by Daniel J. Leonard | May 7, 2020
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!
by Daniel J. Leonard | Jan 23, 2020
Cruciferous vegetables, mostly cool-season annuals in the Brassicaceae (formerly Cruciferae) family, are part of a healthy diet, prized for their high fiber content and unique sulfur-containing compounds known as glucosinolates. This vegetable family includes things many of us love (or love to hate) like Brussels sprouts, cabbage, cauliflower, collards, kale, mustard, turnips, bok choy, and Chinese cabbage. They’re also commonly grown in Panhandle gardens. However, as anyone who has grown these species knows, some are easier than others. For example, kale and radish are among the easiest of all plants to grow. But get beyond the basics and folks often run into difficulty with species like broccoli and cabbage. The high rainfall/humidity and frequent warm spells experienced here during the growing season often lead to serious pathogen problems, dooming my garden in years past. However, this winter, thanks to a couple of new cultivars, ‘Capture’ Cabbage and ‘Burgundy’ Sprouting Broccoli, I’ve enjoyed a plentiful supply of tasty crucifers!
4’x 8′ raised bed planted with ‘Capture’ on 24″ centers.
‘Capture’ Cabbage, developed by Bejo Seeds of California as a mid-season “white” fresh market cabbage for the South, has been an outstanding performer in my garden this year. Touted as highly resistant to Black Rot and Fusarium Yellows (by far the two most devastating pathogens of Cabbage), I had to try it for myself. I planted seeds 24” apart in my standard 4’ wide x 8’ long x 12” deep raised beds filled with mushroom compost and aged pine bark. Seedlings were fertilized once about three weeks after germination with a general purpose 10-10-10 fertilizer. The plants that developed have been extremely vigorous (I’m glad I paid attention to plant spacing guidelines on the seed packet!) and have not shown ANY evidence of disease, even through an unusually warm and wet winter that would have hammered older susceptible varieties. My plants have begun to develop heads and should be ready for harvest and the kitchen in just a couple more weeks! If you’ve had problems getting a cabbage from germination to head formation and harvest without serious disease pressure, give ‘Capture’ a try next fall!
‘Burgundy’ Broccoli in the author’s raised bed garden.
‘Burgundy’ Broccoli, developed by Elsom Seeds in the United Kingdom, is a unique variety sure to turn heads in your garden. True to its name, the prolific florets are a deep, purple color. Though the central “head” on ‘Burgundy’ is quite small, that’s not the primary feature anyway. Considered a “sprouting” broccoli, this cultivar puts out an abundance of side shoots that make ‘Burgundy’ sort of a cut-and-come-again broccoli, allowing for a long harvest window. Another advantage from a disease avoidance perspective is the short maturity time (the time from planting seeds to having harvestable shoots) of around 40 days! For perspective, a “regular” heading broccoli has a maturity of around 60 day, lots more time for problems to happen. In the same growing conditions described above for cabbage, ‘Burgundy’ performed amazingly well for me, growing strong, healthy stalks, large, unblemished leaves and an abundance of purple shoots with a nice flavor profile!
If you want to enjoy homegrown broccoli and cabbage but disease pressures have made your previous efforts unproductive, give ‘Capture’ Cabbage and ‘Burgundy’ Broccoli a try! These two selections have made it easier than ever to enjoy unique, homegrown, healthy cruciferous veggies. Keep these and other quality, disease-resistant cultivars in mind when planning your winter garden in 2020!
by Matt Lollar | Dec 10, 2019
Loquat trees provide nice fall color with creamy yellow buds and white flowers on their long terminal panicles. These small (20 to 35 ft. tall) evergreen trees are native to China and first appeared in Southern landscapes in the late 19th Century. They are grown commercially in subtropical and Mediterranean areas of the world and small production acreage can be found in California. They are cold tolerant down to temperatures of 8 degrees Fahrenheit, but they will drop their flowers or fruit if temperatures dip below 27 degrees Fahrenheit.
A beautiful loquat specimen at the UF/IFAS Extension at Santa Rosa County. Photo Credit: Matt Lollar, University of Florida/IFAS – Santa Rosa County
Leaves – The leaf configuration on loquat trees is classified as whorled. The leaf shape is lanceolate and the color is dark green with a nice soft brown surface underneath. These features help give the trees their tropical appearance.
