CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Greenhouse Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Field Evaluations of Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . .4 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Greenhouse Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Field Evaluations of Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . .7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

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EVALUATION OF COMMERCIAL COTTON VARIETIES FOR RESISTANCE AND TOLERANCE TO THE RENIFORM NEMATODE IN ALABAMA
S. Usery, K.S. Lawrence, C.H. Burmester, R. Akridge, K. Glass, and G..W. Lawrence

INTRODUCTION
he reniform nematode (Rotylenchulus reniformis) has rapidly become the most damaging nematode pest of cotton in the state of Alabama. Since initial identification in 1959, the reniform nematode has spread rapidly throughout cotton-growing regions in Alabama. It is estimated that the reniform nematode causes more than a 9 percent yield loss to Alabama cotton producers. Producers currently implement nematicides and crop rotations as their primary management tool against the reniform nematode. Nematicides such as Telone II and Temik 15G have proven effective at increasing yields but can be prohibitively expensive and offer only short-term protection from the reniform nematode. Although crop rotations with non-host crops such as corn and sorghum are effective in reducing populations and damage incurred by the reniform nematode, rotations with these crops are often prohibited by the lack of an economic return. The availability of a resistant cotton variety would be a profitable solution to yield reduction caused by the reniform nematode, but resistance has not been identified in upland cotton varieties. Tolerance to the reniform nematode would also be an effective management tool, but recent reports are conflicting and provide no information regarding commercially available varieties. Tolerance to several plant parasitic nematodes has been successfully identified and implemented in a wide variety of crops. Levels of tolerance to the root-knot nematode have been identified in cotton and successfully implemented in breeding programs. Several reports speculate that tolerance to plant parasitic nematodes is dependent on location and environmental conditions. Selection of a cotton variety that possesses some level of tolerance would not be a total solution to yield damage incurred from the reniform nematode, but would greatly aid its management.

T

K.S. Lawrence is an associate professor and Usery is a graduate student in the Department of Entomology and Plant Pathology at Auburn University. Burmester is a professor and Glass is a research associate in the Department of Agronomy and Soils at Auburn University. Akridge is superintendent at the Alabama Agricultural Experiment Station Brewton Research Unit. G.W. Lawrence is a professor in the Department of Entomolgy and Plant Patholgy at Mississippi State University.

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EVALUATION OF COTTON VARIETIES FOR RESISTANCE AND TOLERANCE TO NEMATODES

The current study focuses on identification of tolerance among currently available transgenic and non-transgenic cotton varieties in Alabama. Selection of varieties for testing was based on availability to Alabama cotton producers and suitability to the growing region. The objectives of this study were (1) to evaluate reproductive capacity of the reniform nematode on upland cotton varieties in the greenhouse, (2) to determine if tolerance exists by measuring variety yield suppression in the presence of the reniform nematode in multiple field environments, and (3) to determine if selected varieties adapted to Alabama are tolerant or resistant to the reniform nematode.

MATERIALS AND METHODS
Greenhouse Evaluations Greenhouse trials were conducted at the Plant Science Research Center of the Alabama Agricultural Experiment Station on the campus of Auburn University, Auburn, Alabama. Fifty-two transgenic and non-transgenic cotton varieties were evaluated for host suitability to R. reniformis and early season growth parameters. Fifty-two varieties were grown in 150cm3 conetainer® filled with a loamy sand soil. The soil was autoclaved and seeds were planted and allowed to germinate and grow for seven days, at which time standardized solutions of 1,000 reniform nematodes were pipeted into each container. Greenhouse experiments were arranged in a randomized complete block design with five replications and the test was repeated twice. Sixty days after inoculation, plants were harvested, nematodes were extracted from the soil, and eggs were removed from the roots. Reniform nematodes were extracted from the soil. Reniform nematodes collected from the soil and eggs extracted from the roots were counted separately with the aid of an inverted microscope and recorded. After enumeration of R. reniformis vermiform and egg populations, reproductive factor values (Rf = final population / initial population) were determined. Early-season growth parameters were evaluated. Fifty-two cotton varieties were planted and inoculated using the methods previously described. Twenty days following inoculation, plants were harvested. Plant shoots were cut at the soil line, measured, and a fresh weight was obtained. Following initial weight measurements, cotton shoots were dried in an 80.0°C drying oven for 48 hours and weights were recorded. Roots were washed to remove all soil and foreign matter. Root architecture was assessed by determining total root length, root diameter, root surface area, root projected area, root volume, and number of root tips. These analyses were obtained by utilizing WinRhizo software version 5.0 with a Hewlett Packard scanner. Root fresh weights and dry weights were also collected. Field Evaluations of Tolerance Field experiments were conducted throughout 2002, 2003, and 2004 in both north Alabama and south Alabama. The north Alabama test was located in a producer's field in Limestone County that was naturally infested with R. reniformis. The soil

