Weeks Of Bloom Research Articles

Field Evaluation of Cotton Expressing Mpp51Aa2 as a Management Tool for Cotton Fleahoppers, Pseudatomoscelis seriatus (Reuter).

The cotton fleahopper (Pseudatomoscelis seriatus Reuter) is considered a highly economically damaging pest of cotton (Gossypium hirsutum L.) in Texas and Oklahoma. Current control methods rely heavily on the use of foliar-applied chemical insecticides, but considering the cost of insecticides and the critical timeliness of applications, chemical control methods are often not optimized to reduce potential yield losses from this pest. The Bacillus thuringiensis (Bt) Mpp51Aa2 (formerly Cry51Aa2.834_16) protein has proven effective against thrips and plant bugs with piercing and sucking feeding behaviors, but the impact of this toxin on cotton fleahoppers has not been investigated. To evaluate the Mpp51Aa2 trait effectiveness towards the cotton fleahopper, field trials were conducted in 2019, 2020, and 2021, comparing a cotton cultivar containing the Mpp51Aa2 trait to a non-traited isoline cultivar under insecticide-treated and untreated conditions. Populations of cotton fleahopper nymphs and adults were estimated weekly by visually inspecting cotton terminals. Square retention was also assessed during the first week of bloom to provide some insight on how the Bt trait may influence yield. While cotton fleahopper population differences between the traited and non-traited plants were not consistently noted during the pre-bloom squaring period, there was a consistent increase in square retention in cotton expressing Mpp51Aa2 relative to non-traited cotton. Additionally, cotton expressing Mpp51Aa2 offered similar square protection relative to non-traited cotton treated with insecticides for the cotton fleahopper. These findings indicate that the Mpp51Aa2 protein should provide benefits of delayed nymphal growth, population suppression, and increased square retention.

Chlorantraniliprole Residual Control and Concentration Determination in Cotton.

Studies were conducted in 2020 and 2021 at the Delta Research and Extension Center in Stoneville, MS, to determine the residual concentrations of chlorantraniliprole in cotton (Gossypium hirsutum, L.) leaves, as well as the concentrations in petals and anthers that developed after the time of application. Foliar applications of chlorantraniliprole were applied at four rates for leaves and two rates for petals and anthers at the second week of bloom. Additional bioassays were conducted to determine mortality of corn earworm (Helicoverpa zea, Boddie) in anthers. For the leaf study, plants were partitioned into three zones consisting of top, middle, and bottom zones. Leaf samples from each zone were analyzed for chemical concentrations at 1, 7, 14, 21, and 28 days after treatment (DAT). Residual concentrations, although variable, persisted through all sampling dates, rates, and zones tested. In this study, chlorantraniliprole remained detectable up to 28 DAT. Results from the cotton flower petal and anther studies detected concentrations of chlorantraniliprole in petals at 4, 7, 10, and 14 DAT, but no concentrations were detected in anthers. Therefore, no mortality of corn earworm was recorded in the anther bioassays. A series of diet-incorporated bioassays were conducted using concentrations previously found in the petal study to determine baseline susceptibilities of corn earworms and predicted mortality. Results from the diet-incorporated bioassays showed similar susceptibility in field and lab colony corn earworms. Concentrations of chlorantraniliprole could provide up to 64% control of corn earworm when feeding occurs on the petals.

A Dynamic Threshold Approach for Tarnished Plant Bug (Hemiptera: Miridae) Management in the Midsouthern U.S. Cotton.

One of the most economically important pests of cotton, Gossypium hirsutum L., in the midsouth region of the United States is the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois, Hemiptera: Miridae). Tarnished plant bug populations across the region have exhibited widespread resistance to numerous insecticide classes. To minimize late season resistance development, reducing unwarranted applications during the late flowering period can aid in resistance management and potentially reduce input costs. Trials were conducted during 2019 and 2020 to evaluate the impacts of tarnished plant bug populations in the later flowering period of cotton by modifying or terminating threshold regimes during the later weeks of bloom. Results showed that dynamic thresholds altered at the fourth week of bloom or later can reduce the number of late season applications made with no penalty to yield. Additionally, when utilizing a week of bloom termination approach, no significant yield losses were seen when terminating applications after the fourth week of bloom. These data may offer an alternative method to managing tarnished plant bug populations during the later flowering period of midsouth cotton.

