Harvest Aid Research Articles

Mass harvesting of marine microalgae using different techniques

The marine species microalgae are an attractive source of feedstock for biofuel production and other bio-products such as omega-3 fatty acids and aquaculture feeds. The prevailing main nutrients in seawater environment for their growth are believed to be more economical than freshwater in terms of their cultivation system which may lead to low cost for upstream processing. Hence, marine microalgae provide attractive potential to be further explored. However, harvesting process of microalgae is known to be too costly because of their dilute nature that accounts for 20–30% of the overall production costs rendering using microalgae as the raw material not economically feasible. Currently the various harvesting methods including centrifugation, flocculation, flotation, filtration and magnetic separation had been applied to harvest marine species. For instance, harvesting by electrolytic means that require less energy to harvest marine species compared to the freshwater species. This can potentially help to reduce the challenges related to the exploitation of microalgae biomass. However, different techniques have their own advantages and drawbacks, whereas their cost and energy requirement vary accordingly depending on the selection of marine microalgal strains, equipment used and/or the choice of harvesting aid (flocculants, surfactant). Thus far, no single technique may still be proposed. Therefore, this paper aims to provide further details of each method used focusing only for marine species of microalgae with their respective advantages and disadvantages.

Optimizing Swathing and Chemical Desiccant Timing to Accelerate Winter Carinata Maturation

Core Ideas Brassica carinata is an emerging dedicated oilseed feedstock for ‘drop‐in’ biofuels. Sequential flowering produces a mixture pods of different maturity. Harvest aids enhance seed maturation, crop dry down with little effect on yield. Applying harvest aid 14 to 21 d after physiological maturity when seed moisture is <28.5% accelerate transition to summer crops by 7 to 14 d. Brassica carinata (carinata) is an emerging dedicated oilseed feedstock for ‘drop‐in’ biofuels and renewable bioproducts. There is great potential for carinata to be produced as a winter crop providing economic and environmental benefits in the Southeast United States. The indeterminate flowering of carinata produces pods of different maturity making it difficult to determine the optimum harvest time. The objective of this study was to determine the effects of harvest aid and application timing on crop maturation, seed and oil yields, and fatty acid composition. B. carinata was evaluated in a 2‐yr field study at NFREC, Quincy, FL, during the 2014–2015 and 2015–2016 growing seasons. Treatments were initiated when seed moisture was at 501 to 558 g kg–1 and continued at 7 d intervals for 4 wk. In 2015, harvesting at 21 d after physiological maturity (DAPM) produced 28% greater yield than earlier harvest dates while in 2016, harvesting at 14 DAPM or later produced 31% greater yields than earlier harvests. Swathing reduced seed yield by 11% relative to control in 2015, however, no differences occurred in 2016. Seed shattering increased with maturation regardless of harvest aid and was greatest at 21 DAPM. The use of a harvest aid 14 to 21 DAPM, when seed moisture is <285 g kg–1 and more than 80% of the seeds have changed color, would accelerate the transition to summer crops by 7 to 14 d. These results indicate the potential of harvest aids to accelerate seed dry‐down and uniformity thereby facilitating the timely planting of subsequent summer crops.

Memorandum of Understanding between NHSBT, UK and Multi Organ Harvesting Aid Network Foundation, Chennai, India

Memorandum of Understanding between NHSBT, UK and Multi Organ Harvesting Aid Network Foundation, Chennai, India

