Horticultural Sciences Department

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Issue No. 568

The Vegetarian Newsletter 

A Horticultural Sciences Department Extension Publication on 
Vegetable and Fruit Crops 

Eat your Veggies and Fruits!!!!!

Publish Date: 
November, 2011

Higher Tomato Handling Temperatures Allow Tomatoes to Develop Full Flavor.

Jeff Brecht, Horticultural Sciences Department, IFAS, University of Florida, Gainesville, FL

Research shows that even ripe tomatoes taste better if not refrigerated.

Experiencing the flavor and aroma of a great tasting, ripe tomato is something that many people enjoy. Clearly the best way to obtain that experience is by picking and eating a tomato that has ripened on the vine (Fig. 1). However, for most people, the tomatoes they eat have to be transported from distant production areas with the ripening process occurring off the plant. Temperature management is an extremely important factor in successfully delivering tomatoes with great taste to consumers around the country. This is because tomatoes not only ripen best within a narrow temperature range of about 65 to 75°F but are also subject to chilling injury when stored at lower temperatures. But what is the lowest safe temperature for tomatoes to avoid chilling injury?

Recommendations for the lowest safe temperatures for tomatoes to avoid chilling injury have historically been based on threshold temperatures that do not result in development of visual injury symptoms (Hobson 1987). It has long been recognized that the sensitivity of tomatoes to chilling injury decreases as the fruit ripen. For example, in early editions of USDA Handbook 66 (Wright et al., 1954; Lutz and Hardenberg, 1968), the “bible” of postharvest plant physiologists, it was recommended that mature green tomatoes should not be held at temperatures lower than 55°F, but ripe tomatoes could be held at 50°F. Ryall and Lipton (1972) also recommended that mature green tomatoes not be held below 55°F, but they stated that pink tomatoes (Stage 4, USDA AMS, 1991) can be held at 41°F for up to 4 days, and that red fruit (Stage 6) can be held between 35 and 41°F for “a few days” without losing their characteristic aroma and flavor.

This picture began to change in 1978 when Kader et al. from the University of California, Davis reported that temperatures below 61°F may impair tomato flavor by lowering the volatile content and reducing “tomato-like” flavor as judged by taste panels. The negative effects on tomato flavor of temperatures that have traditionally been considered safe in terms of chilling injury were confirmed in 2000, when Maul et al., based on research supervised by Dr. Steve Sargent in the Horticultural Sciences Department at UF in Gainesville, reported that sensory panelists detected less tomato flavor and less ripe aroma when light-red stage (Stage 5, >90% red coloration) tomatoes were held at 55°F for as little as 2 days for the BHN-189 variety (BHN Seeds) and 4 days for the Solimar variety (Seminis) compared to holding at 68°F. They found that those sensory panel results corresponded to significant differences in aroma volatile production by the fruit at the two temperatures (Fig. 2). A research group in Mexico recently reported similar results for Sunseeds’ 7705 variety (Diaz de Leon-Sanchez, et al., 2009).

A research project funded by the USDA Specialty Cops Research Initiative is now underway in the Horticultural Sciences Department at UF in Gainesville in which my graduate student Angelos Deltsidis is determining the “true” chilling threshold temperature for tomatoes. What that means is that he is measuring tomato aroma volatiles during storage of pink tomato fruit at temperatures between 55 and 68°F to determine at what temperature and after how much time the volatile production begins to be inhibited. In addition, he is exploring the use of modified atmosphere packaging (MAP) to see if reduced oxygen and/or elevated carbon dioxide concentrations, which are known to slow tomato ripening, can be used to overcome the negative effects of low temperatures on tomato flavor (Fig. 3).

Alternatively, he is determining if MAP can be used to provide sufficient extension of tomato postharvest life so as to allow tomatoes held at truly non-chilling temperatures to be marketed throughout the United States. As a first step, he has determined the tolerance of pink tomatoes to elevated carbon dioxide at several different temperatures (Deltsidis et al., 2011).

