苗期遮荫对棉花产量与品质形成的影响

为揭示棉麦两熟共生期遮荫对棉花产量与品质形成的影响。在棉花苗期利用模拟棉麦两熟共生期遮荫的方法进行了研究。结果表明,遮荫对棉铃形成的影响因果枝,果节部位而异,遮荫有利于棉株下（1-3果枝）,中（4-6果枝）,上（7-9果枝）部果枝内围（1-2果节）铃的形成,对外围（≥3果节）尤其顶部果枝（≥10果枝）外围铃形成不利,从而决定铃重也随果枝,果节部位相应地变化,但遮荫对单株平均铃重的影响畔 小,变遮荫棉花籽棉产量而论,下,中部果枝的内围铃籽棉产量高于常规棉,在上,顶部果枝则相反,各部位果枝外围铃的籽棉产量均低于常规棉,遮荫棉花内,外围铃分布为1：0.36(常规棉为1：0.58),产量分布为1：0.42(常规棉为1：0.72)。苗期遮荫对棉纤维,棉籽品质性状的影响也主要在顶部果枝和上部果枝外围铃,综合分析遮荫棉花产量与品质的形成,棉花苗期耐遮荫性品种间存在差异。在本研究中以中9418耐遮荫性最强,中棉所19和春矮早次之。     

Effect of Mechanical Stress on Cotton Growth and Development

Agricultural crops experience diverse mechanical stimuli, which may affect their growth and development. This study was conducted to investigate the effects of mechanical stresses caused by hanging labels from the flower petioles (HLFP) on plant shape and cotton yields in four cotton varieties: CCRI 41, DP 99B, CCRC 21, and BAI 1. HLFP significantly reduced plant height by between 7.8% and 36.5% in all four lines and also significantly reduced the number of fruiting positions per plant in the CCRI 41, DP 99B and CCRC 21 lines. However, the number of fruiting positions in BAI 1 was unaffected. HLFP also significantly reduced the boll weight for all four cultivars and the seed cotton yields for CCRI 41, DP 99B and BAI 1. Conversely, it significantly increased the seed cotton yield for CCRC 21 by 11.2%. HLFP treatment did not significantly affect the boll count in the fruiting branches of the 1^st and 2^nd layers in any variety, but did significantly reduce those on the 3^rd and 4^th fruiting branch layers for CCRI 41 and DP 99B. Similar trends were observed for the number of bolls per FP. In general, HLFP reduced plant height and boll weight. However, the lines responded differently to HLFP treatment in terms of their total numbers of fruiting positions, boll numbers, seed cotton yields, etc. Our results also suggested that HFLP responses might be delayed for some agronomy traits of some cotton genotypes, and that hanging labels from early-opening flowers might influence the properties related with those that opened later on.     

Inheritance of seed protein content and other agronomic characters in long bean (Vigna sesquipedalis Fruw.)

Summary Seven varieties of long bean, which included three local and four exotic, were crossed in a complete diallel. This was an attempt to study the inheritance of crude protein content, protein yield, flowering date, pod yield and yield components.Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in crude protein content, number of pods per plant and number of seeds per pod. For seed weight and pod length, additive variance was more important.The crude protein content, protein yield and number of pods per plant appeared to be controlled by overdominance effects. Partial dominance seemed to be the case for flowering date, pod length and seed weight; complete to overdominance for pod yield. High protein appeared to be associated with recessive genes whereas there was a general trend of high yielding parents carrying more dominant genes.     

Removal of early fruit branches triggered regulations in senescence,boll attributes and yield of Bt cotton genotypes

Premature senescence, unopened and rotted bolls are the primary constrictions hampering the accomplishment of yield potential in Bt cotton. An experiment was conducted with the objectives to delay senescence, enhance boll opening and reduce the boll rotting. The experiment was conducted at two randomly selected sites of University of Agriculture Faisalabad, Pakistan, during 2015 and repeated in 2016. Each experiment was laid out in randomised complete block design with two by two factorial arrangement structure and replicated five times. Treatments were comprised of R₀ = no fruit removal; R₁ = removal of early fruit branches (REFB) and two genotypes, viz. V₁ = FH‐142 and V₂ = MNH‐886. Genotypes were selected on the basis of abiotic stress tolerance (FH‐142) and susceptibility (MNH‐886). Nodes above cracked bolls, monopodial branches, opened bolls per plant and seed cotton yield were enhanced by 23, 12, 13 and 17%, respectively, under the influence of REFB over no fruit branch removal, while the REFB‐mediated decrease in boll rotting was 27%. Moreover, the response of MNH‐886 was more remarkable than FH‐142 for all studied variables. Conclusively, REFB increased the number of nodes above a cracked boll, monopodial branches, opened bolls per plant and seed cotton yield while decreased rotted bolls per plant in both genotypes.     

