Home Gardeners Plan Ahead – Plant Resistant Tomatoes

Home Gardeners Plan Ahead – Plant Resistant Tomatoes

Fresh and Healthy tomato

Tomatoes ripening on the vine – Image Credit Matthew Orwat UF/IFAS Extension

It is late-February, so the spring growing season is just around the corner. Now is the time to be thinking about which tasty tomatoes you want to plant in your home garden!  Although tomatoes are a favorite kitchen staple, they prove challenging to grow in the Florida Panhandle climate.

While many tomato diseases can kill plants, damage fruit, and reduce yields, genetic resistance or tolerance to select diseases exist. The following are three of the most common diseases and viruses home gardeners face, for which resistant and tolerant varieties exist.

Tomato spotted wilt affects tomatoes, and numerous other vegetables, ornamentals, field crops and weeds. The disease can cause significant yield losses of tomato. Image Credit UF/IFAS Plant Pathology UScout Site

Tomato spotted wilt affects tomatoes, and numerous other vegetables, ornamentals, field crops and weeds. The disease can cause significant yield losses of tomato. Image Credit UF/IFAS Plant Pathology UScout Site

Tomato Spotted Wilt (TSW) is a viral disease which is transmitted by thrips, a species of insect that is very small and not always visible when checking the garden for insect pests.  They love to feed on the sugary juices of the tomato flowers, and while feeding, they have the opportunity to transmit the virus through their piercing and sucking mouth parts. Lots of different symptoms may occur with TSW. Initially growers will notice light or dark brown spots on leaves of affected tomatoes, next wilting or stunting will occur, along with brown or purple streaks on the stems. Finally, fruit will exhibit unsightly brown rings throughout. The good news is that home gardeners can get a head start on this disease by planting resistant cultivars. When shopping for seed or transplants, growers should look for plants listed with the codes TSW or TSWV, because these have demonstrated resistance to Tomato Spotted Wilt Virus.

 

 

 

 

Another viral disease often found in the tomato garden is Tomato Yellow Leaf Curl (TYLC) Virus. TYLC first appeared in Miami in 1997 and was brought to Florida by infected whiteflies. Much like TSW, TYLC is spread from plant to plant by feeding whiteflies. As the name indicates, TYLC symptoms include curled leaves and stunted growth. Infected plants produce little to no fruit.  Strategies to reduce the possibility of virus transmission to the garden include reducing the population of weedy plants, which may harbor whiteflies. Fortunately, resistant cultivars are available in plant catalogs, and are denoted by TYLC to indicate resistance.

Spread of TYLC is by the feeding of TYLCV infected adult whiteflies. Mechanical or seed transmission is not known to occur. Upward curling and yellowing of the leaves is an early symptom.

Spread of TYLC is by the feeding of TYLCV infected adult whiteflies. Mechanical or seed transmission is not known to occur. Upward curling and yellowing of the leaves is an early symptom. Credit: UF/IFAS Plant Pathology UScout Site

Fusarium wilt

Blighting of leaves and wilting of part or entire plant can expose fruits to sunscalding thereby further affecting yield of affected plants in production. Credit: UF/IFAS Plant Pathology UScout Site

Fusarium Wilt is one of the oldest diseases to affect tomatoes in the state of Florida and is caused by the fungal pathogen Fusarium oxysporum f.sp. lycopersici races 1, 2, or 3. This pathogen is often present in regional soils and moved by wind. Once it enters the roots of tomato plants, fusarium wilt proliferates and clogs the vascular system, much like a clog in the plumbing of a building. Thus, the primary symptom is the wilting of the plant, which will first be noticeable on hot days, despite adequate irritation. Once infected, there is no cure, and infected plants should be removed and destroyed to stop the spread. The good news is that resistant cultivars are available to the various fusarium races. They are usually denoted as F-R 1, 2, or 3 in seed catalogs. Additionally, look for plants labeled VFN. These cultivars are resistant to a different kind of wilt, called verticillium, as well as fusarium and nematodes.

Fortunately, the UF / IFAS publication  “Tomato Varieties for Florida—Florida “Red Rounds,” Plums, Cherries, Grapes, and Heirlooms” by Monica Ozores-Hampton and Gene McAvoy has provided us with a handy chart of tomato varieties with disease resistance. Codes in the columns indicate disease resistance to specific pathogens. While there is no single tomato variety resistant to all possible disease pathogens, planting different varieties with several different types of resistance will allow growers to hedge against attack by a number of potential disease problems. Some of the more common disease resistant tomato varieties planted in this area are ‘Quincy’, ‘Bella Rosa’, ‘Amelia’, ‘Tasti-Lee’, ‘BHN 602’, and ‘Volante’.