Literature cited

Deltsidis, A., E. Pliakoni, and J.K. Brecht. 2011. Establishing CO2 Tolerance of Pink Tomatoes in MAP at Elevated Handling Temperatures. Proc. Fla. State Hort. Soc. 124: (in press)

Diaz de Leon-Sanchez, F. C. Pelayo-Zaldivar, F. Rivera-Cabrera, M. Ponce-Valadez, X. Avila-Alejandre, F.J. Fernandez, H.B. Escalona-Buendia, and L.J. Perez-Flores. 2009. Effect of refrigerated storage on aroma and alcohol dehydrogenase activity in tomato fruit. Postharvest Biol. Technol. 54:93-100.

Hobson G.E. 1987. Low temperature injury and the storage of ripening tomatoes. J. Hort. Sci. 62:55-62.

Kader, A.A., L.L. Morris, M.A. Stevens, and M. Albright-Holton. 1978. Composition and quality of fresh market tomatoes as influenced by some post-harvest handling practices. J. Amer. Soc. Hort. Sci. 103:6-13.

Lutz, J.M. and R.E. Hardenburg. 1968. The commercial storage of fruits, vegetables, and florist and nursery stocks. USDA Agric. Hndbk. No. 66. Washington, D.C.

Maul F., S.A. Sargent, C.A. Sims, E.A. Baldwin, M.O. Balaban, and D.J. Huber. Tomato flavor and aroma quality as affected by storage temperature. 2000. J. Food Sci. 65:1228-1237.

Ryall, A.L. and W.J. Lipton. 1972. Handling, transportation and storage of fruits and vegetables. Vol. 1, Vegetables and melons. AVI, Westport, CT.

USDA AMS. 1991. United States standards for grades of fresh tomatoes. U.S. Dept. Agric., Agric. Mktg. Serv., Washington, D.C.

Wright, R.C., D.H. Rose, and T.M. Whiteman. 1954. The commercial storage of fruits, vegetables, and florist and nursery stocks. USDA Agric. Hndbk. No. 66. Washington, D.C.


Management of bacterial wilt in tomato production by grafting

Mathews L. Paret, University of Florida, North Florida Research and Education Center, Quincy, FL 32351; Theodore McAvoy, Virginia Polytechnic Institute and State University, Department of Horticulture, Blacksburg, VA 24061; Joshua H. Freeman and Steven L. Rideout, Eastern Shore Agricultural Research and Extension Center, Painter, VA 23420; Stephen M. Olson, University of Florida, North Florida Research and Education Center, Quincy, FL 32351.

Bacterial wilt of tomato caused by the soil-borne bacterium Ralstonia solanacearum race 1 (biovar 1, phylotype II) is widely distributed in the southeastern United States and causes considerable economical losses under ideal conditions for disease incidence. Although most soil-borne pathogens have been traditionally managed with soil fumigants, this strategy has been minimally effective against bacterial wilt.  Crop rotation as a disease management strategy is effective but can be difficult because R. solanacearum can infect over 200 plant species.  Although resistance is available in tomato cultivars ‘Hawaii 7996’, ‘Hawaii 7997’, and ‘Hawaii 7998’, these cultivars have not been widely accepted due to poor horticultural traits such as small fruit, a trait linked with bacterial wilt disease resistance.

Grafting has been practiced for decades in Asia as a technique to manage soil-borne diseases. Grafted plants now account for 81% and 54% of the vegetable acreage in Korea and Japan, respectively.  Grafting has recently been gaining popularity in the United States, partly due to the loss of methyl bromide and the increased restrictions of using soil fumigants. Several greenhouse and field studies conducted at the North Florida Research and Education Center, Quincy FL, and Eastern Shore Agricultural Research and Extension Center, Painter, VA during 2009-2010 have demonstrated the ability of grafted plants in reducing bacterial wilt in tomato field production. The rootstocks tested in the studies were ‘Jjak Kkung’ (Seminis Vegetable Seeds, St. Louis, MO), ‘Cheong Gang’ (Seminis Vegetable Seeds), ‘RST-04-105-T’ (DP seeds, Yuma, AZ), ‘RST-04-106-T’ (DP Seeds), ‘Hawaii 7998’ (Public breeding material, University of Florida), ‘BHN 998’ (BHN Seed, Immokalee, FL), ‘BHN 1053’ (BHN Seed), ‘BHN 1054’ (BHN Seed). The scion used was a bacterial wilt susceptible cultivar ‘BHN 602’ (BHN Seed).

