Harvest Aid Research Articles

EVALUATION OF COTTON DEFOLIATION STRATEGIES USING AIRBORNE MULTISPECTRAL IMAGERY

Visual observations and ground measurements are commonly used to evaluate cotton (Gossypium hirsutum L.)harvest aids for defoliation, boll opening, and regrowth control. This article presents a remote sensingbased method forevaluating the effectiveness of different defoliation treatments. Field experiments were conducted on two cotton fields in southTexas in 2001, in conjunction with a study on the effects of defoliants alone and defoliants combined with insecticides on bollweevil mortality. Eight treatments (one control and seven combinations of defoliants and insecticides) with three replicationswere assigned across 24 experimental plots in a randomized complete block design in each of the two fields. Airbornecolorinfrared (CIR) digital images were obtained from the first field six days after chemical application and from the secondfield on four equally spaced dates beginning the day of application. Ground plant reflectance spectra and plant physical datasuch as number of leaves were collected on selected sites within each plot. The reflectance spectra effectively separateddifferent levels of defoliation, but a large number of spectra were required to obtain reliable results. The airbornemultispectral images permitted visual differentiation among the treatments as early as three days after chemical application,although the images collected six days after application revealed most significant differences among the treatments. Forquantitative analysis, the green, red, and nearinfrared (NIR) bands of the CIR images and the normalized differencevegetation index (NDVI) were used as spectral variables to compare the differences among the treatments. Multiplecomparisons showed that the four spectral variables detected significant differences among some of the defoliationtreatments. These results indicate that remote sensing can be a useful tool for evaluating the effectiveness of cotton defoliationstrategies.

Losses in Yield, Quality, and Profitability of Cotton from Improper Harvest Timing

Excessive weathering may diminish cotton (Gossypium hirsutum L.) lint yield and fiber quality to the extent that economic losses occur for the producer. Our objective was to determine the effects of systematic delayed harvest on cotton lint yield, fiber quality, and profitability. Experiments were conducted from 1998 to 2000 at the Coastal Plain Experiment Station, Tifton, GA, on a Tifton loamy sand (fine‐loamy, kaolinitic, thermic Plinthic Kandiudults). The treatments consisted of a standard harvest‐aid combination applied at weekly intervals over a 13‐wk period beginning at first open boll. Harvest aids were applied to each plot according to its week after first open boll designation and machine harvested 2 wk thereafter. After ginning, fiber quality was determined on lint samples from each plot. High volume instrument (HVI) fiber length uniformity was greatest in 1999 and 2000 when harvest aids were applied between 58 and 88% open boll, while the advanced fiber information system (AFIS) fiber length by number coefficient of variation and short fiber content by number were lowest when harvest aids were applied from 40.1 to 46.8% open boll. The HVI upper half mean fiber length and the AFIS mean fiber length by number were greatest when harvest aids were applied between 39.1 and 56.7% open boll. In 1999 and 2000 lint yield and adjusted gross income were greatest when harvest aids were applied from 76.5 to 89.0% open boll. Results from this study indicate optimum fiber quality is established earlier during boll opening than lint yield and profitability.

Effect of preharvest applications of glyphosate on the drying, yield and quality of canola

Potential use of preharvest applications of glyphosate in canola (Brassica rapa L.) in western Canada both as a harvest aid and to control weeds prompted this study. Experiments were conducted from 1988 to 1990 at four locations in the region to document the effectiveness of preharvest applications of glyphosate to enhance canola seed and foliage drydown and to measure the effect of such applications on seed yield and quality. Glyphosate was applied in early August to early September at rates of 0.45, 0.90 and 1.70 kg acid equivalent ha−1 to canola with seed moisture contents ranging from 79 to 12%. Seed and foliage moisture drydown were not enhanced by glyphosate treatment. Glyphosate treatments generally had little or no effect on canola seed yields, seed weight, seed germination, green seed content or oil content except when applied when the pods were green and when seed moisture contents were high. Seed/pod moisture was not a reliable indicator of stage of canola development and thus, should not be used alone as an indicator of when preharvest applications of glyphosate can be applied to canola without decreasing seed yield and quality. Key words: Glyphosate, canola, Brassica rapa L., preharvest application, desiccation, seed quality

Effect of Preharvest Glyphosate Application on Seed and Seedling Quality of Spring Wheat (Triticum aestivum)1

