Horticultural Sciences Department

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Issue No. 615

The Vegetarian Newsletter 

A Horticultural Sciences Department Extension Publication on 
Vegetable and Fruit Crops 

Eat your Veggies and Fruits!!!!!

Publish Date: 
September 2016


UF/IFAS Farm Labor Supervisor scheduled trainings

Trainings will be held at five locations this fall: 

Ft. Pierce: September 20 – 21

Homestead: October 4 – 5

Arcadia: October 11 – 12

Sebring: October 25-26

Immokalee: November 9 – 10


For details, please see the following schedule.   You can find an explanation of each offered class below the schedule.   On-site (private) trainings can be scheduled at any time, in any location. 

The importance of training cannot be emphasized enough.   Several large growers now require their crew leaders and other supervisory personnel to attend classes.   We even completed a training in Georgia recently!

If people take a total of 8 classes and pass a test in each one, they earn a Certificate of Farm Labor Management.  More than 70 people have completed the Certificate of Farm Labor Management so far and many more will earn theirs this year as they finish up the required classes.     

Here is the Fall 2016 schedule


CLASS OVERVIEWS – The following classes are offered in the scheduled trainings this fall.  Other available classes include CPR, First Aid, DOT Audit, Housing, Agricultural Equipment Safety, Pesticide Safety, and Emergency Preparedness/Personal Safety.

1.      FARM LABOR CONTRACTOR BASICS:   Details of legal registrations required by the Department of Labor (DOL) and the Department of Business and Professional Regulations (DBPR) for Farm labor contractors.   Each portion of the process of becoming registered is covered, starting with general eligibility requirements and testing, then leading into authorizations (driving, transporting, and housing) and everything that is needed to support each authorization.   The latter part of the class reviews “Surviving in Inspection” from the various agencies that oversee the activities of FLCs.   Length:  2 hours


2.      WAGE & HOUR:    Basics of Department of Labor (DOL)-and DBPR enforced regulations related to paying workers fairly:  information workers are required to know before and during their employment; importance of correctly recording compensable hours and minimum wage; when to start and stop the clock each day; in-class exercises for calculating pay; and the concept of joint employment.   Length:  2 hours   (REQUIRED FOR CFLM)


3.      RULES FOR BUS/VAN DRIVERS:  This class is designed for drivers with a primary focus on DOT regulations for vehicle inspections and driver preparedness.   WH/DOL and DBPR regulations are also covered, and a discussion of “when is a carpool not a carpool?”  In Vehicle preparedness, we review details of what needs to be inspected on farm labor vehicles, what paperwork is required and who is responsible for related tasks.   Driver preparedness includes the medical examination and how drivers track hours of service.  The class also touches briefly on company responsibilities of driver qualification files and drug & alcohol testing.  


4.      SAFE DRIVING:  This class begins with an overview of the details and importance of vehicle preparation and driver preparation.  The rest of the class focuses on defensive driving principles (Space, Anticipation, Adjustments, and Distractions) and concludes with information on major distractions of drug and alcohol use, cellphones, and texting.  This class is usually taught in conjunction with local county Sheriff’s Department officers.


5.      HUMAN RESOURCE COMPLIANCE:   Equal Employment Opportunity Commission (EEOC) regulations regarding discrimination; harassment, with a special focus on sexual harassment; protected classes; reasonable accommodation and retaliation.   This class is based mostly on real-life case studies that we analyze in class – each year we use four different case studies.   LGBT (Lesbian, Gay, Bisexual and Transgender) protections and a mediation service that can help avoid expensive court cases are also covered.  The class also includes a brief overview of Child Labor laws and signs of Human Trafficking. Length:  2 hours  (REQUIRED FOR CFLM)


6.      MANAGEMENT COMMUNICATIONS, PART 1:   This is part 1 of a 2-part course on management communication skills for supervisors of farm workers.  Part 1 includes the effect of non-verbal communication; importance of body language, facial expressions and tone; cultural awareness and stereotyping that affects communication; a management style test; perceptions of respect; and management skills, including the difference between effective encouragement and praise and between threats and consequences.  Length: 2 hours


7.      HEAT ILLNESS:  Recognizing the symptoms of various levels of heat-related illness can save lives.   This class covers personal risk factors and how to recognize and treat various levels of heat illnesses.   Prevention is a major focus.  Detailed examples of agricultural workers who died from heat-related illnesses are used to emphasize the importance of symptom awareness.   Length:  1.5 hours


For more information, contact Barbara Hyman hymanb@ufl.edu, 239-658-3461, Carlene Thissen carlene@ufl.edu , 239-658-3449 or Fritz Roka, fmroka@ufl.edu  .  


