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Economically damaging infestations of Lygus lineolaris (Palisot de Beauvois), tarnished plant bug, were sporadic in Virginia and North Carolina cotton before 2010. Given the sudden rise of L. lineolaris as an economic pest in these states, regionally specific management practices (i.e., chemical and cultural control) are needed to help producers protect yield potential while minimizing input costs. Field experiments were conducted in Virginia and North Carolina in 2018 and 2019 to 1) determine the effects of various management practices on L. lineolaris density, plant injury (i.e., square retention, internal boll injury), and lint yield, 2) calculate the economic trade-offs between integrated pest management (IPM) systems approach and current management practices for L. lineolaris in these states, and 3) evaluate economic benefits associated with various sampling thresholds. Lygus lineolaris populations peaked mid-season (i.e., August) during cotton flowering in both states. Weekly scouting and applying foliar insecticides when the current University Extension recommended economic threshold was reached was the most critical management treatment in maximizing economic returns. Additional costs among various IPM practices did not translate into significant yield protection and economic gains. Moreover, there were additional economic benefits associated with protecting glabrous and longer maturing varieties in Virginia. Lygus lineolaris density varied significantly between states; therefore, management recommendations should be modified based on the growing region. Results from this study will be used to create an IPM strategy to help cotton producers effectively manage this insect pest in the Southeast.

Neonicotinoid insecticides are currently one of two classes of chemicals available as a seed treatment for growers to manage early season insect pests of cotton, Gossypium hirsutum L. (Malvales: Malvaceae), and they are used on nearly 100% of cotton hectares in the midsouthern states. An analysis was performed on 100 seed-treatment trials from Arkansas, Louisiana, Mississippi, and Tennessee to determine the value of neonicotinoid seed treatments in cotton production systems. The analysis compared seed treated with neonicotinoid insecticides seed treatments plus a fungicide with seed only treated with fungicide. When analyzed by state, cotton yields were significantly greater when neonicotinoid seed treatments were used compared with fungicide-only treatments. Cotton treated with neonicotinoid seed treatments yielded 123, 142, 95, and 104 kg ha-1, higher than fungicide only treatments for Arkansas, Louisiana, Mississippi, and Tennessee, respectively. Across all states, neonicotinoid seed treatments provided an additional 115 kg lint ha-1 comparedwith fungicide only treated seed. Average net returns from cotton with a neonicotinoid seed treatment were $1,801 per ha-1 compared with $1,660 per ha-1 for cottonseed treated with fungicide only. Economic returns for cotton with neonicotinoid seed treatments were significantly greater than cottonseed treated with fungicide only in 8 out of 15 yr representing every state. These data show that neonicotinoid seed treatments provide significant yield and economic benefits in Mid-South cotton compared with fungicide only treated seed.

Whole-plant cage field experiments were conducted in 2014, 2015, and 2016 to characterize cotton injury from a species complex of boll-feeding sucking bugs represented by the verde plant bug, Creontiades signatus (Distant) (Hemiptera: Miridae), brown stink bug, Euschistus servus (Say), green stink bug, Acrosternum hilare (Say), and redbanded stink bug, Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae). Field-collected adult bugs were used to infest cotton plants previously maintained free of insect injury. Plants caged in groups of four were infested at mid-bloom and late-bloom for 7 d with four insect densities: 0 (control), 0.25 bugs per plant, 1 bug per plant, and 2 bugs per plant. Species and water stress conditions varied across years, allowing selective within-year comparisons. Response to feeding resulted in boll injury in the form of lint deterioration and cotton boll rot at mid- and late-bloom stages, and in water limiting and non-water limiting conditions. Although plant injury was apparent across a wide range of conditions, subsequent yield decline attributed to insect feeding was seen primarily under water limiting conditions when plants were infested at mid-bloom. For these conditions, significant yield-insect density relationships were used to calculate economic injury levels (EILs) for each species. EILs expressed as bugs per plant from lowest to highest were the brown stink bug (0.29-0.31 bugs per plant), redbanded stink bug (0.33), verde plant bug (0.49), and green stink bug (0.50). Given the variability observed among species, species-specific EILs may be used where the injurious species is known and combined for stink bugs (a common EIL of 0.34 bugs per plant) where multiple species occur. Verde plant bug was less damaging and can be considered separately, but its EIL was generally within a range of values for the boll-feeders encountered.

Phytophagous stink bugs are economically important pests of annual and perennial crops in the southeastern United States. Because of insecticide resistance and risk of secondary pest outbreaks, there is interest in identifying cultural practices that could lead to reduced insecticide applications. The objective of this project was to assess the importance of cotton planting date on stink bug damage to cotton. Unsprayed cotton plots with biweekly planting dates were established at three locations in southern Georgia in each of two crop years. During the bloom cycle, stink bug-induced boll injury was estimated weekly in each plot. Plots were subsequently defoliated, mechanically harvested, and ginned to assess differences in fiber yield and quality attributable to stink bug injury. Results show that the rate of boll damage generally increased more rapidly through the bloom cycle for planting dates in June compared with May. Similarly, estimates of boll damage from June-planted cotton more frequently exceeded the stink bug treatment threshold compared with May-planted cotton. In 2011, mean lint yield and economic returns from May planting dates were significantly greater than June planting dates. In 2012, lint yield and economic returns were greater in plots established in early May compared with later planting dates. Estimates of HVI color + b, a measure of fiber yellowness, were lower in early May-planted cotton compared with June planting. These data show that growers need to be aware of increased stink bug damage potential when planting late.

Verde plant bugs, Creontiades signatus Distant (Hemiptera: Miridae), were released onto caged cotton, Cossypium hirsutum L., for a 1-wk period to characterize the effects of insect density and bloom period of infestation on cotton injury and yield in 2011 and 2012, Corpus Christi, TX. When plants were infested during early bloom (10-11 nodes above first white flower), a linear decline in fruit retention and boll load and a linear increase in boll injury were detected as verde plant bug infestation levels increased from an average of 0.5 to 4 bugs per plant. Lint and seed yield per plant showed a corresponding decline. Fruit retention, boll load, and yield were not affected on plants infested 1 wk later at peak bloom (8-9 nodes above first white flower), even though boll injury increased as infestation levels increased. Second-year testing verified boll injury but not yield loss, when infestations occurred at peak bloom. Incidence of cotton boll rot, known to be associated with verde plant bug feeding, was low to modest (< 1% [2012] to 12% [2011] of bolls with disease symptoms), and drought stress persisted throughout the study. Caging effect was minimal: a 10% fruit retention decline was associated with caging, and the effect was not detectable in the other measurements. Overall, reduced fruit retention and boll load caused by verde plant bug were important contributors to yield decline, damage potential was greatest during the early bloom period of infestation, and a simple linear response best described the yield response-insect density relationship at early bloom. Confirmation that cotton after peak bloom was less prone to verde plant bug injury and an early bloom-specific economic injury level were key findings that can improve integrated pest management decision-making for dryland cotton, at least under low-rainfall growing conditions.

