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<ul><li><p>22 JanuaryMarch 1999 9(1)</p><p>Developing Mechanized Systems forProducing, Harvesting, and HandlingBrambles, Strawberries, and Grapes</p><p>Justin R. Morris</p><p>ADDITIONAL INDEX WORDS. abscission layer, fruit maturity, mechanization systems, mechanicalharvesting, mechanical shoot positioning, mechanical pruning, processing</p><p>SUMMARY. Mechanization of harvesting, pruning, and other cultural operations on many smallfruit crops for the processing market has occurred in response to the scarcity and expense ofhand labor. Scientists at the Arkansas Agricultural Experiment Station and other experimentstations in the United States and throughout the world have developed new cultural and fruit-handling systems and have determined the effects of these systems on fruit yield and quality.This research has resulted in the development of prototype and commercial machinery as wellas production and handling systems that have assisted in mechanization systems for brambles,strawberries (Fragaria ananassa Duch.), and grapes (Vitis sp.). Much of this body of work isin commercial use and much is simply available, awaiting circumstances that will be beneficialto implementation.</p><p>For some crops, harvest labor accounts for as much as two-thirds ofthe total labor costs. Fruit producers generally use hand laboras long as it is available at a reasonable cost, since mechanizationrequires large capital investments and often reduces the producers flexibility tochange from one crop to another. Consequently, the technology for mechani-zation has usually been developed long before implementation.</p><p>Migrant workers have provided much of the harvest labor. Until re-cently, there was little concern for the welfare of these workers by eitherthe employer or the government. Eventually, concern about the problemsof the migrant workers resulted in major changes and improvements inwages, housing, education, and health benefits. These developmentsincreased the cost of harvesting and have led to an increased interest inharvest mechanization so that producers can remain competitive andmaintain an inexpensive supply of fruit for consumers. This interest inmechanization has brought about developments for producing and har-vesting brambles, strawberries, and grapes.</p><p>BramblesHARVESTERS. Successful mechanical harvesting systems have beendeveloped for many fruit, with brambles and grapes being outstandingexamples.</p><p>Distinguished professor, Institute of Food Science and Engineering, University of Arkansas, 272 Young Ave, Fayetteville AR 72704.</p><p>Published with the approval of the Director, Arkansas Agricultural Experiment Station, manuscript #9703. The cost of publishing thispaper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby markedadvertisement solely to indicate this fact.</p></li><li><p>23 JanuaryMarch 1999 9(1)</p><p>The bramble harvester has, with minoradaptations, been used to pick erect andtrellised blackberries (Rubus subg. rubus),black raspberries (Rubus occidentalis L.), redraspberries (Rubus idaeus L.), and gooseber-ries (Ribes hirtellum Michx.). By the mid-1960s, there were 30 commercial machinesoperating in raspberry plantations in theUnited States (Dale et al., 1995). The proto-type developed in 1964 at the University ofArkansas was one of the first harvesters devel-oped and operated by mechanical shaking ofthe canes (Morris et al., 1978b). The canefruit develops an abscission layer at matura-tion, which allows the more mature fruit to beharvested when shaken. All modern self-pro-pelled commercial pickers work on this shak-ing principle using sets of horizontal beaterspositioned in a vertical plane on each side ofthe row (Fig. 1). These improved beater armson the modern commercial harvesters allowfor a reduction in the number of strokesneeded per minute to harvest the fruit, andcause the least amount of damage to the newcanes compared to the original prototype.</p><p>The range of 100 to 150 strokes perminute at a ground speed of 1 mph (1.6kmh1) is adequate to harvest only the ripefruit. This frequency of stroke also provides acomplete shaking throughout the hedgerow.This is important, since berries that are al-lowed to remain in the interior of the hedg-erow often develop mold and contaminatethe next harvest. Most self-propelled com-mercial bramble harvesters should have thefeature of being able to be raised, lowered andleveled to fit the plane of the field and theheight of the canes. The need for this capabil-ity is due to the low fruiting habit of many ofthe cane fruit crops. The Arkansas harvestercollects all fruit above 15.5 inches (40 cm)and is only one of several successful cane fruitharvesters currently in use. The commercialmodel of the Arkansas harvester, with oneoperator and four field graders, can do thework of 80 to 85 handpickers.