The use of rootstocks with resistance to bacterial wilt had a significant effect on tomato fruit yield and bacterial wilt incidence in studies conducted during 2009 and 2010. Grafting of susceptible cultivars to resistant rootstocks is an effective management option available for growers who are currently abandoning fields infested with R. solanacearum due to the major economic losses associated with the occurrence of bacterial wilt. This will also significantly reduce the cost of moving production from location to location.

One of the restrictions in commercialization of grafting for open field tomato production right now is the lack of major suppliers of grafted tomatoes at affordable costs. A recent economic analysis has determined that cost of a single grafted plant and non-grafted plant were at $0.59 and $0.13 in North Carolina, and $1.29 and $ 0.51 in Pennsylvania, respectively. In Florida, greenhouse tomato growers have been purchasing grafted plants from Canada costing approximately $1.00-1.75 per grafted plant. Even though grafting requires higher initial investment on the costs of transplants, it significantly reduces disease incidence and provides significant increase in marketable yield as indicated in our current study. This could offset any additional expenses that growers may have to spend for purchasing/ producing grafted plants. Elimination of the cost of soil fumigation could also make the use of grafted plants more economically feasible.

The studies conducted by our group illustrated the benefits of grafting a bacterial wilt susceptible tomato scion ‘BHN 602’ onto resistant hybrid rootstocks when planted into soils heavily infested with R. solanacearum.  Disease incidence was greatly reduced and tomato fruit yield was maintained at levels acceptable to commercial producers. Data indicate that several commercially available hybrid rootstocks have high levels of bacterial wilt resistance. ‘Cheong Gang’, ‘BHN 1054’, and ‘BHN 998’ were the most adapted rootstocks with respect to bacterial wilt resistance and resulting tomato fruit yield in field studies conducted at Florida and Virginia.

Insecticides and Resistant Varieties for Management of Whiteflies and TYLCV

Phil Stansly, Monica Ozores-Hampton, and Barry Kostyk

University of Florida/IFAS/SWFREC Immokalee

Tomato yellow leaf curl virus (TYLCV) has been a major concern for Florida tomato growers ever since its first appearance in 1994.  Yield losses are correlated with earliness of symptom expression and may reach 90% if symptoms appear within the first few week of transplanting (Schuster et al., 1996).  Important cultural controls include use of clean transplants, crop removal and field sanitation followed by a crop free period between crops to reduce vector and virus inoculum.  Insecticidal control of the whitefly vector, Bemisia tabaci, is usually effective but not always sufficient to avoid losses.  The use of TYLCV-resistant (R) varieties provides added insurance against virus-induced losses that can be critical during a high whitefly/TYLCV year. 

            Choosing the correct varieties is a cornerstone of a successful tomato industry. The University of Florida/ Southwest Florida Research and Education Center (UF/SWFREC) TYLCV-R variety testing program provides unbiased information about the adaptability and performance of tomato varieties in Florida’s diverse environments, thereby allowing growers to make informed decisions (http://www.imok.ufl.edu/vegetable_hort/variety_testing/tylcv/). There have been several TYLCV-R variety evaluations in Florida (Gilreath et al., 2000; Scott 2004 and Cushman and Stansly, 2006).   The TYLCV-R varieties evaluated produced comparable yields to traditional varieties under low virus pressure and greater yields under high virus pressure (Gilreath et al., 2000; Scott, 2004 and Cushman and Stansly, 2006; Ozores-Hampton et al., 2008 and 2010).  However, resistant varieties have yet to be widely grown in Florida, probably due to a perception of lower fruit quality compared with traditional varieties such as ‘Florida 47’ and ‘Sebring’. Additionally, the grower should confirm that TYLCV-R varieties also have resistance to other common diseases such as fusarium crown rot (Fusarium oxysporum f.sp. radicis-lycopersici) and bacterial spot caused by Xanthomonas species (X. vesicatoria, X. euvesicatoria, X. perforans and X. gardneri) that are prevalent in tomato producing areas.  The variety testing program has evaluated the horticultural performance of TYLCV-R tomato varieties available in the USA market today (Ozores-Hampton et al., 2008 and 2010). 

Here we report on three field experiments conducted to evaluate the relative contributions of insecticidal control and a resistant variety in managing TYLCV. 