Nicholas S. Dufault, Assistant Professor and Extension Specialist of Plant Pathology

Rebecca Barocco, Doctor of Plant Medicine, Postdoctoral Scholar


Blackleg of potato is on many growers’ minds this year, especially with the recent news about the prevalence of this pathogen in Northeastern potato seed producing regions.  Dr. Wyenandt, from Rutgers University, has indicated that the Dickeya blackleg pathogen, Dickeya dianthicola, was found on 3 farms in New Jersey, 5 farms on Long Island, 3 fields in Delaware and has been detected in Maine during 2016.  The disease has been identified on the white rounds potato varieties ‘Superior’, ‘Snowden’, ‘Norwis’ and ‘Waneta’, which may be of interest to many Florida potato growers.  Even though Dickeya blackleg is considered a new potato disease in the USA, it was recently reclassified by the USDA APHIS as a non-reportable/non-actionable pathogen.  However, producers should still be concerned with this disease as it does have the potential to cause 100% yield losses under the right conditions.

Identification of Dickeya blackleg is the most important step for managing this disease.  It is critical to realize that this disease is primarily a seed piece issue, and that disease documentation provides valuable information to the potato industry that will assist with addressing problem situations in a timely matter.  Potato growers, crop consultants and Extension personnel should remain vigilant in their scouting for this disease and should submit samples for diagnostic testing.  Below is more information about how to identify Dickey blackleg and how to submit a sample should you notice symptoms resembling this disease.

Symptoms and disease development

Blackleg is caused by the bacterial pathogens Pectobacterium astrosceptica (formerly Erwinia carotovora subsp. atroseptica), Dickeya dianthicola, and D. solani and is favored by cool, moist conditionsThe two Dickeya species are more aggressive than the more common P. astroceptica.  However, D. solani has not yet been detected in the U.S. Disease begins from below ground on infected tuber seed and moves up to the base of the stem initially causing water-soaked, soft tissue that eventually turns black and may shrivel if the tissue becomes dry (Figure 1).  Whole stems can decay and turn black as the bacteria continues to grow up through the stem and into the upper canopy.  Infections may be limited to the vascular system with no external symptoms.

Figure 1. The image on the left shows a stunted/wilted plant infected with Dickeya blackleg. On the right, the typical water soaked tissue that turns black as the pathogen progresses up the stem. Photos courtesy of Clay Pederson, DPM.


Young plants are more vulnerable to blackleg than older plants.  Initial symptoms on recently emerged plants are stunting, yellowing, and stiff foliage (Figure 1).  Death will usually follow resulting in poor stands.  Rapid, severe wilting is the first noticeable symptom on older plants which can occur on infected stems before the outer tissue turns black.  Yellowing may also be seen.  Infections on older plants may go unnoticed after diseased stems are severely decayed and become covered by the surrounding canopy.  Blackleg symptoms on the foliage can be confused with aerial stem rot caused by a different bacterial species (Pectobacterium carotovorum subsp. carotovorum) that is closely related to blackleg pathogens.  Aerial stem rot does not begin from tubers as with blackleg.  Infection instead begins from damaged stems.

Diseased plants can pass inoculum to tubers through the stolons (Figure 2).  The bacteria will also move from decaying diseased tissue into the soil.  Tubers on nearby healthy plants can become infected as the bacteria moves with water flow.  The infected tuber will continue to become soft and black which progresses more rapidly under poor storage conditions.  However, spread of the pathogen within a tuber may be halted by better storage conditions which results in a dry “hard rot”.  A variety of secondary bacterial pathogens (Erwinia spp., Pectobacterium spp., Pseudomonas spp., Bacillus spp., Clostridium spp.) can also cause soft rot on tubers that have been wounded either in storage or in the field.  The damage on tubers caused by blackleg also invites these secondary pathogens that further rot the tissue.