Harvesting system sustainability in Mediterranean olive cultivation

The mechanization of farming operation plays an important role in improving the profitability of the agricultural sector by increasing work productivity and reducing production costs. However, the new challenges of agriculture also include the environmental issues. The choice between different alternatives to perform a determined agricultural practice should be based on reliable information, considering technical, economic and environmental aspects. Olive growing represents the most important agricultural production in the Mediterranean Basin and its mechanization, particularly harvesting, could have major impacts on the sustainability of this production. This study aims at assessing various olive-harvesting scenarios, while considering technical, economic and environmental aspects in order to build a beta version of the “olive-harvesting database”. The proposed methodology called “modular approach” could represent a useful tool to apply in unitary process assessment in order to obtain a comprehensive database of the diverse agricultural operations. The methodology was based on Life Cycle Assessment and production cost analysis. Technical performance evaluation showed that the recorded work capacities varied between 5 tons of harvested olives per day when employing mechanical harvest aids and 18 tons per day when employing trunk shakers. The economic evaluation highlighted that the harvesting costs are variable as a function of the given cost type (costs per hour, costs per kg of harvested olives and costs per hectare). The LCA revealed that mechanically aided techniques were the most sustainable ones when the functional unit is considered as one harvesting hour, although this FU is not the most suitable unit for choosing the best environmental solution. The surface and production mass units are more appropriate FUs in comparative studies, although they are strictly linked to the “work capacity”. A significant variation in the environmental performances depended on the FUs and on the average yields when the FU represented one kg of harvested olives.

Design Features and Bruise Evaluation of an Apple Harvest and In-Field Presorting Machine

Abstract. In-field presorting of apples, in combination with the harvest aid function, would have advantages of cost savings in postharvest handling and storage, reduced postharvest pest and disease problems, and better inventory management, while also enhancing harvest productivity. A new apple harvest and in-field presorting prototype was developed to help apple growers achieve these potential benefits. The prototype sorts and grades fruit based on color and size, using a machine vision-based sorting system with an innovative fruit singulating and rotating design (SRD), and it handles the graded fruit in the bins using newly designed automatic bin fillers. Bruise damage by impact is a critical factor in the development of the apple harvest and in-field presorting prototype. This article reports on the major design features of the prototype and experimental evaluation of the prototype for potential bruise damage. Experiments were conducted on ‘Gala’ and ‘Fuji’ apples to evaluate bruise damage potential under both empty and partially filled bin conditions. An impact recording device (IRD) was used to measure the impact magnitude in terms of peak acceleration (G) at all critical points of the machine, including harvest conveyors, main conveyor, flat conveyor, SRD, cup conveyor, bin filler, and bins. It was found that bruise damage mainly occurred during bin filling. The number of impacts recorded for the partially filled bin was reduced by 60%, compared to that for the empty bin, indicating that the impact between apples and the wooden bin’s floor was a major cause of bruising. The maximum G value for the partially filled bin was measured at 34.5, while the measured G values were less than 20 from start to the point just before the bin filler, indicating no bruise damage. Bruise evaluation showed that no more than 9% of the test apples would be downgraded from ‘Extra Fancy’ grade for the partially filled bin condition. Higher G values for the empty bin condition suggested the need for further improvement to the discharge of apples from the bin filler to the bin to further reduce bruise damage. Keywords: Apples, Bruising, Fruit, Grading, Harvesting, Sorting, Machine vision.

Cotton Harvest Aid Regimes and Their Interaction with Cotton Cultivar Characteristics Impacting Leaf Grade

Core Ideas Defoliation or desiccation levels did not impact leaf grade values. Leaf grades values increased with higher leaf trichome densities. Plant morphological factors other than leaf hairiness did not impact cotton leaf grade values. Cotton (Gossypium hirsutum L.) leaf grade values significantly increase with remnants of leaf and bract materials in cotton lint and can result in economic discounts to the producers. We are hypothesizing that cotton harvest aid regimes, and level of defoliation and desiccation are contributing factors in higher cotton leaf grades. The interaction of morphological characteristics of cotton cultivars and the various harvest aid regimes were evaluated to identify key factors contributing to the increased leaf grade values. Multiple trials were conducted during 2010, 2011, and 2012 in Burleson, Colorado, and Matagorda counties in South and southeastern Texas. Cotton cultivars were selected with a range of leaf hairiness and were sprayed with five harvest aid treatments to obtain a range of defoliation and desiccation levels. Leaf and bract pubescence, and leaf and bract area were collected, as well as defoliation and desiccation levels, to analyze the resulting impact on cotton leaf grade values. Seed cotton samples were ginned in a microgin and lint quality was measured with high volume instrument (HIV) analysis. Results from trichome density quantification indicated substantial variation in cultivars and discrepancies from company based rating systems. Defoliation level rating ranged from 0 to 84% at 14 d after treatment application, while desiccation levels were low despite the use of herbicidal products. Defoliation or desiccation did not impact leaf grade. Leaf grades generally increased with higher leaf trichome densities, although not always significantly. Among morphological characteristics of cotton, leaf hairiness is more important for cultivar selection to reduce leaf grade.

