Horticultural Sciences Department

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Issue No. 613

The Vegetarian Newsletter 

A Horticultural Sciences Department Extension Publication on 
Vegetable and Fruit Crops 

Eat your Veggies and Fruits!!!!!

Publish Date: 
June 2016

June Vegetarian Newsletter:

Upcoming Events for the Florida Tomato Industry:

Two long-term IFAS extension programs will again be held in conjunction with the 41st Annual Joint Tomato Conference, cosponsored by the Florida Tomato Exchange.



Tuesday, September 6, 2016

Ritz-Carlton, Naples

280 Vanderbilt Road, Naples

1:30 – 5:15 p.m.

“Preparing for FSMA”

Two new Food Safety Rules under the Food Safety Modernization Act, the Produce Safety Rule and the Food Safety Preventive Controls Rule, affect tomato growers, harvesters, packers, and shippers. They were released in 2015 and start to be implemented later this year. Please join us for a Food Safety Update to review these two rules, and how to prepare for their implementation.

COORDINATORS: Steven Sargent, Keith Schneider

Topics will include:

1. 2015-16 Tomato Regulatory Program Update

2. T-GAP and FSMA Produce Safety Rule Review

3. On-Farm Readiness Review/Advisory Program

4.  Implementation Processes for FSMA in the U.S. and in Florida

5. Technical Assistance Programs

6. Food Safety Research Update

Complete registration and program information will be available at the Florida Tomato Committee website: http://www.floridatomatoes.org/




This is a CEU-qualifying program.

9:00 Welcome – Monica Ozores-Hampton, UF/IFAS, SWFREC, Immokalee.

9:00 Opening remarks – Saqib Mukhtar - Associate Dean & Ag. Program Leader, UF/IFAS, Gainesville.

MODERATOR: Crystal Snodgrass, Manatee County Extension, Palmetto

9:10 State of the industry – Reggie Brown, Florida Tomato Committee, Maitland.

9:20 Tospo-resistant variety outlook for South Florida – Samuel Hutton, UF/IFAS, GCREC, Wimauma.

9:40 Wet stem scars and postharvest decay in tomatoes – Jerry Bartz, UF/ IFAS, Plant Pathology Department, Gainesville.

10:00 A research update on tomato grafting: optimizing grafted tomato production systems for enhanced economic sustainability – Xin Zhao, UF, Horticultural Science Department, Gainesville.

10:20 Efficacy of Nimitz (Fluensulfone) using drip irrigation in tomato production – Monica Ozores-Hampton, UF/IFAS, SW FREC, Immokalee.

10:40 Minimizing crop impacts using vertical management zones for nematode control - Joe Noling, UF/IFAS, CREC, Lake Alfred.

11:00 New sensor technology for yield estimation and disease detection - Reza Ehsani - Agricultural and Biological Engineering, UF/IFAS, CCREC, Lake Alfred.

11:20 Lunch (on your own)

MODERATOR: Monica Ozores-Hampton, UF/IFAS, SWFREC, Immokalee

1:00 Keeping your private applicator license current – Crystal Snodgrass, Manatee County Extension, Palmetto.

1:20 Tomato production, trade, and the impact of the suspension agreement – Zhengfei Guan, UF/IFAS, GCREC, Wimauma.

1:40 Social accountability among agricultural employers – Fritz Roka, UF/ IFAS, SWFREC, Immokalee.

2:00 Research efforts to improve target spot management on tomato - Gary Vallad, UF/IFAS, GCREC, Wimauma.

2:20 Reducing reliance on neonicotinoid insecticides in Florida tomato production - Hugh Smith and Phil Stansly, UF/IFAS, GCREC, Wimauma and SWFREC, Immokalee.

2:40 Herbicide resistance management in tomato – Nathan Boyd, UF/IFAS, GCREC, Wimauma.

3:00 Industry Updates – Gene McAvoy, Hendry County Extension Service, LaBelle.