Materials and Methods

Variety x Insecticide Trial 2010.  Seedlings of a TYLCV resistant variety ‘Tygress’ and a susceptible variety BHN-602 obtained from a commercial greenhouse were transplanted at the SWFREC  Immokalee FL. on 23-Mar. Plants were spaced 18-in apart on two sets of three beds 235 ft long covered with black polyethylene film mulch. After incorporating approximately 25% of the fertilizer (13-2-13 N-P-K), the remaining fertilizer was injected later as liquid 8-0-8 through drip tape with 4-in emitter spacing. The center row was left untreated throughout the trial with eight treatments arranged on the other four beds in a randomized complete block design(RCBD). Plots in the four treated rows contained 19 plants, with a single plant left between plots as buffers. Plots were split into two subplots of 9 TYLCV susceptible (BHN-602) and resistant (‘Tygress’) plants separated by a TYLCV symptomatic plant from a local farm to provide virus inoculum.

Applications of Scorpion, Coragen and Admire were made 24-Mar by delivering a 120 ml suspension using an EZ-Dose® sprayer operating at a pressure of 45 PSI and a flow rate of 3.7 gal per minute (Fig. 1). Foliar sprays were applied with a single row high clearance sprayer operating at 180 psi and 2.3 mph provided with two vertical booms fitted with yellow Albuz® hollow cone nozzles, each delivering 10 gpa (Fig. 2). Total spray volume increased as nozzles were added to accommodate plant growth. A standard used for four of the treatments consisted of 2.75 oz of Fulfill on 4 May, 9 oz of Courier and 21 oz of Thionex on 18 May, and 9 oz of Courier on 3 Jun.

Whitefly adults were evaluated weekly from 8-April to 9-June on five leaflets from one mid-canopy level true leaf on four plants per subplot. Immature stages from three plants in each subplot were counted on 4,17,31-May under a stereoscopic microscope from eight, 0.5-in2 discs cut from each of three leaflets of one terminal 7th node trifoliate. Samples on 9 Jun (adults) and 9 and 14 Jun (nymphs) were only obtained from ‘Tygress’ plants due to severe leaf distortion on TYLCV infected BHN-602 plants. All plants were inspected weekly and the date of symptom appearance recorded. Fruit of marketable size was harvested from six plants in each sub-plot on 2 and 16-Jun. Fruit was culled for defects due to stink bug damage, bacterial spot (Xanthomonas species (X. vesicatoria, X. euvesicatoria, X. perforans and X. gardneri) and surface deformities such as shoulder cracking and zippering and number, size, and weight of marketable fruit recorded.

2011 foliar trial Experimental design and procedures were much the same as the previous year except for some details: the susceptible variety was Florida 47, 21 transplants per plot (10 of each variety + one infected plant in the middle) were set 2 Mar, in a RCBD with 12 treatments in four beds, each with two lines of drip, the dry fertilizer was 10-2-10 N-P-K and liquid 7-0-7, drenches were applied 7 Mar, sprays/adults were evaluated weekly from 23 Mar to 11 May, and nymphs on 6, 20 Apr and 4 May. All fruit on six plants per plot were harvested 16 May.

2011 drench/drip trialDesign was identical to 2011 foliar trial except nine treatments in four replicates were spread across three beds. Drenches were again applied in a 120 ml suspension using an EZ-Dose® sprayer operating at a pressure of 45 PSI and a flow rate of 3.7 gal per minute. Drip tape was sectioned off within each treated plot, pressurized using a 12 volt pump at 0.23 gpm with 2 L water, followed by 3 L of the appropriate suspension a finally a 3 L water chase (Fig. 3).  Adults were evaluated weekly from 23 Mar to 11 May and nymphs at 13, 27 Apr and 11 May. All fruit on six plants per plot were harvested 13-May.