The verde plant bug, Creontiades signatus (Distant), has been present in south Texas for several years but has more recently been documented as an economic threat to cultivated cotton, (Gossypium hirsutum L. Our studies over 2 yr (2009 and 2010) and two locations (Weslaco and Corpus Christi, TX) investigated feeding-injury of the verde plant bug to a range of cotton boll age classes defined by boll diameter and accumulated degree-days (anthesis to the time of infesting) for first-position cotton bolls infested with the plant bugs. The most detrimental damage to younger cotton holls from verde plant bug feeding was boll abscission. Cotton bolls04 accumulating daily degree-days (ACDD), or a boll diameter of 1.3 cm were subject to 60-70% higher boll abscission when compared with the noninfested controls. Significantly higher boll abscission occurred from verde plant bug injured bolls compared with the controls up to 162 ACDD or a mean boll diameter 2.0 cm. Cotton seed weights were significantly reduced up to 179 ACDD or a boll diameter of 2.0 cm at Weslaco in 2009, and up to 317 ACDD or boll diameter 2.6 cm for Weslaco in 2010 when compared with the noninfested controls. Lint weight per cotton boll for infested and noninfested bolls was significantly reduced up to 262 ACDD or boll diameter 2.5 for Corpus Christi in 2010 and up to 288 ACCD or boll diameter 2.6 cm for Weslaco, TX, in 2010. Damage ratings (dependant variable) regressed against infested and noninfested seed-cotton weights showed that in every instance, the infested cotton bolls had a strong and significant relationship with damage ratings for all age classes of bolls. Damage ratings for the infested cotton bolls that did not abscise by harvest showed visual signs of verde plant bug feeding injury and the subsequent development ofboll rot; however, these two forms of injury causing lint and seed mass loss are hard to differentiate from open or boll-locked cotton bolls. Based on the results of both lint and seed loss over 2 yr and four studies cotton bolls should be protected up to approximately 300 ACDD or a boll diameter of 2.5 cm. This equilibrates to bolls that are 12-14 d of age dependent upon daily maximum and minimum temperatures.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is an important pest of cotton, Gossypium hirsutum L., in the mid-southern United States. It is exclusively controlled with foliar insecticide applications, and sampling methods and thresholds need to be revisited. The current experiment was designed to establish a plant-based threshold during the flowering period of cotton development. Experiments were conducted in MisSissippi in 2005 and 2006, Arkansas in 2005, and Louisiana in 2005 through 2008. Treatments consisted of various combinations of thresholds based on the percentage of dirty squares that were compared with the current threshold with a drop cloth or automatic weekly applications. Dirty squares were characterized as those with yellow staining on the developing bud resulting from tarnished plant bug excrement. Treatments consisted of 5, 10, 20, and 30% dirty squares. Each plot was sampled weekly, and insecticides were applied when the mean of all replications of a particular treatment reached the designated threshold. At the end of the season, plots were harvested and lint yields were recorded. Differences were observed in the number of applications and yields among the different treatments. The 10% dirty squares threshold resulted in a similar economic return compared with the drop cloth. A threshold of 10% dirty squares resulted in a similar number of insecticide applications, yields, and economic returns compared with that observed with the drop cloth. These results suggest that a threshold of 10% dirty squares could be used to trigger insecticide applications targeting tarnished plant bugs in flowering cotton.

Cotton, Gossypium hirsutum L., bolls from 17 field locations in northeastern North Carolina and southeastern Virginia, having 20% or greater internal boll damage, were studied to determine the relationship between external feeding symptoms and internal damage caused by stink bug (Hemiptera: Pentatomidae) feeding. In 2006 and 2007, two cohorts of 100 bolls each were sampled at all field locations. The first cohort was removed as bolls reached approximately quarter size in diameter (2.4 cm). External and internal symptoms of stink bug feeding were assessed and tabulated. Concurrent to when the first cohort was collected, a second cohort of quarter-size-diameter bolls was identified, tagged, examined in situ for external feeding symptoms (sunken lesions), and harvested at the black seed coat stage. Harvested bolls were assessed for internal damage and locks were categorized (undamaged, minor damage, or major damage), dried, and ginned. Lint samples from each damage category were submitted for high volume instrument and advanced fiber information system quality analyses. Significant, moderately strong Pearson correlation coefficients existed between number of external stink bug feeding lesions and internal damage. Pearson correlation of total external lesions with total internal damage was stronger than any correlation among the other single components compared. Predictability plots indicated a rapid increase in relationship strength when relating external stink bug lesions to internal damage as the number of external lesions increased. Approximately 90% predictability of internal damage was achieved with four (2006) or six (2007) external lesions per boll. Gin-turnout and fiber quality decreased with increasing intensity of internal stink bug damage.

Insecticide applications to control tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), during cotton, Gossypium hirsutum L., bud formation are common throughout the Midsouth of the United States. Cultivation practices and the pest complex have changed since action thresholds were established for this pest. A trial was conducted at 33 locations over 3 yr throughout the Midsouth to evaluate tarnished plant bug damage to cotton during the prebloom period. There was no consistent yield response to action thresholds, but average tarnished plant bug density and average square loss were both significant factors impacting lint yield. Based on the yield responses and application frequency of the various action thresholds, the best economic scenario occurred when tarnished plant bug density during the prebloom period averaged eight per 100 sweeps and square retention averaged 90%. The action thresholds required to achieve these averages are expected to be higher than these levels because pest pressure is not normally constant during the prebloom period. When insecticides are required, an application interval shorter than one week may be needed to obtain satisfactory control.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), has become the primary target of foliar insecticides in cotton, Gossypium hirsutum L., throughout the Midsouth over the past several years. This prompted a reevaluation of existing action thresholds for flowering cotton under current production practices and economics. A trial was conducted at 19 locations throughout the Midsouth during 2006 and 2007. Threshold treatments ranged from a weekly automatic insecticide application to a very high threshold of 10 tarnished plant bugs per 1.5 row-m on a black drop cloth. Individually, all locations reached the lowest threshold, and eight locations had a significant yield loss from tarnished plant bugs. Across all locations, lint yield decreased 0.85 to 1.72% for each threshold increase of one tarnished plant bug per 1.5 row-m. Yield loss was most closely correlated to pest density during the latter half of the flowering period. The relationship between plant bug density or damage and yield was similar for drop cloth, sweep net, and dirty square sampling methods, but the correlations among these sampling methods were not high. Incorporating actual insecticide application data from the trial and average production and economic factors for Midsouth cotton, the economic threshold, if monitoring once per week, should be between 1.6 and 2.6 tarnished plant bugs per 1.5 row-m during the flowering period. More frequent monitoring or situations where insecticide applications are more efficacious may alter this threshold.