Wild bees and natural enemies prefer similar flower species and respond to similar plant traits

Designing wildflower habitats to support beneficial insects providing pollination and pest control services is important for supporting sustainable crop production. It is often desirable to support both groups of insects, making the selection of resource plants for insect conservation programs more challenging. Moreover, the process of selecting resource plants is complicated by the array of possible options in each region, and the need to provide resources over the entire growing season. Identifying traits shared by resource plants that are attractive to both bees and natural enemies can reduce the need to evaluate new plants in each region, by providing a guide for the types of plants expected to be rewarding to these insects. Using insect visitation data collected from replicated common garden plantings of native wildflower and shrub species from the Great Lakes region of the United States, we found a high degree of correlation between the abundance of bees and natural enemies visiting native plant species. These results were used to identify a set of 15 plant species that can provide resources for these insects throughout the summer. Across all tested species, pollen quantity per flower and the week of bloom were positively correlated with some, but not all, taxonomic groupings of beneficial insects. In contrast, floral area was consistently positively associated with visitation of both natural enemies and wild bees. This trait is easy to document and can allow for efficient local testing of potential resource plants, providing a faster path to implementing insect conservation in working landscapes.

Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton.

Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.

Evaluating Optimal Spray Timing, Planting Date, and Current Thresholds for Lygus lineolaris (Hemiptera: Miridae) in Virginia and North Carolina Cotton.

Economically damaging infestations of Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), the tarnished plant bug, have been increasing in North Carolina and Virginia cotton since 2009. We conducted experiments to compare prophylactically timed sprays based on cotton phenology and current action thresholds based on sweep net and drop cloth sampling. In the second year of the study, we included planting date as a factor, with early and late-planted cotton. We found L. lineolaris nymph densities were reduced by at least 60% in North Carolina and 74% in Virginia in threshold plots when compared with the untreated control. Protecting the crop from first square through the fourth week of bloom afforded at least 30% control across planting dates in Virginia and at least 40% control in North Carolina. Economic returns were two to three times greater in early-planted cotton than in late-planted cotton. Treating cotton at action threshold or using prophylactic sprays from first square until the sixth week of bloom in early-planted cotton yielded over $500/ha in net returns in both North Carolina and Virginia. This study supports previous research that shows controlling L. lineolaris infestations during squaring and early weeks of flowering is critical for maximizing yield potential. Our findings also suggest that prebloom and bloom thresholds based on adult and nymphal density devised in the Mid-South may need revision in North Carolina and Virginia.

Peach Fruit Set and Buttoning after Spring Frost

Peach fruit set is affected by cumulative chill and spring frost. A spring frost occurred on 29 Mar. 2015 at the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) Byron station after 3 weeks of bloom, reducing fruit set and resulting in many buttons (abnormally small fruit with dead embryos). Fruit set was rated in 2014, 2015, and 2016 and button set rated in 2015 using the same scale (0 = no fruit/button to 9 = 1–2 fruit/button at every node). The overall fruit set rating was substantially different in the 3 years, averaging 5.61 in 2014, 2.61 in 2015, and 6.04 in 2016. Buttons and skin-damaged fruit in 2015 varied among peach genotypes. Comparison of fruit and button set ratings showed that there was no difference between cultivars and selections, but some significant differences in fruit set for four ripening months, among the 3 years, and among the nine chilling classes, respectively. Among the cultivars, the most common button set rating was 0–3. For example, ‘Sunprince’, ‘Loring’, and ‘Carored’ trees had a high button set rating, whereas ‘Flameprince’, ‘Julyprince’, and ‘Contender’ trees were low. As for peach selections, BY04P1690n was among those with the highest button set rating. In the population derived from a cross of button-prone BY04P1690n and button-free BY99P3866w, fruit and button counts from 10 long fruiting shoots ranged from 4 to 53 fruit (21.63 on average) and 2 to 27 buttons (10.39 on average). The peach button rate ranged from 5.36% to 87.10% (30.70% on average). The range, distribution, and percentage of the button counts suggested that, if buttoning was genetically controlled, it appeared quantitative. Further assessment is needed.