Studies were conducted to determine effects of preharvest applications of glyphosate on the seed and seedling quality of ‘Alpowa’ and ‘Penawawa’ soft white spring wheat (Triticum aestivum) varieties. Glyphosate was applied at 0.62 or 0.84 kg ae/ha at the milk (Zadoks' scale 70 to 79), soft dough (Zadoks' scale 85), or hard dough stage (Zadoks' scale 87) of wheat development; 7 d following the hard dough treatment; and 1 d prior to wheat harvest. In harvest aid applications, wheat yields were reduced only with glyphosate applied at the milk stage of development. Yield reduction ranged from 20 to 77% depending on the year, variety, and glyphosate rate. Likewise, kernel weight and germination were affected only by glyphosate applications at the milk stage with reductions from 19 to 73% and from 2 to 46% for kernal weight and percent germination, respectively, compared to untreated wheat. Using wheat from harvest-aided glyphosate treatments at the milk stage as seeds the following year resulted in reductions ranging from 28 to 99%, 19 to 39%, and 12 to 97% for seedling density, plant height, and seed yield, respectively, compared to seeds from untreated wheat. In this study, wheat seed and seedling quality following preharvest glyphosate applications were most greatly influenced by crop maturity stage at time of application than by herbicide rate or variety.Nomenclature: Glyphosate, N-(phosphonomethyl)glycine; spring wheat, Triticum aestivum L. ‘Alpowa,’ ‘Penewawa.’Additional index words: Desiccation, germination, harvest aid, herbicide.

TECHNICAL NOTES: ECONOMICAL EVALUATION OF AN APPLE HARVEST AID FOR INCLINED TRELLISED CANOPIES

An economic analysis was conducted to compare harvesting costs of an experimental mechanical appleharvest aid and commercial hand harvesting for an 8- and 12-week harvest season. Under no conditions were harvestcosts for the mechanical apple harvest aid at or below current commercial hand harvesting costs. However, athree-worker harvest aid operated for 12 weeks with workers picking at 8.17 kg/worker-min came close to being abreakeven situation with hand harvesting. If a financial breakeven situation between the harvest aid and hand harvestingexist, the harvest aid may be adopted by the apple industry since the harvest aid requires less labor.

Economic Analysis of the Harvest-Aid Decision for Cotton in West Tennessee

Economic tradeoffs influence producers' decisions in applying a harvest-aid before a once-over or twice-over harvest for cotton (Gossypium, hirsutum L.). This decision may be affected by responses of first harvest yield and quality to the harvest-aid, cotton prices, harvest-aid treatment costs, cotton harvesting and handling costs, and weather between harvests. The objective of this study was to evaluate how these factors influence net revenues (NR) to alternative harvest-aids. Yields and fiber quality data were from a 1992 to 1994 harvest-aid study at Jackson, TN. Tbe study evaluated 12 treatments including commercial defoliants (Folex [S,S,S,tributyl phosphorotrithioate], Dropp [thidiazuron], Harvade [2,3 Dihydro-5 6-Di-methyyl 1,4-Dithiin], and Defol [sodium chlorate]) with and without a boll opener (Prep [ethephon]). Net revenues for the treatments were estimated using North Delta price quotations, harvest-aid costs, harvesting costs, and handling costs. Dropp (0.05 lb a.i./acre) and Prep (1.0 lb a.i./acre) produced the largest positive influence on effective lint price and NR for farmers interested in once-over or twice-over harvest systems. First harvest NR was significantly higher than for no harvest-aid treatment. However, a once-over harvest using this treatment would have to be delayed from the times in this experiment to allow more bolls to open to minimize second harvest NR foregone. Dropp and Prep also produced the largest two harvest NR. The most important factors influencing NR for Dropp and Prep were a low lint trash content, which resulted in a better LEAF and lower price discounts, and higher first harvest yields.

APPLE HARVEST AID FOR INCLINED TRELLISED CANOPIES

A mechanical harvest aid was developed to position two pickers to remove apples from a narrow inclinedtrellis. Design concept maximized the pickers time spent locating and detaching fruit, and minimized time spent handlingfruit and controlling the unit . In medium to high yields, picker productivity was increased by 36 to 44% over conventionalhand harvesting. Fruit quality from the harvest aid was nearly as good as that from conventional hand harvesting.Ground and tree losses were low for both harvesting techniques. All mechanical and electrical systems functionedreliably.