Previous research showed that the most precise estimates of stink bug damage in developing cotton bolls are obtained by collecting soft quarter-sized bolls and dissecting them for signs of internal feeding damage, such as internal boll wall warts and/or stained lint. However, this method requires considerable time and effort; therefore, scouts and growers are unwilling to invest adequate resources to make sound pest management decisions. Here, the authors evaluated enumeration of external feeding lesions on groups of 10, 15, 20, or 25 bolls per sample as an alternative sampling procedure. Results relate the similarity of external boll feeding lesions to internal damage as a function of boll sample size and external lesion tally. Inverse prediction confidence intervals (CIs) were also calculated to predict internal boll damage on a new sample based only on external feeding lesions. Results show that linear regression model fit increased when examining at least 20 bolls per sample, and only one external lesion per boll provided as good of model fit as using a minimum of two, three, or four lesions per boll. Inverse prediction CIs suggested that more than one sample (20 bolls per sample) will be required to make external lesions an acceptable method for making reasonably accurate management decisions. F-test lack of fit and significant regression models suggest that examination of external lesions is a promising a method for estimating stink bug damage in cotton.

This study examined a non-insecticidal tactic for suppressing boll weevil, Anthonomus grandis grandis Boheman, damage to cotton, Gossypium hirsutum L. In cage assays, kaolin, a reflective white mineral, applied to excised cotton squares or to the cotton foliage, initially resulted in lower levels of boll weevil injury to squares than nontreated squares. Boll weevil oviposition and feeding on kaolin-treated squares and squares on kaolin-treated cotton plants increased when nontreated squares and cotton plants were in short supply. A laboratory assay and field trials suggested that boll weevils distinguished between cotton plots based on color differences caused by kaolin and this appeared to influence levels of damage to squares. Random sampling in small plots indicated that oviposition damage to squares in plots treated with kaolin was reduced (P < 0.05) compared with nontreated controls, except when rain washed the kaolin off the foliage. Lint yield differences were not detected between the small plots, but the kaolin-treated small plots yielded as much as 2.36 times more cotton lint than a large but unreplicated adjacent nontreated control plot, and up to 1.39 times more than another large but unreplicated adjacent plot sprayed twice with preemptive applications of azinphosmethyl when cotton squares were first developing (pinhead stage). Potentially important avenues for future research on boll weevil injury suppression using kaolin are discussed.

The study was conducted in the northern Texas Rolling Plains in 1999 to define the relationship between number of cotton aphids, Aphis gossypii Glover, and resulting contamination of cotton lint by honeydew. Whole-plot treatments were three furrow irrigation management treatments: cotton grown without supplemental irrigation (dryland), irrigated cotton with last irrigation in mid August, and irrigated cotton with last irrigation in late August. Subplots within each irrigation treatment included an untreated check, a plot treated with lambda-cyhalothrin to stimulate aphid population increase, a plot treated with lambda-cyhalothrin followed by pymetrozine after aphids began to increase, and a plot treated with lambda-cyhalothrin followed by thiamethoxam after aphids began to increase. Cotton aphids were counted on leaves picked from the top and bottom half of the plant. Cotton lint was analyzed for contamination by glucose, fructose, sucrose, and melezitose secreted by cotton aphids, and percentage leaf moisture and nitrogen and leaf sucrose concentrations were determined. The manual sticky cotton thermodetector was used to determine degree of lint stickinesss. There was a significant relationship between thermodetector counts and melezitose contamination on lint, and a melezitose concentration of 90.9 μg/g of lint was associated with a thermodetector count of 10, the threshold for sticky lint problems in textile mills. An equation was developed to estimate melezitose concentration on lint as a function of average numbers of aphids per leaf and the interaction between percentage leaf moisture and nitrogen. The number of aphids per leaf associated with a melezitose concentration of 90.9 μg/g of lint ranged from 11.1 to 50.1, depending on percentage leaf moisture and nitrogen. The threshold for sticky lint problems occurred when aphid numbers ranged between 11.1 and 50.1 per leaf after bolls open.

A full-season, threshold-based insecticide control program, primarily for boll weevils, Anthonomus grandis grandis Boheman, was compared with no insecticide control in irrigated cotton in the northern Texas Rolling Plains from 1993 to 1995. These 2 insecticide-use options were compared in 3 cotton varieties (Paymaster HS-26, TAMCOT HQ95, All-Tex Quickie) and 2 row spacings (76 cm and 102 cm). Cotton was planted in late April–early May each year, which is an earlier planting time than the preferred period of late May–early June. Net returns per hectare were calculated for each treatment and used to determine the most cost-effective chemical and row spacing management option for each cultivar. Of the 29 insecticide applications for thrips, boll weevils, bollworms, Helicoverpa zea (Boddie), and cotton aphids, Aphis gossypii Glover, during the 3-yr study, 23 were for management of boll weevils. Boll weevil damage was lowest in HS-26 in the 76-cm spacing and in Quickie in the 102-cm spacing; these cultivars produced fewer squares and bolls in these 2-row spacings, respectively, than did the other 2 cultivars. Average yield and net income were higher in the 76-cm row spacing than in the 102-cm spacing, and yield and income were higher in HS-26 and HQ95 than in Quickie in both row spacings. Average yields were higher in treated plots, but average net income was higher in untreated cotton. In the 76-cm row spacing, highest net return was obtained from untreated Quickie ($161.10/ha), whereas in the 102-cm row spacing, highest net returns were obtained in treated HS-26 ($174.47/ha) and untreated HQ95 ($167.25/ha). In treated and untreated cotton, the break-even yields were 697 and 514 kg lint per hectare, respectively. In treated plots, yields for HS-26 in both 76- and 102-cm row spacings and for HQ95 in the 76-cm row spacing exceeded the break-even yield. Yields in all untreated plots, except Quickie in the 102-cm row spacing, exceeded the break-even yield. Based on comparisons of net returns between treated and untreated plots of each cultivar, only HS-26 in the 102-cm row spacing responded adequately to a full-season insect control program. In all other comparisons, net returns were numerically higher in untreated plots. Insecticidal control should be tailored to the cultivar and row spacing used.

