Horticultural Sciences Department

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Issue No. 605

The Vegetarian Newsletter 

A Horticultural Sciences Department Extension Publication on 
Vegetable and Fruit Crops 

Eat your Veggies and Fruits!!!!!

Publish Date: 
September 2015

Overview of Protected Agriculture Research and Training Provided by the Gulf Coast Small Farm Team

Blake Thaxton, UF/IFAS Extension Santa Rosa County

J. Bryan Unruh, UF/IFAS WFREC Associate Director

The Gulf Coast Small Farms (GCSF) initiative is a partnership between the University of Florida - West Florida Research and Education Center (WFREC) and UF/IFAS County Extension faculty from the seven westernmost counties in the state of Florida (Escambia, Santa Rosa, Okaloosa, Walton, Holmes, Washington, and Bay). The purpose of GCSF is to provide hands-on training programs for those working on farms and small agribusinesses on current and relevant topics utilizing resources and strengths at the WFREC and County Extension. The team of agents and researchers provide training through field days, workshops, field consultations, and other educational programs that give current and new producers the knowledge and skills to manage a successful agribusiness. Family Consumer Science Extension Agents working with the team have formed the Panhandle Produce Pointers (PPP) division of the initiative that provides education to consumers on nutrition, preservation, and preparation of the local produce to support increased purchasing.

The team has been researching high tunnel production of fresh market vegetables for small growers targeting local markets in northwest Florida. Trials include variety trials of heirloom tomatoes, hybrid tomatoes produced in organic systems, and Beit Alpha cucumbers. Future trials will include variety testing of strawberries, insect exclusion for tomato production, and others. The information and experience gathered from the high tunnel trials has been valuable to local producers using or considering the use of the protected agriculture system. Most published information regarding high tunnel systems originates from outside the southeastern United States. The information from the other geographical areas gives producers general ideas on how the system should perform in the panhandle of Florida but does provide specific information on its performance locally. The reports for the Beit Alpha cucumbers cultivar trial and the hybrid tomato cultivar trial in the organic system will be released later this year.

The research and demonstrations gives the GCSF team a great opportunity for hands-on experiences for area producers. A series of workshops called the Fall Tomato School was held at the WFREC in fall 2014. This Extension program featured 4 sessions spread throughout the growing season to give the beginning small farmers a look at the entire crop production cycle from start to finish. The sessions included lectures from UF/IFAS Extension Agent Bob Hochmuth on cultivar selection, Dr. Mathews Paret on disease identification and management, Dr. Steve Sargent on harvest and postharvest storage and handling, and Dr. Ayanava Majumdar from Auburn University on Integrated Pest Management (IPM). The Agents led the hands-on portions of the sessions which included sprayer calibration by Jennifer Bearden (Okaloosa County Extension Agent) and the WFREC staff demonstrating trellising and the stake and weave system.

The school had great results with a minimum of 75% of participants gaining knowledge on topics of drip irrigation, tomato cultivar selection, sprayer calibration, tomato diseases, staking and trellising, harvesting, and other topics as well. Agents have observed participants practice changes that were learned at the workshop.

The second GCSF team program to be highlighted is the 2015 Spring Field Day at the WFREC. This field day featured the organic tomato high tunnel trial, the Beit Alpha cucumber trial, a seedless watermelon trial, petiole sap testing, use of a TDR moisture meter, and discussion led by Dr. Mathews Paret on vegetable disease identification. There were 39 attendees at the field day and surveys suggest that the producers gained new knowledge from attending the event.

The hand-on trainings and research described is the type of work the GCSF team aims to provide for beginning and small farmers in Northwest Florida. Another goal on the horizon for the team will be to provide workshops targeted at veterans looking to enter the agricultural industry. The Florida panhandle and southern Alabama have 304,327 total veterans due to the high number of military installations in the area such as Naval Air Station Pensacola, Naval Air Station Whiting Field, Eglin Air Force Base, Hurlburt Field, and others. 2016 should bring opportunity to meet the needs of veterans interested in small farm production through GCSF activities.   