Yield and Income Response to Planting Dates and Harvest Aid Chemicals in Texas Cotton Production

The production of cotton, Gossypium hirsutum L., within the Texas Rolling Plains can be affected by many interrelated environmental factors, including moisture, temperature, insects, and length of the growing season. The use of new varieties, insecticidal and harvest aid chemicals, and alternative planting dates to attain maximum yields must be achieved within their level of cost-effectiveness. The objective of this study was to determine the effects of planting dates and harvest aid chemicals on yield and net income per hectare under 3 cotton production systems. The 3 production systems were dry land, short-season irrigated, and medium-season irrigated. Planting cotton in May in each of the 3 systems did not result in significantly reduced yields or net income. Harvest aid chemicals did not significantly increase yields or net incomes over the test period.

Apple Harvesting Concepts for Inclined Trellised Canopies

Two concepts were developed and tested for harvesting apples from Y-trellised canopies. The harvest aid concept placed two pickers under the arms of the trellis and required only that they pick and drop the fruit onto a padded catching surface. The other concept impacted individual limbs for fruit removal. The fruit fell to a padded catching surface. Initial field evaluation showed fruit quality from the harvest aid to be as good as that from conventional hand harvesting. Fruit quality obtained from impacting individual limbs was not as good as from the harvest aid; but better than previous research where fruit removal was caused by impacting the tree trunk.

Late-Season Termination Effects on Cotton Fruiting, Yield, and Boll Weevil (Coleoptera: Curculionidae) Damage in Texas Dryland Cotton

The plant growth regulator ethephon, Prep ([2-chloroethyl] phosphonic acid), and the desiccant arsenic acid, Desiccant L-10, were evaluated for their effects on late-season squares, green bolls, and yield of the cotton, Gossypium hirsutum, cultivars, ‘Lankart 511’, ‘Lankart Sel. 611’, and ‘TAMCOT CAB-CS’, in a dryland cotton production system in 1990 and 1991. Damage to squares and bolls by the boll weevil, Anthonomus grandis grandis Boheman, was evaluated in 1991. All cotton cultivars treated with Prep (1.26 kg(AI)/ha) and Desiccant L-10 (2.63 1(AI)/ha) in September had reduced numbers of squares in October and November compared with untreated cotton. Plots were harvested in early December after a killing freeze. Both Prep and Desiccant L-10 reduced the number of green bolls and cotton squares damaged by boll weevils in all cultivars in October. Yield was not significantly reduced by either chemical in 1990 or in 1991. The late-maturing ‘Lankart Sel. 611’ had lower yields across treatments in 1990 and in 1991 than the intermediate-maturing ‘Lankart 511’ and the early-maturing ‘TAMCOT CAB-CS’. A single late-season application of a harvest aid chemical for reduction of fall food may help control boll weevils and reduce the need for fall insecticide applications in dryland cotton. Relevance of this research to the Texas Boll Weevil Eradication Program is discussed.

Ethephon Tissue Penetration and Harvest Effectiveness in Olive as a Function of Solution pH, Application Time, and BA or NAA Addition

Fruit removal force (FRF) and percent leaf drop (LD) of fruit-bearing olive (Olea europaea L.) shoots were examined 120 hours after being sprayed with ethephon at 600 mg·liter-1 and held under controlled-environmental conditions analogous to those found in the field in California at harvest time in mid-October. FRF was not significantly affected by solution pH, but FRF of all treated shoots was significantly lower than that of the untreated controls. Only at pH 5 was percent LD significantly greater than that of the controls, but, of the shoots treated with ethephon, the lowest percent LD occurred at pH 3. Percent LD after treatment with ethephon at pH 3 was not affected by application time, but FRF was significantly less than the controls' when shoots were treated at 7 am or 12 pm but not at 5 pm or 10 pm. Adding NAA to the ethephon solution raised FRF and adding BA lowered FRF compared to ethephon alone. Adding NAA or BA did not mitigate percent LD significantly. Adding BA advanced anthocyanin production in fruit. Ethephon penetration of rachides was ≈70% that of petioles. Correlation between ethephon penetration of petioles and percent LD was greater than that between penetration of rachides and FRF. Correlation was significant for both tissues only in the 12 pm pH 3 treatment; correlation was also significant for petiole penetration and percent LD at pH 5. Autoradiographic studies of the 14C-ethephon penetration showed no pH effect, greater penetration into petioles than rachides, and that radioactivity was limited largely to intercellular spaces, with accumulation in vascular bundles, especially xylem. Regardless of treatment, FRF and percent LD are negatively correlated (r2 = 0.615). Mean results to be expected using ethephon as an olive harvest aid under these conditions are an FRF of ≈3 N and a percent LD of ≈15%. The desired low FRF and percent LD were obtained by applying ethephon alone at pH 3 at 7 am. Raising ethephon solution pH does not increase harvest effectiveness. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), naphthalene acetic acid (NAA), 6-benzylaminopurine (BA).