Flowers – 30 to 100 flowers can be present on each terminal panicle. Individual flowers are roughly half an inch in diameter and have white petals.
Fruit – What surprises most people is that loquats are more closely related to apples and peaches than any tropical fruit. Fruit are classified as pomes and appear in clusters ranging from 4 to 30 depending on variety and fruit size. They are rounded to ovate in shape and are usually between 1.5 and 3 inches in length. Fruit are light yellow to orange in color and contain one to many seeds.
A cluster of loquat flowers/buds being pollinated by a honey bee. Photo Credit: Matt Lollar, University of Florida/IFAS – Santa Rosa County
Propagation – Loquat trees are easily propagated by seed, as you will notice as soon as your tree first bears fruit. Seedlings pop up throughout yards containing even just one loquat tree. It is important to note that the trees do not come true from seed and they go through a 6- to 8-year juvenile period before flowering and fruiting. Propagation by cuttings or air layering is more difficult but rewarding, because vegitatively-propagated trees bear fruit within two years of planting. Sometimes mature trees are top-worked (grafted at the terminal ends of branches) to produce a more desirable fruit cultivar.
Loquat trees are hardy, provide an aesthetic focal point to the landscape, and produce a tasty fruit. For more information on growing loquats and a comprehensive list of cultivars, please visit the UF EDIS Publication: Loquat Growing in the Florida Home Landscape.
by Danielle S. Williams | Aug 22, 2019
Recently, I received a call about a garden not producing the way it used to. After speaking with the homeowner, I decided to take a visit to see what was going on. On my visit, I could see that the tomatoes were stunted, yellow and wilting, the squash plants were flowering but not setting fruit, and the okra was stunted. After digging up some of the sick plants and examining the roots, the problem was as clear as day…root-knot nematodes.
Galls on roots from root-knot nematodes
Root-knot nematodes are microscopic, unsegmented roundworms that live in the soil and feed on the roots of many common garden plants. Some of the most commonly damaged crops are tomatoes, potatoes, okra, beans, peppers, eggplants, peas, cucumbers, carrots, field peas, squash, and melons. Root-knot nematodes enter the root and feed, causing knots or galls to form. These galls are easily recognizable on the roots. If you’re inspecting the roots of beans or peas, be careful not to confuse nematode galls with the nitrogen-fixing nodules that are a normal part of the root system. As the nematodes feed, the root system of the plant becomes damaged and the plant is unable to take up water and nutrients from the soil. As a result, the plant may show symptoms of stunting, yellowing, and wilting.
What can I do about nematodes?
There are currently no nematicides labeled for use in the home garden but the best means of root-knot nematode management involves using a combination of strategies that make your garden less susceptible to attack.
Grow Resistant Varieties
Some varieties of crops are resistant to root-knot nematodes. This means is that a particular nematode can’t reproduce on the plant roots. When buying seed, read the variety label. The label may have ‘VFN’ written in capital letters. These letters indicate that the variety has resistance to certain diseases: V = Verticillium wilt; F = Fusarium wilt; and N = root-knot nematode. It’s best to use resistant varieties when root-knot nematodes are present.
Tomato plant showing signs of nematode damage – yellowing and wilting.
Sanitation
If you suspect you may have a nematode problem, be sure not to move soil or infected plant roots from an infected area to a clean area. Nematodes can easily be spread by garden tillers, hand tools, etc. so be sure to disinfect all equipment after use in problem areas.
Infected roots left in the soil can continue to harbor nematodes. After the crop is harvested, pull up the roots and get rid of them. Tilling the soil can kill nematodes by exposing them to sunlight.
Cover crops and Crop Rotation
Cover crops and crop rotation isn’t just a concept for farmers…gardeners need to implement the same practices! While this may take some planning, it is the most effective way to reduce pests and diseases.
Cover crops are crops that are not harvested and are typically planted between harvestable crops. They help improve soil quality, prevent soil erosion, and help control pests and diseases. Selecting cover crops that aren’t susceptible to root-knot nematode attack is key. When growing a cover crop that nematodes can’t reproduce on, populations should decline or not build up to begin with. Grain sorghum and millet can be planted as a summer cover crop and rye in the winter. French marigolds have been shown to reduce nematode populations as well.