Aggregation and Association of NDVI, Boll Injury, and Stink Bugs in North Carolina Cotton.

Sampling of herbivorous stink bugs in southeastern U.S. cotton remains problematic. Remote sensing was explored to improve sampling of these pests and associated boll injury. Two adjacent 14.5-ha cotton fields were grid sampled in 2011 and 2012 by collecting stink bug adults and bolls every week during the third, fourth, and fifth weeks of bloom. Satellite remote sensing data were collected during the third week of bloom during both years, and normalized difference vegetation index (NDVI) values were calculated. Stink bugs were spatially aggregated on the third week of bloom in 2011. Boll injury from stink bugs was spatially aggregated during the fourth week of bloom in 2012. The NDVI values were aggregated during both years. There was a positive association and correlation between stink bug numbers and NDVI values, as well as injured bolls and NDVI values, during the third week of bloom in 2011. During the third week of bloom in 2012, NDVI values were negatively correlated with stink bug numbers. During the fourth week of bloom in 2011, stink bug numbers and boll injury were both positively associated and correlated with NDVI values. During the fourth week of bloom in 2012, stink bugs were negatively correlated with NDVI values, and boll injury was negatively associated and correlated with NDVI values. This study suggests the potential of remote sensing as a tool to assist with sampling stink bugs in cotton, although more research is needed using NDVI and other plant measurements to predict stink bug injury.

Within-field spatial distribution of stink bug (Hemiptera: Pentatomidae)-induced boll injury in commercial cotton fields of the southeastern United States.

Spatial distribution of boll injury caused by stink bugs to developing cotton (Gossypium hirsutum L.) bolls was studied in five commercial fields (≍22 ha each) in 2011 and 2012 to understand variability in boll injury dynamics within fields. Cotton bolls and stink bugs were sampled weekly from a georeferenced grid of sampling points (one sample per 0.40 ha) in each field, but no samples were taken within 30 m of field edges. The inverse distance weighted interpolation, variogram analysis, and Moran's I were used to describe spatial variability of boll damage within the fields. Boll injury was found to be spatially associated at distances ranging from ≍75 to 275 m with an average distance ≍150 m. An exponential variogram model was selected as the best fitting model to describe the spatial association in four of the five fields. Moran's I indicated that spatial association was significant in three of the five fields. The spread of boll injury from stink bugs was gradual in most fields and always exceeded the treatment threshold during the fourth or fifth week of bloom. Capture of stink bugs using a sweep net was inefficient, strongly suggesting that quantifying boll injury is a better sampling method and predictor of stink bug activity when sampling all but the edges of the field. These data suggest that scouts need to sample boll injury from sample locations separated by at least 150 m to assure independence in the central part of large fields. Second, future researchers who plan to use parametric statistical methods could use a 150-m grid, as opposed to a denser grid that would require greater time and effort.

INCREASED NUTRIENT SOLUTION CONCENTRATION DURING EARLY FRUIT DEVELOPMENT STAGES ENHANCES PUNGENCY AND PHENYLALANINE AMMONIA-LYASE ACTIVITY IN HOT CHILI (<i>CAPSICUM ANNUUM</i> L.)