Whitefly honeydew contamination resulting in sticky cotton lint is a significant problem in the textile industry throughout the world. We conducted studies in 1995 and 1996 to determine the effects of cotton cultivars, cotton plant densities, and insecticides on Bemisia argentifolii Bellows & Perring populations and the subsequent effects on honeydew cotton lint contamination. In 1995, cotton plant densities of 25 or 100,000 plants per hectare had no effect on numbers of B. argentifolii, adults, eggs, or nymphs based on adult leaf turns and immatures counted on leaf disks. There also was no effect on extracted honeydew sugars from lint samples or thermodetector sticky cotton counts (the international standard for measuring cotton lint stickiness). Higher numbers of whiteflies occurred in early-season in 'Pima S-7' cotton than in 'Deltapine (DPL) 50' in 1995 and 1996 or 'DPL 5415' cotton in 1995. In 1995, amounts of trehalulose and melezitose (insect honeydew sugars) extracted from cotton lint and thermodetector counts of lint samples were higher for DPL 50 compared with Pima S-7 but not DPL 5415. Insecticide treatments, in both years, reduced thermodetector counts and honeydew sugars extracted from lint. Increases in thermodetector sticky cotton counts and trehalulose and melezitose were significantly correlated to increasing B, argentifolii nymphal and adult populations. Thermodetector sticky cotton counts did not reach levels of concern (≥5) until adult leaf-turn counts were 8.9 or when all life stage nymphs were 3.2 per square centimeter of leaf disk during the open mature cotton boll period.

The effect of early-season flower bud damage on yield, quality, and maturity of cotton, Gossypium hirsutum L., was determined at Florence and Blackville, SC, from 1989 to 1994. From 1989 to 1991, yields from insecticide-treated plots for Heliothis virescens (F.) during June were compared with plots left untreated during June. In all cases from 1989 to 1991, no significant differences in yield were observed between treated and untreated plots. From 1992 to 1994, H. virescens damage was simulated by hand-removal of flower buds. In 1992, no significant differences were observed in yield, maturity, or lint quality following removals as high as 100% for 4 consecutive weeks. In 1993, a 1-wk delay in maturity was observed in 'DES 119' and 'Deltapine 90' at both locations following removals of 100% for 3 and 4 wk, and in 1994 at Blackville following removals of 100% for 3 wk. From 1992 to 1994, there were no significant yield effects following any flower bud removal level or duration, but in 1993 at Blackville, there were significant removal X planting date and removal X planting date X cultivar interactions. In this instance, DES 119 planted late (28 May) and grown under irrigated and dryland conditions experienced yield reductions of 30-45% after 100% removal for 3 or 4 wk that extended into mid-July. No other significant interactions with removal occurred, and no differences in lint quality were observed. Our data indicate that cotton compensates adequately for flower bud loss in June in South Carolina, and that insecticides for H. virescens seldom are needed early in the season. Opportunities to ameliorate traditional insecticide approaches for cotton insect management are discussed by considering our data in conjunction with the expansion of the Boll Weevil Eradication Program and the deployment of cotton cultivars that contain genes for expression of the delta-endotoxin of Bacillus thuringiensis in other areas of the Cotton Belt.

In 1999, crop consultants scouting for stink bugs (Hemiptera spp.) in South Carolina discovered a formerly unobserved seed rot of cotton that caused yield losses ranging from 10 to 15% in certain fields. The disease has subsequently been reported in fields throughout the southeastern Cotton Belt. Externally, diseased bolls appeared undamaged; internally, green fruit contain pink to dark brown, damp, deformed lint, and necrotic seeds. In greenhouse experiments, we demonstrated transmission of the opportunistic bacterium Pantoea agglomerans by the southern green stink bug, Nezara viridula (L.). Here, green bolls were sampled from stink bug management plots (insecticide protected or nontreated) from four South Atlantic coast states (North Carolina, South Carolina, Georgia, and Florida) to determine disease incidence in the field and its association with piercing-sucking insects feeding. A logistic regression analysis of the boll damage data revealed that disease was 24 times more likely to occur (P = 0.004) in bolls collected from plots in Florida, where evidence of pest pressure was highest, than in bolls harvested in NC with the lowest detected insect pressure. Fruit from plots treated with insecticide, a treatment which reduced transmission agent numbers, were 4 times less likely to be diseased than bolls from unprotected sites (P = 0.002). Overall, punctured bolls were 125 times more likely to also have disease symptoms than nonpunctured bolls, irrespective of whether or not plots were protected with insecticides (P = 0.0001). Much of the damage to cotton bolls that is commonly attributed to stink bug feeding is likely the resulting effect of vectored pathogens.

DES 119 cotton, Gossypium hirsutum L., and a smooth-leaf isoline were monitored, for cotton aphid, Aphis gossypii Glover, densities and effects on yield in aphicide-treated and untreated plots. The interactions of cotton genotype and aphicide treatment regime were significant for aphid density and cotton yield. Aphids caused a yield loss (≈140 kg lint per hectare) in DES 119 cotton when it was not treated with aphicide. No yield differences were observed between aphicide-treated and untreated plots containing the smooth-leaf isoline of DES 119. Yields for DES 119 with aphicide, the smooth-leaf isoline without aphicide, the smooth-leaf isoline with aphicide, and DES 119 without aphicide were 1105.0, 996.3, 971.0, and 964.0 kg lint per hectare, respectively. DES 119 treated with aphicide yielded more cotton than each of the other treatments. No differences were observed in the densities of, nor damages caused by, other cotton pests, which could account for yield losses that we attributed to cotton aphid. The data also indicated that the smooth-leaf isoline of DES 119 offers substantial resistance to cotton aphid. Thus, high-yielding, smooth-leaf cotton lines that do not respond to aphicide treatments might be viable alternatives to currently used chemical approaches, to cotton aphid management.

This study measured the influence of planting date, cotton cultivar, and insecticidal control on pest abundance, damage, yield, and net returns in irrigated cotton. Cotton was planted in late April, late May, and late June from 1986 to 1989 at the Texas Agricultural Experiment Station at Monday. Densities of drips, Franklin fella occidentals (Pervade), were highest in cotton planted in late April and lowest in cotton planted in late June. Densities were not affected by the cultivates TOMCAT CANDIE or Lankart Sel 611. Lowest densities of cotton fleahoppers, Pseudatomoscelis seriatus (Reuter), were recorded in cotton planted in late April and highest in cotton planted in late June. Cotton fleahopper densities were significantly higher in ‘CAMD-E’, as compared with ‘Lankart Sel. 611’, in the late June planting; but differences were not observed between cultivars in the other two planting dates. Densities of overwintered boll weevils, Anthonomus grandis grandis Boheman, were highest in cotton planted in late April. When averaged over the four years, densities of bollworm, Helicoverpa zea (Boddis), larvae were not influenced significantly by planting date or by cultivar. Boll weevil damage during the growing season was almost twice as high in the late-June planting compared with damage in the late-April and late-May plantings. Percentage square damage was reduced in both cultivars treated with insecticides compared with damage in untreated plots when cotton was planted in late April; there were no differences between treated and untreated plots in either cultivar when cotton was planted in late May. When cotton was planted in late June, percentage square damage was reduced in ‘CAMD-E’ plots treated with insecticides compared with damage in untreated plots, but differences were not observed between treated and untreated plots in ‘Lankart Sel. 611’. Ninety-four percent of the insecticide applications were for management of boll weevils. Lint yields were similar in the late-April and late-May planting dates; both dates produced higher yields than those in the late June planting. Yields were higher in ‘CAMD-E’ than in ‘Lankart Sel. 611’, and yields in treated plots were higher than those in untreated plots. Net returns were lowest in late June cotton, but they were similar in the late-April and late-May plantings. Net returns for ‘CAMD-E’ were higher than those for ‘Lankart Sel. 611’. Returns were higher in untreated cotton compared with treated cotton in the late-April and late-June planting dates. Differences were not observed between returns in treated and untreated plots in the late-May planting date.