Influence of Harvest Aid Herbicides on Seed Germination, Seedling Vigor and Milling Quality Traits of Red Lentil (Lens culinaris L.).

Most red lentil produced worldwide is consumed in dehulled form, and post-harvest milling and splitting qualities are major concerns in the secondary processing industry. Lentil producers in northern temperate regions usually apply pre-harvest desiccants as harvest aids to accelerate the lentil crop drying process and facilitate harvesting operations. This paper reports on field studies conducted at Scott and Saskatoon, Saskatchewan, Canada in the 2012 and 2013 cropping seasons to evaluate whether herbicides applied as harvest aids alone or tank mixed with glyphosate affect seed germination, seedling vigor, milling, and splitting qualities. The site-year by desiccant treatment interaction for seed germination, vigor, and milling recovery yields was significant. Glyphosate applied alone or as tank mix with other herbicides (except diquat) reduced seed germination and seedling vigor at Saskatoon and Scott in 2012 only. Pyraflufen-ethyl (20 g ai ha−1) applied with glyphosate as well as saflufenacil (36 g ai ha−1) decreased dehulling efficiency, while saflufenacil and/or glufosinate with glyphosate reduced milling recovery and football recovery, although these effects were inconsistent. Application of diquat alone or in combination with glyphosate exhibited more consistent dehulling efficiency gains and increases in milling recovery yield. Significant but negative associations were observed between glyphosate residue in seeds and seed germination (r = −0.84, p < 0.001), seed vigor (r = −0.62, p < 0.001), dehulling efficiency (r = −0.55, p < 0.001), and milling recovery (r = −0.62, p < 0.001). These results indicate application of diquat alone or in combination with glyphosate may be a preferred option for lentil growers to improve milling recovery yield.

Peanut (Arachis hypogaea L.) Response to Carfentrazone-ethyl and Pyraflufen-ethyl Applied Close to Harvest

ABSTRACT Morningglory (Ipomoea spp.) and other weeds are often present at peanut harvest and can interfere with digging pods and inverting vines. Carfentrazone-ethyl and pyraflufen-ethyl control large morningglory and could be an effective strategy as harvest aids in peanut. However, crop response to these herbicides has not been determined for Virginia market type peanut cultivars in North Carolina. One experiment was conducted during 2012, 2013, and 2014 to determine peanut response to carfentrazone or pyraflufen-ethyl applied postemergence 1 and 2 weeks prior to digging peanut pods and inverting vines. In a second experiment conducted during 2014 and 2015, peanut response to carfentrazone-ethyl, diclosulam, pyraflufen-ethyl, lactofen, and 2,4-DB applied 4 wk before digging (WBD) was determined. Visible peanut injury from carfentrazone-ethyl and pyraflufen-ethyl did not exceed 40% regardless of application timing or rate, and peanut yield was not affected compared with non-treated peanut regardless of visible injury when applied 1 or 2 WBD. However, when applied 4 WBD, peanut yields were 9 to 10% lower when carfentrazone-ethyl or pyraflufen-ethyl were applied compared with non-treated peanut. Diclosulam, lactofen, and 2,4-DB did not adversely affect yield. These results show that carfentrazone-ethyl and pyraflufen-ethyl will not affect peanut yield within 2 WBD but can reduce yield when applied earlier in the season during pod fill.