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Figure 1. Bob Hochmuth teaching about drip irrigation system at the Fall Tomato School (2014). Credit: Blake Thaxton

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Figure 2. Participants getting up close and personal with the organic tomato trial at the Spring Field Day held at the WFREC (2015). Photo Credit: Matt Smith


Article 15 - Comparison of Fungicide Products and Their Application Strategies for Management of Fusarium Wilt in Watermelon

Authors: Tatiana Sanchez, Mathews Paret, Nicholas Dufault

Fusarium wilt is a soil-borne disease of watermelon that has increased in incidence over the last five years for Florida producers. The Fusarium wilt pathogen, Fusarium oxysporum f. sp. niveum, can survive on seeds, transplants and soil (Egel and Martyn, 2007; Martyn and Vakalounakis, 2012). Typical symptoms include wilting of the whole plant or just one of the lateral runners (Figure 1., A and B), reduced growth, discoloration of the vascular system and lateral sections of the stem (Figure 1.C), and appearance of nutritional deficiencies. In a commercial setting, several plants can become infected, resulting in poor ground cover and gaps in the field (Figure 1.D).

Figure 1. A. Wilted watermelon plant five weeks after transplanting. B. Wilted watermelon runner. C. Dark streak along the stem following infection by Fusarium.  C. Scarce ground cover in an infected field. Locations: A-C Marion county, Florida. D. Levy county, Florida.

 Management of Fusarium wilt requires an integrated approach to effectively control the disease. In the past, producers have relied on long, non-host crop rotations of 7 to 10 years and host resistance to manage this disease. However, varietal resistance is only available for two of the four races of this pathogen, so even long rotations are not an entirely reliable management strategy. Thus, alternative management techniques are required to adequately manage this devastating disease in the future.

 Researchers at the University of Florida are currently evaluating techniques to improve the integrated management of Fusarium wilt. These include fumigation methods, grafting techniques and fungicide applications. In addition, UF researchers are collaborating with the University of Georgia and Clemson University to examine the population structures of this pathogen in the southeast. The information gained from these research studies will help producers understand the biology of this important pest and how management methods can be combined to create optimal disease management strategies.

Promising results were observed from fungicide product efficacy trials conducted during the spring of 2015. Experimental plots were established at the Plant Science Research and Education Unit (PSREU) in Citra, Florida and the North Florida Research and Education Center (NFREC) in Quincy, Florida to explore the management of this disease in two different areas, central and north Florida. The selected products (Figure 3) were applied using two different methods: drench and drip. Experimental plots were inoculated with the Fusarium wilt pathogen at transplanting to ensure uniform distribution of the disease within the treatments. Disease progressed more rapidly at the NFREC than the PSREU (Figure 2), highlighting the importance of environment on disease development. In general, environmental conditions were slightly warmer and wetter at NFREC compared to PSREU (Table 1).  

 Figure 2. Cumulative Area Under Disease Progress Curve (AUDPC) of drip and drench trials conducted at Citra and Quincy, FL. AUDPC was calculated from five severity ratings taken weekly during 2015 spring trials. AUDPC summarizes disease intensity over time; lower area values indicate that less disease occurred throughout the trial.

Table 1. Comparison of environmental factors during spring trials conducted at two research stations located at Citra and Quincy, FL.

Factor

Citra

Quincy

Soil temperaturez

80°F

83°F

Soil pH

5.6

6.1

Rainfally

3.38 in

6.01 in

zAverage calculated from Apr 2 to May 13, 2015. Sensors located approximately 2 inches deep in center of the bed.

yTotal rainfall from Apr 2 to May 13, 2015.

Over the past 8 years, multiple researchers from universities in Georgia, Maryland and Indiana have examined the efficacy of various fungicidal products on Fusarium wilt control. Multiple products, such as Topsin®4.5 FL, Actigard® 50 WG and Proline®480 SC, have provided some disease control, but results have varied across the experimental trials (Everts et al., 2014; Sanders and Langston, 2009; Sanders and Langston, 2011; Zhou and Everts, 2009). The results from the 2015 trials at PSREU and NFREC found similar trends to data collected from other states’ efficacy trials. The products Proline® 480 SC (active ingredient prothioconazole), Actigard® 50 WG (a.i. Acibenzolar-S-methyl) and Velum® Total (a.i. Fluopyram and imidacloprid) generally reduced disease severity when compared to the untreated check (Figure 3). However, significantly higher yields were only observed in the drench application treatments for the products Proline® 480 SC and Actigard® 50 WG (Figure 4). This data indicates that there are available products with potential to provide disease control, especially if they are part of an integrated management program.