3:45 Adjourn

The Ritz-Carlton Hotel, Naples, Florida • September 6-11, 2016


Qingren Wang, UF/IFAS Miami-Dade County Extension

Christian F. Miller, UF/IFAS Palm Beach County Extension

The growing season for most winter commercial vegetables concludes by the end of April or May in South Florida, just ahead of the hot and rainy summer months. Wisely managing the land after spring crop residues cleaned up or cultivated into the soil has become a serious consideration for vegetable growers. Having fallow land during the summer wet season, when as much as 40-50 inches of rain can fall, results in substantial losses of water and nutrients. Leaching of these vital resources is especially troublesome in sandy and gravelly soils such as those farmed in parts of Palm Beach and Miami-Dade Counties, respectively. Further complicating matters on bare land are the weeds that grow wildly if left unmanaged and form viable seed perpetuating the problem. Consequently, growers typically disk the land at least 2-3 times through the long summer to kill weeds at a cost of nearly $100 per acre for labor and fuel.

An alternative approach to better conserve soil and water, and suppress field weeds is to grow summer cover crops. Such cover crops as sunn hemp, sorghum sudangrass, and pearl millet grow quickly and densely cover the land before most weed species can get established. These cover crops possess the added benefit of scavenging leftover soil nutrients applied to crops in previous seasons. By doing so, they accumulate the residual soil nutrients in their plant tissues along with large amounts of biomass.  Consequently, cover crops not only deter leaching but also improve soil fertility when used as a green manure and suppress weeds through shading effects. Another added benefit of using cover crops is that some, such as sunn hemp, can suppress soil pests like root-knot nematodes.

Currently, cover crop seed costs are reasonably affordable. For instance, sunn hemp seed can be found for $1.54 per pound, sorghum sudangrass costs $0.69 per pound, and Japanese millet is about $0.75 per pound. With seeding rates at 25-30 lb per acre for sunn hemp and sorghum sudangrass, it costs $40 - $45 per acre of sunn hemp and $17-$20 per acre of sorghum sudangrass. Japanese millet on the other hand is less expensive to plant at $11 per acre because of the lower seeding rate at 15 lb per acre. The seed cost is obviously much lower than that of the labor and fuel required to repeatedly disk a weedy fallow field.

A tye-drill planter with adjustable seeding rates is typically utilized to sow the cover crop seed (Figure 1) to a depth of 1/4 -1/2 inch. The seed can germinate in 3-5 days (Figure 2) under adequate soil moisture. Typically, these cover crops are seeded from the middle of May to mid-June and within a month, the previously bare land can be covered completely.  After 2 months, sunn hemp and sorghum sudangrass plants can reach a height of 5-6 ft (Figure 3). Each may be ratooned and allowed to regrow or flail-mowed and incorporated into the soil.

Sunn hemp can grow year round in south Florida but seeding too early (e.g., March or April) or too late (August or September) limits biomass production due to the short-day length nature of the crop (Figure 4). Pearl millet cannot be ratooned (Figure 5), and must be mowed and incorporated into the soil prior to setting seed, otherwise volunteers will be seen during the vegetable growing season.  


Fig. 1. A tye-drill planter is using for cover crop planting. Credit: Qingren Wang


Fig. 2. Sunn hemp in the first week after seeding. Credit: Qingren Wang


Fig. 3. Field view of sorghum sudangrass. Credit: Qingren Wang


Fig. 4. Sunn hemp blooming through the winter. Credit: Qingren Wang


Fig. 5. Field view of pearl millet. Credit: Qingren Wang

Challenging 2016 Florida Blueberry Harvest Season

G.K. England and J.G. Williamson

Over the past 20 years or so, the Florida blueberry industry has experienced rapid expansion to approximately 7-8 thousand acres of production and an average annual value of approximately $70 M in sales of fresh market product.  Although Florida has fewer acres of commercial blueberries in production than many states, its unique marketing window as the first significant north American source for fresh market blueberries in the northern hemisphere ranks it among the top producing states in value of the crop.