Early Application of Harvest Aid Herbicides Adversely Impacts Lentil

Core Ideas Improper application timing of harvest aids may reduce lentil seed yield and quality, and leave unacceptable herbicide residues in seed. Application of harvest aids before 30% seed moisture content reduced lentil seed yield and thousand seed weight. These application timings resulted in lentil seed samples exceeding residue levels of 2 and 0.03 mg kg−1 for glyphosate and saflufenacil, respectively. Applying harvest aid herbicides can dry down lentil (Lens culinaris Medik.) crops evenly and quickly, and can help control late‐emerging weeds. However, improper application timing may reduce yield and quality, and leave unacceptable herbicide residues in seed, which can cause commercial issues when marketing lentil. The objective of this research was to determine the response of lentil to various application timings of glyphosate, saflufenacil, and the combination of these two herbicides. A field experiment consisting of a randomized complete block design was run at Saskatoon and Scott, SK, Canada in 2012, 2013, and 2014 to address the objective. Application of harvest aid herbicides before 30% seed moisture content reduced seed yield and thousand seed weight up to 25 and 8%, respectively. Moreover, application timings before 30% seed moisture resulted in lentil seed samples exceeding residue levels of 2.0 and 0.03 mg kg−1 for glyphosate and saflufenacil, respectively. Adding saflufenacil to glyphosate did not reduce glyphosate residue in lentil seed compared to glyphosate applied alone. However, this tank mixture significantly reduced seed residues of saflufenacil and improved crop desiccation compared with either glyphosate or saflufenacil applied alone. Our data lead us to conclude that a tank mix of saflufenacil+glyphosate should be recommended for crop desiccation and pre‐harvest weed control in lentil over using either product alone. In addition, it is critical to ensure applications of glyphosate or saflufenacil are not made prior to 30% seed moisture in lentil crops.

Impact of Early Defoliation on California Pima Cotton Boll Opening, Lint Yield, and Quality

Chemical defoliation is a necessary pre-harvest practice in Pima cotton (Gossypium barbadense L.) production in California. Growers begin defoliating as early as possible but yield and quality loss can occur if the bolls are not fully mature. Harvest aids can advance harvest dates, avoid late-season pests, and adverse weather conditions in California. A study was conducted on Pima cotton, cv. ‘Phytogen-802’. Different rates of Ginstar (ai thidiazuron/diuron, Bayer CropScience) or Ginstar plus Finish 6-Pro (ai ethephon/cyclanilide, Bayer CropScience) were applied at 6 to 7 nodes above cracked boll (NACB) or 4 to 5 NACB at various rates. Results showed that these harvest aids could be applied at the tested rates at both timings without any adverse effects on percent open bolls, and lint yield and quality. Therefore, application of these harvest-aid materials starting at 6 to 7 NACB can benefit Pima cotton growers in California as early harvests can be achieved without compromising lint yield or quality.

Defoliant Effects on Cover Crop Germination, Cover Crop Growth, and subsequent Cotton (Gossypium hirsutum) Development

The price of nitrogen (N) fertilizer has increased to the point where it may be cost effective to grow winter legume cover crops as a sole source of nitrogen for a subsequent cotton crop in North Carolina. Establishing these cover crops is critical to the success of this strategy. In order to optimize legume cover crop establishment, cotton producers may have to overseed legumes into cotton that has or will be sprayed with cotton harvest aids, which may interfere with legume germination and growth. A greenhouse experiment was conducted to determine the effects of commonly used cotton harvest aids on legume germination and growth. This was followed by a field study to determine the optimum time to overseed legume cover crops in cotton, to determine the effects of cotton defoliants on legume establishment in the field, and to determine the effects of cover crop species and overseeding timing on cotton growth and yield in a field in which N was not depleted. Cotton defoliants containing thidiazuron plus diuron reduced greenhouse legume germination and growth more than any other cotton harvest aid tested; however, field studies indicate that cover crop germination and cover crop dry weight are not affected by thidiazuron plus diuron. Crimson clover (Trifolium incarnatum L.) and Austrian winter pea (Pisum sativum L.) positively affected cotton yield equally. However, timing of cover crop overseeding played an important role in cover crop germination, accumulated biomass, and lint yield. We observed that overseeding legumes 14 days prior to defoliation resulted in the highest cover crop dry weight and cotton yield.