ALABAMA AGRICULTURAL EXPERIMENT STATION

5

was classified as a silt loam. Plots were conventionally tilled in all years. Varieties were compared with and without a nematicide in all years. In 2002, 5 pounds per acre Temik 15G was applied to nematicide-treated plots. Temik 15G was applied at planting in the seed furrow with chemical granular applicators attached to the planter. In 2003 and 2004, 3 gallons per acre of Telone II was applied one month before planting. The Telone II was applied using a modified John Deere ripper/bedder injection device. Di-Syston 15G was used to control insects in non-Temik plots in 2002 and in all plots in 2003 and 2004. Varieties were planted on April 18, 2002, April 22, 2003, and April 29, 2004 with a MaxEmerge® plot planter. Plots consisted of two rows, 25 feet long with 40inch row spacing in all years. The 2002 test was arranged as paired plots in a randomized complete block design with four replications. The 2003 and 2004 tests were arranged in a split plot in a randomized complete block design with four replications. In all years, plots were sampled for reniform nematode populations at planting, mid-season, and maturity. All plots in 2004 were evaluated for early season vigor characteristics after planting at the two true leaf growth stage. A visual vigor rating on a 1-5 scale with 1 being the least vigorous and 5 being the most vigorous was performed. Stand counts and plant height measurements were determined on all plots in 2004. Plant height measurements consisted of a five plant sub-sample of each plot. Plots were harvested on September 30, 2002, October 14, 2003, and October 27, 2004. Seed cotton weights were recorded for each plot in all years. Thirty-two transgenic and non-transgenic cotton varieties were examined with and without the nematicide Telone II in south Alabama in Escambia County in 2003. The southern Alabama field was a sandy loam, naturally infested with the reniform nematode. The Telone II was injected at 3 gallons per acre one month prior to planting. The test was planted April 30, 2003. Di-Syston 15G was used to control insects in all plots. Plots consisted of one row, 25 feet long with a 38-inch row spacing and were arranged as a split plot in a randomized complete block design with six replications. All plots were sampled for R. reniformis populations at planting and maturity. The plots were harvested on October 25, 2003. Seed cotton was weighed and recorded at harvest.

RESULTS AND DISCUSSION
Greenhouse Evaluations All cotton varieties tested supported reniform nematode reproduction, with reproductive factors between 59.4 and 4.1 (Table 1). While statistical differences existed between total populations of reniform nematodes, the lack of any variety exhibiting a reproductive factor lower than 1.0 indicated that all varieties are susceptible to the reniform nematode. Reproductive factors of SG 105, DPLX 03Q301DR, DPLX 01W93BR, and FM 989 R were in the lowest 5 percent of the varieties tested. It was theorized that larger root systems of certain varieties could support more reniform nematode populations; however, the lack of a correlation between early sea-

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EVALUATION OF COTTON VARIETIES FOR RESISTANCE AND TOLERANCE TO NEMATODES