Naturalis-L, which contains conidia of an insect-specific fungus, Beauveria bassiana (Balsamo) Vuillemin (ATCC 74040, ARSEF 3097, FCI 7744), was evaluated in field trials for activity against boll weevil, Anthonomus grandis grandis Boheman. Effectiveness was evaluated against overwintered adults in the spring and throughout the cotton production season for control of adults in the Lower Rio Grande Valley of Texas. In 1991, Naturalis-L was as effective as azinphosmethyl in protection of the cotton crop; lint production was 247.2 and 223.1 kg/0.4ha, respectively. In 1992, lint production in cotton protected by Naturalis-L was 373.1 kg compared with 469.5 kg lint production in cotton protected by a combination of bifenthrin and acephate. In 1991 and 1992, the integration of Naturalis-L for early-season boll weevil protection and insecticides for boll weevil infestations occurring after bloom provided the best protection and lint yields (302.1 and 469.5 kg/0.4hal, respectively.

Three experiments were done between 1984 and 1987 in manually simulated pest damage with up to 14 damage treatments in any year, involving different types and levels of damage at three stages of the season applied to three varieties, two plant populations, and two irrigation regimes. In these experiments, the cotton plant has again shown a considerable ability to compensate in terms of total lint yield for early damage, involving either the loss of the growing point or squares. Although severe damage or combinations of tip and square removal sometimes caused considerable delay in maturity, light and moderate damage had little effect. Damage treatments did not affect fiber attributes sufficiently to have incurred price penalties commercially, despite extreme delay in some cases. Damage treatments did not interact with plant populations and irrigation regimes but the locally bred okra leaf variety ‘Siokra’ was more responsive to damage than the normal leaf variety ‘Deltapine 90’, with increased yield at light to moderate levels of early damage and decreased yield at severe levels. Evidence was found in the data from these experiments for the occurrence of three out of four previously identified physiological mechanisms involved in compensation by the crop plant for damage: damage substituting for physiological shedding, increased boll weight and increased rate of flowering. There was no evidence of the fourth mechanism, increased boll set.

The effect of early-season cotton, Gossypium hirsutum L., square loss and insect control (primarily thrips, Frankliniella occidentalis (Pergande)), on the ability of cotton plants to replace lost fruit as well as maintain lint quality was examined in several field trials of differing experimental design in Arizona during 1986-1987. All trials indicated some degree of compensation for damage to fruiting structures and yield depending upon the timing and plant growth stage. Significant differences in yield were detected only in plots that had squares removed 4 wk after initiation of square production. Most measures of cotton quality were similar among treatments. No differences in fiber strength, elongation, or any color or trash index were calculated for any test. Only a few significant differences between treatments were detected in length, micronaire, or uniformity. However, differences among treatments in all tests were small and all values within a test were still within the same relative range, either “average” or just below “average” range. The treatment with squares removed at 4 wk after square initiation had shorter fiber lengths than those with squares removed early or no removals. ‘Deltapine 90’ cotton treated with aldicarb at pinhead square had higher micronaire than aldicarb-treated ‘Deltapine 77’, but there were no differences between treated and untreated plots. Treated ‘Deltapine 90’ had higher uniformity than untreated ‘Deltapine 90’, but there were no differences between cultivars or between treated and untreated ‘Deltapine 77’. Cotton from plots treated with phorate at planting had higher uniformity ratios than cotton from either aldicarb-treated or control plots. Comparisons of the results of this study are made with those of other regions. Possible factors producing different results are discussed.

Phytophagous stink bugs (Hemiptera: Pentatomidae), including green stink bug [Acrosternum hilare (Say)], southern green stink bug [Nezara viridula (L.)], and brown stink bug [Euschistus servus (Say)], have become a serious production issue for southeastern U.S. cotton, Gossypium hirsutum L., growers. To investigate how different agronomic crops may affect stink bug damage and fiber quality in neighboring cotton fields, replicated 1.6-2.0-ha trials were planted with corn (Zea mays L.), peanut (Arachis hypogaea L.), and soybean [Glycine max (L.) Merr.] bordering a centrally located cotton plot (each of the four crops composed of approximately 0.4-0.5 ha per trial). Three trials were conducted in 2007 and three additional trials were conducted in 2008. Stink bug damage in the cotton plot was sampled weekly during weeks 3 through 6 of bloom at distances of 0.5, 5.3, 9.6, and 18.7 m from the adjacent crop. At the end of the year, representative lint samples at distances of 0.5, 9.6, 18.7, and 31.8 m from each adjacent crop were mechanically harvested, ginned, and classed. Results show that boll damage, seedcotton yield, gin turnout, fiber color, and lint value were negatively affected when the cotton was located adjacent to peanut and soybean. Regardless of the adjacent crop, there were no differences among yield and fiber quality parameters comparing seedcotton obtained 18.7 m from the plot edge and samples obtained from the middle of the cotton plot (approximately 31.8 m from an adjacent crop). These data suggest that integrated pest management programs for the stink bug complex in cotton may include farmscape level planning and targeted interventions as opposed to a crop specific management approach.

The southern green stink bug, Nezara viridula (L.), is a significant pest of cotton, Gossypium hirsutum L., and is becoming an increasing challenge due to the decrease in use of broad-spectrum insecticides on the crop. The southern green stink bug can vector an opportunistic Pantoea agglomerans strain (designated Sc 1-R) into cotton bolls, resulting in infection. The appearance of stink bug damage varies, and pest managers cannot readily identify its source. This research reports a systematic depiction of green, immature boll responses at various stages of maturity (1, 2, and 3 wk post-anthesis [WPA]) to stink bug injury and to infection by the vectored cotton pathogen by demonstrating the progression of effects 1, 2, and 3 wk after exposure (WAE). When laboratory-reared adult southern green stink bug not harboring Sc 1-R deposited bacteria into greenhouse-grown bolls at 1, 2, or 3 WPA during feeding/probing, bacteria reached concentrations of 10(9), 10(9), and 10(3) colony-forming units (CFUs)/g tissue, respectively, at 3 WAE, yet caused minimal seed and lint damage regardless of the age of the bolls that were penetrated. Bolls at a maturity of 1 or 2 WPA showed similar susceptibility when exposed to stink bugs that vectored Sc 1-R. After a week of infection, seeds were salmon-pink with normal white lint and up to 10(4) CFUs/g tissue when Sc 1-R was detected. Necrosis of the entire inoculated locule(s) with a maximum Sc 1-R concentration detected at 10(8) CFUs/g tissue occurred in samples harvested 2 or 3 WAE. Conversely, seed and lint deterioration due to the transmitted opportunist into bolls exposed 3 WPA was confined to the puncture site. In summary, after a week of development, bolls were tolerant to southern green stink bug feeding/ probing damage and to nonpathogenic bacteria, but they were severely damaged when the opportunistic pathogen Sc 1-R was transmitted. At 3 WPA, the fruit was immune to the spread of the pathogen with infections confined to the puncture site.

