Leonard P. Gianessi Cressida S. Silvers Sujatha Sankula Janet E. Carpenter

Transcription

1 Plant Biotechnology: Current and Potential Impact For Improving Pest Management In U.S. Agriculture An Analysis of 40 Case Studies June 2002 Herbicide Tolerant Strawberry Leonard P. Gianessi Cressida S. Silvers Sujatha Sankula Janet E. Carpenter National Center for Food and Agricultural Policy 1616 P Street, NW Washington, DC Phone: (202) Fax: (202) ncfap@ncfap.org Website: Financial Support for this study was provided by the Rockefeller Foundation, Monsanto, The Biotechnology Industry Organization, The Council for Biotechnology Information, The Grocery Manufacturers of America and CropLife America.

2 8. STRAWBERRY Herbicide Tolerant Production The 1997 Census of Agriculture indicates that there were 5,227 acres of strawberries in nine Northeastern states (Connecticut, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Vermont) [6]. Strawberry acreage in these nine states has declined steadily: 7,909 acres in 1982, 7,238 acres in 1987, and 6,000 acres in 1992 [5]. Table 8.1 delineates strawberry acreage by state in the Northeast from 1982 to Strawberry fields in the Northeast typically yield about 4,000 pounds of strawberries per acre with a value of about $1 per pound [14]. About 98% of the strawberry production in the Northeast is sold fresh, with the majority sold directly from the farmer to the consumer [7]. Most strawberries in the Northeast are grown in matted row culture, known by this name because plants are allowed to runner freely within a certain row width to produce solid beds (or mats) of plants [1]. Dormant plants are planted in mid-spring and are not harvested until the following year. Bearing plantings are renovated each year in July after harvest. This consists of removing foliage, narrowing rows, an herbicide application, and then allowing runner plants to fill in the rows again. Plantings normally are maintained for three to five years [1]. Weed Control Weeds are cited as the largest problem that growers face in strawberry production in the Northeast [1]. Weeds cause more economic loss in Northeast strawberries than diseases and insects combined [13]. Strawberry plants are shallow rooted and compete poorly against weeds for sunlight, nutrients and moisture. Weeds can exacerbate disease problems by restricting air movement through the canopy. Uncontrolled weed infestations can reduce yields up to 40% or more [2]. Weed control is especially difficult with the matted row system since there is so much bare cultivated soil for much of the first year. Weeds will take over a strawberry bed and reduce yields severely [13]. The total number of acres of strawberries in the Northeast has declined 2

3 greatly in recent years, in part, because of weed pressure in matted row production farms. Fields heavily infested with hard-to-control weed species sometimes have been abandoned [17]. There are very few herbicides remaining for use in strawberries and only one pre-emergent herbicide (napropamide) that is labeled for use in new strawberry plantings. Immediately after planting, napropamide typically is applied for pre-emergent weed control. Many growers use terbacil immediately after mowing in July, but this herbicide can injure strawberries. There are no herbicidal chemical options to control yellow nutsedge once the strawberry crop is established. Handweeding and cultivation are ineffective, or even deleterious, because the nutlets produced by the weedy plants are spread [1]. Canada thistle and dandelions are perennials that are the target of numerous cultivations in order to exhaust taproot reservoirs. Cultivation and handweeding are begun right after planting and are repeated as often as required to prevent the establishment of weeds. Mechanical cultivation and handweeding may again be necessary when herbicides lose their effectiveness, usually about two months after planting. It has been estimated that cultivation and handweeding are practiced on essentially 100% of the strawberry acreage in the Northeast [4]. In the East, few acres of strawberries are grown because growing them is labor intensive. Handweeding and cultivation account for the greatest labor input (75% of labor hours in the planting year). 85% of the strawberries consumed in the East are grown outside the region. In the late 1980 s, the registrations for two herbicides used widely in strawberries were canceled voluntarily by their registrants: chloroxuron and diphenamid. In the mid-1980 s, it had been estimated that these two herbicides had been used on 35% to 55% of the strawberry acreage in the Northeast [9, 10, 11]. Chloroxuron and diphenamid provided residual preemergent control of 3