GREENHOUSE EVALUATIONS OF 52 COTTON VARIETIES FOR RENIFORM NEMATODE REPRODUCTION1
Variety SG 105 DPLX 03Q301DR DPLX 01W93BR FM 989 R DP 5690 R ST 4793 R STX 6848 R SG 747 SG 215 BR ST5599 BR STX 3636 B2R STX 4575 BR SG 521 R DP 432 R DP Deltapearl FM 991 R PM 1218 BR BCG 28 R DP 434 R DP 555 BR ST 5303 R DP 494 R BCG 24 R STX 4686 R STX 5454 B2R STX 6636 BR ST 4892 BR FM 966 LL FM 960 BR DP 493 DP 451 BR DP 458 BR ST 5242 BR FM 989 BR DP 449 BR FM 991 B2R FM 960 R DP 444 BR DP 424 B2R DP 5415 R FM 991 BR DPLX 00W12 DPLX 02T57R DP 436 RR PHY 410 R FM 958 LL DP 491 FM 960 B2R DPLX 02X39BR ST 4646 B2R BCG 50 R DP 488 BR LSD (P < 0.05) Reniform nematodes2 1646 i-k 520 k 595 k 833 jk 2124 h-k 3361 f-k 1151 jk 2441 g-k 3546 f-k 2078 h-k 1715 i-k 2472 g-k 1840 i-k 2673 g-k 4929 d-k 5122 c-k 7802 c-g 4738 e-k 4574 e-k 2001 h-k 5622 c-k 5817 c-k 1978 h-k 2943 g-k 2804 g-k 4581 e-k 10066 b-e 3811 f-k 3438 f-k 4612 e-k 3925 f-k 6034 c-k 4319 f-k 4604 e-k 15280 ab 6798 c-i 2094 h-k 10344 b-d 8490 c-f 7409 c-h 10626 bc 3623 f-k 4427 f-k 6273 c-j 5670 c-k 20487 a 18834 a 2457 g-k 4015 f-k 5524 c-j 3909 f-k 19699 a 5528 Reniform nematode eggs 2446 p 4252 op 5264 n-p 6682 m-p 9154 l-p 8285 l-p 11225 j-p 10480 k-p 10477 k-p 14160 i-p 16029 h-p 17266 g-p 17974 g-p 17582 g-p 18849 f-o 18669 f-o 16429 h-p 20291 e-n 20832 e-n 23828 e-l 21012 e-m 22017 e-m 25879 d-k 26072 d-j 26729 d-j 25161 d-k 19856 e-n 26858 d-i 27424 d-i 27115 d-i 28093 d-i 28712 d-i 30952 d-h 30720 d-h 20111 e-n 29123 d-i 34067 b-f 26085 d-j 28300 d-i 30214 d-h 27066 d-i 34067 b-f 34029 b-f 32316 c-g 34631 b-e 26291 d-j 28145 d-i 46543 a-c 48050 ab 47535 a-c 51325 a 39655 a-d 15582 Rf value3 4.1 4.8 5.9 7.5 11.3 11.6 12.4 12.9 14.0 16.2 17.7 19.7 19.8 20.3 23.8 23.8 24.2 25.0 25.4 25.8 26.6 27.8 27.9 29.0 29.5 29.7 29.9 30.7 30.9 31.7 32.0 34.7 35.3 35.3 35.4 35.9 36.2 36.4 36.8 37.6 37.7 37.7 38.5 38.6 40.3 46.8 47.0 49.0 52.1 53.1 55.2 59.4 --Shoot dry weight (g) 0.256 a-m 0.270 a-i 0.206 i-r 0.212 h-r 0.274 a-h 0.302 ab 0.261 a-k 0.239 b-n 0.259 a-l 0.297 a-c 0.252 b-n 0.267 a-j 0.198 k-r 0.201 j-r 0.229 e-q 0.228 e-q 0.297 a-c 0.199 k-r 0.216 g-r 0.231 c-p 0.236 b-p 0.227 e-r 0.163 qr 0.298 ab 0.170 p-r 0.292 a-e 0.222 f-r 0.228 e-q 0.219 g-r 0.172 o-r 0.246 b-n 0.250 b-n 0.290 a-e 0.281 a-g 0.217 g-r 0.296 a-d 0.247 b-n 0.227 e-r 0.231 c-p 0.190 m-r 0.286 a-f 0.226 e-r 0.258 a-l 0.191 m-r 0.230 d-p 0.221 f-r 0.187 n-r 0.194 l-r 0.319 a 0.237 b-o 0.291 a-e 0.161 r 0.0669 Root dry weight (g) 0.140 c-i 0.161 a-e 0.079 i-n 0.100 e-n 0.106 d-n 0.107 d-n 0.132 c-j 0.129 c-k 0.118 d-l 0.129 c-k 0.142 c-h 0.098 f-n 0.101 e-n 0.078 i-n 0.064 l-n 0.079 i-n 0.149 c-h 0.048 n 0.092 g-n 0.090 h-n 0.113 d-m 0.219 a 0.051 mn 0.128 c-k 0.069 k-n 0.120 d-l 0.078 i-n 0.108 d-n 0.089 h-n 0.088 h-n 0.114 d-l 0.072 j-n 0.212 ab 0.184 a-c 0.157 a-f 0.167 a-d 0.153 b-g 0.120 d-l