Figure 2. A potato infected with Dickeya dianthicola showing the soft rotting symptoms of the tuber. Photos courtesy of Clay Pederson, DPM.



Diseased tubers used for seed are the primary source of inoculum, since this bacterium does not survive well in the soil.  Infected tubers may be asymptomatic making it difficult to exclude them from seed production.  The most important way to control blackleg is by planting certified disease-free tubers, but several cultural practices can help minimize disease spread if fields do become contaminated. 

Tuber seed production

·         Produce seed stock from tissue culture.

·         Sanitize equipment used for seed production and cutting.

·         Plant whole seed pieces when possible.

·         Maintain seed pulp temperatures at 50-55oF (10-13°C).

·         Limit field generations of seed lots to 5-7 years.

Cultural field practices

·         Plant in well-drained soils after temperatures have reached 50°F (10°C).

·         Do not irrigate before emergence.

·         Maintain proper irrigation without overwatering.

·         If possible, increase plant spacing to improve aeration through the canopy.

·         Rouging diseased plants can be helpful as long as the tissue does not contact healthy plants.

·         Rotating away from potatoes and other Solanaceous crops for 2 to 3 years, especially after confirmation of Dickeya blackleg.


Harvest and storage

·         Calibrate equipment and handling methods to reduce bruising and damage to tubers.

·         Harvest tubers when soil temperatures are below 68°F (20°C).

·         Cover transportation trucks to reduce heat from sunlight to promote wound healing that will prevent cell desiccation.

·         Sanitize postharvest machinery and equipment.

·         Remove rotted tubers.

·         Store tubers under 95% relative humidity and temperatures of (50-55°C) 10-13°C with good ventilation to prevent condensation.


What to do if you suspect Dickeya Blackleg

If you suspect that Dickeya Blackleg is present either in your seed or field contact Dr. Nicholas Dufault (nsdufault@ufl.edu) and/or your local county extension office.  We will help confirm the symptoms and ensure that your sample is sent to the proper testing facility.  It is also possible to send suspect samples directly to the plant disease clinic, however it is critical to notify Dr. Dufault or your local extension agent about this sample as well.

In addition to testing a sample, it is important to have your seed health certificate handy as well as field history information.  The certificate will provide information about the source of your potato seed lot which is important to identifying problematic seed sources.  Your field history is critical for further understanding the epidemiology of this disease and how to better management it in the future.

More information about seed production and Dickeya Blackleg can be found at:


Maine Department of Ag.

Maine Potato Board

Cornell University

University of Delaware



De Boer, S. H. 2004. Blackleg of potato. The Plant Health Instructor. DOI:10.1094/PHI-I-2004-0712-01. http://www.apsnet.org/edcenter/intropp/lessons/prokaryotes/Pages/Blacklegpotato.aspx

Powelson, M. L. and Franc, G.D. 2001. Blackleg, Aerial Stem Rot, and Tuber Soft Rot. Compendium of Potato Diseases, 2nd edition. APS Press.




High Tunnel Hybrid Tomato Variety Study using Organic Production Methods

West Florida Research and Education Center – Jay, FL


Blake Thaxton – UF/IFAS Extension Santa Rosa County

Six varieties of hybrid tomatoes were grown with five replications in a high tunnel system on plasticulture with fertigation.  Our goal was to produce these tomatoes using organic methods; all products used were OMRI (Organic Material Review Institute) approved.  Organic pre-plant fertilizer was applied in an amount estimated to provide 80% of crop needs (160 lb/A nitrogen). In addition 16-0-0 organic water soluble fertilizer was applied as needed through an injection system. Petiole sap testing was performed at various times throughout the trial to determine if nitrogen and potassium levels were in line with University of Florida IFAS recommendations for field tomatoes and fertilizer applications were adjusted as needed.

The tomato plants were staked using the Florida stake and weave method.  Transplants were planted March 9, 2015. First harvest began on May 12, 2015. Fruit was harvested at or after the pink stage twice a week. Fruit was weighed and graded as #1’s, #2’s, and culls with direct to consumer local fresh market sales in mind.