Another simple way to manage root-knot nematodes is by crop rotation. Crop rotation is the practice of not growing crops that are susceptible to nematode attack, in the same spot for more than one year. Crops that aren’t susceptible to attack are cool season crops in the cabbage family such as broccoli, cauliflower, Brussels sprouts, collards and kale.
Root-knot nematodes can wreck havoc on a garden so it’s important to take the necessary precautions to avoid them. It may require planning and patience but it will be worth it in the long run!
For more information on this topic, use the links to the following publications:
Nematode Management in the Vegetable Garden
Featured Creature: Nematodes
by Daniel J. Leonard | Aug 20, 2019
Though Okra (Abelmoschus esculentus) fruit isn’t much more than a thick green hull, slime and seeds and the plant itself is impossibly irritating to the skin, few plants are as integral to Southern heritage. In my mind, okra is among the best vegetables Panhandle gardeners can grow. Not only is it a gorgeous plant – Okra belongs to the Mallow family which also includes beauties like Hibiscus and Cotton – but it’s exceedingly versatile in the kitchen, excellent fried, grilled, roasted, boiled (though you have to acquire a taste for slimy textures to enjoy this method) and most famously, as a thickening agent in Cajun gumbo. Because of this exalted status in Southern culture, whether you enjoy eating okra or not, it’s almost mandatory here to include the plant in one’s garden. Most gardeners stick with the old standard varieties such as ‘Clemson Spineless’ or ‘Cowhorn’ and there is nothing wrong with them, however, these plants are almost too prolific for most gardens (growing upwards of 6-7’), especially for those of us growing in the close confines of raised beds. In the search for a less rambunctious but still ultra-productive cultivar, this summer I trialed ‘Jambalaya’, an F1 hybrid developed by Sakata Seed in 2012, with impressive results!
‘Jambalaya’ Okra in the author’s garden.
From my experience growing the cultivar this summer, ‘Jambalaya’ merits consideration in the garden, and is a must for raised bed gardeners, for two primary reasons. First, it was bred to be compact and is considered a dwarf cultivar. This is an awesome attribute, as I typically end the growing season picking okra from a small ladder! Most seed purveyors tout the plant as reaching a maximum height of 3-4’ and while this estimate might be a little conservative, I can attest that ‘Jambalaya’ is greatly reduced in height compared to the standard cultivars. The second advantage of growing this variety is that it begins producing very early relative to its peers and bears heavily. ‘Jambalaya’ fruit begin to ripen in about 50 days, about ten days to two weeks earlier than ‘Clemson Spineless’, a definite advantage if rotating behind a late maturing spring crop like potatoes as I typically do. Though ‘Jambalaya’ is a dwarf plant, in no way are yields reduced. My specimens have produced continuously since late-July and will continue to do so as long as adequate fertility and consistent harvesting are provided.
‘Jambalaya’ flower & fruit production.
Like any other okra cultivar, ‘Jambalaya’ has a couple of basic requirements that must be met for plants to thrive. In general, all okra cultivars love Southern summers and patience sowing seed is recommended, allow the soil to warm to at least 70 degrees before planting. Okra also prefers full sun, at least 6 hours per day, any less and yields will be reduced and plants will stretch towards the light. Belonging to the Mallow family, okra requires consistent moisture, particularly when in the flowering and fruiting phase. Finally, it is critical to keep up with your okra harvest as the plants produce! Okra pods grow quickly and should be harvested when they are no more than 3-4” long and still tender, larger pods are tough to the point of being inedible!
‘Jambalaya’ in the author’s garden.
Whether you’re new to the okra growing game or you’re a seasoned gumbo gardener, I highly encourage you to give ‘Jambalaya’ Okra a look next summer. While ‘Jambalaya’ is available through many seed sources, Johnny’s Selected Seeds sells a conveniently small package perfect for backyard gardeners, though they’ll be happy to provide larger quantities as well. In ‘Jambalaya’ you’ll find a nice compact plant that won’t outgrow your space, provide you a summer long harvest of tender green pods, and will rival the ornamentals in your landscape for the title of prettiest plant on your property! Happy gardening and as always, if you have questions about vegetable gardening or any other horticultural or agronomic topic, please contact your local UF/IFAS County Extension office!