0.092 g-n
0.051 0.150 0.130 0.089 mn b-h c-k h-n

0.137 c-i
0.127 c-k 0.078 i-n 0.100 e-n 0.134 c-j 0.138 c-i 0.094 g-n 0.131 c-k 0.060 l-n 0.0628

1 Reprodution measured by numbers of reniform nematodes, eggs per root system, and the reproduction factor, and plant growth parameters measured by shoot dry weight and root dry weight. 2 Populations per 150cm3 of soil. 3 Rf = total vermiform nematodes and eggs / initial populations. Means within columns followed by different letters are significantly different according to Fisher's protected least significant difference test (P < 0.05).

ALABAMA AGRICULTURAL EXPERIMENT STATION

7

son growth parameters and reniform nematode populations did not support this theory. Root architecture analyses measuring total root length, total root surface area, total projected area, total root volume, average root diameter, and total number of root tips were determined for 17 varieties. ST 5599 BR had the highest values for each parameter tested (Table 2). Correlation coefficients indicated there were no relationships between any of the root architecture parameters tested and the populations of reniform nematodes. Field Evaluations of Tolerance Limestone County, Alabama: Reniform nematode populations in 2002 were extremely high; however, seed cotton yield differences between varieties treated with a nematicide and untreated varieties were not observed. Soil from the north Alabama location was analyzed for Temik microbial degradation. The results of the Temik microbial degradation test indicated that microbial degradation occurred within 10 days after planting and Temik was ineffective in reducing populations of the reniform nematode. Due to the microbial degradation of Temik, differences between nematicidetreated and untreated varieties were undetectable in 2002. In 2003 reniform nematode populations at planting were extremely low. Although seed cotton yield differences existed between Telone II-treated varieties and untreated varieties, differences were minimal possibly due to low populations of reniform nematodes at planting. Seed cotton yields varied from a high of 5,260 pounds per acre for ST 5599 BR treated with Telone II to a low of 3,623 pounds per