Quantitative trait loci mapping for yield and its components by using two immortalized populations of a heterotic hybrid in Gossypium hirsutum L.

Quantitative trait loci (QTL) mapping provides a powerful tool for unraveling the genetic basis of yield and yield components as well as heterosis in upland cotton. In this research, a molecular linkage map of Xiangzamian 2 (Gossypium hirsutum L.)-derived recombinant inbred lines (RILs) was reconstructed based on increased expressed sequence tag–simple sequence repeat markers. Both the RILs and immortalized F2s (IF2) developed through intermating between RILs were grown under multiple environments. Yield and yield components including seed-cotton yield, lint yield, bolls/plant, boll weight, lint percentage, seed index, lint index and fruit branch number were measured and their QTL were repeatedly identified across environments by the composite interval mapping (CIM) method. From a total of 111 non-redundant QTL, 23 were detected in both two populations. In the meantime, multi-marker joint analyses showed that 16 of these QTL had significant environmental interaction. QTL for correlated traits tended to be collocated and most of the QTL for seed-cotton yield and lint yield were associated with QTL for at least one yield component, consistent with the results observed in correlation analyses. For many QTL with significant additive effects, positive alleles from CRI12, the inferior parent with lower yield performance, were associated with trait improvement. Trait performance of IF2s and the large number of QTL with positive dominant effects implied that dominance plays an important role in the genetic basis of heterosis in Xiangzamian 2 and that non-additive inheritance is also an important genetic mode for lint percentage in the population. These QTL can provide the bases for marker-assisted breeding programs of upland cotton.     

Influence of Nezara viridula feeding on cotton yield, fiber quality, and seed germination

The influence of southern green stink bug, Nezara viridula (L.), adults (males and females) and fourth to fifth instars on cotton, Gossypium hirsutum L., boll abscission, seedcotton yield, fiber quality, and seed viability was evaluated in field studies conducted during 2004 and 2005. Cotton bolls representing several age classes ranging from 0-600 heat units were individually infested with a specific gender or life stage of southern green stink bug. Adults and nymphs induced abscission of bolls that accumulated 0-280 heat units after anthesis. Seedcotton yield was significantly lower in bolls infested with adults (males and females) and late instars through approximately 500 heat units after anthesis. Southern green stink bug feeding on bolls significantly affected the physical fiber properties of micronaire (measure of fiber fineness or maturity), strength, uniformity, and fiber length. Discolored cotton lint in the stink bug-infested bolls was more common than in noninfested bolls. Seed germination and development of normal seedlings for seed harvested from stink bug-infested bolls that accumulated < or =500 heat units beyond anthesis were significantly lower compared with noninfested bolls. No significant differences in boll abscission, yield, fiber quality, and seed germination were detected between southern green stink bug males and females or between adults and fourth to fifth instars.     

In vitro induction of mutation in cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.) and isolation of mutants with improved yield and fiber characters

This paper describes a protocol to develop cotton mutant lines with improved yield and fiber characters. Immature ovules [(15-day post-anthesis ovules (dap)] were irradiated with 10–50 Gy gamma rays and treated with 1–5 mM EMS and SA to investigate the stimulatory effects of mutagenic treatments. During the subsequent field trials, the mutant lines showed significant variations from control lines. Lower dose/concentration of mutagenic treatments effectively stimulate the agronomical characters like early flowering, plant height, number of bolls, yield of seed cotton, ginning percent, seed index, harvest index and fiber characters while exposure at higher dose/concentration results in lowering the value of the parameters. Consequently, we use this approach to induce genetic variability for obtaining novel mutant cotton cultivars. Among the 19 different mutant lines isolated from the study, M7 showed higher morphological variations in terms of yield characters such as plant height, number of bolls, yield of seed cotton, ginning percent and fiber characters. Significant increase in cellulose content was also noted in mutant lines, whereas moderate increase was observed in total fiber units of the mutant lines. The selected cotton mutant lines for cultivars were investigated systematically; these lines significantly increased the potential for agronomical enhancement of cotton yield.     