                Data from this work not only provides insights about product efficacy, but also about how these products should be applied for Fusarium wilt control. Data analysis revealed that statistical reductions in disease severity and yield were only observed when the products were drench applied (Figures 3 and 4). This result indicates the importance of deliverying these products to key host tissues (i.e. roots) when looking for optimal disease control. It is possible that drip applications are not delivering enough product to the roots especially if products are applied early in the season before plant roots expand. Thus, insufficient delivery of the products would minimize the effects of these compounds. It should be noted that even though drench products provided the best control for Fusarium wilt in this trial, the application of these fungicidal compounds must follow labeled guidelines. Further research at the University of Florida will examine product applicaton methods and timings. Improvements to product application methods should increase the effectiveness of fungicidial compounds and create more consistent results.

                Figure 3. Area Under Disease Progress Curve (AUDPC) of drench and drip trials conducted at Citra and Quincy, FL. Fungicides treatments consisted of Actigard 50 WG (0.6 oz./A), Topsin® 4.5 FL (10 fl oz/A), Proline® 480 SC (5.7 fl oz/A), Quadris® Flowable (15.5 fl oz/A), Velum® Total (18 fl oz/A) and an untreated check (water only). Treatments with the same letter do not significantly differ according to a protected Fisher’s least significant difference test [P=.05, LSD = 780.9 (Drip-Quincy), 295.37 (Drip-Citra), 381.89 (Drench-Citra)].

Figure 4. Total yield in kg/ha for drench and drip trials conducted at Citra and Quincy, FL. Fungicides treatments consisted of Actigard 50 WG (0.6 oz./A), Topsin® 4.5 FL (10 fl oz/A), Proline® 480 SC (5.7 fl oz/A), Quadris® Flowable (15.5 fl oz/A), Velum® Total (18 fl oz/A) and an untreated check (water only). Treatments with the same letter do not significantly differ according to a protected Fisher’s least significant difference test [P=.05, LSD = 39833.2 (Drip-Quincy), 40565.9 (Drip-Citra), 54359.9 (Drench-Citra)].

The variability within these results have led to more questions than answers about how to control Fusarium wilt with chemicals. However, it is clear from this study that integrated management approaches consisting of both cultural and chemical practices will more likely be successful than programs relying on only one practice. Further research is still needed to optimize disease management programs with these tools as well as other novel disease control practices. Continued research is being conducted at the University of Florida which examines these and many other facets of Fusarium wilt and its control.

References:

Egel D.S. and Martyn R.D. 2007. Fusarium wilt of watermelon and other cucurbits. Plant Health Instructor. DOI: 10.1094/PHI-I-2007-0122-01. Available online at http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Pages/FusariumWatermelon.aspx

K.L. Everts, D.S. Egel, D. Langston, X.G. Zhou. Chemical control of Fusarium wilt of watermelon. Crop Prot. 66: 114-119.

Martyn R.D. and D.J. Vakalounakis. 2012. Fusarium wilts of greenhouse cucurbits: melon, watermelon, and cucumber.  In: M.L. Gullino, J. Katan, and A. Garibaldi (eds). Fusarium Wilts of Greenhouse Vegetable and Ornamental Crops. APS PRESS, St. Paul, MN

Sanders F.H. and Langston D.B. 2011. Evaluation selected fungicides for the control of Fusarium wilt of watermelon and watermelon fruit blotch in Georgia, 2010. Plant Disease Management Reports, Volume 5, Report No. V156

Sanders F.H. and Langston D.B. Jr. 2009. Evaluation fungicide drench treatments for the control of Fusarium wilt of watermelon in Georgia, 2008. Plant Disease Management Reports, Volume 3, Report No. V155

Zhou X.G. and Everts K.L. 2009. Field evaluation of fungicides for control of Fusarium wilt of watermelon, 2008. Plant Disease Management Reports, Volume 3, Report No. V093