Critical Carrot Diseases for North Florida and a Disease Management Plan for 2019

Critical Carrot Diseases for North Florida and a Disease Management Plan for 2019

Susannah Da Silva, Fanny Iriarte, Bob Hochmuth and Mathews Paret, UF/IFAS North Florida Research and Education Center

Carrots are produced in Florida on an estimated area of 4,000 acres; most of which are in North Florida. The planting time for carrots in North Florida is August – December, with crops taking anywhere from 120-150 days to reach maturity. With weather conditions varying so much during the crop cycle, it makes carrots a prime target for several fungal pathogens. Surveys conducted by a UF/IFAS research team at the North Florida Research and Education Center (NFREC), Quincy and Live Oak, from 2015-2018 detected three main diseases that might be encountered during this growing season. A summary of these diseases, and periods of the year when they could be a problem are shown below.

Cottony Rot

Cottony Rot (called white mold on other vegetables), caused by the fungus Sclerotinia sclerotiorum, is active from December through April in North Florida.  It appears later in the season and can even affect plants after harvest. Symptoms can include brown lesions on lower foliage, or on the tops of carrots. A cottony white mold will form on the plant near the soil line and will eventually produce black sclerotia (Fig. 1). For disease management, see the 2018-2019 Vegetable Production Handbook of Florida, and Integrated Management of White Mold on Vegetables in Florida.

Cottony rot

Fig. 1. Cottony rot on carrot (left) and black sclerotia (right) collected from the soil line.

Alternaria Blight

Alternaria blight is caused by at least two species of Alternaria. The disease is most active from January to June in North Florida, and occurs most often under wet conditions, with temperatures ranging from 60-77°F. Symptoms initially appear as water-soaked spots and leaf marginal necrosis, but as the disease progresses, lesions become dark brown to black, and sometimes present chlorotic halos with yellowing of the surrounding leaf area. Lesions expand to turn entire leaf dark brown or black (Fig. 2). Symptoms may also appear on stems of the carrot tops. This disease can cause the foliage to drop off, making harvesting difficult, as at least 50% of the foliage is required for the common harvester, which pulls the carrot tops mechanically. Alternaria spp. is spread by spores, which can be moved by the wind, water splashing, or other mechanical means.

carrot leaf blight

Fig. 2. Leaf blighting on carrot caused by Alternaria spp.

Over the the fall 2017  through spring 2018 growing season, an experiment was conducted to test the efficacy of a fungicide rotation program that used protectant and systemic fungicides. Disease severity evaluations taken for several weeks were used to determine the efficacy of the fungicide rotation program in comparison to a water only control. The fungicide rotation program (Table 1) kept the disease well below the maximum threshold (50% of the disease severity/blighting), and allowed for efficient use of a mechanical harvester, as indicated by the final disease severity data (Fig. 2). The disease severity of the water control was above the maximum threshold of disease severity.

Disease Severity chart

Fig. 2. Percentage disease severity of Alternaria blight indicating efficacy of a fungicide rotation program in comparison to the water control.

Southern Blight

Southern Blight (Sclerotium rolfsii) is active from April to June in North Florida.  This disease can damage foliage, but mostly affects carrot roots. Ideal conditions for this pathogen are moderately cool to warm temperatures, following wet conditions. Symptoms appear as a white fan like fungal growth at the crown of the plant, which eventually form sclerotia (small, white  to mustard colored) (Fig. 3). Sclerotia can spread the pathogen and survive for many years in the soil. The pathogen can spread from plant to plant through the soil, and can spread between fields on farm equipment. For disease management, see the Vegetable Production Handbook of Florida.

Fungal Sclerotia

Fig. 3. Sclerotia of Sclerotium rolfsii are mustard like fungal structures usually found at the base of infected plants.

Northwest Florida Beef Conference & Trade Show – February 13

Northwest Florida Beef Conference & Trade Show – February 13

Mark your new 2019 calendar!  Cattle ranchers from the Tri-state Region (FL, AL, GA) are invited to attend the 34th annual Northwest Florida Beef Conference and Trade Show, to be held on Wednesday, February 13, 2019 in Marianna, Florida.  The Conference will be held at the Jackson County Extension Office, located at 2741 Penn Avenue, Marianna, Florida. There will be a $5 per person registration fee, payable at the door.  Registration and the Trade Show open at 7:30 AM central time, the program starts at 8:15 AM, and concludes with a steak lunch.

