October 2005
ToxTalk
The General Accounting Office (GAO) audit of the U.S. Department of Agriculture’s (USDA) IPM program during 2000-2001 was conducted to determine whether USDA appropriately met the stated goal of the 1994 IPM Initiative, which was to foster adoption of IPM practices on 75% of U.S. planted crop land by the year 2000. Indeed, from 1994 through 2000, adoption of IPM practices increased from around 40% to nearly 70%, yet pesticide use (in terms of weight per unit of area) increased slightly. The GAO concluded that USDA’s IPM program had not yet developed the methods for measuring IPM’s environmental and economic results, among other things.
However, during this same time frame, national agriculture was changing drastically with the advent of genetically modified (GM) crops. Many of these crops were altered to withstand the herbicide glyphosate. Although there are many benefits to the use of these crops, one unintended consequence of their use is the amount of product required. Glyphosate, which is applied at over a pound per acre, replaced many herbicides which were being applied at grams per acre. The national conversion to glyphosate-resistant crops masked the reduction in higher toxicity pesticide (usually insecticide) use.
As a rebuttal to the GAO findings, this analysis will demonstrate that Florida fresh market tomato growers are committed to IPM principles and practices. Lack of adherence to these principles often leads to resistance, which in turn leads to crop loss or failure. The USDA has collected and published pesticide use data on select Florida crops every other year from 1992 through 2004. Fresh market tomatoes have been enumerated each of these years, for a total of seven data sets. Data for all eight active ingredients examined in this analysis are available for even-numbered years. The total pounds of each active ingredient used in Florida fresh market tomato were divided by the amount of Florida tomato acreage (between 40,000 and 50,000 acres) each year. The values from 2004 were compared to peak years of use (either 1992 or 1994 for the eight active ingredients).
Year
Total Insecticide Use (Pounds)*
Tomato Acreage
Pounds/Acre
1992
227,300
49,400
4.6
1994
385,100
47,900
8.0
1996
129,100
40,000
3.2
1998
85,400
40,600
2.1
2000
69,800
42,000
1.7
2002
77,400
45,000
1.7
2004
84,400
42,400
2.0
*Pounds of endosulfan, esfenvalerate, methamidophos, methomyl, and permethrin combined.
From the table, it is apparent that use reductions of between 74 and 79% (in comparison to the peak year of 1994) have occurred since 1998, with the last year of data (2004) reflecting a 75% reduction in restricted or “Danger”-labeled insecticide use in Florida tomato production.
A similar but less dramatic reduction has occurred in fumigant use in Florida fresh market tomato production. In this case, the impetus for reduction in use has come mainly from the methyl bromide phaseout that is occurring under the Montreal Protocol on Substances that Deplete the Ozone Layer.
Year
Total Fumigant Use (Pounds)*
Tomato Acreage
Pounds/Acre
1992
9,053,400
49,400
183
1994
10,109,500
47,900
211
1996
7,187,800
40,000
180
1998
6,844,300
40,600
169
2000
8,922,900
42,000
212
2002
7,077,100
45,000
157
2004
7,518,300
42,400
177
*Pounds of methyl bromide and chloropicrin combined.
Use reductions of between 17 and 26% (in comparison to the peak year of 2000) have occurred since 2002. The use of methyl bromide will continue to shrink, until it is completely phased out as an agricultural pesticide. However, its use may well be supplanted by methyl iodide, which would likely carry the restricted use status and “Danger” labeling.
Use of the only restricted herbicide (paraquat) in Florida-grown fresh market tomatoes has also decreased from the historic highs. In this case, use reduction is cost and IPM related. Glyphosate pricing was easing during the decade of the 90's, and paraquat-resistant weeds (such as American black nightshade and goosegrass) were noted in several areas of the state.
Year
Total Paraquat Use (Pounds)
Tomato Acreage
Pounds/Acre
1992
33,000
49,400
0.67
1994
20,600
47,900
0.43
1996
22,900
40,000
0.57
1998
12,600
40,600
0.31
2000
10,000
42,000
0.24
2002
4,200
45,000
0.09
2004
19,400
42,400
0.46
Use reductions of paraquat between 31 and 87% (in comparison to the peak year of 1992) have occurred since 1998 in Florida fresh market tomato production.
This reduction in use of restricted and “Danger”-labeled pesticides decreases potential hazards for mixer/loader and application personnel, as well as harvest crews. It also reduces potential hazards for associated wildlife and watersheds. Unfortunately, data that would document these trends do not exist. However, data are available for pesticide residues in vegetables, including fresh market tomato. The USDA’s Pesticide Data Program has reported residues of pesticides in fresh market tomato yearly from 1996. Reduced spraying of restricted pesticides is reflected in a 50% decrease in methamidophos residues (from 0.016 PPM to 0.008 PPM) in fresh market tomato from the period 1997-1998 to 2003. These values are far from the 1.0 PPM tolerance in tomato for methamidophos, demonstrating proper use of the insecticide when employed for pest control.
Another manner to measure IPM adoption is use of “reduced risk” pesticides, which are generally more selective than restricted or “Danger”-labeled pesticides. Insecticides such as spinosad and imidacloprid have been adopted by Florida fresh market tomato growers as early as the mid to late 90's, and 2004 data have revealed use of other such materials including indoxacarb, pymetrozine, and pyriproxyfen. None of these insecticides are restricted or “Danger”-labeled when purchased individually in Florida. It is important to note that these “reduced risk” products are always more expensive than older, off-patent materials. Extension agents and professionals have been essential in educating Florida tomato growers, so that costs using “reduced risk” materials are commensurate with previous costs.