Boll injury and yield losses in cotton associated with brown stink bug (Heteroptera: Pentatomidae) during flowering

Brown stink bug, Euschistus servus (Say), was infested on cotton, Gossypium hirsutum L., plants during reproductive stages to determine the effects on boll injury and seedcotton yield. During each week in 2002 and 2003, significantly more bolls with > or = 1 injured locule, bolls with > or = 2 injured locules, and bolls with discolored lint were recorded on stink bug-infested plants compared with that on noninfested plants. Significantly fewer bolls displayed external injury on the boll exocarp compared with bolls with only internal locule injury. Boll injury was significantly underestimated by the presence of external symptomology. The boll population increased 6.6- and 5.1-fold from weeks 1-5 in 2002 and 2003, respectively. There was a corresponding 6.2- and 4.6-fold increase in 2002 and 2003, respectively, for total bolls injured from weeks 1-5. Percentage of boll injury ranged from 10.7 (week 4) to 27.4 (week 2) in 2002 and from 9.2 (week 3) to 16.0 (week 2) in 2003. Percentage of injury was greatest during weeks 1 and 2 in both years and also in week 5 in 2002. Brown stink bug significantly reduced seedcotton yield of bolls present on cotton plants during weeks 1, 2, and 5 in 2002 and in weeks 4 and 5 in 2003. However, total seedcotton yield, as a function of bolls exposed to brown stink bug and subsequent bolls produced on plant in the absence of stink bugs, was not significantly different for plots infested during weeks 1-4 in 2002 and weeks 1-3 in 2003. Flowering period and boll population influence the severity of stink bug injury on seedcotton yield. Infestation timing and number of bolls should be considered, in addition to insect densities, when initiating treatments against brown stink bug.     

一年生陆地棉细胞核雄性不育系洞A的宿生栽培效应

植物细胞核雄性不育系具有易于恢复但保持困难的特点。根据广西南部冬季无霜冻的气候特点,在广西南宁进行了一年生陆地棉细胞核雄性不育系洞A的三年露地栽培。结果表明:二、三年生洞A在5月上旬开花、6月下旬吐絮,这是一年生洞A在相同环境条件下难以达到的;与一年生洞A相比,二、三年生洞A的子指、单株铃数、产量显著增加,但单铃重、衣分显著下降,僵瓣率显著增加;纤维品质基本没有显著变化。说明利用陆地棉细胞核雄性不育系在南亚热带的宿生栽培进行良种繁育具有较好的前景。     

Oviposition on and mining in bolls of Bt and non-Bt cotton by resistant and susceptible pink bollworm (Lepidoptera: Gelechiidae)

Transgenic cotton that produces insecticidal crystal protein Cry1Ac of Bacillus thuringiensis (Bt) has been effective in controlling pink bollworm, Pectinophora gossypiella (Saunders). We compared responses to bolls of Bt cotton and non-Bt cotton by adult females and neonates from susceptible and Cry1Ac-resistant strains of pink bollworm. In choice tests on caged cotton plants in the greenhouse, neither susceptible nor resistant females laid fewer eggs on Bt cotton bolls than on non-Bt cotton bolls, indicating that the Bt toxin did not deter oviposition. Multiple regression revealed that the number of eggs laid per boll was negatively associated with boll age and positively associated with boll diameter. Females also laid more eggs per boll on plants with more bolls. The distribution of eggs among bolls of Bt cotton and non-Bt cotton was clumped, indicating that boll quality rather than avoidance of previously laid eggs was a primary factor in oviposition preference. Parallel to the results from oviposition experiments, in laboratory no-choice tests with 10 neonates per boll, the number of entrance holes per boll did not differ between Bt cotton and non-Bt cotton for susceptible and resistant neonates. Also, like females, neonates preferred younger bolls and larger bolls. Thus, acceptance of bolls by females for oviposition and by neonates for mining was affected by boll age and diameter, but not by Bt toxin in bolls. The lack of discrimination between Bt and non-Bt cotton bolls by pink bollworm from susceptible and resistant strains indicates that oviposition and mining initiation are independent of susceptibility to Cry1Ac.     