4 many weed species. Chloroxuron was particularly useful since it could also be applied postemergence for control of small broadleaf weeds without damage to strawberry plants. Since the cancellation of diphenamid and chloroxuron, certain broadleaf weed species have become more of a problem in the Northeast [18]. In 1981, it was estimated that 40 hours of hand hoeing and weeding per acre were used in the establishment year of strawberries in New York while 10 hours per acre were required in fruiting years one through three [12]. In 1998, it was estimated that 52 hours per acre were required for handweeding in the establishment year and 39 hours per acre typically was required in the bearing years [13]. Geese are used occasionally for weed control in new strawberry fields because they preferentially eat young grasses. They are especially useful in wet years when grasses are abundant, herbicides do not work and the fields are too wet to cultivate. Six to eight geese can keep an entire acre free of grasses [13]. However, the geese must be confined to the strawberry field with a fence, and they require supplemental food and water and a shelter. By placing the supplemental grain, the shelter and the water at different corners of the field, the geese will be compelled to move throughout the field rather than stay in one place. Geese can be messy and may repel some pick-your-own customers [13]. Geese work best in a newly planted strawberry field. They should be introduced when the weeds are just starting to germinate they will not readily eat established grasses. One-month-old birds are best as they have large appetites. With recent concerns over microbiological contamination of fruits and vegetables, geese should be restricted to nonfruiting fields [13]. Pennsylvania State University weed scientists rate herbicides labeled for use in strawberries in terms of their effectiveness in controlling 35 weed species [3]. The two registered preemergent herbicides, napropamide and terbacil, provide fair to good control of many annual broadleaves, poor to fair control of perennial grasses, poor control of perennial broadleaves and good control of annual grasses. Napropamide is rated as providing good control of 18 species, fair control of 2 and poor control of 15. Terbacil is given good control ratings for 22 weed species, fair ratings 4

5 for 7 and poor ratings for 6. Glyphosate is assigned a good control rating for 32 of the weed species, a fair rating for 1 and a poor control rating for 2. Herbicides are used on approximately 95% of the strawberry acreage in Northeastern states [4]. Table 8.2 delineates the use of the seven herbicides that typically are used in the nine Northeastern strawberry producing states. As can be seen, the preemergence herbicides napropamide and terbacil are the major herbicides applied typically to 67%-78% of the acreage. Sethoxydim and 2,4-D are used postemergence on 54%-61% of the acreage. Paraquat is used as a non-selective burndown or for hooded spraying between rows on 13% of the acreage. Table 8.2 indicates that strawberry growers in the Northeast currently use 24,000 pounds of active ingredient with a material cost of $431,000. Assuming 95% of the acreage is treated implies an annual use rate of 4.9 pounds of active ingredient per acre with an average per acre cost of $87 for materials. Strawberry cost of production budgets delineate the typical weed control operations practiced in the planting year and bearing years. These costs are displayed in Table 8.3. As can be seen, weed control costs total approximately $500 per acre per year. The typical acre receives two to four herbicide treatments, three to four cultivations and three to four handweeding operations. Assuming that all strawberry acres in the Northeast are handweeded and cultivated three times on average, implies a total expense for handweeding of $1.2 million per year and for cultivation of $0.465 million per year. Herbicides are estimated to cost $0.67 million per year (95% of the acres treated at $135 per acre). Transgenic Strawberries Research has been ongoing to develop strawberry varieties that are tolerant to glyphosate, the active ingredient in Roundup herbicide. This will allow the use of glyphosate over the top of strawberries without crop damage. A number of strawberry cultivars have been transformed with an EPSPS gene from a soil bacterium that confers tolerance to glyphosate applications. The strawberry plants currently are being screened for vegetative and floral tolerance to commercial application rates of Roundup [8]. 5

6 Estimated Impacts It is assumed that strawberry growers in the Northeast would make three applications of glyphosate with the Roundup Ready strawberries. Each application would consist of 0.75 pound of active ingredient per acre and would cost $12 per acre for the herbicide and $7 per acre for each application. In addition, it is assumed that a $100 per acre technology fee would be charged for use of the Roundup Ready technology. These estimates imply a total per acre cost of $157 per acre for the Roundup Ready Strawberry System. It is assumed that these three applications would replace the three herbicide applications that typically are used currently ($135 per acre), three handweedings ($234 per acre) and one of the cultivations ($30 per acre). Thus, the Roundup Ready Strawberry System would be $242 per acre less costly for weed control than the current system. In the aggregate, the Roundup Ready Strawberry System would save Northeastern strawberry growers $1.265 million per year in weed control costs and eliminate the need for 203,000 hours of handweeding. As noted above, strawberry growers currently use 4.9 pounds of active ingredient per acre while in the Roundup Ready Strawberry System 2.25 pounds of active ingredient per acre would be used. In the aggregate, strawberry growers would apply 13,851 pounds less active ingredient per year in the Roundup Ready Strawberry System. Roundup resistance could have a greater impact on strawberries than, perhaps, on any other crop because labor costs would be reduced dramatically while yields would likely increase [7]. Table 8.4 shows a distribution of the impacts by state. 6