TYLCV-R variety trials: Seven field variety evaluations were conducted in South Florida during a spring season from 2006 to 2011. TYLCV-R variety evaluations were conducted under commercial growing conditions in multiple locations Estero, Immokalee and Homestead with a RCBD . In addition to yields and post-harvest quality,

Results

Variety x Insecticide Trial 2010. Whitefly infestation was initially light due to cold weather including freezes. Nevertheless, most BHN-602 (susceptible) plants eventually showed symptoms of TYLCV (Fig. 4).  Fewer adults than the check were seen with all treatments on 8 Apr. except for Coragen drenches and AdmirePro + Movento, whereas only AdmirePro + Movento, Oberon or Rimon provided significant control on 5 May. All products provided significant control of adults for the next 5 weeks, although Scorpion and the low rate of Coragen both with the standard sprays failed to do so on 9 Jun. Over all dates, fewest adults were seen with AdmirePro + either Movento or Oberon, although these were not significantly different from AdmirePro + the standard or + Rimon. Nymphs were most reduced on 4 May before sprays were applied by Scorpion, followed by the high rate of Coragen which was not different from one of the 7 oz AdmirePro treatments.  On 17 May, only applications of Scorpion + the standard or AdmirePro + Movento, Oberon or Rimon provided control.  AdmirePro + Rimon provided best control on 14 Jun although not different the other treatments that included AdmirePro.  The other 3 treatments were not different from the check.  Only Scorpion + the standard, or AdmirePro + either Movento or Rimon resulted in significant reduction of virus symptoms in the susceptible BHN-602 variety on 27 May.  None of the other treatments resulted in lower incidence of TYLCV on that date or any other date.

Surprisingly, higher yields of marketable fruit were seen from the susceptible BHN-602 plants due to excessive cracking and zippering of ‘Tygress’ fruit. Greater yields were seen from all treated plants compared to the check, with no differences among treatments regardless of variety.

2011 Foliar Trial: By 6 April, all effective treatments were working, including the rotations with AdmirePro, AdmirePro + pyrifluquinizon and BYI02960 .  Three oz of Scorpion was not effective against adults though 5 oz was better and about equivalent to 4 oz of Venom except on 27 Apr.   Two applications of Movento did not improve adult suppression with AdmirePro followed by rotations of Thiodan and Baythroid but did improve control of nymphs.  Similar levels of control were obtained with Admire followed by pyrifluquinizon and with BYI102960 except for the latter on 4 May. Incidence of TYLCV rose from an average 1.5% on 31 Mar to 98% on 11 May with no significance differences among any treatment on any one date. No significant treatment effects were seen on yield although production of ‘Tygress’ (9,58 ± 30.2 boxes/ac) was greater than FL-47 (450 ± 26.4 boxes/ac), reflecting the high incidence of TYLCV.

2011 Drip/Drench: The drench application of BYI02960 at 21 oz was generally the best treatment for controlling adults, even compared to the 28 oz rate applied through drip.  However, no differences were seen between Venom treatments applied by drip or drench.  Drip application of Durivo following the AdmirePro drench did not improve adult control obtained with the drench alone. By 13-Apr, all treatments significantly reduced the number of nymphs when compared to the untreated control with the Venom drench application outperforming the Venom drip application.  Likewise, the BYI02960 drench application resulted in fewest nymphs.  On 27 Apr, only the 21 oz drench and 28 oz drip applications of BYI02960 were providing significant levels of control. These two were joined by the drench application of AdmirePro on 11-May.  Incidence of TYLCV mirrored the foliar trial except for plants treated with the 28 oz drip rate or 21 oz drench rate of BYI02960 which were significantly lower on two or three sample dates respectively, including the last on 4 May.    Due to poor weather conditions near harvest and the general health of the plants most fruit in both varieties were culled but the total weight was again greater for ‘Tygress’, 606 ± 31.2 boxes per acre, compared to 466 ± 22.1 boxes per acre with no differences among insecticide treatments.

TYLCV-R Variety Trials: No clear advantage was found by using TYLCV-R varieties under low TYLCV pressure (Ozores-Hampton et al., 2008 and 2010).In contrast, TYLCV-R varieties were observed to produce a high percentage of unmarketable fruit due to blossom end scar, zippering, catfacing, sunscald, yellow shoulders, odd shapes, and radial or concentric cracking compared to susceptible varieties. ‘Tygress’, ‘SVR 200’, ‘Security 28’, ‘Charger’ and grafted varieties (‘BHN 833’/’Tygrees’) have proved to be among the best TYLCV-R varieties for South Florida Spring tomato market. These varieties have high marketable x-large fruit and total marketable yield and lower unmarketable fruits, fruit firmness and high intense red color.

