Citrus canker symptoms on twigs, leaves and fruit. Photo by Timothy Schubert, FDACS
Citrus canker was found for the first time in the Florida panhandle in Gulf Breeze in southern Santa Rosa County in November 2013. Since that time, citrus canker has spread widely in the Gulf Breeze area and just recently in 2020 was found in two locations in Panama City and Panama City Beach in Bay County.
Citrus canker is a serious bacterial disease that only infects citrus trees. It will not infect any other plant species nor is it a threat to human health. Severely affected trees experience substantial leaf loss and premature fruit drop and serve as a source for infecting nearby citrus. The disease spreads through wind, rain, and transportation of infected plant material from other locations.
This highly contagious disease has no cure although progression of the disease can be slowed through the use of copper-based products. This publication guides the homeowner on using copper.
Citrus canker lesions on leaves are raised, rough and visible on both sides of the leaf. Photo by Timothy Shubert, FDACS.
Not all citrus varieties are equally susceptible to this disease. Grapefruit, lemon, and lime are some of the most vulnerable while tangerine and tangelo varieties are among the most resistant.
What should you do if you suspect your citrus is infected with this disease?
- Look at this guide for more information and compare the symptoms on your tree to the photos. Lesions on the leaves penetrate through the leaf so they are visible on the upper and lower leaf surfaces, are rough, and have a yellow halo. The lesions look similar on the fruit and stems. Lesions (or cankers) on the stems usually indicate a longer standing infection of a year or more.
- Consult your local Horticulture Extension Agent to confirm the diagnosis and obtain more information and control/removal strategies.
- Proper removal of infected trees is recommended to prevent the spread of citrus canker but is not mandatory. The best way to dispose of infected trees is through cutting them down and burning them onsite; this ensures than none of the plant material leaves your yard to infect other areas. Consult your local burn regulations before burning. Stray leaves, branches and fruit should be raked and burned or double bagged for the trash. Please avoid disposing of any of your citrus trees by putting them by the side of the road for pickup by the county yard waste recycling or regular waste disposal. The bacterium will survive in the plant tissue and be spread to other neighborhoods in the county. You can, however, double bag infected plant material in sturdy bags and place it in the trash.
For more information please see:
UF IFAS Gardening Solutions: Citrus
Citrus Culture in the Home Landscape
UF IFAS Extension Online Guide to Citrus Diseases
The weather is warmer and plans and planting for spring vegetable gardens are in full swing. Last week many vegetable gardening topics were addressed in our Gardening in the Panhandle LIVE program. Here are all the links for all the topics we discussed. A recording of last week’s webinar can be found at: https://youtu.be/oJRM3g4lM78
Home grown Squash. Gardening, vegetables. UF/IFAS Photo by Tom Wright.