The effect of increased nutrient concentration during different fruit development stages on the yield, pungency and PAL enzyme activity in hot chili cv. ‘Super hot’ was studied during August 2009-January 2010. The seedlings were planted in plastic containers containing 20 L of coconut-coir-dust substrate placed inside a plastic-roofed net house and received Resh’s Tropical Dry Summer nutrient solution at a constant concentration (measured by Electrical Conductivity, EC) of 1.2 mS cm during the vegetative stage and 2.4 mS cm during the first week of blooming. Then, they were divided into treatments: Treatment 1 (control), plants continuously received nutrient solution at a constant concentration of 2.4 mS cm until end of harvest, while treatments 2-6 received nutrient solution with a change in concentration from EC 2.4 to 3.6 mS cm at 1, 2, 3, 4 and 5 weeks after the week of first bloom, respectively. The results showed that the increase in nutrient concentration at different fruit development stages did not significantly influence chili fruit characteristics and yield. However, the oleoresin, capsaicin, dihydrocapsaicin and capsaicinoid contents increased significantly when hot chili plants received the nutrient concentration increase at the 1st and 2nd week after first bloom. Phenylalanine ammonia lyase activity in the full-ripening fruits increased significantly when the nutrient solution concentration increase occurred at 1st and 2nd weeks after first bloom. The highest PAL activity of 827.48 mmole mg protein was recorded in full-ripened fruits, when the nutrient concentration increase occurred at the 2nd week after bloom.

An evaluation of Fruit-Boost™ as an aid for honey bee pollination under conditions of competing bloom

SummaryAn experimental situation was created in which watermelon and sunflower were blooming simultaneously and competing for pollinators. Measures of watermelon flowering and bee visitation were made for three consecutive weeks of bloom and followed by measures of fruit at harvest. The honey bee attractant Fruit Boost™ was tested for its efficacy in focusing honey bees onto the target crop (watermelon) and improving pollination. Fruit Boost did not significantly affect total number of honey bees visiting watermelon flowers, the proportion of honey bee visits that occurred on female flowers, fruit-set, or fruit weight. The onset of sunflower bloom on week 2 was associated with a sequential drop in honey bee numbers on watermelon between weeks 1–3, a near absence of fruit set after week 1, and significant decrease in melon size between weeks 1 and 3. More broadly, this study suggests that pollination is compromised in agro-ecosystems where crops or feral plants are competing for limited pollinators.

(79) All-America Daylilies: Landscape Performance and Rust Observations

All-American daylily cultivars named from 1994–2004 were evaluated for landscape performance and daylily rust (Pucciniahemerocallidis) susceptibility during 2003 and 2004. Cultivars included `Black-Eyed Stella', `Bitsy, `Leebea Orange Crush', `Plum Perfect', `Judith', `Starstruck', `Frankly Scarlet', `Lullaby Baby', `Lady Lucille', and `Chorus Line'. Bareroot plants were planted in raised beds composed of an Olivier silt loam soil in full sun and received irrigation as needed to prevent stress. Visual quality ratings were made weekly from 19 Apr.–25 Oct. 2003 and 15 Mar.–20 Sept. 2004. Visual quality ratings included growth habit, based on compactness, foliage color, uniformity, and overall aesthetics, and flowering, based on longevity and visual appeal. Other flower observations were made in regard to time in bud and peak blooming periods over the same time frames. Flowering observations indicated that `Black Eyed Stella' and `Bitsy' were the only cultivars showing reliable repeat bloom potential. Among the other cultivars, `Judith' was the earliest to bud and bloom, but also had a blooming period of only 2–3 weeks compared to 4–5 weeks of bloom for other cultivars. Daylily rust ratings were taken in Sept. and Nov. 2003 and in Aug. and Nov. 2004. Rust was most severe on `Judith', `Leebea Orange Crush', `Starstruck', and `Lady Lucille'. `Judith' and `Leebea Orange Crush' showed rust symptoms earlier than other cultivars. `Plum Perfect', `Frankly Scarlet', `Bitsy', `Black Eyed Stella', and `Lullaby Baby' were least susceptible to daylily rust.