Tomato Varieties for North Florida

For a further look at the various diseases of tomato, the EDIS publication “A Series on Diseases in the Florida Vegetable Garden: TOMATO” offers more detail. Another resource UF/IFAS offers for disease diagnosis is the NFREC U-Scout website. U-Scout provides information on more than 40 potential disease issues in tomato. Additionally, any plant disease can be diagnosed through your County Extension Office or by submitting samples to the Plant Pathology Clinic, at the North Florida Research and Education Center, for only $30/sample for basic services.

 

Gardening in the Panhandle LIVE! 2021

Gardening in the Panhandle LIVE! 2021

We are back with new topics and guest speakers for 2021! All sessions are Thursdays at noon CDT or 1:00 p.m. EDT.

There are two ways to join the Gardening in the Panhandle LIVE! webinars:

1. Facebook Live – Follow us on Facebook and follow individual webinar Events.
2. Zoom Webinar – Pre-registration is required for Zoom. Users must have an authenticated account (free at Zoom Link). Be sure you have security settings up to date to prevent connection delays. Links to Zoom registration will be added to the topic one week before the webinar and a closed captioned recorded link to YouTube will be available approximately one week after the program. (Underlined words have active links!)

 

Date

Topic

Panelists

12-1 pm CDT

2/4/2021

Weeds
Reference links

Dr. Chris Marble, Beth Bolles, Mark Tancig, Larry Williams

3/11/2021

Spring Vegetables
Reference links

Dr. Josh Freeman, Matt Lollar, Sheila Dunning, Evan Anderson

4/8/2021

Lawns
Reference links

Dr. Bryan Unruh, Dr. Pat Williams, Mark Tancig, Larry Williams

5/13/2021

Herbs

Beth Bolles, Julie McConnell, Mary Salinas, Trevor Hylton

6/10/2021

Ornamental & Turf Diseases

Dr. Phil Harmon, Stephen Greer, Larry Williams, Matt Orwat

7/29/2021

Beneficial Insects: Predators!

Dr. Adam Dale, Beth Bolles, Julie McConnell, Danielle Sprague

8/12/2021

Open landscape topics Q&A

Beth Bolles, Mark Tancig, Matt Lollar, Evan Anderson

9/9/2021

Beginning Beekeeping

Chris Oster, Ray Bodrey, Evan Anderson, Matt Orwat

10/14/2021

Invasive Species

Dr. Stephen Enloe, Dr. Pat Williams, Dr. Gary Knox, Sheila Dunning, Ray Bodrey

11/4/2021

Houseplants

Marc Frank, Dr. Pat Williams, Stephen Greer, Matt Orwat

12/9/2021

Selecting and Maintaining Trees

Larry Figart, Mark Tancig, Larry Williams, Matt Orwat, Dr. Ryan Klein

Missed a session and want to catch up?
All webinars are archived with closed captioning on our YouTube Gardening in the Panhandle LIVE! Playlist.

 

 

Clean Up for the Fall Vegetable Garden

Clean Up for the Fall Vegetable Garden

A common question for gardeners at the end of the season is if one should till the soil or use no till practices.  Opinions vary regarding this question, even among Extension Agents.  However old crops harbor insects, both good and bad.  This phenomenon was noticed on some recently cut back tomato plants.  The intention was to cut the leftover spring garden tomatoes back to encourage fall production.  Instead, a host plant for mealybugs was provided.

Whitefly larvae on a tomato plant.

Mealybugs on a tomato plant. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments.  They are about 1/8 inch in length and usually pinkish or yellowish in color.  Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental and vegetable plants.  Mealybug damage produces discolored, wilted, and deformed leaves.

One very common example of an insect pest likely to claim residence in your garden’s crop residue, are squash bugs. They like to overwinter on squash, cucumber, and other cucurbit crop residue.  If you choose to not till your garden and leave a portion of last seasons crop in your garden, then you should consider applying an insecticide to your spent crop at the end of the season.  A product containing a pyrethrin or pyrethroid as an active ingredient would be a good broad spectrum insecticide to control any pest that may reside on plant residue.  More information on pyrethrins and pyrehtroids can be found at the EPA webpage: Pyrethrins and Pyrethroids.  If you choose to apply an insecticide, it is important that you follow the information on the label regarding pollinator protection.  Another option is to plant a trap crop on the edge of your garden to help attract pest insects away from your desired crops.  More information on trap crops can be found in the EDIS PublicationIntercropping, Pest Management and Crop Diversity.

An adult squash bug on a zucchini leaf.

An adult squash bug on a zucchini leaf. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

So the answer to the till or no till question is…it depends.  It is really up to the gardener.  Yes, the residue from crops will add nutrients and organic matter to your soil, but it could also increase pest pressure in your garden.  If you don’t plan to remove crop residue and don’t plan to till, then keep an eye out for what could be hiding in your garden.

