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Cotton Varieties

Cotton yield has been significantly influenced by the biotech revolution in the United States. The incorporation of transgenic pest management traits in cotton, coupled with continued cotton variety improvement, has accelerated the rate of yield over the past ten years by approximately 33 percent, compared to the rate of cotton yield improvement before the introduction of transgenic cultivars59. SSP has funded many University-based field trials of transgenic varieties with herbicide-resistant and combined insect- and herbicide-resistant traits, as well as numerous studies of cotton breeding and variety evaluation.

Our survey included questions that considered the extent of use of Roundup Ready and Bt cotton and what impact using these varieties has had on profitability. For growers who plant Bt cotton, we asked a general question about the impact on their overall use of insecticides as well as several questions on the use of specific pesticide chemicals (organophosphates and pyrethroids). Finally, we asked growers to list up to four varieties they plant the most and presented them with a list of factors that potentially influence their decisions about what varieties to plant. For each factor, growers selected a number from 1 (not at all important) to 4 (very important).

Results

Table 2 shows grower responses to questions about Roundup Ready and Bt cotton. More than 80% of growers report planting both Roundup Ready and Bt cotton. We also observed that less than one-third (29.6%) report planting Roundup Ready Flex cotton. For those who plant either type of cotton, more than two-thirds report that is has had a positive impact on profitability. In addition, the overwhelming majority (91.8%) of those who plant Bt cotton report that it has decreased their overall use of pesticides. More specifically, 63.1% of Bt cotton users said it decreased their use of organophosphates and 79% said it decreased their use of pyrethroids.

Our survey included questions that considered the extent of use of Roundup Ready and Bt cotton and what impact using these varieties has had on profitability. For growers who plant Bt cotton, we asked a general question about the impact on their overall use of insecticides as well as several questions on the use of specific pesticide chemicals (organophosphates and pyrethroids). Finally, we asked growers to list up to four varieties they plant the most and presented them with a list of factors that potentially influence their decisions about what varieties to plant. For each factor, growers selected a number from 1 (not at all important) to 4 (very important).

Table 2 - Roundup Ready/Bt Cotton and Profitably

* reflects proportion of growers planting both Roundup Ready and Roundup Ready Flex

Specific Varieties Planted

Consistent with the finding that the overwhelming majority of growers are planting genetically-modified (GM) cotton. All but 2 of the specific varieties that growers identified as planting the most of were GM. Delta and Pineland (D&PL) varieties were the most common (24), followed by Stoneville/ Fibermax (19 ) and Phytogen (9).

Figure A shows grower responses to items about factors in their decisions about which varieties to plant. Specifically, the graph depicts the proportion of growers who indicate that a factor is very important. Yield potential was by far the most critical, with 92.5% of growers saying this was a very important factor. Nearly two-thirds (63.1%) indicated that fiber quality was very important and more than half (50.7%) identified plant vigor. Seed cost was very important 42.5% of respondents. The remaining factors of diseases tolerance, time to maturity, nematode tolerance and cool germ value were deemed to be very important by a lesser proportion of growers.

Figure A - Importance of Factors In Varietal Decisions

Analysis

Choice of varieties to plant

The high degree of importance that growers assign to yield potential and fiber quality is consistent with the current understanding of best management practices5. However, other recommended best practices (e.g. selecting varieties for disease or nematode tolerance and cool germ value) appear to be relatively less important factors in grower decisions.

Conclusions

Although respondents ascribed relatively lower value to disease and nematode tolerance when answering this question, they nonetheless responded that they relied substantially on such traits in other questions on pest management. Therefore, we conclude that although the survey question on variety decisions (Question 19), did not ask them to rank the various choices, they may have unconsciously done so. Apparent preference for such straits may indicate a predisposition to plant new varieties that better incorporate tolerance to nematodes as well as other pests as a means to reduce reliance on chemical controls.

Analysis

Roundup Ready Cotton

Evidence regarding the use of varieties designed to tolerate over-the-top applications of glyphosate is clear. The widespread use of Roundup Ready cotton we observed is consistent with several independent reports revealing that up 98% of acreage planted in Georgia in 2005 was composed of transgenic cotton 89,46. In addition, the Roundup Ready® trait was found to be the innovation most frequently mentioned as important by a majority of growers and other experts surveyed by others 59. On the other hand, the relatively modest use of Roundup Ready Flex that we observed conflicts with previous predictions of higher levels of usage for varieties with this trait58. However, the relatively recent introduction (2006) of Flex cotton, combined with the relatively low yield potential of some varieties and some state recommendations against its use, offer a likely explanation for this finding.