Occurrence, Severity and Initiation of Internal Necrosis in ‘Covington’ Sweetpotato

A series of studies were conducted to better understand the occurrence and causes of internal necrosis (IN) in ‘Covington’ sweetpotato (Ipomoea batatas). Assessment of the problem among the industry was done for 2 years and revealed that IN was widespread in commercial storage facilities throughout the state of North Carolina; both incidence and severity were generally low (&lt;10% incidence with minimal severity of symptoms). A few storage rooms had a high percentage of IN with severe storage root symptoms but results were inconsistent across years and among rooms. Preharvest studies with commercially used insecticides did not induce IN, but the harvest aid ethephon consistently induced IN with an incidence higher than 50%. Internal necrosis symptoms were not detectable at harvest, and earliest consistent incidence was observed 6 days after harvest (DAH) during the curing phase. Symptoms became more prevalent and severe at 30 DAH. However, in commercial storage rooms, no relationship was found between IN incidence and postcuring storage temperature or relative humidity (RH) conditions. Sweetpotato storage roots stored in air-tight barrels and exposed to 100 ppm ethylene after curing showed no relationship between the presence of ethylene gas in storage and incidence of IN. Our results indicate that IN incidence of ‘Covington’ is erratic with no obvious cause among storage rooms and that initiation of IN may occur most frequently during the first week following harvest.

Road map to organ donation in Tamil Nadu: an excellent model for India.

Road map to organ donation in Tamil Nadu: an excellent model for India.

Effect of an Upper Temperature Threshold on Heat Unit Calculations, Defoliation Timing, Lint Yield, and Fiber Quality in Cotton

In cotton production, delaying defoliation exposes open bolls to rainfall, reducing lint yield and fiber quality. However, premature defoliation has detrimental effects on both yield and quality. Currently, one management strategy for defoliation is based on heat-unit (HU) accumulation after physiological cutout or five nodes above white flower (NAWF = 5). Results have been inconsistent across environments when utilizing HU accumulation; therefore, adoption of this method has been limited. Studies were conducted in the Brazos River bottom and upper Texas Gulf Coast to identify an upper temperature threshold (UTT) for calculating degree days for defoliation timing. Experimental design was a split-plot with main plots of temperature thresholds (32°C, 35°C, and no upper limit) and subplots of HU timings (361, 417, 472, 528, and 583) accumulated from cutout. Utilizing an UTT to calculate daily HU failed to explain differences in the optimum time to defoliate based on accumulated HU; however, accumulated HU had an impact on defoliation timing. Comparison of locations showed that maximum lint yield was obtained at 472 HU and 52% open boll in Wharton County versus a maximum of 528 HU and 62% open boll for Burleson County. Employing the NACB = 4 method to time defoliation at both locations would have resulted in premature application of harvest aids and reduced lint yields. There were no differences in adjusted gross income values at Wharton County among the 417, 472, 528, and 583 HU treatments. For Burleson County, adjusted gross income peaked in value at 528 HU.

Plant height and seed yield of castor (Ricinus communis L.) sprayed with growth retardants and harvest aid chemicals

The perennial growth habit of castor plants (Ricinus communis L.) limits mechanical harvest because the plant grows very tall when the environmental conditions are favorable and produces many immature fruits, fresh stems, and green leaves at harvest time. There is a demand for chemicals that prevent excessive growth and defoliate the plant to prepare the crop to be harvested. This study had the objective of evaluating two growth retardants and three harvest aids (desiccants and defoliants) applied on castor crop at different times and doses. The experiments were conducted in Lubbock, TX, USA from 2007 to 2010. The growth retardants were Pix® (mepiquat chloride) and Stance® (mepiquat chloride+cyclanilide) applied one time at five development stages. The harvest aids were ET® (pyraflufen), Ginstar® (thidiazuron+diuron)+Finish® (etephon+cyclanilide), and paraquat. The growth retardant Pix® promoted rather than inhibited the vertical growth of castor plants, but in general, this product did not influence the seed yield. Stance® did not influence vertical growth, but increased doses were associated with higher castor seed yields. The effect of Stance® on seed yield was more intensive when applied from the 8th node stage through the first expanded leaf after the primary inflorescence. Early termination caused seed yield reduction compared with frost-killed plants, but the loss was progressively diminished as the termination occurred later in the season. There were differences in the effect of harvest aids. The reduction of mean seed yield caused by paraquat was not significant, but ET® and Ginstar®+Finish® reduced the mean seed yield compared with untreated plants.

