, "There's been a lot said and claimed about this bill, but that is primarily what this bill does." Greiner was further cited as saying that no Iowa cities or counties have tried to regulate what can be planted, but some in Jefferson County have indicated an interest in declaring one area in that county an organic crop zone. The use of crop seeds in Iowa is regulated by the Iowa Department of Agriculture and Land Stewardship. Iowa is one of 23 states to move ahead with measures that would stop local governments from taking action against genetically modified seeds. (Sioux City Journal, 3/15/05).
  • wpdoc22.gifFrench experts were cited as saying they had found the key to a disease that widely affects commercial rubber trees and hits producers deeply in the pocket. Rubber tree bark necrosis, which first came light in Cote d'Ivoire in 1983, causes the latex sap, tapped by a cut made on the tree's trunk, to dry up. For years, scientists have wondered if the disease was viral, perhaps transmitted by an insect or even the blade used by plantation workers to make the tapping cut. But a multi-discipline team from France's Institute for Development Research (IRD) and other agencies has found after exhaustive detective work that there is a far simpler but quite unexpected cause: the bulldozer. The scientists noticed that trees with bark necrosis often had poorly developed root systems and were invariably located near plantation paths used by bulldozers, IRD said in a press release. (Agence France Presse, 3/24/05).

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