2019 Focus:  Rebuilding for a Better Future

 Beef Confernce Crowd

The 2019 program will focus on Rebuilding for a Better Future with speakers providing ideas on improving income and restoring or improving productivity. Credit: Doug Mayo, UF/IFAS

The Tri-state area was hammered by Hurricane Michael, so cattle producers in the region were really challenged in 2018.  Because of this, the 2019 Beef Conference educational program will focus on Rebuilding for a Better Future, with speakers providing ideas on improving income and restoring or even improving productivity.   Jared Decker, Beef Genetics Extension Specialist, University of Missouri will be the keynote speaker. He will discuss genomic-enhanced EPDs and EPD Indexes to help producers make effective choices to improve the genetics of their herd.  Other topics will focus on improving overall income sources, such supplemental income sources, adding value to cattle and hay sold, and rebuilding operations better than before the storm.  More details of the specific topics and speakers will be provided, once the complete program is set.

Trade Show

18 Beef Conference Trade Show

The Beef Conference will also feature a Trade Show of businesses and agencies that offer goods and services to cattle producers. Credit Doug Mayo, UF/IFAS

In addition to the educational program, the Beef Conference will also feature a Trade Show of businesses and agencies that offer goods and services to cattle producers. There will be time allotted on the schedule to visit with the company representatives to learn about specific products and services they offer for cattle producers in this region. The program will have designated times for ranchers to visit with the Trade Show Exhibitors:  45 minutes during registration, 45 minutes in the middle of the program, and 1 hour immediately after lunch is served.

If you are interested in participating in the as an exhibitor/sponsor, utilize the Trade Show Eventbrite Registration website .  You will be entering the required information online and paying in one simple step.  No other action required. Registration deadline is Friday, February 8.

Trade Show booth at the Northwest Florida Beef Conference.

The Northwest Florida Beef Conference and Trade Show is an educational program provided by the UF/IFAS Panhandle Agriculture Extension Team. For more information on the Beef Conference, or participating in the Trade Show as an exhibitor, contact Doug Mayo, at 850-482-9620.

EPA Registrations for Dicamba and Chlorpyrifos Use in Row Crops

EPA Registrations for Dicamba and Chlorpyrifos Use in Row Crops

Traditional cotton with dicamba drift injury on one row vs healthy. Photo - Jay Ferrell

Traditional cotton with dicamba drift injury on one row vs healthy. Photo – Jay Ferrell

The past two months have been life altering for many farmers in the southeast, especially the Florida Panhandle. Hurricane Michael made landfall in the Panhandle on October 10th and left a path of destruction spanning several counties as it continued into Southwest Georgia. With the aftermath of Michael, farmers from Walton to Gadsden counties were left without power and severe damage to crops and equipment.

On October 31st, the Environmental Protection Agency (EPA) announced that it was extending the registration of Dicamba for over-the-top (OTT) use for weed control in transgenic cotton and soybean. Dicamba products approved for use on dicamba-tolerant crops include Engenia (BASF), XtendiMax (Monsanto), and FeXapan (Corteva). This announcement came during a period when much of Jackson and Calhoun Counties, a large cotton producing area, wwere without power. The purpose of this article is to help promote the announcement and raise awareness regarding label changes for products approved for use in Dicamba-tolerant cotton and soybean. Another product to follow is chlorpyrifos, better known as Lorsban, which, depending on outcomes of legal/regulatory proceedings, will likely still be available for use during the 2019 season.


Along with the EPA announcement of the two-year extension in registration of dicamba products used in row crops (now through 2020), new restrictions were revealed that will be integrated into product labels. It is imperative that growers read these labels and understand what these changes mean regarding product use. Dicamba is currently registered for OTT use in cotton and soybean in 34 states, including Florida, Georgia, and Alabama.