ALL-AMERICA DAYLILIES: LANDSCAPE PERFORMANCE AND RUST OBSERVATIONS 2003 AND 2004

All-American daylily cultivars named from 1994-2004 were evaluated for landscape performance and daylily rust (Puccinia hemerocallidis) susceptibility during 2003 and 2004. Cultivars included `Black-Eyed Stella', `Bitsy', `Leebea Orange Crush', `Plum Perfect', `Judith', `Starstruck', `Frankly Scarlet', `Lullaby Baby', `Lady Lucille', and `Chorus Line'. Bareroot plants were planted in raised beds composed of an Olivier silt loam soil in full sun and received irrigation as needed to prevent stress. Visual quality ratings were made weekly from 19 Apr. to 25 Oct. 2003 and 15 Mar. to 20 Sept. 2004. Included in the visual quality ratings were growth habit and flowering with favorable growth habit being compactness, foliage color, uniformity, and overall aesthetics, and favorable flowering being longevity and visual appeal. Flower observations were made in regard to time in bud and peak blooming periods over the same time frames. Daylily rust ratings were taken in September and November 2003 and in August and November 2004. Flowering observations indicated that Black Eyed Stella and Bitsy were the only cultivars showing reliable repeat bloom potential. Among the other cultivars, Judith was the earliest to bud and bloom but also had a blooming period of only 2 to 3 weeks compared to 4 to 5 weeks of bloom for other cultivars. Rust was most prevalent on Judith, Leebea Orange Crush, Starstruck and Lady Lucille. Judith and Leebea Orange Crush have rust symptoms earlier than other cultivars. `Plum Perfect', `Frankly Scarlet', `Bitsy', `Black Eyed Stella', and `Lullaby Baby' were least susceptible to daylily rust.

Ontogenic Resistance to Powdery Mildew in Grape Berries

ABSTRACT Berries of Vitis vinifera are reported to be susceptible to infection by Uncinula necator until soluble solids levels (brix) reach 8%, and established colonies are reported to sporulate until brix reach 15%. However, our analysis of disease progress on fruit of selected V. vinifera cultivars indicated that severity became asymptotic several weeks earlier in fruit development. When mildew-free fruit clusters of V. vinifera 'Chardonnay', 'Riesling', 'Gewürztraminer', and 'Pinot Noir' were inoculated at stages ranging from prebloom to 6 weeks postbloom, only fruit inoculated within 2 weeks of bloom developed severe powdery mildew. Substantial ontogenic resistance to infection was expressed in fruit nearly 6 weeks before fruit brix reached 8% and over 2 months before they reached 15%. Rachises of 'Chardonnay' and 'Riesling' fruit clusters developed severe powdery mildew when inoculated at bloom, and disease increased steadily over the next 60 days. The rachis of fruit clusters inoculated 31 days after bloom developed only trace levels of powdery mildew. Berry weight of all four cultivars at harvest was reduced when fruit clusters were inoculated at bloom or 16 days postbloom, primarily by splitting, rotting, and dehydration of mildewed berries, but the weight of later-inoculated berries was not reduced. Inoculation of berries just as ontogenic resistance increased markedly, approximately 3 to 4 weeks postbloom, resulted in the development of inconspicuous, diffuse, non-sporulating mildew colonies on berries, sometimes associated with a network of necrotic epidermal cells. Rather than a protracted and relatively static period of berry susceptibility lasting 3 months, fruit of V. vinifera appear to acquire ontogenic resistance rapidly after fruit set. A refocusing of disease management on this critical period of high fruit susceptibility should greatly improve the efficacy of fungicides directed against powdery mildew.

Pollination effects on fruit mineral composition, seeds and cropping characteristics of ‘Braeburn’ apple trees