TABLE 2. GREENHOUSE EVALUATIONS OF 17 COTTON VARIETIES ROOT ARCHITECTURE1
Total root Total root length surface area cm cm2 ST 5599 BR 326.5 a 153.3 a FM 989 BR 312.7 ab 126.0 a-d DP 5415 R 305.0 a-c 128.2 a-c FM 960 BR 304.2 a-c 102.9 b-f DP 444 BR 302.9 a-c 135.7 ab DP 451 BR 294.5 a-d 130.8 a-c PM 1218 BR 275.8 a-e 87.8 d-f FM 989 R 266.4 a-f 111.0 c-e STX 4686 R 250.0 b-f 87.7 d-f DP 458 BR 248.7 c-f 93.5 c-f SG 215 BR 234.9 d-f 93.9 c-f FM 991 BR 232.2 d-f 86.9 d-f ST 4892 BR 226.3 e-f 102.4 b-f DP 555 BR 224.6 e-f 95.0 c-f DP 449 BR 222.1 e-f 77.1 ef ST 4793 R 217.5 e-f 68.6 f DP 436 R 210.5 f 80.2 ef LSD (P<0.05) 63.2 39.1 Variety Total projected area cm2 49.128 a 40.118 a-d 40.816 a-c 32.756 b-g 43.202 ab 36.512 b-e 31.758 d-h 35.344 b-f 27.924 e-h 29.750 d-h 29.880 d-h 27.676 e-h 29.414 e-h 30.220 c-h 24.552 gh 21.838 h 25.532 f-h 10.657 Total root volume cm3 5.97 a 4.09 b-d 4.43 a-c 2.80 c-f 4.98 ab 3.61 b-e 2.90 c-f 3.80 b-d 2.48 d-f 2.89 c-f 3.02 c-f 2.63 d-f 3.14 c-f 3.20 c-f 2.07 ef 1.73 f 2.45 d-f 1.6512 Average root diameter mm 1.498 a 1.284 a-d 1.339 a-c 1.067 de 1.430 ab 1.236 b-e 1.148 c-e 1.340 a-c 1.105 c-e 1.159 c-e 1.267 a-d 1.194 b-e 1.305 a-d 1.347 a-c 1.070 de 0.996 e 1.175 c-e 0.2482 Total number of root tips 333.6 a 257.2 a-d 302.2 ab 269.6 a-c 222.2 b-d 219.8 b-d 211.8 cd 227.8 b-d 264.6 a-c 217.2 cd 230.0 b-d 241.0 b-d 178.2 d 194.0 cd 222.6 b-d 212.2 cd 207.0 cd 83.343

1 Root architecture measured by total root length, root surface area, projected area, root volume, number of root tips, and average root diameter. Means within columns followed by different letters are significantly different according to Fisher's protected least significant difference test (P < 0.05).

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EVALUATION OF COTTON VARIETIES FOR RESISTANCE AND TOLERANCE TO NEMATODES

acre for PM 1199 R untreated (Table 3). DP 451 BR and ST 4793 R produced equal or greater seed cotton yields in untreated plots compared to Telone II treated plots. In 2004, no variety performed as well as its nematicide-treated counterpart. Seed cotton yields varied from a high of 5,237 pounds per acre for ST 5599 BR treated with Telone II to a low of 3,579 pounds per acre for ST 4793 R untreated (Table 4). The greatest response to Telone II was recorded on ST 4793 R with a seed cotton increase of 19.4 percent and the least response on FM 989 R with an increase of 2.1 percent. Consistent tolerance to the reniform nematode was not observed across three years of testing. Out of a possible four varieties tested in the three-year period, DP 451 BR was the higher-yielding variety in the untreated plots in 2003 and 2004. Compared to eight varieties tested in 2003 and 2004, DP 451 BR produced the greatest yields in the untreated plots with the exception of 2004, when ST 5599 BR outyielded it by 8.8 pounds per acre. While DP 451 BR consistently produced greater yields in the untreated plots, the application of Telone II in 2004 increased yields, thus eliminating the possibility of tolerance. Although no tolerance is present in DP 451 BR and ST 5599 BR, the positive performances of these varieties in the absence of a nematicide indicates they should be economically profitable selections in the north Alabama growing region. ST 5599 BR produced comparable yields to DP 451 BR in the untreated plots in 2003 and 2004. Root architecture data of total root length and total root surface area collected from the greenhouse revealed that ST 5599 BR and DP 451 BR have a prolific root structure compared to other varieties tested. We hypothesize that the larger root systems of ST 5599 BR and DP 451 BR gives them a competitive advantage in soils naturally infested with the reniform nematode. Escambia County, Alabama: Although tests were set up in 2002, 2003, and 2004 at Escambia County, Alabama, hurricanes in south Alabama prohibited collection of seed cotton yields in 2002 and 2004. Reniform nematode pressure in 2003 in the south Alabama location was sufficient to decrease seed cotton yields in the plots not treated with Telone II. Seed cotton yields ranged from 2,849 to 850 pounds per acre for FM 991 BR treated with Telone II and DP 436 R untreated, respectively (Table 5). ST 4793 R and SG 521 R exhibited greater or equal performance when not treated with a nematicide, which could indicate possible tolerance. While the positive performance in 2003 by ST 4793 R and SG 521 R seem to indicate possible tolerance, the inability to test over multiple years at the same location and poor performance by these two varieties in north Alabama prohibits calling these two varieties tolerant. If further testing indicated that ST 4793 R and SG 521 R could maintain seed cotton yields equal or greater than those produced by the addition of a nematicide, tolerance of a site specific level could possibly be identified. Although ST 4793 R and SG 521 R produced higher yields in the untreated plots compared to the Telone II plots, FM 991 BR in the untreated plots outyielded both varieties by 376 and 718 pounds per acre, respectively, indicating that FM 991 BR could be the most economically profitable variety for the producer at this time.