In 2019, only restricted use pesticide applicators will be allowed to make applications. The purchase and application of dicamba products used on herbicide tolerant crops will not be permitted by those without a pesticide license and the appropriate category, even under the supervision of a licensed applicator. This means that authorized purchasers on an applicators license will no longer be able to purchase the products, only the certified applicatorthemselves. Everyone must now have their own license if they wish to buy or apply these products registered for use on Dicamba-tolerant crops. Depending on their situation, Florida growers will be required to have a Private Applicator or commercial license with the Row Crop category. Obtaining a license means individuals must pass the two necessary pesticide exams with at least a 70 percent, the Core exam and the category exam (Private or Row crop). Exams can be administered at your local Extension Office, but please call ahead to make an appointment. They can also help you decide which license designation (private or commercial) bests applies to your situation. On top of having a restricted use pesticide license, applicators will also be required to attend a 2019 dicamba training, which will be similar to what was provided in March 2018. All individuals who will want to purchase or apply these products (or want the future option) during the 2019 season will need to attend the new dicamba training, regardless of if they attended the one in 2018. A training date has not yet been selected for Florida, but it will likely be a similar timeframe to the 2018 training. Early spring probably around March, using a web format, broadcast from one central location to participating Extension Offices. The date will be announced once the Florida Department of Agriculture and Consumer Services (FDACS) has finalized the specifics, stay in contact with your local Extension Office.

The training will address updates to product labels such as the postemergence application window, number of applications, buffer zones, sensitive areas, application hours, record keeping, spray solution pH, and more.

For more information regarding the 2019 dicamba updates, check out the links below:
Registration of Dicamba for Use on Dicamba-Tolerant Crops
EPA Announces Changes To Dicamba Registration
Dicamba: Moving Forward- 7 Label Changes


Since 1965 chlorpyrifos has been used as a pesticide in the agricultural sector. It is commonly used as an insecticide in the production of crops such as corn, peanut, and soybean, among others. It is recognizable to most farmers under the brand name Lorsban. Chlorpyrifos is a cholinesterase inhibitor which can cause problems in people exposed to high enough doses. This means that it can overstimulate the nervous system resulting in symptoms such as nausea, dizziness, and confusion.

Since 2000, the EPA has evaluated and modified the use of chlorpyrifos several times. In 2017, the EPA denied a petition requesting to revoke of all pesticide tolerances (residue level allowed in food) for the chemical and for the cancellation of all chlorpyrifos registrations. On August 9, 2018, the Ninth Circuit Court of Appeals ordered the EPA to ban chlorpyrifos within 60 days. In September the EPA appealed the decision, and the Department of Justice asked the Ninth Circuit to reconsider its opinion. Over 100 days have passed since the ban was requested with the 60-day deadline, and it appears that chlorpyrifos will remain available for use until the legal/regulatory proceedings are finished.

For more information regarding the 2019 use of chlorpyrifos or the EPA’s history regarding this product, check out the links below:
Lorsban should be available for 2019 use, MSU finds


Beasts that Bite and Things that Sting

Beasts that Bite and Things that Sting

Our recent storm was traumatic in a lot of ways, and not only for humans. Many animals found their homes destroyed by the weather, which may unfortunately make cleanup and recovery even more difficult for everybody. While cooler temperatures in the fall and winter seasons will keep a lot of creatures from being too active, it can also send those who lost their shelter looking for new places to hide. If you live in a storm affected area – and most of the Florida panhandle was, in one way or another – watch out for dangerous wildlife.

Paper wasps often build their nests overhead on the eaves of buildings or in trees. Watch out!

Insects that build nests, such as bees, yellowjackets, and wasps, may still be on the wing. When their nests are destroyed or disturbed, individuals who are displaced may be flying around, looking for food or shelter. New nests will undoubtedly be built in areas that may not have had any previously, and any source of food is bound to attract attention. Piles of debris are good places for insects such as these to seek shelter, so wear protective clothing and pay close attention while doing cleanup. A brush pile that stays in the same place for a week or more might gain some unwelcome tenants. Look for paper wasp nests on eaves or in plant material, yellowjacket burrows in the ground or in hollow trees or stumps, and hornets in trees. Remove potential sources of food such as garbage with sugary residues or tree debris with sweet sap. Don’t forget that any pets or livestock you own might be affected by insects as well, so keep a close eye on pastures and areas where pets reside for signs of new infestations of stinging insects. A simple homemade trap may help to keep wasps and yellowjackets under control (you can find more information on making traps:  Do-It-Yourself Insect Pest Traps. If you find a nest and need to use insecticides to get rid of it, remember to read the label before using the product.