‘Braeburn’ apple ( Malus domestica Borkh) trees were supplementary hand-pollinated or partially netted over a 3–4 week period during early and mid-blossom and compared with trees pollinated only by bees. Trees were later hand-thinned to a moderate or heavy level. In addition, individual fruit from flower clusters which had reached king petal fall in the first or fourth week of bloom were compared on supplementary hand and bee-only pollination treatments which had been moderately thinned. Partially netting trees reduced, while supplementary pollination increased, initial and final set on spur and terminal sites, seed number and final fruit Ca concentrations. Final set on 1-year axillary sites was increased by partial netting but reduced by supplementary pollination. Final yield, fruit Mg and K concentrations and average fruit size were unaffected by pollination treatment while hand-thinning level had no effect on fruit distributions, cropping or fruit mineral concentrations. For fruiting sites in trees and fruit of known blossom dates, initial fruit set and seed number per fruit were greater for later flowering sites but fruit Ca concentrations and bourse leaf areas were less than those from early flowering sites. Supplementary hand-pollination increased initial fruit set, seed numbers and fruit Ca concentrations on early flowering sites but had little effect on late flowering sites. These results show that poor pollination during the early blossom period can reduce fruit Ca concentrations for the ‘Braeburn’ cultivar. This effect may occur by reducing seed numbers in fruit as well as by altering fruit distributions on the tree.

Accumulation of copper, iron, manganese and zinc by four cotton cultivars

Abstract There has never been an intensive study of the micronutrient nutrition of cotton ( Gossypium hirsutum L.) when growing on slightly acid soils. A basic understanding of the micronutrient uptake characteristics of cotton is needed to fully understand the nutritional requirements of modern cotton cultivars and to make efficient use of micronutrient fertilizers. A field study was conducted for two years to evaluate the Cu, Fe, Mn and Zn uptake characteristics of selected cotton cultivars that are representative of cultivars used in the southern United States. Four cultivars, Deltapine 90, Stoneville 825, Coker 315 and Paymaster 145, were grown on a non-irrigated Norfolk fine sandy loam (fine loamy, thermic, siliceous, Typic Paleudults) and a non-irrigated Decatur silt loam (clayey, thermic, kaolinitic, Rhodic Paleudults). Micronutrient uptake was evaluated by sampling whole cotton plants at 2-week intervals over the growing season, beginning at 15 days after plant emergence. The plants were partitioned into leaves, stems, burs, seed and lint. Leaves, stems, burs and seed were analyzed for Cu, Fe, Mn and Zn. Results of this study demonstrate that the four cultivars accumulated similar amounts of Cu, Fe, Mn and Zn when grown on non-irrigated soils considered to have adequate levels of these elements. The cultivars also partitioned Cu, Fe, Mn and Zn in a similar manner. Total Cu, Fe, Mn and Zn uptake when averaged over both soils and all four cultivars was 28 ± 14, 626 ± 277, 388 ± 184 and 103 ± 38 g ha −1 , respectively. This corresponded to an average accumulation of 4.0 ± 2.3 g Cu, 90 ± 18 g Fe, 56 ± 15 g Mn and 15 ± 0.6 g Zn for every 100 kg lint produced. Total Fe and Zn uptake was very similar for the two soils. However, total Cu and Mn uptake was lower on the norfolk soil as compared to the Decatur soil. Daily maximum accumulation of the elements occurred at 58 to 98 days after planting (first to fourth week of bloom), which was very close to the time of maximum dry-matter production. The data generated from this study should serve as useful baseline information regarding micronutrient uptake by cotton growing on slightly acid soils. On deficient soils this information could be used in making decisions regarding the use of micronutrient fertilizers.

Thrips Control; Effect on Plant Growth, 1989

Abstract This test was conducted to evaluate insecticides applied in-furrow for thrips control and determine the effect on plant height and earliness. The plots were 4 rows wide, 40 ft long, with 4 replicates in a randomized complete block design. Treatments were applied in-furrow at planting with a John Deere Flex 71 planter on 20 Apr. The .soil type was a Dalco Clay. Plants from the outside rows were pulled and beaten on hardware screen over a white pan and thrips and aphids counted on 25 plants/plots. Thrips and aphid counts were made on 8 and 19 May. Plant height was measured on 5 consecutive plants on each of the center rows on 25 May. Plant height was determined by measuring from the cotyledon node to the first unfolded leaf. Earliness was determined by counting white and red blooms every other day on the center 2 rows from the first week of bloom, 23 to 30 Jun. Yield was determined by brush stripping the two center rows of each plot on 27 Sep.