Response of Fast Fruiting Cotton Cultivars to Nitrogen on a Clayey Soil

The present cotton (Gossypium hirsutum L.) N recommendations for Arkansas were developed primarily on silt loam and sandy loam soils, but interest in cotton production on clayey soils has increased. The objective of this study was to determine the appropriate quantity of N for the new faster fruiting cotton cultivars grown on clayey soils. Experiments were conducted from 1988 to 1990 on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic, Vertic Haplaquept) at Keiser, AR. The response of cotton cultivars 'Deltapine 20', 'Deltapine 5O', 'Stoneville 453', and 'Stoneville 506' were evaluated at five N rates (O, 50, 100, 150, and 200 lb/acre). Cultivars were found to respond similarly to increasing N fertilizer. These cultivars yielded differently each year but averaged the same across years []

Influence of Harvest Factors on Cotton Yield and Quality

Research studies were conducted during the 1980s to evaluate the relationship between harvest systems, harvest aid chemicals, and harvest environments to cotton yield and quality. Cotton yield and quality were reduced in three out of five years with once over and delayed harvesting compared to twice over harvesting. The most significant factor influencing yield and grade in these studies was rainfall occurring after the cotton was open. Rainfall totaling 50 mm or more significantly reduced yield and quality. Defoliation reduced lint yield by an average of 44 kg/ha but increased grade index. Application of Prep (ethephon) to accelerate boll opening significantly reduced yield and grade if applied at the 40% or 60% open stage, but had no detrimental effect on yield or grade if applied at the 80% open stage.

Effects of Ethephon on Morphology, Yield, and Lodging in Williams 82 Soybean

Lodging reduces yield in soybean [Glycine max (L.) Merr.j. Ethephon [(2-Chloroethyl) phosphonic acid] has been proposed as a harvest aid to improve soybean lodging resistance. The effects of ethephon rate and time of application on ‘Williams 82’ soybean grown at Urbana, IL, were investigated using a Drummer silty clay loam (fine-silty, mixed, mesic Typic Haplaquoll). Ethephon was applied at V3 and V7 stages of development at rates of 0, 0.13, 0.25, and 0.38 lb a.i./acre. Plants were divided into one upper and one lower portion to facilitate closer examination of plant morphology. Ethephon reduced stem length and leaf area, particularly in the lower plant. Upper stem elongation compensated for ethephon induced lower stem length reduction in the 1987 V3 treatments. Ethephon application increased lodging in 1987, a favorable year for soybean production. But in 1988, smaller, drought stressed plants did not lodge. Application at V3 significantly increased leaf abscission compared with the later application. Total nonstructural carbohydrate and starch in the three basal stem internodes declined with increasing ethephon rates for the V3 application, but increased for the V7 application. Free sugar levels in these basal nodes were unaffected by treatment. Midstem free sugar levels declined with increasing ethephon rate. Relative water contents in R5 lower stem segments were reduced by ethephon treatments relative to midstem segments in 1988. Ethephon treatment reduced leaf area more than plant height, especially in the lower plant. This may have reduced yield for all ethephon treatments and reduced lower stem carbohydrate status for V3 treatments. Ethephon also reduced pod number in the lower plant for V3 but not V7 applications. While ethephon application produced the desired stem morphological change, 1987 results indicate that other effects weakened the lower stem's resistance to bending.

Sweeping efficiencies of a macadamia nut harvester on different orchard surfaces

Many small macadamia nut orchards are on clay soils. Harvesting is usually done by expensive hand labour, as commercial nut sweepers cannot be economically justified. A compact nut harvesting aid for small farms could greatly enhance profitability. Large macadamia orchards in Hawaii have generally been planted on marginal land with coarse surfaces. The orchard surfaces are too rough for commercial nut sweepers, so nuts must be gathered by hand or shake harvesting. Improvement of these rough surfaces could allow machine nut sweeping; however, very little work with quantified surfaces as related to nut sweeping has been done in the past. A need exists to define minimum top course rock size for the operation of surface sweepers. An inexpensive tractor-mounted nut recovery attachment was developed. It was sized for a 20 ha farm, and can be used on both soil and prepared orchard surfaces. Trials on clay soil showed that it could replace 30 hand pickers. Nut sweeping on prepared surfaces showed that a top course rock size of less than 4·5 cm can be recommended for rough orchard resurfacing.