Some snakes are harmless, like this hognose rattlesnake. Similar looking snakes such as the pygmy rattlesnake might be dangerous to people and livestock.

Snakes are another potentially dangerous creature that may be displaced, and constant wet weather may have them residing in areas they wouldn’t otherwise consider. Anywhere that might offer some warmth in these cool months is particularly attractive to a cold-blooded creature, and damaged buildings or brush piles fit the bill perfectly. Rattlesnakes, copperheads, and cottonmouths are some of the more dangerous snakes we have around, but remember that not every species of snake is dangerous. For help in identifying snakes, consult our EDIS publications on this topic: Dealing with Snakes in Florida’s Residential Areas—Identifying Commonly Encountered SnakesRecognizing Florida’s Venomous Snakes, and Native Snakes Easily Mistaken for Introduced Constrictors in Florida.  Keep leaf piles, cut branches and trees, and other debris away from homes and areas where domesticated animals and pets live, if possible .

Remember that you can always contact your local Extension office for help in identifying and advice on controlling pests, whether they’re snakes or hornets, spiders or scorpions, or something even more exotic.

Evan Anderson, Walton County Agriculture Agent

Gadsden Tomato Forum – December 6

Gadsden Tomato Forum – December 6

Freshly picked tomatoes

Freshly picked tomatoes. Credit: UF/IFAS Photo by Tyler Jones

The annual Tomato Forum will be held in Gadsden County on Thursday, December 6, 2018.  The event will be hosted by the North Florida Research and Education Center in Quincy, Florida from 8:00 AM to 12:00 PM eastern time.

Topics to be covered will include tomato variety selection, recommended production practices, pest and disease management, and best management practices for water quality protection. Pesticide CEUs will also be provided for restricted pesticide applicators who attend this event.  The annual meeting of the Gadsden County Tomato Growers Association will be held immediately following a sponsored lunch.

Meeting Agenda (All Times Eastern)

  • 8:00 AM     Registration and coffee
  • 8:15     Opening remarks – Dr. Glen Aiken – NFREC Center Director
  • 8:30     Update on Tomato Varieties and Soil-borne Pest Management Strategies – Dr. Josh Freeman, UF NFREC
  • 9:00     Update on Tomato Diseases Management for 2019 Planning – Dr. Mathews Paret, UF NFREC
  • 9:30     Use of Soil Moisture Probes for Irrigation Scheduling Rad Yager – Certified Ag Resources, Camilla, GA
  • 10:00   Break
  • 10:15   Pest Management Updates in Tomatoes – Dr. Xavier Martini, UF NFREC
  • 10:45   Cover Crops for Tomato and Vegetable Production – Dr. Cheryl Mackowiak, UF NFREC
  • 11:15   Drone Research on Melon Disease Assessment Dr. Melanie Kalischuk, UF NFREC Research Associate
  • 11:30   Continuous Water Tracking for Optimum Crop Productivity – Doug Crawford – BMP Logic, Inc.
  • 11:45   BMP’s and Available Cost Share for Producers – Dr. Andrea Albertin – UF Regional Specialized Water Agent
  • 12:00 PM  Q&A and Sponsors Presentation
  • 12:15   Lunch
  • 1:00   Annual meeting of Gadsden Tomato Growers

The meeting location address is:

North Florida Research and Education Center (Quincy)
155 Research Road,
Quincy, FL  32351

For more information, contact:
Shep Eubanks


Fumigant and Non-fumigant Nematicides for Nematode Management in Potato Production

Fumigant and Non-fumigant Nematicides for Nematode Management in Potato Production

Tractors gathering potatoes

Plant-parasitic nematodes are a major yield-limiting pest in potato production in Florida. Nematicide application is one of the main management strategies available to growers in potato production. (Harvesting potatoes in Hastings, Florida. UF/IFAS)

Plant-parasitic nematodes are a major yield-limiting pest in potato production in Florida.  Nematicide application is one of the main management strategies available to growers in potato production.  In recent years, new nematicide chemistries have been developed and these products are becoming available to growers.  This article summarizes results of work with new and old nematicides over the past 3 years at the Hastings Agricultural Extension Center.  Work in 2016 and 2017 was conducted by Dr. Joe Noling, UF/IFAS professor emeritus and Dr. Noling collaborated on work in 2018.