Sampling of pink bollworm, Pectinophora gossypiella (Saunders), eggs was evaluated during 1987 as an alternative to conventional sampling of larvae for making insecticide treatment decisions. Eight cotton, Gossypium hirsutum L., fields, ≈16 ha each, were managed using a treatment threshold of 4-6% egg-infested bolls. The remaining eight fields were managed by pest control advisers and treated when 5% of susceptible green bolls were infested with one or more larvae. Total insecticide applications in the egg and larva threshold fields averaged 6.26 and 8.13 per field, respectively. Despite the significant 23% reduction ( P ≤ 0.05) in insecticide use and significantly higher larval infestations in the egg threshold fields (8.8 compared with 4.6% in larva threshold fields) ( P ≤ 0.05), there were no significant differences in yield ( P = 0.49 for lint weight) between the fields assigned to each management scheme. Results are discussed in light of previous studies on pink bollworm treatment thresholds.

Field studies were conducted in 1972 and 1986 to determine the effect of selected, commercial insecticides and acaricides (pesticides) on growth, fruiting patterns, and yield of ‘Acala SJ-2’ cotton, Gossypium hirsutum L. There was a strong tendency in the 1972 study toward less boll retention in plots treated “season-long” with methyl parathion at all test sites, as well as a significant reduction in the weight of lint cotton at one site. In the 1986 study, four weekly applications of methyl parathion significantly reduced mesophyll conductance, boll retention, number of mature and open bolls per plant, number of first position bolls per plant on mainstem nodes 5-7, weight of lint cotton at harvest, and dry weight accumulation of fruiting forms. None of the other pesticides tested in the 1986 study, including chlordimeform, significantly increased any plant growth parameter when compared with the control.

Damage to cotton by adult green stink bugs, Acrosternum hilare (Say), was evaluated in field cage studies. Adult green stink bugs significantly reduced harvestable cotton at levels of three bugs per plant in a 6-d exposure. Puncture number continued to increase with longer exposures, but losses in harvestable cotton plateaued at the longer exposures. In addition, lower seed germination rate and fiber maturity of lint harvested from cotton bolls previously exposed to stink bugs occurred. In 1987, the number of punctures was related to boll age, but boll age and amount of harvestable cotton from these bolls were not related. In 1986 boll shed tended to increase with increasing exposure time to green stink bugs, but this effect was not observed in 1987.

The effects of planting dates 2–3-wk apart on boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), field-level populations, and feeding and oviposition damage to cotton, Gossypium hirsutum L., squares and bolls, were studied during 2002 and 2003 in the Lower Rio Grande Valley of Texas. Squares were 44–56% more abundant in some later planted treatments than in the earlier planted treatments, but mean cumulative numbers of oviposition- and feeding-damaged squares were 2.7–4.8-fold greater in some later planted treatments than in earlier treatments. Increased square production in later planted cotton was offset by boll weevil infestations that occurred when squares are most vulnerable and contribute most toward the pest’s reproduction. Early planting avoided boll weevil population buildups in the field when large squares were abundant. Lint yields in 2002 did not differ significantly between the planting date treatments, but in 2003, mean yield in the middle treatment was 23% greater than in the early and late-planted treatments. Insecticide sprays in the earliest planted treatment of each year, based on the 10% damaged squares threshold, were >33% and >43% fewer than in the corresponding middle and latest planting treatments, respectively. Delayed planting, relative to the onset of favorable cotton-growing weather, at the field level, even when not applied uniformly on an areawide scale, is more cost-effective than planting too early or too late.

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 withor = 1 injured locule, bolls withor = 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.

Investigations of Heliothis zea (Boddie) attack on cottons differing in growth and fruiting characteristics were conducted in Texas in 1971–72. Numbers of fruits damaged on the indeterminate variety ‘Deltapine 16’, were similar to that recorded on experimental semidwarf determinate strains. Bollworms, as they fed, moved much less on the diminutive cottons in comparison to Deltapine 16. Thresh-hold studies showed that 9000 worms/acre for 3 infestation periods reduced yields 134–144 lb lint/acre. However, the 3 infestation subplots still produced ca. 1000 lb lint/acre. Delayed maturity as a result of the released infestations was recorded in the Deltapine 16 subplots; maturity was unaffected in the experimental semidwarf strain.

Commercially produced cotton, grown in fields that ranged from 2.4 to 32.4 ha, was closely monitored during 1981. Field data were used to estimate two equations; one described square damage and another described boll damage, both as a function of the number of Heliothis larvae and of cotton fruit load. An equation describing cotton lint yield as a function of damage during various times of the growing season was also estimated. These relationships, along with knowledge of cotton price and control cost and effectiveness, are used to estimate treatment thresholds. Based on our estimated relationships, the economic threshold varies over time and appears to be higher than some previous estimates.

Late in the season, the cotton plant ceases initiation of new branches, severely reduces fruit initiation on existing branches, and sheds many flower buds and small bolls. Plants exhibiting these characters are said to be cutout. The potential for additional harvestable bolls is restricted shortly before and after cutout. Management decisions to apply insecticides in late season should consider that many fruits will shed during plant cutout and that fruit already on the plants may not have sufficient growing conditions for maturation of fiber. One indication that plants are approaching cutout is white blooms on branches near the top of the plant. Use of the number of nodes between the uppermost white bloom and the first unexpanded mainstem leaf to assess cotton status and onset of cutout is described. The number of blooms retained (set) and the number of set blooms becoming harvestable bolls were summarized for intervals between average node counts. The interval between an average node count of four (rounded to nearest whole number) and the last bloom in a field had the lowest number of blooms, set blooms, and harvestable bolls than any other interval. The lint contribution to overall yield of harvestable bolls in the interval was estimated to be

Several mutants in upland cotton, Gossypium hirsutum L., sustained less seed damage from pink bollworm (PBW), Pectinophora gossypiella (Saunders), than the check cultivars ‘Deltapine 16’, ‘Deltapine 61’, ‘Stoneville 7A’, and ‘Stoneville 213’. These mutants were as follows: glabrous, early-maturing, high-terpenoid (gossypol and related compounds), Okra-leaf and Super Okra-leaf. Earlier studies had shown that glabrous, nectariless, glabrous-nectariless, and highly pubescent mutants, and an upland cotton of complex background (AET-5), had sustained less seed damage than the check cultivars. Cottons having as much as or more seed damage than checks were Red plant, late-maturing, glandless, and frego-bract, and also strains carrying exotic cytoplasms from 6 other Gossypium spp. Practically all the cottons tested that showed resistance to PBW were earlier maturing and yielded less lint than the check cultivars. Exceptions were: ‘Westburn M’, slightly earlier, with significantly lower seed damage, and with a slightly lower lint yield the 1st season but a significantly higher yield the 2nd season; ‘DES 56’, significantly earlier, with slightly lower seed damage, and with a comparable lint yield the 1st season, and a significantly higher lint yield the 2nd season; and Stoneville 7A Okra-leaf, significantly earlier, with significantly less seed damage, and with slightly lower lint yields. No single character reduced seed damage sufficiently to be adequate for PBW control.