Sweeping efficiencies of a macadamia nut harvester on different orchard surfaces

Many small macadamia nut orchards are on clay soils. Harvesting is usually done by expensive hand labour, as commercial nut sweepers cannot be economically justified. A compact nut harvesting aid for small farms could greatly enhance profitability. Large macadamia orchards in Hawaii have generally been planted on marginal land with coarse surfaces. The orchard surfaces are too rough for commercial nut sweepers, so nuts must be gathered by hand or shake harvesting. Improvement of these rough surfaces could allow machine nut sweeping; however, very little work with quantified surfaces as related to nut sweeping has been done in the past. A need exists to define minimum top course rock size for the operation of surface sweepers. An inexpensive tractor-mounted nut recovery attachment was developed. It was sized for a 20 ha farm, and can be used on both soil and prepared orchard surfaces. Trials on clay soil showed that it could replace 30 hand pickers. Nut sweeping on prepared surfaces showed that a top course rock size of less than 4·5 cm can be recommended for rough orchard resurfacing.

A simulation analysis of alternative methods of hand harvesting cauliflower

A discrete event based computer model has been written to simulate the selective hand-harvesting of cauliflower on to a mobile packhouse. The distribution of plants ready for harvesting is generated by a computer program. A series of simulated experiments has been conducted using the model with data derived from a study of commercial gangs. A number of alternative harvesting aids have been assessed and compared with traditional methods. The fastest workrate combined with minimum product damage was obtained by allowing the cutters to place cauliflower on to “finger” conveyors which extend forward in the direction of travel.

Glyphosate as Harvest Aid for Corn (Zea mays)

Glyphosate was evaluated as a preharvest treatment for enhancing corn kernel dry down and quackgrass control. Glyphosate at 0.4, 0.8, 1.3, and 1.7 kg ae/ha was applied to corn before physiological maturity (kernel moisture 44 to 47%) and at physiological maturity (kernel moisture 35 to 39%). Three weeks after treatment, grain moisture of plants treated at physiological maturity was 2.3 to 6.9% less than that of plants treated before physiological maturity which was 2.2 to 5.5% less than that of untreated plants. Glyphosate did not increase corn kernel drying effectively under high humidity conditions. Glyphosate applied to pre-physiologically-mature corn controlled quackgrass 49 to 64% in the fall of 1984 and 69 to 91% in the fall of 1985. None of the glyphosate treatments reduced corn yield. Glyphosate applied preharvest above the corn canopy may increase the rate of corn kernel drying and may control fall quackgrass in the northern corn belt.

Trunk Injected Ethephon as a Potential Harvest Aid Mechanism for Pecans

Abstract Ethephon was trunk injected into the transpiration stream of pecan trees 10 to 21 days before shuck split in an attempt to expedite shuck opening in 1983. Ethephon concentrations were based on the estimated amount of water flowing through the tree per day. At College Station and Hondo, Texas, a 10 ppm injection significantly increased shuck opening. Leaf drop was only 35% at 10 ppm compared to much higher leaf drop in previous research. There was no difference in number of nuts set and the extent of limb dieback between the control trees and those trunk injected with 10 ppm ethephon. At Ft. Stockton and Midkiff, Texas, injections of 10, 20, and 40 ppm increased nut opening and early leaf drop, but reduced fruit set in the following year (1984). There was no limb dieback at these locations. Injections of trees in El Paso failed to cause shuck opening.

A Harvesting Aid for Pickling Cucumbers

A harvesting aid for burley tobacco was adapted as a harvesting aid for picking cucumbers. Harvesting rates of pickling cucumbers while riding on the harvesting aid were 78% greater by mass, and 46% greater by product value than conventional hand harvest. Harvesting on the machine was more continuous, less fatiguing because of reduced bending, more picking with both hands, and carrying of the cucumbers by the machine; and more comfortable due to the shade of canopy. The machine performed satisfactorily during harvesting.