The place to start is with UF’s ever popular and comprehensive Florida Vegetable Gardening Guide https://edis.ifas.ufl.edu/pdffiles/VH/VH02100.pdf
Many viewers expressed interest in natural methods of raising their crops. Take a look at Organic Vegetable Gardening in Florida https://edis.ifas.ufl.edu/pdffiles/HS/HS121500.pdf
The Square Foot Vegetable Planting Guide for Northwest Florida helps plan the layout of your garden https://sfyl.ifas.ufl.edu/media/sfylifasufledu/leon/docs/pdfs/Vegetable-Square-Foot-Planting-Guide-for-Northwest-Florida-mcj2020.pdf
Maybe you would like the convenience of starting with a fresh clean soil. Gardening in Raised Beds can assist you. https://edis.ifas.ufl.edu/ep472 Also see Gardening Solutions Raised Beds: Benefits and Maintenance https://gardeningsolutions.ifas.ufl.edu/design/types-of-gardens/raised-beds.html
Here is a guide to Fertilizing the Garden https://edis.ifas.ufl.edu/vh025
The Florida Panhandle Planting Guide will help you decide what to plant and when: https://www.facebook.com/SRCExtension/posts/4464210263604274
The Ever-Popular Tomato
To start your journey to the best tomatoes, start with UF/IFAS Gardening Solutions – Tomatoes https://gardeningsolutions.ifas.ufl.edu/plants/edibles/vegetables/tomatoes.html
If you are looking to grow in containers: https://sfyl.ifas.ufl.edu/media/sfylifasufledu/leon/docs/pdfs/Container-Gardening-Spacing-Varieties-UF-IFAS-mcj2020.pdf
Vegetable grafting is gaining in popularity, so if interested, look at this Techniques for Melon Grafting: https://edis.ifas.ufl.edu/hs1257
Blossom end rot occurs when irrigation is irregular and the calcium in the soil does not get carried to the developing fruit. The U-Scout program has a great description of this common problem: https://plantpath.ifas.ufl.edu/u-scout/tomato/blossom-end-rot.html
Our moderators talked about some of their favorite tomato varieties. Josh Freeman is partial to Amelia, a good slicing tomato. Matt Lollar shared some of the best tomato varieties for sauce: Plum/Roma types like BHN 685, Daytona, Mariana, Picus, Supremo and Tachi. For cherry tomatoes, Sheila Dunning recommended Sweet 100 and Juliette.
Whatever variety you choose, Josh says to pick when it starts changing color at the blossom end and bring it indoors to ripen away from pests.
Garden Pest Management
Let’s start with an underground pest. For those of you gardening in the native soil, very tiny roundworms can be a problem. Nematode Management in the Vegetable Garden can get you started: https://edis.ifas.ufl.edu/pdffiles/NG/NG00500.pdf
Leaffooted bugs are quite a nuisance going after the fruit. Here is how to control them: http://extension.msstate.edu/newsletters/bug%E2%80%99s-eye-view/2018/leaffooted-bugs-vol-4-no-24
Cutworms are another frustration. Learn about them here: http://nwdistrict.ifas.ufl.edu/hort/2020/02/27/cutworms-the-moonlit-garden-vandals/
Maybe your tomatoes have gotten eaten up by hornworms. https://gardeningsolutions.ifas.ufl.edu/care/pests-and-diseases/pests/hornworm-caterpillars.html
There are beneficial creatures helping to control the pest insects. Learn to recognize and conserve them and make for a healthier environment. Natural Enemies and Biological Control: https://edis.ifas.ufl.edu/pdffiles/IN/IN12000.pdf
If the beneficials are not numerous enough to control your pests, maybe a natural approach to pest control can help. Natural Products for Managing Landscape and Garden Pests in Florida: https://edis.ifas.ufl.edu/in197
Fungal and bacterial problems can also plague the garden. Go to Integrated Disease Management for Vegetable Crops in Florida for answers: https://edis.ifas.ufl.edu/pdffiles/PP/PP11100.pdf
Get control of weeds early and consult Controlling Weeds by Cultivating & Mulching https://hgic.clemson.edu/factsheet/controlling-weeds-by-cultivating-mulching/
Companion planting is a strategy that has been around for ages and for good reason: https://www.almanac.com/companion-planting-chart-vegetables Some good flowering additions to the garden that Sheila talked about are bee balm, calendula, marigold, nasturtiums, chives, and parsley.
And Some Miscellaneous Topics…
Peppers are another popular crop. Get some questions answered here: https://aggie-horticulture.tamu.edu/archives/parsons/vegetables/pepper.html
When can we plant spinach in Northeast Florida? http://blogs.ifas.ufl.edu/nassauco/2017/07/15/q-can-plant-spinach-northeast-florida/
Figs are a great fruit for northwest Florida. Get started here: https://edis.ifas.ufl.edu/pdffiles/MG/MG21400.pdf and with this https://aggie-horticulture.tamu.edu/extension/homefruit/fig/fig.html
American fringetree Chionanthus virginicus), a native deciduous small tree with delicate blooms in spring. Photo credit: Mary Salinas, UF/IFAS Extension.