</p><p>FRUIT QUALITY. Unlike hand harvesting,machines are able to operate at night to allowfor the harvesting of fruit at a lower tempera-ture (Morris et al., 1978b). Research andexperience have shown that night harvestingis necessary in warm production regions tomaximize fruit quality. The mechanically har-vested fruit can be of better quality thanhand-harvested fruit when all operations arecarried out in a proper and timely manner.Machine-harvested berries are larger and havehigher total soluble solids, lower acidity, andsuperior color compared to hand-harvestedberries, which generally do not have uniformmaturity (Morris et al., 1978b). By machineharvesting at the lowest possible tempera-ture, fruit quality can be maintained during</p><p>subsequent handling before processing.Treating brambles with the growth regu-</p><p>lator ethephon before harvest can improvethe fruit quality. Ethephon reduces the num-ber of required harvests, increases color, andlowers acidity of both raw and processedblackberries (Morris et al., 1978a; Sims andMorris, 1982). Most insects can be elimi-nated from cane fruit before machine harvest-ing by following recommended spray pro-grams for specific insect problems. Of thosethat remain, 95% can be removed beforeprocessing by a washing technique in whichinfested berries pass through water contain-ing a dilute nonalkaline, anionic wetting agent.There is no loss of quality with this method(Crandall et al., 1966; Christensen et al.,1973).</p><p>CULTURAL SYSTEMS. In many cases, modi-fications of old cultural systems must be madeto successfully machine harvest brambles. Amechanical pruner, developed at the Univer-sity of Arkansas, properly shapes the hedg-erow for maximum harvesting efficiency oferect cane fruit (Morris et al., 1978b) andreduces the labor necessary for pruning. Oldcanes left in the hedgerow, do not affect yieldor fruit quality.</p><p>Hedgerow culture of erect blackberriesis conducive to mechanical harvesting. Fiveto seven harvests at 4- to 5-d intervals may berequired to harvest the entire crop mechani-cally; therefore, it is desirable to breed forconcentrated maturity to reduce the numberof harvests. Breeding programs on brambles</p><p>Fig. 1. Commercialmodel of University ofArkansas cane fruitharvester, manufacturedand sold by BlueberryEquipment Co., Inc.,South Haven, Mich.</p></li><li><p>24 JanuaryMarch 1999 9(1)</p><p>at some land-grant institutions, at the USDA,and in Canada have developed cultivars oferect blackberries that adapt well to mechani-zation (Moore, 1979, 1984). These breedingprograms remain active and should continueto produce more cultivars better adapted tomechanical harvesting.</p><p>Most blackberry plantings need to berenovated after 5 or 6 years. Renovation can beaccomplished by mowing the entire hedgerowto 3 to 4 inches (8 to 10 cm) immediately afterthe final harvest. All mowed canes should beremoved from the field. A mechanical harvestercannot be used in the year following thisrenovation. However, the fruit from theseshorter vines can be hand harvested if an eco-nomical supply of labor is available.</p><p>The Pacific Northwest has adapted wellto mechanical harvesting of brambles. Grow-ers in Oregon machine harvest most of their1500 acres (600 ha) of black raspberries andmost of 8000 acres (2800 ha) of trailingblackberries and hybrid berries (Dale et al.,1995). The lack of rain in harvest season inthe Pacific Northwest makes mechanical har-vesting feasible. Where rainfall at harvest timeis common, harvest days are reduced, and thesofter fruit is more easily damaged, as are theprimocanes, which then easily succumb tocane death by the fungus Leptosphaeriacoriothyrium (Fckl.) Sacc. (Dale et al., 1995).</p><p>StrawberriesAt the University of Arkansas, several</p><p>harvesting principles had to be evaluated inthe process of developing a mechanical har-vester for strawberries since, historically, straw-berries have been considered one of the cropsleast adaptable to mechanization (Morris etal., 1978c; Nelson and Kattan, 1967; Nelsonet al., 1978).</p><p>HARVESTERS. A tractor-drawn prototypeof a mechanical strawberry harvester was de-veloped at the University of Arkansas in 1967,and since then it has undergone continualrevision (Fig. 2) including development intoa self-propelled machine. This prototype wasa stripping harvester. It used a reel withalternating brush and comb that rakedthrough the crop. Air suction lifted the ber-ries and foliage (Fig. 3). An airlock berryremoval system evacuated the debris whilethe berries dropped through the airlock valveonto the conveyor. A grower in Copemish,Mich., purchased this machine and suggestedthat it be built to accommodate two rows forbetter commercial acceptance. Subsequently,Blueberry Equipment Co., Inc. (BEI), ofMichigan modified and produced the Uni-versity of Arkansas harvester as a two-rowhydraulic-powered machine for commercialsale. In those early years, researchers workingwith the harvesters mentioned and othertypes of mechanical strawberry harvesters re-ported picking efficiencies from 31% to 87%(Denisen and Buchele, 1967), 91% to 97%(Morris et al., 1978c), and 24% to 92%(Booster et al., 1970a, 1970b; Booster, 1973.)