广西南部宿生陆地棉的产量构成因素及其通径分析

棉花宿生栽培对于雄性不育系的多年生保持和杂交制种,固定杂种优势、加速杂种优势利用和保存种质资源具有重要意义。探讨陆地棉宿生栽培的产量构成因素及其对产量形成的影响,为陆地棉宿生栽培提供理论依据。采用随机区组设计,对三年生、二年生宿生陆地棉的产量构成因素及其对产量形成的影响进行比较研究。结果表明:与一年生棉比较,宿生棉单位面积总铃数明显增多,多数品种的单铃重无明显变化,衣分变化因品种而异。三年生和二年生各因素对产量影响的趋势一致,总铃数影响最大,衣分影响次之,两者主要是直接影响;单铃重通过总铃数的间接影响较大。一年生各因素对产量影响略有不同。宿生栽培的总铃数明显增多,是增产的主要原因,同时应选择衣分高、受宿生年限影响小的品种。     

The occurrence of Aspergillus flavus in vegetative tissue of cotton plants and its relation to seed infection

Twenty-seven mature cotton bolls with Aspergillus flavus Link colonies naturally occurring on the surface of the boll or lint were collected in the field in Arizona along with their subtending stems and peduncles. Bolls inoculated through the carpel wall 30 days after anthesis were allowed to mature in the field and were collected in the same manner. The seed and stem and peduncle sections of each boll were surface-sterilized, plated on agar media and observed for A. flavus. Seventy-eight percent of the naturally contaminated bolls with A. flavus in the seed also had the fungus in the stem and peduncle, whereas only 31% of the naturally contaminated bolls with no A. flavus in the seed had the fungus in the stem or peduncle. This difference was significant (P=0.0125), indicating a positive relationship between seed infection and stem and peduncle infection. All of the bolls inoculated through the carpel wall had A. flavus in the seed, but only 11% of the stem and peduncle sections were infected, indicating that the fungus does not readily grow downward from the boll into the supporting stem or peduncle.This unidirectional pattern of movement (upward) was further substantiated in greenhouse experiments where cotton seedlings were inoculated at the cotyledonary leaf scar with A. flavus and plants were sequentially harvested, surface sterilized and plated. Aspergillus flavus was isolated from the cotyledonary leaf scar, flower buds, developing bolls, and stem sections in the upper portion of the plant. It was never isolated from roots or stem sections below the cotyledonary node, again indicating that the fungus does not readily move downward through the plant.     

Effect of the populations of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) on cotton crop at two sowing distances

The objective of this research was to evaluate the incidence of damage by the leafworm Alabama argillacea (Hübner) on yields of cotton grown under rows spaced 0.38 m and 0.76 m at the irrigation area of Santiago del Estero, Argentina. The period evaluated was extended from first flower to first open boll. Treatments were T1 - without control of larvae, T2 - with control of larvae, T3 - control since first flower to the end of effective blooming, and T4 - with larval control since the end of effective blooming to first open boll. The effect of injuries on the crop was evaluated trough boll cotton yield. Larvae were sampled in a weekly basis and insects were present from the first flower until harvest. Populations of A. argillacea decreased crop yields in the two distances tested, by decreasing the weight or number of open bolls.     

Pathogenic aspects of Pantoea agglomerans in relation to cotton boll age and Dysdercus cingulatus (Fabricius) transmitting seed and boll rot in cotton germplasm

Bacterial seed and boll rot is a newly emerging cotton disease in Pakistan. Twenty-one cotton varieties were screened to find resistance source against the disease. None of these was found to be resistant. Five cotton varieties (CIM-595, MK2, BT-986, BT-986 & SG-1) having 700–1400 Area under disease progress curve (AUDPC) units were found to be moderately resistant to the disease. SLH-317, FH-942, BT-222, BT-666, MNH-457 ranging from 1401–1700 AUDPC units were moderately susceptible while MNH-456, SLH-336, 9811, FH-942, MNH-886 susceptible to boll rot. Seven varieties (FH-114, FH-113, BT-7, BT-212, SLH-BT-4, BT-212 and FH-941) were highly susceptible to bacterial seed and boll rot indicated by 2001–2300 AUDPC units. Biochemical tests identified bacterial isolates as Pantoea agglomerans. Different inoculation techniques were assessed for bacterial pathogenicity and symptoms of boll rot were only observed in needle punctured bolls. One, two and three weeks old bolls were mechanically inoculated by injecting bacterial suspension to evaluate the boll’s age impact on disease severity. Maximum severity was observed in two weeks old bolls. Red cotton bugs (Dysdercus cingulatus) were fed on artificially inoculated diseased bolls and then transferred on healthy bolls. Diseased symptoms were noticed on healthy cotton bolls. Bacterial colonies were recovered and red cotton bug was confirmed as the disease-transmitting vector.     