Summary

During 2011. drench applications of insecticides protected plants from whiteflies and even virus better than drip applications and foliar sprays.  This has been a consistent pattern in our trials over a number of years.  Contrasting results from the insecticide x variety trials run in 2010 and 2011 illustrate the different outcomes that can occur depending on growing conditions and their effect on disease incidence.  In 2010 virus movement was relatively slow such that many plants escaped infection until late in the season. Furthermore, a wet spring caused high levels of bacterial spot to which ‘Tygress’ is more susceptible that BHN-602.  Consequently, yield from the susceptible variety was better that year.  In contrast, virus incidence rose quickly in 2011 and consequently, ‘Tygress’ yielded better than the susceptible variety, FL-47.  We know that these diseases can be managed with resistant varieties; however the lack of consistent fruit quality is a major factor that limits adoption of TYCLV-R varieties by the Florida tomato industry.

Literature cited

Cushman, K and P. A. Stansly.  2006.  TYCLV-resistant tomato cultivar trial and whitefly control.  Proceedings: Florida Tomato Institute. P. Gilreath [Ed.], Vegetable Crops Special Series, IFAS, U. of Florida, Gainesville, pp. 29-34.

Gilreath, P., K. Shuler, J. Polston, T. Sherwood, G. McAvoy, P. Stansly, and E. Waldo. 2000. Tomato yellow leaf curl virus resistant tomato variety trials. Proc. Fla. State Hort. Soc. 113:190-193.

Schuster, D. J., P. A. Stansly, and J. E. Polston. 1996.Expressions of plant damage of Bemisia, pp. 153-165. In D. D. Gerling and R. T. Mayer [eds.], Bemisia 1995:  Taxonomy, Biology, Damage, Control, and Management. Intercept Andover, Hants, UK.

Scott J.W. 2004. Tomato Yellow Leaf Curl Resistant Varieties Available Now and Future Outlook from IFAS. P. Gilreath and W. Stall (Eds.). Vegetable Crop Special Series, IFAS, U. of Florida. Gainesville, PRO 521 pp. 15-17.

Ozores-Hampton M.P., E. J. McAvoy, S. Sargent and P. Roberts. 2010. Evaluation of tomato yellow leaf curl virus (TYLCV) and Fusarium crown rot (FCR) resistant tomato variety under commercial conditions in Southwest Florida. Fla. Tomato Inst. Proc. PRO 527, pp.11-15.

Ozores-Hampton, M.P., G. McAvoy, E.H. Simonne, and P. Stansly. 2008. Evaluation of TYLC virus-resistant varieties under commercial conditions in Southwest Florida. Fla. Tomato Inst. Proc. PRO525, pp.12-17.

Minimum wages and implications on agricultural piece rates

Fritz M. Roka

University of Florida

Food and Resource Economics

Southwest Research and Education Center

2685 State Road 29 N, Immokalee, FL  34142

Piece rates are a common method of payment for farm workers who harvest fresh fruit and vegetable crops. Piece rates are a convenient system to pay for labor services where “units of work” are easily measurable and can be characterized by repeatable actions. In agriculture, a unit of work varies by the crop and the task being performed. For example, workers who tie tomato plants could be paid per 100 linear feet. During tomato harvesting, a piece rate worker is paid for every bucket weighing between 30 and 35 pounds which is delivered to a gondola or collection bin on the back of a flat-bed truck.

A worker’s daily earnings are calculated by multiplying the piece rate by his or her productivity, which is defined as the number of units of work accomplished that day. Productivity of harvest workers varies by crop, growing conditions, weather, and the physical stamina of a worker. Most tomato harvesters average between 15 and 27 buckets per hour. If the piece rate for harvesting tomatoes is 50 cents per 32-pound bucket and a man picks 150 buckets during the course of one day, his total (gross) earnings for that day would be $75. If the same worker spent 8 hours harvesting, his average productivity would be 18 buckets per hour and his average hourly earnings would be $9.37.

From an employer’s perspective, a piece rate system provides two advantages over an hourly wage system. First, a piece rate establishes in advance the unit cost for the job a worker is hired to do. Second, a piece rate system does not require close and constant supervision of a worker’s productivity. Since workers’ earnings are related directly to their productivity, a worker is self-motivated to achieve a suitable performance standard. The higher a worker’s productivity, the more income a worker earns.