</p><p>In addition to the University of Arkansasharvester, several others have been developedfor strawberries. Three different strippingtype machines were developed in Italy duringthis same period (Di Ciolo and Zoli, 1975;Lucignani, 1979; Rosati, 1980), and research-ers in Denmark produced a commercial ma-chine called the Danpluck harvester, whichuses 62-inch-wide (160-cm) rakes on a slop-ing belt to lift the berries. A unique finger reelplucks the leaves from the berries as an airejector expels them. (Thuesen, 1988).</p><p>Quick and Denison (1970) described astripping-type harvester that used a bank ofdiverging, vibrating ramps instead of a reel.Shikaze and Nyborg (1973) developed avariation on this design by replacing thevibrating action with a bank of small belts.However, there has been no commercial useof these machines. More recently, H. Lee ofthe University of Guelph, Canada, and BraggEnterprises in Canada have developed an-other version of the stripping harvester(Swinkles and Murray, 1991). Their machineuses a reel with cam-controlled finger barsthat work through the plants, stripping thestrawberries from their peduncles and dump-ing them through the cam mechanism onto aconveyor system.</p><p>The British National Institute of Agri-cultural Engineering developed a mower-type harvester that was modified by MichiganState University and then commercialized insomewhat different forms by two machinerycompanies, Smallford Planters of Silsoe, En-gland, and Conners Machinery, Inc. (CMI),</p><p>Fig. 2. First commercialsingle-row mechanicalstrawberry harvesterdeveloped by theUniversity of Arkansasand manufactured byBlueberry EquipmentCo., Inc., South Haven,Mich. A two-rowharvester was success-fully tested and usedcommercially inOregon.</p></li><li><p>25 JanuaryMarch 1999 9(1)</p><p>of Simcoe, Ontario,Canada (Hansen et al.,1983). The Smallford ma-chine used a cutter bar withfingers that lifted the ber-ries above the bar (Kemp,1976). The berries wereconveyed to a belt wherecutting blades clipped thetrusses, and debris wasblown back into the field.The CMI harvester em-ployed a more effective air-blast system to separate thedebris from the berries andused reciprocating clippersto cut berry trusses. Theheavy output of this har-vester led to the develop-ment of mechanisms thatwould support and alloweasy handling of shallowbulk bins and a suitablebox-filling system (Lauroand Hergert, 1987). Researchers in Arkansas(Booster, 1973), Oregon (Hecht, 1980) andGermany (Fiedler, 1987) developed similarharvesters, although the German machineused people seated on the harvester to sortand destem the fruit.</p><p>Research at the University of Arkansashas shown that certain strawberry cultivarsare more adapted to machine harvesting,cleaning, and sorting without loss of quality(Morris et al., 1978c, 1979c, 1980; Nelson etal., 1979). Quality of machine-harvested fruitfrom certain strawberry cultivars is improvedby prior handpicking (Morris et al., 1979c,1980). Once-over machine harvested straw-berries, after one or two hand harvests, havehad a higher percentage of ripe berries thanfruit machine harvested without a previoushand harvest. The percentage of total solublesolids, firmness, and color intensity of theonce-over harvested strawberries after one ortwo hand pickings was the same or higherthan that of hand-harvested fruit (Morris etal., 1980). Sensory quality of fruit puree fromboth machine-harvested and handpicked fruitwas rated as acceptable.</p><p>One of the most objectionable aspects ofmachine-harvested strawberries is the pres-ence of green, immature fruit. Many imma-ture berries can be separated from maturefruit in the processing plant, based on fruitsize. However, large green fruit that is sortedwith the large ripe fruit eventually ends up inthe processed product. Research has shownthat strawberry products made from cultivarscontaining high anthocyanin levels can toler-ate as much as 50% immature fruit in theproduction of commercially acceptable jam(Morris et al., 1979a; Sistrunk and Morris,</p><p>1978). Strawberry jam made from Cardinalstrawberries, which have extremely high an-thocyanin levels, can contain as much as 75%large immature fruit and still be rated accept-able (Spayd and Morris, 1981).</p><p>Strawberries are highly perishable. Re-search has shown that extremely firm-fruitedstrawberries for processing can be mechani-cally harvested, properly cleaned and handled,and then held for up to 48 h at 75 F (24 C)and up to 7 d at 35 F (1.7 C) withoutexcessive quality loss (Morris and Cawthon,1979). It also showed that fungicide dipsbefore storage suppress mold growth andreduce loss of soluble solids. An acetaldehydeatmosphere and a combination of atmospheresand dips are effective in maintaining goodcolor, freedom from browning and productacceptability of machine-harvested strawber-ries held for 72 h at 75 F (24 C) (Morris et al.,1979a, 1979c). However, these techniqueshave not been commercially implemented sinceit has never been practical to use machine-harvested fruit for the fresh market, and berriesare usually processed immediately....</p></li></ul>