7 TABLE 8.1: Strawberry Acreage: Northeastern States Connecticut Maine Maryland Massachusetts New Hampshire New Jersey New York 1,538 1,991 2,365 2,817 Pennsylvania 1,409 1,547 1,899 2,064 Vermont Total 5,227 6,000 7,238 7,909 Source: [5,6] TABLE 8.2: Herbicide Use: Strawberry Acreage, Northeast Acres % Acres Total Treated 1 Treated 2 Lbs AI 1 $/Lb AI 3 $(000) 2,4-D 3, , DCPA , Glyphosate 1, Napropamide 4, , Paraquat Sethoxydim 2, Terbacil 3, , , From [15] total usage in the nine Northeastern states 2 Acres treated/5,227 3 From [16] 7

8 TABLE 8.3: Strawberry Weed Control Expenses: New York # of Hours per Hours Planting Year Trips Trip Total $ Total Herbicides Cultivation Handweeding (Total All Costs) (2,707) Bearing Years Herbicides Cultivation Handweeding (Total All Costs) (5,233) Source: [13] TABLE 8.4: Herbicide Tolerant Strawberry Impacts: Northeastern States Acreage Cost Savings 1 (000$) Herbicide Use Impact 2 (lbs/ai) Connecticut Maine Maryland Massachusetts New Hampshire New Jersey New York 1, Pennsylvania 1, Vermont Total 5, Calculated at $242/A 2 Calculated at 2.65lbs AI/A 8

9 References 1. USDA, Crop Profile for Strawberries in Pennsylvania, available at: 2. USDA, Crop Profile for Strawberries in New York, available at: 3. Small Fruit Production and Pest Management Guide , Penn State College of Agriculture, Sorenson, Kenneth A., et al., The Importance of Pesticides and Other Pest Management Practices in U.S. Strawberry Production, USDA, 1-CA USDC, 1987/1992 Census of Agriculture, Volume 1, Geographic Area Series, (separate volumes). 6. USDA, 1997 Census of Agriculture, Volume, 1 Geographic Area Series. 7. Pritts, M.P., Are We Ready for Roundup Ready Strawberries?, paper presented at the 2001 meeting of the Weed Science Society of America. 8. Morgan, Alison, and Charleen Baker, Production of Herbicide Tolerant Strawberries Through Genetic Engineering In 1999 Proceedings International Conference on Methyl Bromide Alternatives and Emissions Reductions. 9. Meade, J.A., Rutgers University, Weed Survey for Pritts, Marvin, Cornell University, Weed Survey for Kuhns, L.J., Penn State University, Weed Survey for Phelps, Joel B., and R. Brian Howe, Planning Data for Small Scale Commercial Vegetable and Strawberry Production in New York, Cornell University, AE Res , October Pritts, Marvin, and David Handley, eds., Strawberry Production Guide for the Northeast, Midwest and Eastern Canada, Cooperative Extension, NRAES-88, USDA, Noncitrus Fruits and Nuts: 2000 Preliminary Summary, National Agricultural Statistics Service, January Gianessi, Leonard P., and Monica B. Marcelli, Pesticide Use in U.S. Crop Production: 1997, National Center for Food and Agricultural Policy, November 2000, available at: 9

10 16. Gianessi, L.P., and M.B. Marcelli, Prices of Pesticide Active Ingredients (1996), National Center for Food and Agricultural Policy, October Ahrens, J.F., Control of Field Violet in Strawberries with Acifluorfen and Oxyflourfen In 1988 Proceedings Northeastern Weed Science Society. 18. Pritts, Marvin., Cornell University, personal communication, June