A flat hourly, or wage, rate is an alternative payment system to piece rates. A worker, who agrees to work for a constant hourly rate of pay, may prefer a guaranteed hourly income. Since a flat wage removes the productivity incentive, however, a worker does not have the opportunity to earn more than the stated hourly wage. An employer may also be disadvantaged if worker performance has a direct influence on unit costs of production. If hourly or daily output levels are important, close supervision of worker effort is required under a wage payment system to prevent low productivity from increasing overall unit costs of production.

The harvesting of fresh vegetables is well suited to a piece rate payment method because harvesting involves repetitive actions and a piece rate is an efficient means of achieving adequate levels of worker productivity. While close supervision to monitor productivity is not important, supervision of piece rate workers to ensure performance quality is necessary to avoid adverse consequences. For example, productivity incentives tend to drive workers to harvest at faster speeds, which, in turn, could damage or prematurely destroy a plant. Rough handling of a tomato bush during the first harvest could damage a plant so that a second, third, or even fourth harvest from the same plant is not possible. In addition, fruit quality may suffer as workers disregard market standards for faster harvesting speed. Tomatoes grown in Florida are produced for the fresh market and require higher quality cosmetic standards than tomatoes produced for processing. Blemished fruit or harvested fruit that does not meet market quality requirements must be culled or discarded, resulting in a direct financial loss to the grower.

Piece-rate workers, like all other workers, are guaranteed by federal employment laws to earn at least the minimum wage as an average hourly rate for each pay period. At the end of a pay period, a worker’s gross earnings (piece rate multiplied by total units) is divided by the total hours worked. So long as the average hourly earnings are greater than minimum wage, nothing more needs to be done. However, if average hourly earnings are below minimum wage, the employer must “build-up” a worker’s earnings until the worker’s average hourly earnings for the pay period are at least equal to the minimum wage. Agricultural employers who pay their workers by a piece rate must keep extensive records that document the total number of hours of compensable time as well as the total number of units a worker produced during the pay period. When the “clock” starts and stops determines total hours worked, and hence, become important record-keeping items. For example, time spent on a crew bus while being transported from home to a field is NOT compensable time so long as the worker is not asked to perform any work functions. Once a crew arrives at the field, however, the clock starts even if workers must wait for early morning dew to dry off the field before they can start harvesting. If worked hours are not recorded properly, an employer can face significant fines from state and federal regulatory agencies as well as exposure to civil law suits if workers retain a private attorney to litigate their wage and hour grievances.

Increases in the minimum wage can have an important effect on unit harvesting costs. In 2002, the federal minimum wage was $5.15 per hour. A tomato harvester, who averaged 15 buckets per hour, would have to have been paid at least 35-cents per bucket to cover the minimum wage. In 2004, a state constitutional amendment established a Florida minimum wage, and since then employers had to pay the higher of the federal or state rates. Effective January 1, 2012, Florida’s minimum wage will increase to $7.67 per hour (the federal minimum wage will remain at $7.25). Consequently, the same tomato harvester who averages 15 buckets per hour has to be paid a piece rate of at least 51cents per bucket.

For highly productive workers, meeting the minimum wage requirements is not a challenge. For workers on the lower end of the productivity spectrum, however, an increase in the minimum wage changes the “effective” piece rate for those workers. If the prevailing piece rates for harvesting tomatoes is 55 cents per bucket, minimum wage is met for all workers who can average at least 14 buckets per hour ($7.67 divided by 55 cents). For a worker who can average only 10 buckets per hour, however, his effective piece rate has risen to nearly 78 cents ($7.67 divided by 10 buckets).

Growing and harvesting fresh vegetables relies on the extensive use of hand labor. It is likely that vegetable growers in Florida will continue to utilize hand labor to harvest their tender crops well into the future. Robotic technologies, while evolving rapidly, cannot match the discernment of a human eye, gentleness of a human touch, nor the outright speed of a human hand to cost-effectively harvest appropriate fruits for the fresh market. A piece rate system is a viable method of employing workers to many functions required during a vegetable growing season. Piece rates reward productivity and require minimal supervisory expenses. The system also requires that accurate records are kept to document the proper total number of hours worked during each payroll period and the total units produced by each worker. Piece rates need to be high enough to attract a sufficient number of workers and satisfy minimum wage thresholds, but low enough to maintain a viable competitive position within a crop’s respective commodity market.