Impact of Pima Defoliation Timings on Lint Yield and Quality

Chemical defoliation is a necessary pre-harvest practice in Pima cotton (Gossypium barbadense L.) production in the San Joaquin Valley of California. Cotton growers are advised to begin defoliation as early as possible with both Pima and Upland cotton, but not so early that it results in yield and quality loss Potentially harvestable bolls often fail to reach full maturity due to the recommended defoliation timing. Applying harvest aids before the recommended maturity can advance the start of harvest, avoiding late-season pests and adverse weather that can damage lint quality. The objective of this research was to compare different rates of Ginstar® (thidiazuron/diuron, Research Triangle Park, NC) or Ginstar plus Finish® (ethephon/cyclanilide, Research Triangle Park, NC) on defoliation, yield, and fiber quality of Pima cotton when applications began at an earlier timing, six to seven NACB (nodes above cracked boll), versus the common four to five NACB timing. ‘Delta Pine DP-340’ (Monsanto Company, St. Louis, MO) was treated with harvest aid materials in field trials and was analyzed as a factorial split-plot design with four replications. Starting the defoliation of Pima at six to seven NACB rather than four to five NACB brought about a potential seven to ten day earlier harvest and did not significantly affect yield or cotton fiber quality characteristics except for micronaire in one year of the study. These data indicate that earlier defoliation could be beneficial when later-maturing crops or worsening harvest-season weather necessitate the initiation of an earlier harvest.

Developing a castor (Ricinus communis L.) production system in Florida, U.S.: Evaluating crop phenology and response to management

While castor (Ricinus communis L.) oil is an essential component in many industrial products, the U.S. currently imports all castor oil stocks due to the lack of domestic production of the crop since 1972. To reestablish U.S. production of castor, regional agronomic assessments of cultivars and management systems are required to assess the economic sustainability of the crop. A comparison of two castor cultivars (Hale and Brigham) and management systems using plant growth regulators and harvest aids was conducted at two different locations (PSREU and WFREC) within Florida during two years (2011 and 2012) with the goal of assessing yield potential and phenological development of the crop in this semi-tropical climate. Yields were low in comparison to other U.S. regions where the crop has been tested with the highest yields being 1357kgha−1 for Brigham at PSREU in 2011 and the lowest being 686kgha−1 for Brigham at PSREU in 2012. Mold observed on both cultivars and significant rates of shatter could have led to upwards of 60% yield loss, indicating that yield potential in the region may be much higher. Oil percentages on average across sites and years were very consistent between the cultivars, with 45.0 and 45.4% for Brigham and Hale, respectively. Typical growth patterns of height, leaf area index (LAI), reproductive development, and root architecture were characterized for the region. The maximum height recorded for either cultivar did not exceed 115.2cm and the maximum seasonal LAI value was 2.87. Brigham produced between 3 and 8 more racemes than Hale by the end of the season, depending on the site/year. The application of a mepiquat chloride based plant growth regulator (PGR) did not reduce plant height at either location and had no consistent impact on photosynthetic capacity of the crop. The harvest aid paraquat led to over six times more leaf desiccation and leaf defoliation within 11 days after treatment and was more effective overall than the tribufos harvest aid.