Injury to preflowering and flowering cotton by brown stink bug and southern green stink bug

The impact of brown stink bug, Euschistus servus (Say), and southern green stink bug, Nezara viridula (L.), injury was evaluated on preflowering and flowering cotton, Gossypium hirsutum L., plants in no-choice tests. Vegetative stage cotton seedlings and reproductive structures, including flower buds (square) and bolls, were infested with adults and/or nymphs of both species. There were no significant differences in height, height to node ratio, square retention, and flower initiation for cotton seedlings or plants with a match-head square between southern green stink bug adult- or brown stink bug adult-infested and noninfested treatments. Abscission for individual large squares (precandle) and multiple squares (medium and small square on the same sympodial branch) was not significantly different among infested and noninfested treatments for the following species and developmental stages: brown stink bug adults, southern green stink bug adults, and third and fourth to fifth instar southern green stink bug nymphs. In boll infestation studies, the relationship between boll maturity, expressed as heat units beyond anthesis, and boll growth, abscission, hard locked carpels, seedcotton yield, and seed germination was measured. Brown stink bug induced abscission in bolls that had accumulated > 0-350 heat units beyond anthesis. Boll growth and seedcotton yield was significantly lower for bolls infested with brown stink bug through 266.5 and 550 heat units beyond anthesis, respectively. The proportion of hard locked carpels per boll was significantly greater for the infested treatment in a cohort of bolls that accumulated from 51 to 400 heat units beyond anthesis. Seed germination in bolls infested with brown stink bug was significantly lower in bolls aged 101-600 heat units beyond anthesis.     

Role of Pantoea agglomerans in opportunistic bacterial seed and boll rot of cotton (Gossypium hirsutum) grown in the field

AIMS: To investigate the aetiology of seed and boll rot of cotton grown in South Carolina (SC). METHODS AND RESULTS: Bacteria were isolated from diseased locules of cotton bolls collected in a field in SC, USA and tested for the ability to cause comparable disease symptoms in greenhouse grown cotton fruit. Spontaneously generated rifampicin-resistant (Rif(r)) mutants of the isolates were used in confirmatory pathogenicity tests. Resistance to the antibiotic was both stable and effective in differentiating between an inoculated Rif(r) strain, rifampicin-sensitive contaminants and/or endophytes. A series of inoculation methods was tested at various boll developmental stages and at different fruiting nodes on the plant. Field disease symptoms were reproduced by inoculating bolls at 2 weeks postanthesis with bacterial suspensions ranging from 10(3) to 10(6) CFU ml(-1). Pathogenic isolates were categorized as Pantoea agglomerans on the basis of phenotype testing, fatty acid profiling (similarity index = 0.94), and 16s ribosomal DNA sequence analysis (99% nucleotide identity). CONCLUSIONS: Pantoea agglomerans isolates from field-collected immature, diseased cotton caused comparable infection symptoms in greenhouse produced cotton fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: In 1999, significant yield losses in SC cotton resulted from a previously unobserved seed and boll rot that has since been reported in other southeastern states. This study demonstrated a role of P. agglomerans in producing opportunistic bacterial seed and boll rot of cotton.     

Response of cotton to prebloom square loss

In 1996 and 1997, various intensities of prebloom square removal were applied to three cultivars of cotton grown in Mississippi. With the exception of one cultivar in 1997, all cultivars were B. thuringiensis (Bt)-transgenic cotton. At harvest, the number of bolls and seed cotton weight was recorded for all plants in each square removal treatment. All cultivars responded similarly to square loss. A yield increase (overcompensation) was observed in the treatment where all squares were removed from the plant one week after squaring began. Only the treatment where all squares were removed before bloom significantly reduced yield and caused a large (>7 d) delay in crop maturation. Otherwise, moderate levels of square removal (approximately 20-50% of prebloom squares) had little impact on overall lint production. However, the patterns of cotton production on the plants were significantly influenced by the square removal treatments. The removal of relatively more or larger squares increased seed cotton production in late-season fruiting cohorts and on 'vegetative' branches. Compensation for square loss occurred by increasing the relative number and weight of bolls produced subsequent to early-season square removal. Typically, early-season square loss increased the value of later-season fruiting cohorts, especially the midseason cohorts and bolls on vegetative branches. The implications of prebloom square loss, including the compensatory ability of the cotton plant, on insect management are discussed.     