Development of many “low chill” southern highbush (SH) blueberry cultivars adapted to Florida growing conditions by the UF/IFAS Blueberry Breeding Program has been a key factor in the expansion of the Florida industry.  Like other deciduous fruit crops, blueberries have a chill requirement that must be met to attain optimum bloom and fruit set.  Chill requirement is defined by hours between 32°F and 45°F during the dormant period (November to early January).  Chill requirement for northern highbush cultivars produced in more northerly blueberry production regions can be two to three times greater than the 100 to 300 hour requirement of most SH cultivars released by the UF program.

The 2016 Florida blueberry harvest season ended up being very challenging for most producers.  Harvests were very low during the typical late March/early April traditional “Florida blueberry harvest window”.  Once significant volumes of Florida fruit ripened for harvest, ample volumes of product from other southeastern states, California and Mexico had entered the marketplace and lowered demand for Florida blueberries.  Most of the problems faced by Florida growers this season were weather related.

As mentioned above, blueberry cultivars grown in Florida are considered “low chill” but not “no chill”.  As depicted in the chart below, little to no chill accumulation had occurred in most Florida blueberry production regions by the end of December 2015.


It should be noted that south Georgia blueberry production regions received some chill accumulation, although much less than normal by the end of December 2015.  It appears that this chill accumulation may have been enough to initiate bloom and crop set on many Georgia blueberry farms.

A plant growth regulator called hydrogen cyanimide (HC: Trade names Dormex and Bud-Pro) is applied during the dormant period by many commercial southern highbush blueberry growers.  Application of the product tends to enhance early development of foliar buds and resulting in earlier leaf canopy establishment; a challenge for many southern highbush cultivars grown in Florida.  Enhanced early leaf development supports fruit development and often results in an earlier and more uniform harvest.  In most southern highbush blueberry cultivars, some chill accumulation is required to make this product effective and also to avoid burning developing flower buds.  This season, numerous growers reported application of HC with little to no chill accumulation resulted in severe early flower bud damage in more susceptible SH blueberry cultivars such as Jewel; an additional fact negatively impacting early harvest volumes.

Once flowering, pollination, and fruit set have commenced, temperature can have a dramatic effect on the rate of fruit development.  Growing degree days (GDD) are calculated using daily high and low temperature related to a base temperature for a given crop.  GDD calculations are used in a wide variety of crops to model expected crop development rates for given temperature regimes.  Additionally, GDD are utilized for prediction of emergence for certain insect pest species.

Although there are no documented GDD correlations to rate of development in southern highbush blueberries, there appears to be a relationship.  A blueberry industry group in Georgia has been working with GDD in their crop forecasting for a few years and the concept may be evaluated in Florida starting next season.  For discussion, we have placed a chart utilizing AgroClimate GDD data generated from temperature readings at the Dover Florida Automated Weather Network (FAWN) station, which is situated in close proximity to a significant portion of the central Florida blueberry production region.  A base temperature of 50°F is used for the GDD calculations, as it is the value utilized by the Georgia group.


As depicted in the chart, GDD accumulation for both 2015 and 2016 were mainly below historical averages until sometime in early March; a period approximately one month after initiation of the bloom period this year.  In the winter of 2014-15 the climate phase was on the borderline of neutral and weak El Niño.  Somewhat warmer conditions in January 2015 initiated bloom and fruit set somewhat earlier than that experienced in 2016.  This combined with much warmer than normal temperatures for mid and late March, 2015 resulted in a harvest that peaked approximately the same time as most years in Florida. The Chart below depicts movement of 12 pint flats in lots of 10,000 lbs. for two week reporting segments as reported by the United States Department of Agriculture (USDA)/Agricultural Marketing Service (AMS).


As demonstrated on the chart, the 2016 harvest “mirrors” that of 2014 very closely.  When one considers that the acres of blueberries harvested in 2014 were significantly less than 2016, the fact that the total 2014 harvest exceeds that of 2016 reflects the seriousness of the situation faced by most Florida producers this season. 

The fact that in 2014, late harvest volume was higher than any other season, indicates that early harvest volume in states to the north was low, permitting Florida growers to extend their harvest.  In most years, many farms have harvestable product in mid to late May but volume being harvested in other states depletes the harvesting work force and tends to bring market prices down to a level where it becomes unprofitable to continue the harvest.