Apple, Insect Control, Hudson Valley, Highland, New York, 1984

Abstract Treatments were applied to 8-tree plots replicated 3 times in a randomized complete block design. Treatments were applied at pink, 7 May, petal fall, 3 or 4 Jun, and in cover sprays 18 Jun, 2 Jul, 16 Jul, 30 Jul, and 15 or 16 Aug. The 2 Dimilin treatments were applied 7 May, 2 Jul, and 16 Jul; the DPX Y5893 treatments 7 May; and the Spur treatment on 7 May, 4 Jun, 2 Jul, and 30 Jul. Guthion was applied to the Dimilin and DPX plots on the remaining dates. Pounce was applied 7 May and 4 Jun, while Advantage was applied on the remaining dates. Treatments were applied to runoff using a high-pressure handgun sprayer at 400 psi delivering 4.2 gal spray/tree or 403 gal/ acre. Trees were 20-years-old, 12 ft high, spaced 15 by 30 ft, and on EMU rootstock. Additional applications over the entire block included: Bravo 500 8 qt/ acre, 18 Apr; Captan 50WP 3 lb/acre, 4 Jun and 28 Jun; Vangard 10WP 30 oz/acre, 28 Jun; Benlate 50WP 1 lb/acre, 13 Jul; and Dithane M-45 78WP 6 lb/ acre, 26 Jul and 15 Aug. Plictran 50WPP6 oz/100 gal, was applied for mite control in the Pounce and Dimilin/Guthion plots on 26 Jul. AA were evaluated on 1 ‘Rhode Island Greening’ tree/plot on 20 Jul; RAA on 1 ‘Cortland’ tree/plot on 8 Jun; EAS from 1 ‘McIntosh’ tree/plot on 12 Jun; and STLM on 1 ‘Empire’ tree/plot on 17 Oct. Insect damage to fruit was assessed at harvest by examining 100 fruits/cultivar/plot from ‘McIntosh’ 10 Sep, ‘Empire’ 24 Sep, and ‘Golden Delicious’ 4 Oct. A cool, wet spring resulted in bloom lasting longer than normal. Continual rainfall during the final week of bloom prevented timely application of the petal fall spray.

Seasonal Phenology of Allelochemicals in Cotton and Resistance to Bollworm (Lepidoptera: Noctuidae)

Seasonal phenology of condensed tannin quantity and quality, and terpenoid aldehyde quantity of 4 Upland cotton phenotypes were determined in the field during 1983. Tannin quantity and quality gradually increased from cotyledonary stage to a peak in late bloom. At the one-third-grown square stage of growth, we observed a sudden drop in both tannin quantity and quality followed by rapid recovery. Terpenoid aldehyde quantity was highest at the initiation of fruiting following which it dropped significantly and remained relatively constant for the remainder of the plants' life history. Fruit damage by bollworm, Heliothis zea (Boddie), at the one-third-grown square stage of growth was found to be highly negatively correlated with tannin quality. Terpenoid aldehyde quantity was negatively correlated with bollworm damage at the second week of bloom. Implications for host plant resistance and IPM are discussed.

Flowering and Nectar Secretion as they Relate to Honeybee Foraging Activity in Birdsfoot Trefoil (Lotus Corniculatus)

SummarySix cultivars of commercial birdsfoot trefoil differed in their flowering patterns and attractiveness to honeybees, but not in nectar secretion characteristics. Florets contained from 0·16 to 0·28 μl of nectar, with sugar concentrations ranging between 13·1% and 19·5% (0–03-0·07 mg sugar/floret). All cultivars began to flower within a week of one another and bloomed over a 13-week period, producing 2 floral peaks, except for one cultivar which produced 3. Honeybee activity was closely associated with the progression of flowering throughout the season, and cultivar foraging levels were related to the magnitude of the floral display. The cultivars that produced the most florets had the largest number of foragers. Activity was heaviest during the fifth and sixth weeks of bloom when flowering was at its peak. Introduction of honeybee colonies into fields should be delayed until cultivars are approaching peak floret production.