by Mark Tancig | Jan 13, 2022
Asian citrus psyllid, Diaphorina citri. UF/IFAS/Entomology Photo: Michael Rogers.
In late 2016, as many of us were enjoying the harvests from our backyard citrus, a bacterial plant disease that can affect all citrus, citrus greening, was widespread in central and south Florida but had not made it this far north. That year, the vector, the insect that spreads the disease from tree to tree, had been found in Leon County and a few other surrounding Panhandle counties, but the disease had not. By mid-2017, the disease had been confirmed in Franklin County and we hoped that our cooler temperatures could keep the insect and disease at bay. Well, I regret to inform you that the disease has also now been confirmed in Leon County, growing in a residential yard in Tallahassee. Now that it is confirmed in non-coastal (and cooler) north Florida locations, I thought a review of the signs and symptoms – as well as what to do with your tree if you suspect or confirm greening – would be helpful.
The tricky part about diagnosing citrus greening is that it has symptoms that look very similar to soil nutrient deficiency symptoms, especially when first infected. This is a good time to mention that citrus require certain micro-nutrients for optimal growth and a citrus-specific fertilizer product should be used when applying fertilizer. Both the disease and certain nutrient deficiencies cause yellowing of the leaves. With greening, the yellowing is typically blotchy and/or not in any particular pattern. Nutrient deficiencies typically cause unique patterns of yellowing, such as a V-shape or artistic-like symmetrical patterns on each side of the leaf’s midvein. The soil’s acidity, or pH, can also cause some nutrients to not be taken up by the plant even if they are present. Soil testing, available from your local UF/IFAS Extension office, and scheduled fertilizations with a citrus-specific fertilizer can ensure that nutrients are not to blame for the discoloring of leaves. More advanced stages of the disease cause such symptoms as leaf drop, fruit drop, lop-sided fruit, uneven inner fruit cores, and reduced fruit quality.
Citrus greening symptoms of the fruit. Photo by Brooke Moffis.
A more obvious sign of potential problems for your citrus are the presence of the insect vector, the Asian citrus psyllid. This is a tiny little insect that goes from one leaf to the other sucking up plant saps for food and unknowingly spreading the bacterium responsible for citrus greening. You can monitor for them by looking closely at the new flushes of growth. If the psyllids are present, you will likely notice most their small, peach-colored eggs and/or white, waxy secretions. If found, it doesn’t necessarily mean that your tree has greening, but you will want to minimize the chance that they could carry it to your tree. The psyllids can be treated with pesticides, ranging from the less harsh options (horticulture oils, neem oil, kaolin clay) to the more hardcore stuff (malathion, carbaryl, imidacloprid). Of course, always read the label of any pesticide before use and/or consult a qualified landscape professional for assistance.
Blotchy leaf symptom of citrus greening. Photo by Jamie D. Burrow.
If you suspect your tree is infected, a diagnostic test can be performed by UF/IFAS plant pathologists at the North Florida Research and Education Center (NFREC) in Quincy to confirm. The test does cost $50, which may seem a little steep, but it’s an expensive lab analysis to run and may be worth piece of mind.
If citrus greening is confirmed in your tree, the right thing to do, unfortunately, is to remove and burn the plant material as there is no known cure. While the Florida Department of Agriculture and Consumer Services (FDACS) doesn’t have any removal requirements for infected dooryard citrus, tree removal is best to prevent additional spread of the disease to other trees, especially those grown by commercial producers in our area. This may seem drastic but eventually the health of the tree and quality of the fruit will decline to a point where you will want to remove it anyway. Don’t forget that movement of any citrus plant outside of the state is prohibited for the very reason of preventing spread of citrus diseases.
You may be asking, “Is it okay to replace it with another citrus tree?” The answer is yes you can, but you do risk re-infection and will want to be monitoring the new planting.
You may also be thinking, “What is going to happen to Florida citrus?” That’s a question that many researchers at UF/IFAS are trying to answer. There is some hope that intense irrigation and nutrient management, as well as specific pruning practices, can help infected trees continue to be profitable for commercial growers. Recently, UF/IFAS researchers were awarded several grants to try and figure a way out of this problem. Some of the lines of research focus on exploring the resistance found in different citrus varieties, including an Australian lime that appears to be greening resistant. This could potentially be used as a future rootstock. Another approach is to try and treat the plants with a particular peptide that would prevent the disease from binding in the insect’s gut. Isn’t that amazing?
Until a fix is found, we should be monitoring for this disease in our area and taking steps to reduce its presence through controlling the psyllids and removing infected trees. If you suspect a tree has greening, please contact your local county Extension office to review the symptoms and discuss your options.
Much more information on citrus greening is available at the following Ask IFAS website: https://edis.ifas.ufl.edu/entity/topic/citrus_greening and from this 2017 article – https://nwdistrict.ifas.ufl.edu/phag/2017/03/03/disease-alert-citrus-greening-and-asian-citrus-psyllids-found-in-the-panhandle/.
by Ray Bodrey | Jan 13, 2022
January and February are typically the coldest months in Florida. Low temperatures can damage even the more cold-hardy plants. However, there are measures that can be done to help cold-damaged plants recover.
After a frost or freeze, see if your plants are dry. Even injured plants need water. Plants can be greatly damaged if the temperature drops suddenly, as they have no time to acclimate to the freezing temperatures. These freezing temps cause ice crystals to form in plants cells. These crystals expand, rupturing the cell walls and preventing the plant from maintaining shape. If severe, this can certainly kill tender plants. On more cold hardy plants, damaged foliage will appear wilted and curled down. In a few hours or days, it will darken and turn black. Flowers, buds, and new growth often dieback under freezing temps.