January and February are ideal months for adding a tree or two to your landscape in the Florida panhandle. In the cooler weather, the ground stays moist for a longer time, which helps prevent drought stress and the drying out of the rootball. Also, the winds are generally milder, and the tree will have a chance to get established and anchored in before the wilder winds of summer roll in.
Before investing time and money in a tree, take a few minutes and be sure that the species you choose is right for your particular landscape.
Here are some things to consider:
- Whether the area can accommodate the ultimate size of the tree, both height and width, and not grow into overhead wires, streetlights, or your house.
- Are there any underground utilities or septic? A call to 811 can check on where your utilities are.
- The hardiness zone for the tree. Be aware that zone 8 or 9 in the western United States is a different climate with respect to moisture than the same zone 8 or 9 in Florida.
- Whether the tree can thrive in your soil – sandy, loam or clay, loose or compacted, high and dry, or wet and low.
- The amount of sun it requires.
- Whether you want native species that provide food and habitat for native birds and animals.
- Salt-tolerance if located on the coast.
- Wind tolerance, especially if located on the coast. Many fast-growing trees are brittle and susceptible to breakage.
- Whether you prefer an evergreen or deciduous tree. Evergreen trees, like hollies, provide a natural screen all year while some deciduous trees, like maple and bald cypress, provide fall color.
- Is the tree messy, dropping large seed pods, fruit, or leaves?
- The color and shape of leaves and flowers and other ornamental qualities.
- Whether the tree species has known disease or pest issues.
Florida red anise (Illicium floridanum), a small tree/large shrub for shady locations. Photo credit: Mary Salinas UF/IFAS Extension.
Once you choose what species of tree you will add to your landscape, here’s information on Selecting Quality Trees from the Nursery.
Optimum tree health and vigor also depends on the correct methods of Planting and Establishing Trees.
And this site has even more comprehensive information on trees and shrubs: University of Florida/IFAS Landscape Plants.
Stoke’s aster ‘Mel’s Blue’ 20 days after Hurricane Sally’s landfall. Notice how soil was washed away from root ball, all the leaves emerged post-hurricane. Photo credit: Mary Salinas, UF/IFAS Extension.
Hurricanes can wreak havoc in your landscape, but they can also reveal what plants are the toughest and most resilient. It’s a great learning opportunity.
A few weeks ago, Hurricane Sally came along and brought about 10 feet of surge and waves across my landscape and completely covered everything except the tallest trees for about 18 hours. (Fortunately, our house is on stilts and we did not have intrusion into our main living areas.)
As expected, the trees, including Dahoon Holly and Sweetbay Magnolia, took a beating but stayed intact. With their dense fibrous root system, most of the clumping native grasses also stayed put.
Perennial milkweed 3 weeks post-hurricane. New topsoil and compost now covers the rootball. Photo credit: Mary Salinas, UF/IFAS Extension.
The most surprising plant species that survived were about a dozen Stoke’s aster and 3 perennial milkweed. 4-5 inches of soil all around them was washed away, most of the roots were exposed, and the leaves were stripped or dead. The other perennials that had lived nearby were all washed away. To my surprise, within about 10 days after the storm, these two plant species started poking up new stems and leaves.
Here’s a list of some of the plants either in my yard or in the neighborhood that survived Hurricane Sally’s storm surge and may be suitable to add to your coastal landscape:
- Dahoon holly, Ilex cassine
- Muhly grass, Muhlenbergia capillaris
- Dwarf Fakahatchee grass, Tripsacum floridanum
- Perennial milkweed, Asclepias perennis
- Stoke’s aster, Stokesia laevis, specifically the cultivars ‘Mel’s Blue’ and ‘Divinity’
- Bottlebrush, Callistemon citrinus
- Gardenia, Gardenia jasminoides
- Bougainvillea, Bougainvillea spp.