Pruning Makes All The Difference

Pruning Makes All The Difference

I live in the woods, so I mainly have a “natural” landscape.  I remove trees, shrubs, and weeds as I see fit, but for the most part things just grow wild.  However, there are a few spots in the yard where the previous owners did a little landscaping.  Unfortunately, these spots have become a bit overgrown.  One spot in particular features some gardenia plants around the HVAC units.  At first, I was a little hesitant to prune these shrubs because they provide some shade to the units.  However, they have become overgrown and I know they will grow back.  I was patient to wait for them to finish flowering.

Gardenia Shrub

A gardenia shrub that has become a bit overgrown. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

As you can see in the photo above, this gardenia has become a bit leggy.  It is important to also note the good amount of branching and new growth at the base of the plant.  There are a few pruning options available for shaping shrubs such as hedging/terminal pruning, selective pruning, and renewal pruning.  While a tree form gardenia can be attractive, it wasn’t desired in this situation.  This particular case called for renewal pruning to improve the form of the plant.  Renewal pruning is probably the easiest type of pruning, because it requires the least amount of thinking.  It basically involves removing the majority of old growth.

A gardenia shrub that has been renewal pruned

A gardenia shrub that has been renewal pruned. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

The picture above is of the same shrub that has been pruned heavily.  Not only have the older, leggy branches been removed, but some of the newer growth has been removed to allow for better air circulation within the shrub.  This will help reduce the incidence of disease.

A gardenia shrub six weeks after renewal pruning.

A gardenia shrub six weeks after renewal pruning. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Six weeks after being pruned, this shrub is flowering for a second time.  In a matter of short time it will be providing much needed shade for the HVAC units again.  (That is..if I remember to selectively prune throughout the year.)  For more information on how to prune and what to prune, please visit the UF/IFAS Gardening Solutions page on pruning.

Protect Your Laurel Trees from Ambrosia Beetles with Verbenone.

Protect Your Laurel Trees from Ambrosia Beetles with Verbenone.

Fig. 1 An adult redbay ambrosia beetle compared to the size of a single penny. Credit: UF/IFAS File Photo.

While most bark beetles are important in forest ecology by recycling fallen dead trees and eliminating sick and damaged trees, some of them may impact healthy trees. A group of bark beetles that has become a major concern to forest managers, nurseries, and homeowners is the ambrosia beetle. Ambrosia beetles are extremely small, 1-2 mm in length, and live and reproduce inside the wood of various species of trees (Fig. 1). Ambrosia beetles differ from other bark beetles in that they do not feed directly on wood, but on a symbiotic fungus that digests wood tissue for them. Every year, non-native species of ambrosia beetles enter the United States through international cargo and we have now nearly forty non-native species of ambrosia beetles confirmed in the United States. Among them, the redbay ambrosia beetle (Xyleborus glabratus), originally from Southeast Asia, is the vector of the fungal pathogen causing laurel wilt, a disease that devastated the Lauracaea population in the southeastern USA, killing millions of redbay, swamp bay, sassafaras and silk bay.

Fig. 2: A mature dooryard avocado tree with large sections of dead and missing leaves, caused by laurel wilt disease. Summer 2009 Impact Magazine image. Credit: UF/IFAS File Photo.

When these beetles attack a laurel tree, the symbiotic fungus is vectored to the tree’s sapwood after the beetle has tunneled deep into the tree’s xylem, actively colonizing the tree’s vascular system. This colonization leads to an occlusion of the xylem, causing wilting of individual branches and in a matter of weeks progresses throughout the entire canopy, eventually leading to tree death (Fig. 2). The laurel wilt disease has spread rapidly after the vector was first detected in Georgia in 2002.  The redbay ambrosia beetle was first detected in Florida in 2004, in Duval County, attacking redbay and swamp bay trees. At this point, it is estimated that more than one-third of redbay in the U.S.A., 300 million trees, have succumbed to the disease.

Starting in 2017, we examined the efficacy of verbenone against redbay ambrosia beetle in live laurel trees in a natural forest setting. Verbenone is an anti-aggregation pheromone that has been used since the 1980’s to protect lodgepole pine. Verbenone also has the potential to be used over large areas and is currently being used to protect ponderosa pine plantations from the Mountain Pine Beetle in the western US.

We have found verbenone to be an environmentally friendly and safe tool to prophylactically protect laurel trees against redbay ambrosia beetle. Our protocol consists of the application of four 17 g dollops of a slow-release wax based repellent (SPLAT Verb®, ISCA technology of Riverside, CA) to the trunk of redbay trees at 1 – 1.5 m above ground level (Fig. 3). The wax needs to be reapplied every 4 months during fall and winter and every 3 months during spring and fall when temperature is higher. When compared to the control trees without repellents, we found that trunk applications of verbenone reduced landing of the redbay ambrosia beetle on live redbay trees and increased survivorship of laurel trees compared to untreated trees (Fig. 4). Verbenone should be considered as part of a holistic management system against redbay ambrosia beetle that also includes removal and chipping of contaminated trees.