ALABAMA AGRICULTURAL EXPERIMENT STATION

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TABLE 3. COTTON VARIETY EVALUATIONS CONDUCTED IN 20031
Harvest reniform populations2 Telone II treated DP 5415 R 276 b ST 4892 BR 792 ab DP 451 BR 225 b DP 436 R 270 b DP 444 BR 1577 a DP 449 BR 277 b PM 1218 BR 779 ab SG 215 BR 347 b PM 1199 R 225 b ST 4793 R 277 b ST 5599 BR 476 b FM 989 BR 135 b LSD (P<0.05) 1081.8
1

IN

NORTH ALABAMA

Variety

Harvest reniform Seed cotton Seed cotton % yield inpopulations2 lb/ac lb/ac crease from untreated Telone II treated untreated Telone II 650 a-c 4312 c-e 4204 bc 2.6 405 bc 4152 de 3942 cd 5.3 360 c 4781 a-c 4837 a -1.2 599 a-c 4555 b-d 4361 a-c 4.4 624 a-c 5135 ab 4532 ab 13.3 418 bc 4673 a-d 4388 a-c 6.5 888 ab 4608 b-d 3912 cd 17.8 508 a-c 4676 a-d 4302 a-c 8.7 497 a-c 3876 e 3624 d 6.9 225 c 4431 c-e 4444 a-c -0.3 985 a 5260 a 4532 ab 16.1 412 bc 4856 a-c 4266 bc 13.8 504.2 597.86 553.85

Measured by reniform nematode harvest populations and seed cotton yields. 2 Populations per 150cm3 of soil. Means within columns followed by different letters are significantly different according to Fisher's protected least significant difference test (P<0.05).

TABLE 4. COTTON VARIETY EVALUATIONS CONDUCTED IN 20041
Harvest reniform populations2 Telone II treated DP 444 BR 1410 ab DP 449 BR 2028 ab DP 451 BR 1777 ab DP 5415 R 1448 ab FM 960 BR 1506 ab FM 989 R 579 ab FM 991 BR 811 ab PM 1218 BR 1236 ab ST 4793 R 1081 ab ST 4892 BR 2395 a ST 5599 BR 444 b STX 4686 R 1255 ab LSD (P<0.05) 1854.7 Variety

IN

NORTH ALABAMA

Harvest reniform Seed cotton Seed cotton % yield inpopulations2 lb/ac lb/ac crease from untreated Telone II treated untreated Telone II 1931 a 4805 ab 4231 a-c 13.6 1776 a 4118 c-d 3801 cd 8.3 2105 a 4774 a-c 4441 ab 7.5 2143 a 3859 d 3725 cd 3.6 2414 a 4770 a-c 4542 a 5.0 1911 a 4474 b-d 4382 ab 2.1 1429 a 4257 b-d 4166 a-c 2.2 1217 a 4364 b-d 3990 b-d 9.4 2259 a 4274 b-d 3579 d 19.4 2395 a 4411 b-d 4047 a-d 9.0 1699 a 5237 a 4450 ab 17.7 1467 a 4624 a-c 4425 ab 4.5 1534 669.32 514.26

1 Measured by reniform nematode harvest populations and seed cotton yields. 2 Populations per 150cm3 of soil. Means within columns followed by different letters are significantly different according to Fisher's protected least significant difference test (P<0.05).