Several studies have found yield of transgenic varieties, including "stacked" varieties, to be quite variable. In addition, while Liberty Link (LL) and Roundup Ready varieties were the least expensive, they are only in the middle or bottom for yield and net return45. There is also evidence that some high-yielding conventional (non-transgenic) cultivars can compete with, and in some cases, out-perform transgenics in yield and net return13,67. While there are high-yielding and profitable cultivars with non-transgenic, herbicide-resistant and combined insect- and herbicide-resistant traits13. varieties with combined insect- and herbicide-resistant (BR and B2R) characteristics were generally the most expensive, but also among the most profitable10.

Other reports cite the benefit of adopting Roundup Ready varieties as being related to reductions in herbicide costs, tillage and scouting26. Marra et al 57, by compiling available public domain data on the impacts of transgenic cotton, concluded that growing transgenic cotton is more likely than not to be profitable in most years and most states compared to conventional varieties. Furthermore, Benbrook 7 supports the contention that farmers using RR cotton are saving money from herbicide resistant varieties, although this is largely because the price of herbicides has dropped so dramatically since 1996.

But while widespread adoption of Roundup Ready cotton would appear to affirm its benefits, new challenges have emerged that may ultimately affect grower profitability. For example, the intensive reliance on particular herbicides have resulted in weed shifts, with Amaranthus, annual grasses, dayflower (Commelina sp.), morning glory (Ipomoea sp.) and winter annuals becoming a problem18. Cotton Scientists have also noted that horseweed and giant ragweed have developed resistance to glyphosate54. and feel that such shifts are a significant economic concern to growers.(GA,FL,AL,MO,NC and TX)

Analysis

Bt Cotton

The widespread use of Bt cotton we observed can most likely be attributed to the superior bollworm/budworm control achieved and the resulting increase in lint yield and reduction in levels of crop loss 26. Moreover, it is clear from our survey results that growers perceive that adoption of Bt cotton has increased profitability while decreasing use of insecticides. This perception is consistent with conclusions of Marra et al.57 that adoption of Bt cotton was more likely than not to be profitable and reduce pesticide use in most years and most states.

Because Bt cotton provides excellent control of tobacco budworm as a pest, a significant amount of cotton acreage no longer needs to be sprayed for lepidopteran pests, and crop losses in the presence of management from heliothine insects was lessened from an average of 3% to 1.5% in 2005 104. In addition, Bt cotton adoption has been shown to have reduced insecticide use markedly in Arizona and Mississippi7. The results of our survey are consistent with earlier predictions that the overall number of insecticide applications against the bollworm/budworm complex would fall in response to adoption of Bt cotton27.

There appears to be general agreement with Frisvold 27 that "economic variables affecting grower gains from adoption of Bt cotton have influenced the rate of adoption" of this technology. It has been estimated 41 that the cost of bollworm/budworm control in 1995 (a severe pressure year), approximated $215 million, and that, combined with production loss, total economic loss to this pest complex alone was approximately $476 million.

Several international studies 42,34,77,8 have also found that gains achieved from the combination of increased yield and decreased pesticide costs outweighed increased seed costs and thus resulted in improved gross margins.

As seen in other aspects of the production system, in developing approaches for dealing with some issues, new problems can emerge. Decreased use of organophosphates has coincided with increased damage from and need to spray for pests that were formerly controlled by bollworm sprays, in this case, the stink bug complex104. Grower concern that the increased cost of dealing with stink bugs may serve to offset some of the increases in profitability from using Bt cotton may partly explain the relatively lower number who feel that Bt cotton has increased their profitability. In addition, variability in bollworm/budworm pressure from year to year in the U.S., purchasing the more expensive Bt transgenic seed may not be the most economical decision for all farmers in all years26.

Nonetheless, even considering tech fees and increased bug damage, research in North Carolina 4 found slightly lower insect control costs in Bollgard cotton compared to conventional.

Conclusions

Glyphosate Resistant and Bt Cotton

According to a recent report,59 cotton yield has been significantly influenced by the biotech revolution in the United States. Biotech cotton traits, coupled with continued cotton variety improvement, have accelerated the rate of yield increase over the past ten years by approximately 33 percent compared to the rate of cotton yield improvement before the introduction of transgenic cultivars.

Grower self assessment and research results lead us to conclude that transgenic cotton has improved profitability, despite a substantial amount of year-to-year, site-to-site and varietal (yield and quality) variability. However, we would note the suggestion13 that profitability may be more closely associated with yield potential than with pest management costs, and that growers should therefore avoid selecting transgenic cultivars that have high technology fees but low yield potentials or that produce cotton with poor fiber quality. Given the inherent variability in variety cost versus yield and quality factors, additional research to further identify cultivars with high yield and quality would appear to be a good investment. Demonstration that transgenic cultivars can consistently result in maximal profitability will likely improve grower knowledge about how best to take advantage of the technology.

 

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