Lepidoptera damage was found just prior to first harvest.   Bacillus thuringiensis was sprayed on a weekly schedule to prevent crop losses.  OMRI listed fungicides were applied as needed, particularly during periods of increased rainfall. Mite damage was discovered and treated with horticultural oil and later with oil plus Azidirachtin. Nine plants were culled because of tomato spotted wilt virus (TSWV). Early Girl, BHN 589, and Mountain Fresh Plus were the varieties to lose plants due to TSWV. 

First harvest began nine weeks after transplant. Tomatoes were harvested twice a week at approximately a three day interval. At the end of production 5437 tomatoes had been harvested. The results were 2320 lb total, 1653 lb of #1’s, 445 lbs. of #2’s, and 227 lb of culls. Final harvest was June 26, 2015.

The first month’s data was analyzed to determine if any of the cultivars exhibited an earliness characteristic that could be used to help small growers get product to market quicker. The data for harvest for the first month showed ‘Red Morning’ to be significantly greater yielding than all cultivars except ‘BHN 589’, which was not significantly greater than ‘Dixie Red’ and ‘Bella Rosa’. ‘Early Girl’, a commonly planted early tomato and considered a standard, yielded significantly less than ‘Red Morning’ and ‘BHN 589’ but was not different from the other cultivars. There were no differences in number of tomatoes that graded #1 among the culitvars evaluated.

The total harvest data analyzed for the entirety of the trial showed different results. Production of all cultivars was significantly greater than ‘Early Girl’, except for ‘Dixie Red’. In addition, ‘Dixie Red’ was not significantly different from any of the other cultivars. ‘BHN 589’ and ‘Mountain Fresh Plus’ had numerically greater yields of #1 grade tomatoes but were only significantly greater than ‘Early Girl’. See the Table 2 for the full harvest results.

The 87lb. per plot (60,154 lb/A) average harvest for the 7 plant per plots of ‘Red Morning’ compares favorably to conventional field yields (64,452 lb/A) in north Florida for the same year and cultivar. One of the top performing cultivars, ‘Red Morning’, could have a potential yield of 2,982 lb in the same size tunnel as used in this trial (66'x 33', 240 plants, or 360 linear bed feet). Many direct sales small farmers can command a premium of up to $4/lb if tomatoes are available for sale before or after peak tomato season. There is great potential for high tunnel tomato production in northwest Florida. These cultivars show great promise but should be used on a trial basis until several years of data can show a consistent performance in the system. Other cultivars need to be trialed in the system as well.

Table 2. High tunnel cultivar trial in an organic system—Jay, FL 2015.


First Month of Harvest

Total Harvest

Total Weight

No. 1 fruity

 No. 2 fruit


Total Weight

No. 1 fruit

No. 2 fruit


‘Dixie Red’

19.061 bcz

13.986 a

3.837 c

1.216 b

72.672 ab

56.615 ab

12.228 cd

3.798 c

‘Red Morning’

29.049 a

15.667 a

7.425 a

5.988 a

87.077 a

54.102 ab

19.351 a

13.689 a

‘BHN 589’

24.251 ab

13.683 a

6.964 ab

3.895 ab

83.949 a

62.515 a

14.768 bc

6.856 bc

‘Early Girl

17.245 c

10.884 a

3.195 c

3.3 ab

59.764 b

44.219 b

9.846 d

5.816 bc

‘Mountain Fresh Plus

14.654 c

10.023 a

3.356 c

1.287 b

80.841 a

61.368 a

15.753 abc

4.313 c

‘Bella Rosa’

19.626 bc

9.626 a

4.342 bc

5.6 a

79.695 a

51.793 ab

16.99 ab

10.911 ab

z Means followed by the same letter(s) in a column are not significantly different, according to Fisher’s Protected LSD (P=0.05), except for height means separated at alpha =0.10.[MJN1]

y Grades were determined by the following with local direct sales in mind:

1s were XL to Medium and <10% of the fruit surface had blemishes.

2s were XL to Medium and <30% of the fruit surface had blemishes. Culls were >30% of the fruit surface had blemishes or were too small.