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EVALUATION OF COTTON VARIETIES FOR RESISTANCE AND TOLERANCE TO NEMATODES

TABLE 5. COTTON VARIETY EVALUATIONS CONDUCTED IN 20031
Harvest reniform populations2 Telone II treated BCG 28 R 1158 a-e DP Delta Pearl 1236 a-e DP 436 R 695 c-e DP 444 BR 953 b-e DP 448 B 1390 a-e DP 449 BR 2163 ab DP 451BR 927 b-e DP 458 BR 1236 a-e DP 491 334 e DP 493 1004 b-e DP 5415 R 1622 a-e DP 555 BR 1957 a-c DP 5690 R 1931 a-d DP 33 B 772 c-e FM 991R 1390 a-e FM 958 B 1159 a-e FM 960 BR 1390 a-e FM 966 1081 a-e FM 989 1236 a-e FM 989 BR 1081 a-e FM 991BR 1159 a-e PM 1218 BR 1158 a-e PHY 410 R 618 c-e PHY 510 R 1159 a-e ST 4793 R 2394 a ST 4892 BR 1236 a-e ST 5303 R 541 e ST 5599 BR 1236 a-e STX 0203 BR 1339 a-e SG 215 BR 566 de SG 521 R 1931 a-d SG 747 1004 b-e LSD (P<0.05) 1368.9 Variety

IN

SOUTH ALABAMA

Harvest reniform Seed cotton Seed cotton % yield inpopulations2 lb/ac lb/ac crease from untreated Telone II treated untreated Telone II 1236 b 1611 j-l 1232 h-l 30.8 850 b 2380 b-e 1811 c-g 31.4 875 b 1902 g-k 850 l 123.7 1854 b 1575 kl 1385 e-k 13.7 4171 a 2359 c-f 1246 h-l 89.3 1545 b 2132 d-i 1698 d-h 25.6 1468 b 1913 g-k 1184 i-l 61.6 1313 b 2402 b-e 1355 f-k 77.3 1545 b 2079 d-i 932 j-l 123.1 2008 ab 1972 f-k 1620 d-i 21.7 1931 ab 2207 d-g 1385 e-k 59.3 2086 ab 2777 ab 2314 ab 20.0 2085 ab 2376 b-f 1866 b-e 27.4 3090 ab 2423 b-d 1594 d-i 52.0 1545 b 2656 a-c 2524 a 5.2 2472 ab 2041 d-i 1307 h-l 56.2 2703 ab 2001 e-j 1565 e-i 27.9 2240 ab 1734 i-l 1284 h-l 35.0 1622 b 1935 g-k 1180 i-l 64.0 2240 ab 2094 d-i 1133 i-l 84.8 1004 b 2849 a 2614 a 9.0 1390 b 1929 g-k 1384 e-k 39.4 1236 b 1922 g-k 891 kl 115.8 1390 b 2226 d-g 1498 d-i 48.6 1313 b 1891 g-k 2238 a-c -15.5 1236 b 1790 h-l 1336 g-l 34.0 1777 b 2173 d-h 1215 h-l 78.8 1468 b 1800 h-l 1282 h-l 40.4 1004 b 1483 l 1206 h-l 23.0 2008 ab 2101 d-i 1844 b-f 13.9 1236 b 1862 g-l 1896 b-d -1.8 2086 ab 2104 d-i 1416 d-j 48.6 2304.2 405.29 495.58

1 Measured by final reniform nematode populations and seed cotton yields. 2 Populations per 150cm3 of soil. Means within columns followed by different letters are significantly different according to Fisher's protected least significant difference test (P<0.05).

SUMMARY
Our overall results of greenhouse testing and field testing at two locations indicate the absence of a cotton variety tolerant to R. reniformis. Although there are available cotton varieties tolerant to the reniform nematode, knowledge of a high-yielding variety suited to the area of production can aid in increased yields in the presence of the reniform nematode. Results from north Alabama and south Alabama locations indicated that varieties such as DP 451 BR, ST 5599 BR, and FM 991 BR, which are considered intolerant, can be of economic value if nematicides are not implemented.