Genetic relationships and discrimination of ten influential Upland cotton varieties using RAPD markers

Influential Upland cotton ( Gossypium hirsutum L.) varieties are those that have the higher genetic contributions to modern Upland cultivars than other germplasms. Our previous research has shown significant differences in general combining ability (GCA) effects for yield, yield components, and fiber properties among ten influential cotton varieties. In this study, we used random amplified polymorphic DNA (RAPD) data to evaluate DNA variation of these ten varieties. Of 86 random decamer primers screened for their capability of amplifying DNA via the polymerase chain reaction (PCR), 63 generated a total of 312 DNA fragments. Forty two bands were polymorphic, which showed a low percentage (13.5%) of DNA variation among these influential varieties. Genetic similarities among the ten varieties based on RAPD data were from 92.7% to 97.6%. All of the varieties were individually identified by variety specific markers in genetic fingerprinting. One primer, UBC-149, amplified a 1,430-bp DNA fragment that was absent in five varieties and present in the other five varieties. This RAPD marker had significant negative relationships with GCA-effect estimates for seed cotton yield, lint yield, number of bolls per plant and micronaire, and significant positive relationships with GCA effects for boll size and seed index. This finding, for the first time, identifies a DNA fragment in cotton that is a potential DNA marker linked to a yield gene(s) or a yield-related gene(s).     

膜下滴灌水氮调控对南疆棉花产量及水氮利用率的影响

为探明水氮调控对膜下滴灌棉花的生长特性、产量构成因素以及水氮利用效率的影响,设置了3个灌溉水量和5个氮素水平进行大田棉花膜下滴灌试验.结果表明: 随着灌溉水量的增加,棉花的株高、主茎叶数、果枝数和叶面积指数显著增加,棉花叶、茎干物质积累增加,但抑制了根系生长,与低(4950 mm·hm^-2)和高(6750 mm·hm^-2)灌水量处理相比,中灌水量(5850 mm·hm^-2)处理平均单株有效铃数和单铃质量分别增加0.96、0.4个和0.22、0.11 g.与其他施氮处理相比,施氮量为300 kg·hm^-2时棉花茎直径显著增加,促进了棉花蕾、铃和根系的发育,而且在灌水量为5850 mm·hm^-2条件下,棉花干物质由营养器官向生殖器官的分配比灌水量为4950和6750 mm·hm^-2处理分别增加5.1%和29.6%.灌溉水量对棉花产量有显著影响,对衣分率影响不显著,而施氮量对棉花产量和衣分率都有一定的影响,但灌溉水量过低会抑制氮肥增产效应的发挥.在本试验条件下,灌水量为5850 mm·hm^-2、施氮量为300 kg·hm^-2时,棉花生长健壮,株型结构优化,显著促进了干物质向生殖器官的运转,有效铃数、单铃质量和衣分增加,产量达到最高(6992 kg·hm^-2),水分利用效率和氮肥利用率分别达1.45 kg·m^-3和45.9%.     

Boll weevil (Coleoptera: Curculionidae) survival through cotton gin trash fans

There is concern that cotton gins may serve as loci for reintroduction of boll weevils, Anthonomus grandis grandis Boheman, to eradicated or suppressed zones when processing weevil-infested cotton from neighboring zones. Previous work has shown that virtually all weevils entering the gin in the seed cotton will be removed before they reach the gin stand. Those not killed by the seed cotton cleaning machinery will be shunted alive into the trash fraction, which passes through a centrifugal trash fan before exiting the gin. The objective of this study was to determine survival potential of boll weevils passed through a trash fan. Marked adult weevils were distributed in gin trash and fed through a 82.6-cm (32.5-in.) diameter centrifugal fan operated across a range of fan-tip speeds. A small number of boll weevils were recovered alive immediately after passage through the fan, but all were severely injured and did not survive 24 h. In another experiment, green bolls infested with both adult- and larval-stage weevils were fed through the fan. Several teneral adults survived 24 h, and there was no evidence that fan-tip speed affected either initial survival of weevils, or the number of unbroken boll locks that could harbor an infesting weevil. Thus, designating a minimum fan-tip speed for ensuring complete kill is not possible for the boll weevil. Experiments suggest that a device installed in a gin that partially crushes or cracks bolls open before entering a trash fan will increase mortality, possibly enough that further precautions would be unnecessary.