Damage to young cotton, Gossypium hirsutum L., by Heliothis virescens (F.) delayed boll opening and decreased first-harvest yields. Larvae placed on plants in the fourth to sixth true-leaf stage caused more delay and fewer cumulative blooms than larvae placed on plants in the sixth to eighth true-leaf stage. The short-season plant type recovered from early-season terminal damage faster than did the long-season plant type. Lint cotton yields decreased as budworm infestation increased. Total yield reductions (Tamcot SP-37) were significant at 60 and 40% infestation levels in 1978 and 1979, respectively. Because earliness is the primary objective of a short-season production system, terminal damage may negate the advantage of these plant types. Longseason plant types may overcome the effects of terminal loss; however, increased hazards such as late-season tobacco budworm damage and rainfall also must be considered. Damaged plants ultimately produced more vegetation than undamaged plants. This increased plant volume could impede the mechanical operation of the stripper harvester and increase the probability of barky lint and reduced quality.

Greenhouse and field studies were conducted to evaluate the effects of multiple applications of chlordimeform on the growth and development of cotton, Gossypium hirsutum. L., plants, and on early season insect populations. Plants were sprayed six times with chlordimeform either alone or in combination with fenvalerate at 5- to 7-d intervals, beginning at the six-leaf stage of plant development. In the absence of early season insects and when insect populations were maintained at a relatively low level, no increases in lint yield occurred on the chlordimeform-treated plants. However, yield increases did occur and insect populations became lower in these treated plots when early season insect populations in the test area were relatively high. None of the treatments influenced the boll components boll Size, seed index, lint index, and lint percentage, or the fiber properties length, strength, and micronaire.

Cage studies were conducted to investigate the effects of 2 stink bug species, Euschistus conspersus Uhler and Chlorochroa uhleri Stal, upon cotton. Damage was measured in terms of cotton seed weight, germination, and lint yields. Results showed damage to cotton was most severe in cages containing 8 bugs/plant.

Relationships of the number of larvae present and the percent and number of damaged squares and bolls were developed. Also developed was a highly significant relationship between the number of larval days and percent lint loss. These relationships will enhance the ability of economists to evaluate large scale programs such as the effect of removing certain insecticides from commercial use, eradication, or management of other insect pests and other pest management practices.

Data from a pest management program on cotton in dryland and irrigated conditions was used to develop an economic evaluation of insect control in the Lower Rio Grande Valley of Texas during 1973-75. A strong economic advantage was shown for dryland production. Dryland cotton had 89% of its harvested bolls set by June 19 while irrigated cotton had 88% set by July 17; thus, irrigation delayed maturity. Dryland cotton required 5.5 kg/ha (4.91 lb/acre) less insecticide AI than irrigated cotton. Lint yields for dryland cotton were 541 kg/ha (483 lb/acre) vs. 615 kg/ha (549 lb/acre) for irrigated cotton and were equal by statistical analysis. However, production costs for dryland cotton were $266.88/ha ($108.05/acre) less than irrigated cotton and dryland cotton returned net profits of $142.99/ha ($57.89/acre) above those of irrigated cotton.

Four major chemical classes of insecticides are currently used for insect control on cotton. Some of these chemicals are reported to have secondary effects on the cotton plant, which influence development and yield. Representative insecticides from the four chemical classes were evaluated under greenhouse and field conditions for secondary effects on leaf gas-exchange rates and developmental alteration of cotton plants. Insecticide applications were initiated during early phases of floral bud development and at 10-d intervals thereafter for a total of five applications. Physiological measurements made 24 and 48 h after each application indicated that insecticide treatment had no effect on CO2 assimilation rate, stomatal conductance, and intercellular CO2 concentration. Insecticide treatments influenced growth and development of the plant, although differences were not always significant. Trends existed for flucythrinate to increase total plant size and dry weight, whereas chlordimeform increased reproductive growth while decreasing vegetative growth. Malathion significantly increased boll numbers per plant. Final lint yield was not significantly altered by any insecticide treatment, primarily because of the relatively short growing season existing on the Texas High Plains, which did not allow all fruit forms to complete development.

Studies of the relationship of Anthonomus grandis Boheman to short season cottons cultured in different planting arrangements were carried out in Texas for 3 seasons; a single experiment was conducted in each season. Effective blooming periods of ca. 30 days before buildup of 2nd generation boll weevil populations resulted in yields of 600–800 lb lint/acre from certain genotypes. This increased production was associated with the ability of a genotype to retain a high percent of its flowers during the blooming period. Maximum earliness and yields were recorded with genotypes planted 2 drills on 40-in. beds or single drills on 26⅔-in. beds.

Ethephon (2-chloroethyl) phosphonic acid) (“Prep”) was applied in 1985 and 1986 to cotton, Gossypium hirsutum (L.), during early to late September to remove late season fruiting forms and to determine the effects on boll weevil, Anthonomus grandis grandis Boheman, population development, cotton quality, lint yield, fiber quality, and boll opening. In 1985, boll weevils ranged from approximately one to five per 4 m of cotton row at the time of application on 6 and 13 September. Populations decreased in ethephon-treated plots thereafter, and average numbers found in infested bolls and squares were reduced >95% as compared with infestations in untreated check plots. In 1986, boll weevils ranged from zero to less than one per 4 m of row at the time of treatments on 15, 23, and 29 September. Populations increased in all plots thereafter, but were on average 9.5 times greater in check plots than in ethephon-treated plots 30 to 44 d following treatment. In 1985, ethephon at rates of 1.12 kg (AI)/ha applied 6 or 13 September did not affect cotton lint yield, but 2.24 kg (AI)/ha applied 6 September reduced yield significantly, possibly because of delayed cotton harvest. In 1986, ethephon at 1.68 kg (AI)/ha had no effect on cotton yields or cotton fiber quality characteristics, but the fiber-length uniformity ratio was significantly higher in the ethephon-treated plots. Ethephon accelerated mature boll opening in the experimental plots in both years, demonstrating the potential for earlier harvest, stalk destruction, and cotton plow down, which are desirable cultural practices that help reduce overwintering boll weevil populations.