Trial Layout

In 2016, 2017, and 2018, a trial comparing Nimitz (active ingredient fluensulfone), a non-fumigant registered for use in potato this year, at various rates with the commercial standard Telone II (1,3-dichloropropene) and an untreated control, was conducted.

Table 1. Nematicide treatments for trial conducted in 2016, 2017, and 2018
Treatment Number Product Rate
1 Nimitz 2.5 pints /acre
2 Nimitz 3.5 pints /acre
3 Nimitz 5.0 pints /acre
4 Nimitz 7.0 pints /acre
5 Telone II 6.5 gal/acre
6 Untreated Control ——

In 2018, a trial was also conducted to compare a range of nematicides available on the market (Table 2).

Table 2. Nematicide treatments for trial conducted in 2018 only.
Treatment Number Product Rate
1 Nimitz 5.0 pt/ acre
2 Mocap EC 1.5 gal/acre
3 Velum Prime 6.8 oz/acre
4 Telone ll 6.5 gal/acre
5 Vydate C-LV 2 gal/acre
6 Untreated Control

Nimitz, MoCap EC (ethoprop), and Velum Prime (fluopyram) are liquid products that were applied with a boom 3 weeks before planting and incorporated with rotary tillage.  Telone fumigant was inject in-row 3 weeks before planting.  Vydate C-LV (oxamyl) was sprayed in a band in the seed furrow followed by 3 foliar sprays.  Treatments were applied to 100’ plots with 4 rows at 40” row spacing.  There were 6 replicates in each trial.  Soil abundances of plant-parasitic nematodes were counted before planting and at harvest, and tuber yield was measured. Sting nematode was the primary plant-parasitic nematode present in the trial.

Results of Nimitz rate trial 2016-2018

In all 3 years of the Nimitz rate trial, all rates of Nimitz and Telone significantly reduced sting nematode abundances at harvest relative to untreated control (Fig. 1).  Nematode management was better with Telone than Nimitz at 2.5 pt/a in 2016, but Nimitz and Telone performed similarly in all other cases.

Nematode Graph

The influence of nematicide treatments on potato yields varied somewhat from year to year (Fig. 2).  In 2016, higher rates of Nimitz (5 or 7 pt/a) and Telone increased marketable yield compared with untreated control.  In 2017, lower Nimitz rates (2.5, 3.5, or 5 pt/a) increased potato yield, but high rates of Nimitz (7 pt/a) and Telone had yields similar to untreated.  Phytotoxicity is a potential explanation for reduced yields with Nimitz at 7 pt/a and Telone, although no specific symptoms were observed.  In 2018, all Nimitz and Telone treatments increased tuber yield except Nimitz 7 pt/a, which was similar to untreated.

Marketplace Yield Graph

Results of 2018 commercial nematicides trial

In the 2018 trial testing various nematicides, none of the products significantly reduced final sting nematode abundances compared with untreated control although strong numerical trends occurred (Fig. 3).  Only Mocap significantly reduced stubby-root nematode abundances relative to untreated control (Fig. 4).  Nematicide treatments did not affect marketable potato yield (Fig. 5).  This suggests that nematode pressure was too low to affect yield in this trial.

Sting Nematodes GraphGrabau Stubby nematode populationMarketplace Yield Graph

Summary and action items

In summary, Nimitz shows promise for effectively managing sting nematodes and increasing potato yields when used at the optimum rate.  Telone also continues to be an effective option.  Due to relatively low nematode pressure in the 2018 trial, further testing is needed to determine the efficacy of other relatively new (Velum Prime) or returning (Vydate) products.

Action items: 1. Determine nematode pressure by taking soil samples, preferable while a prior crop is still growing, when considering nematode management, including nematicide application.  2. Consider UF/IFAS research results when choosing a pesticide. 3. Integrate multiple forms of management into your nematode management plan including nematicide application, crop rotation, and weed management.

For more information on nematode management in Irish potato see the UF/IFAS publication, Nematode Management in Potatoes