2013 Cotton Defoliation and Harvest Aid Guide

In Florida, cotton requires about 155 days of growth from planting to harvest. Throughout the growing season, growers must make important management decisions about defoliation, boll opening, and regrowth suppression. These factors can affect the quality and storage time if the crop is put into modules. The greatest losses in quality are caused by stain from poorly defoliated plants or regrowth and moisture from green tissue. This 8-page fact sheet was written by R.G. Leon, D. L. Wright and B. J. Brecke, and published by the UF Department of Agronomy, October 2013.&#x0D; http://edis.ifas.ufl.edu/ag188

Desiccation in dry edible beans with various herbicides

Soltani, N., Blackshaw, R. E., Gulden, R.H., Gillard, C. L., Shropshire, C. and Sikkema, P. H. 2013. Desiccation in dry edible beans with various herbicides. Can. J. Plant Sci. 93: 871–877. There is little information available on the effect of diquat, carfentrazone-ethyl, glufosinate ammonium, flumioxazin and saflufenacil applied alone or in tankmix combination with glyphosate as harvest aids in dry bean production under environmental conditions of the various production regions in Canada. A total of 11 field trials were conducted over a 3-yr period (2010, 2011, 2012) at Exeter, Ontario, Carman, Manitoba, and Lethbridge, Alberta, to evaluate various harvest-aid herbicides in dry bean. Comparison of leaf, pod and stem visual dry down at 4 and 8 d after desiccation application (DAA) indicated that adding a tankmix partner to glyphosate increased visual dry down of leaf, pod and stem 17, 10 and 15% at 4 DAA and 20, 17 and 14% at 8 DAA, respectively. At 8 DAA, glyphosate (450 or 900 g a.e. ha−1), diquat, glufosinate ammonium, carfentrazone-ethyl, flumioxazin and saflufenacil provided 13–58, 65–80, 64–71, 12–34, 36–52 and 41–73% dry down of the dominant weeds (AMARE, AMBEL, CHEAL and SETVI), respectively. Diquat, glufosinate ammonium, carfentrazone-ethyl, flumioxazin and saflufenacil tankmixed with glyphosate (450 or 900 g a.e. ha−1) provided 67–77, 65–71, 22–62, 45–69 and 44–74% weed dry down, respectively. Dry bean yield was not reduced with any of the desiccation treatments. Among desiccant treatments that provided consistent desiccation of dry bean and weeds, saflufenacil had the least environmental impact followed by flumioxazin, glufosinate ammonium and then diquat. Based on this study, diquat, glufosinate ammonium, flumioxazin and saflufenacil alone or in combination with glyphosate (450 or 900 g a.e. ha−1) provide consistent desiccation of weeds and dry bean.

Evaluation of Harvest Aid Chemicals for the Cotton-Winter Wheat Double Cropping System

Timing of harvest is critical for mechanical picking in cotton production, especially in those regions with double cropping system. Appropriate and safe harvest aids will improve timing and facilitate harvest of cotton in the double cropping system. Three defoliants (dimethipin, thidiazuron, and thidiazuron-diuron) and one boll opener (ethephon) were included in this research. They were evaluated for their effects on defoliation, boll opening, seedcotton yield, seed quality, and fiber quality of field grown cotton when used alone or as a mixture in 2009 and 2010. Defoliation and/or boll opening were increased by all three defoliants and ethephon, especially by mixtures of a defoliant and ethephon. First harvest of seedcotton was significantly increased with defoliant-ethephon mixtures. No significant adverse effects were observed on boll weight, lint percentage, seed quality, and fiber properties. It was estimated that tank mixes of ethephon and one of the three defoliants can improve the adjusted gross revenue. Boll opening can be used as an alternative indicator for the adjusted gross revenue, because, it was linearly and positively correlated with the relative adjusted gross revenue and convenient in measurements. Wheat seedling growth was not affected by thidiazuron, whereas its seedling emergence, root dry weight, relative water content, and electrolyte leakage were adversely affected by dimethipin and thidiazuron-diuron when concentration was above 340 and 100 g (a.i.) ha−1, respectively. 90% defoliation and 80% boll opening were observed with the high rate of thidiazuron-ethephon mixture, but no adverse effects on winter wheat. The results suggested that tank mixes of ethephon with thidiazuron can be used effectively and safely in the cotton-winter wheat double cropping system to improve yield without adverse effects on seed quality and fiber quality.