If you have Redbay or other bay species on your property and are concerned about Laurel Wilt Disease or Redbay Ambrosia Beetle damage, contact your local UF/IFAS Extension Agents for help!

This article is courtesy of Dr. Xavier Martini and Mr. Derek Conover of the UF/IFAS North Florida Research and Education Center (NFREC) in Quincy.

Fig. 3: Application of SPLAT Verb on a redbay tree during a field trial

Figure 4: (A): Cumulative capture of redbay ambrosia beetles Xyleborus glabratus following a single application of verbenone vs untreated control (UC). (B) Survivorship of redbay and swamp bay trees treated with verbenone on four different studies conducted in 2017 and 2018.

 

Tomato Leaves Spotty and Yellowing?  Could Be Bacterial Leaf Spot.

Tomato Leaves Spotty and Yellowing? Could Be Bacterial Leaf Spot.

Early BLS symptoms appear on lower leaves. Photo courtesy of the author.

Tomatoes are among the most notoriously difficult vegetable species to grow in Florida.  Even when you do everything right (choose disease resistant varieties, buy clean seed/healthy transplants, plant early, rotate crops, scout for insects, prune and support vines, etc), things can go wrong in a hurry.  Bacterial Leaf Spot (BLS) caused by the pathogen Xanthomomas perforans, is one of those things.  BLS often hitches a ride into gardens undetected on seed and transplants and presents itself as warm and humid weather arrives in late April/early May.  Outbreaks typically happen in concurrence with the frequent heavy rainstorms that accompany these months and quickly wreak havoc on tomato plants.

BLS occurrence, much worse in some springs than others, has exploded this year in home gardens.  First noticed on the plant’s lower leaves, BLS pathogens enter through natural openings in leaves called stomata, manifest as small, “water-soaked” leaf lesions and then develop within days into dark circular spots, sometimes surrounded by a yellow halo.  As conditions worsen, all these individual infections cause a general yellowing or “blighting” of entire leaves.  Though the issue begins on tomato leaves, BLS can affect all parts of the plant, including stems, flowers and fruit too! It’s at this point, when blighted leaves become obvious and lesion developing on flower stalks cause both flowers and small fruit to drop, that most home gardeners notice that something is up.

Advancing progression of BLS with “blighted” leaves. Photo courtesy of the author.

Unlike with many other pathogens, gardeners don’t have an abundance of options to control BLS.  However, taking the following preventative measures can reduce the pathogen’s impact and stave off disease progression until ripe fruit can be harvested.

  • Don’t irrigate overhead. Utilize drip/microirrigation or hand water beds and containers at soil level. This prevents the leaves from becoming wet; wet leaves become a perfect host for BLS.
  • Never work tomato plants when leaves are wet. No staking, pruning, tying, or anything else until plant tissue is dry.  Working wet tomato plants is an excellent way to spread bacteria!
  • Sanitize pruning tools often and wash hands after working infected plants.
  • Maintain airflow in plants by planting at correct spacing and thinning interior leaves as necessary to facilitate quicker drying of the plant.
  • Prune lower leaves to at least 12” from the soil’s surface to prevent disease transmission from soil to leaves through splashing water.
  • Remove infected leaves (when plants are dry!) to slow disease progression.
  • Rotate crops and destroy infected plants to prevent buildup of BLS organisms in soil.

    BLS lesions on tomato flowers. Photo courtesy of the author.

  • Preventative measures are best, but if your garden has a history of BLS and local weather forecasts call for warm/wet/humid weather, it is best to spray fungicides proactively to protect your crop. A weekly spray with a tank mixture of copper and mancozeb is effective at keeping BLS at bay.  This is the only chemical spray combination proven to be effective in controlling BLS.
  • Unlike many common tomato pathogens that can be reliably avoided through planting resistant cultivars like ‘Big Beef’, ‘Celebrity’ and others, no varieties are resistant to BLS.

While BLS is an extremely destructive pathogen of both home and commercially grown tomatoes, growers can lessen the disease’s effects by following the preventative measures outlined above and spraying with a copper/mancozeb mix if necessary.  Growing tomatoes this year hasn’t been easy, but it’s worth it to fight back and realize a harvest despite difficulties like BLS!

If bacteria have given you the blues or other garden issues are bringing you down, give your local UF/IFAS County Extension Agent a call!  We’re here to help you be successful in all your horticultural endeavors.   Happy gardening!