Chlordimeform was evaluated in four large-plot field tests over 2 years to determine its effect on yield enhancement for a short-season, dryland cotton system under typical insect pest management. Four or seven applications of chlordimeform (0.14 kg [AI]/ha) were made at the sixth true leaf stage and reapplied at 5-day intervals. Densities of early season cotton fleahoppers, Pseudatomoscelis Seriatus (Reuter), and blasted squares were reduced as much as 50% by multiple applications of chlordimeform. Fleahopper nymph densities were reduced 85%. Predaceous insects and spiders were not significantly affected. Chlordimeform increased early square and boll counts, earliness of harvest, and total bolls (12.2%)and lint harvested (6.4%) per ha, but had no measurable effect on lint per boll or boll diameter. Significant increases in yield and earliness of fruit set were attributed, in part, to reduced insect damage in the chlordimeform-treated plots.

The effects of the numbers of pink bollworm (PBW), Pectinophora gossypiella (Saunders), per boll of Deltapine 16, a cultivar of upland cotton, Gossypium hirsutum L., and Pima S-5, a cultivar of American Pima cotton, G. barbadense L., were evaluated. For each PBW per boll, lint losses were 14 and 24%, and seed weight losses were 12 and 22%, in Deltapine and Pima, respectively. The relationship between PBW per gram seed-cotton and boll dry weight was the same in both cultivars, which indicated that the infestation susceptibility was the same in both cultivars. However, in the smaller bolls with equal larval densities, the percentages of damaged seed were greater in Pima than in Deltapine. In both cultivars, the lint per seed was negatively correlated to the percentage of damaged seed. The percentage of fluorescent seed (an index of aflatoxin-forming fungus) increased with the number of larvae per boll. Lint quality decreased as the infestation level increased.

A presence-absence egg sampling plan for pink bollworm (PBW), Pectinophora gossypiella (Saunders), developed to provide a more accurate index of moth (target stage) activity, was evaluated during 1986 to determine whether egg sampling rather than conventional larval sampling provided more optimal timing of insecticide applications. The large-scale field test (260 ha) consisted of 16 commercial fields, ca. 16.2 ha each, in the Palo Verde Valley, Calif. Of the eight fields that were treated based on egg sampling (treatment threshold, 6 to 8% egg-infested bolls), an average 35% seasonal reduction in insecticide use was obtained when compared with larval sampling. Despite the reduction in insecticide use, PBW larval infestations were not significantly different in fields sampled for eggs and fields sampled for larvae from June to September. Lint yields as well as lint quality parameters were also not significantly different between the two sets of fields. Economic and environmental benefits of a 35% reduction in insecticide use is discussed.

Yield parameters (insect control, lint yield, lint percentage, and micronaire) of 2 cotton, Gossypium hirsutum L., genotypes (‘Coker 310’, an adapted cultivar, and an insect nonpreferred strain, OFNRS = okra leaf, frego bract, nectariless, and red stem) varied according to different insecticide spray programs. Insecticides included organophosphates, pyrethroids, organophosphate: pyrethroid combinations, and an experimental molt inhibiting insecticide. Bollworms, Heliothis spp., and the boll weevil, Anthonomus grandis grandis Boheman, were reduced in the OFNRS genotype and yield was significantly higher than Coker 310 during an intense infestation when chemical control was poor. Of 14 insecticide treatments tested, combinations of certain pyrethroids with methyl parathion had greatest efficacy and yield of seed cotton. Fiber properties were influenced by insecticide treatment and date of initial spray application.

In a 3-yr field study, a short-season cotton production system was compared with the traditional long-season system. Average cotton lint yields of 3 short-season cultivars were 826 kg/ha as compared with 670 kg/ha for the long-season grower check fields. Four fewer insecticide applications and one less irrigation were required on the short-season test plots as compared with the check long-season fields. Production costs were lower for the short-season system as compared with the Lower Rio Grande Valley (LRGV) of South Texas conventional long-season system. In 1978, the production cost advantage of the short-season production as compared with the conventional was $dollar;0.39/kg of lint produced. A shift to an integrated short-season production system in the LRGV has both economical and environmental advantages over the conventional, long-season system.

Results from field experiments conducted during 1961 and 1962 revealed that infestations of the carmine spider mite, Tetranychus cinnabarinus (Boisduval), artificially established at different times of the growing season, reduced yield of seed cotton 14 to 44%. In general, yield depression was directly related to population density and duration of infestation. Spider mite injury also reduced boll size and appeared to adversely affect several characters of the seed and lint. Infestation counts and climatic data from each experiment revealed that mite populations and subsequent damage were greatest during periods of hot, dry weather. Hard and heavy rainfall reduced population density. Heavy mite infestations caused typical foliage discoloration and desiccation, but rarely caused extensive defoliation.

In a 2-year replicated field-cage experiment with boll weevils, Anthonomus grandis Boheman, first-generation progeny from estimated overwintered populations of 0, 14, 25, 50, and 100 weevils per acre damaged 0, 28, 46, 66, and 83% of the squares, respectively. Second-generation weevils damaged from 84 to 96% (weevil-free check excluded) of the squares. Seed cotton harvested from the respective treatments averaged 2802, 1875, 1678, 1318, and 847 lb per acre. Differences in lint quality were detected between plots infested with 100 overwintered weevils per acre and those infested at the other 4 levels. These differences were observed in the first and third harvesting in 1961. No other quality differences were observed.

Damage to individual cotton plants ‘Deltapine 16’, by uniform and continuous infestations of 1 late-stage nymph or adult male Lygus hesperus Knight per cage during 4 infestation periods was studied at Tucson, Arizona, in 1969. Nymph-infested plants grew taller and showed altered patterns of squaring, flowering, and bolling, as compared with noninfested controls, but no significant reductions in seed cotton yield or lint quality were detected. Nymph-infested plants yielded lower percentage weights of lint and higher percentage weights of seed. Plants infested with nymphs from the time of 1st square until Aug. 16 had significantly increased numbers of main stem vegetative branches. Plants infested with adults from the time of 1st square until 1st bloom showed altered patterns of squaring and flowering but no significant yield reductions. Lint quality and monetary value were lower on plants exposed to adults during the late infestation period from July 26 to Aug. 16.

Cotton crop value was reduced by 34% when seasonal infestation counts averaged at least 60% of the bolls infested by pink bollworm ( Pectinophora gossypiella (Saunders)) in experiments at Brownsville, Texas. At this level of infestation, losses were about equally distributed between reductions in yield and quality of lint and seed. Lower infestations resulted in losses due chiefly to reduced quality of lint and seed. Reductions in staple length, strength, and fineness or immaturity of fiber were directly related to pink bollworm infestation levels. Likewise, losses in yield and quality of seed were related to pink bollworm infestation levels. In artificially infested bolls, the degree of damage was related to age of boll and number of larvae per boll.