- Flax Lily, Dianella tasmanica
- Crapemyrtle, Lagerstroemia spp.
- Cabbage palm, Sabal palmetto
- Canary Island date palm, Phoenix canariensis
- Sweetbay magnolia, Magnolia virginiana
- Augustinegrass, Stenotaphrum secundatum
- And, unfortunately, the rhizomes of the invasive torpedograss also survived.
For more information on salt tolerant and hurricane resistant plants, see:
UF/IFAS Gardening Solutions: Coastal Landscapes
UF/IFAS Gardening Solutions: Salt-tolerant Lawngrasses
UF/IFAS Gardening Solutions: Trees That Can Withstand Hurricanes
Perennial milkweed, Asclepias perennis, with oleander aphids; notice the brown aphid mummies that have been parasitized. Photo credit: Mary Salinas UF/IFAS Extension.
Milkweeds are appreciated for their beauty, but often we cultivate it for the benefit of the monarch butterflies who lay their eggs only on this plant genus. Avid butterfly gardeners want the monarch caterpillars to eat up the milkweed and become beautiful butterflies. Often instead, thousands of aphids show up and compete for space on the plants. These bright yellow aphids are known as oleander aphids.
Just how do aphids build up their populations so quickly? It seems that one day you have a small number on a few plants and then a few days later, thousands are all over your milkweed. Oleander aphids have a few advantages for quickly building their populations:
- All oleander aphids are female and do not need to mate to produce their young
- Aphids give birth to live young who immediately start feeding on the plant
- Aphids start reproducing when they are 4 to 10 days old and keep reproducing during their one-month life span
- When populations get heavy or the plant starts to decline, winged individuals are produced to migrate to new areas and plants.
Parasitic wasp and aphid mummies. Photo credit: University of California.
What can or should you do to control this pest?
One option is to do nothing and let the natural enemies come in and do their job. One of the best is a very tiny wasp that you will likely never see. This parasitoid lays its eggs only inside aphids. The wasp larva feeds on the inside of the aphid and turns it into a round brown ‘mummy’ and then emerges when mature by making a round hole in the top of the aphid. Look closely with a hand lens at some of those brown aphids on your milkweed and you can see this amazing process. Another common predator I see in my own garden is the larvae of the hover fly or syrphid fly. You will have to look hard to see it, but it is usually there. Assassin bugs and lady beetles also commonly feed on aphids. The larvae of lady beetles look nothing like the adults but also are voracious predators of aphids – check out what they look like.
Lady beetle larva feeding on aphid on tobacco. Photo credit:
Lenny Wells University of Georgia Bugwood.org.
If you think your situation requires some sort of intervention to control the aphids, first check carefully for monarch eggs and caterpillars, keeping in mind that some may be very small. Remove them, shoo away any beneficial insects, and spray the plant completely with an insecticidal soap product. Recipes that call for dish detergents may harm the waxy coating on the leaves and should be avoided. The solution must contact the insect to kill it. Always follow the label instructions. Soap will also kill the natural enemies if they are contacted. One exception is the developing wasp in the aphid mummies – fortunately, they are protected inside as the soap does not penetrate. Oils derived from plants or petroleum can serve the same purpose as the insecticidal soap.
Syrphid fly larva and oleander aphids. Photo credit: Lyle Buss, University of Florida.
You also can squish the aphids with your fingers and then rinse them off the plant. If you only rinse them off, the little pests can often just crawl back onto the plant.
There are systemic insecticides, like neonicotinoids, that are taken up by plant roots and kill aphids when they start feeding on the plants. However, those products also kill monarch caterpillars munching on the plant and harm adult butterflies, bees, and other pollinators feeding on the nectar. So those products are not an option. Always read the product label as many pesticides are prohibited by law from being applied to blooming plants as pollinators can be harmed.
In the end, consider tolerating some aphids and avoid insecticide use in landscape.
Happy butterfly gardening!