After freezing temperatures occur, it’s important to remove damaged leaves and flowers as soon as they turn brown or black. This will help prevent diseases from occurring. Pruning should be postponed until cold temperatures are no longer expected and new growth begins to appear on the plant. This practice ensures live wood, which appears dead from losing its leaves, is not mistakenly removed from the plant. Cold damaged wood can be detected by examining the cambium layer (under the bark) of the plant. If it has black or brown discoloration, it is damaged and should be pruned back behind these points. Plants should be fertilized in the spring, to encourage new growth.
Cold damage. Photo Credit: University of Florida/IFAS
What about proactive care? You can accomplish this by moving potted plants indoors and covering tender landscape plants with a protective covering. Protective covering can include old bed sheet, pieces of material or fabric, and cardboard boxes. Be careful not to let the protective covering touch the plants. The surface of the covering will become as cold as the air temperatures and may damage any tender leaves it encounters. Also, don’t forget to remove the covering the next day when temperature raises this is important so the plants do not “bake” in the warmer temperatures. Plants placed near the house, lights, or other structures, which shelter them from wind, will be more protected than those fully exposed to the cold air.
Use frost cloth to completely cover cold sensitive plants. Be sure to make complete contact with the ground and use heavy objects to keep the fabric secure. Photo by Jonathan Burns.
For more information on freeze damage plants contact your local county extension office.
Supporting information for this article can be found in the UF/IFAS Extension EDIS publication: “Cold Protection of Landscape Plants”, by Sydney Park Brown: https://edis.ifas.ufl.edu/publication/mg025
by Larry Williams | Jan 6, 2022
Q. When is citrus fruit ready to harvest?
Satsuma fruit ready to harvest. Photo credit: Larry Williams
A. Florida uses five indexes to determine maturity of citrus, including soluble solids, juice content, acid level, soluble solids/acid ratio and skin color. But, the home gardener can easily decide when most citrus types are ready to be harvested. As the fruit reaches full size and the skin color changes from green to greenish yellow to orange, simply pick some fruit and taste it to see if it is sweet. If not, wait a little longer (a week or two) and taste test another fruit. Meyer lemons are ready when the skin color changes from green to greenish yellow. Satsuma fruit may be ready to eat before the skin becomes completely orange, especially if the early fall is warm. Kumquats are usually at their peak in taste when they become fully orange.
Citrus fruit does not ripen additionally after it is harvested. So, let it mature sufficiently on the tree.
Harvest season for satsuma is October to December. Harvest season for Meyer lemon is November to March. Harvest season for kumquat is November to April. Most grapefruit have a harvest season from November to May. Harvest season for sweet oranges varies. Early season oranges are harvested October to January, mid-season oranges are harvested December to February and late-season cultivars are harvested March to June. Citrus fruit may mature a little earlier in the harvest season on mature trees and more toward the end of the harvest season on young, vigorous trees.
Q. What cold-hardy citrus is best for North Florida?
A. Citrus species are tropical and subtropical in origin. As a result, citrus is not well suited for extreme North Florida. Commercial citrus production has progressively moved further south in Florida due to historic freezes. So, you’d be wise to choose the more cold-hardy citrus types for our area. But, even cold-hardy citrus can be severely injured or killed by a hard freeze in North Florida.
Some of the better choices for cold-hardy citrus in North Florida include kumquat, satsuma, calamondin and Meyer lemon. There has been some success with grapefruit and sweet oranges in our area. Lemon and lime are much less likely to survive in North Florida. There has been some discussion concerning future success with growing citrus a little more north in its current range related to climate change. There already has been some success with growing the more cold-hardy citrus types such as satsuma and kumquat in middle Georgia. We’ll see how this works out.
More information on cold-hardy citrus is available from the UF/IFAS Extension Office in your County and through this link. https://crec.ifas.ufl.edu/extension/trade_journals/2018/2018_june_coldhardy.pdf
by Matt Lollar | Jan 6, 2022
A mixed vegetable garden. Photo Credit: eXtension.org.
It’s never too early to start thinking about your spring vegetable garden. Have you ever wondered how much it costs to grow your own vegetables? Does it cost less to grow your own vegetables or buy them from the grocery store or farmers market? A number of factors are involved with answering these questions and budgeting for your home garden.
Materials
The materials used are specific to your own vegetable garden. If you do everything by hand you may need a hoe, rake, and spade along with a number of other tools you can use from year to year. When budgeting for you garden you would need to think about the life expectancy of these tools. Let’s say a $20 rake lasts for 10 years. In that case, you would budget $2/year ($20 ÷ 10 years = $2/year) for the rake. This might also be the case with a bag of fertilizer. You may buy a 50 pound bag of fertilizer and use half the bag in year one and the other half in year two, so the cost of the fertilizer would be cut in half for your yearly budget. Other materials may be purchased for just one growing season such as pine straw for weed suppression or you may buy only enough seeds for the season.
Labor
A lot of work goes into growing your own vegetables. If you have the time and enjoy gardening then you may choose to charge yourself nothing for your work. However, from a cost analysis perspective you may want to put a value on your work. This will give you a better comparison to buying vegetables.
Budgets
Of course you could create your own budget based on all the costs that go into gardening. But why do that, when it’s already been done for you. The UF/IFAS Costs and Benefits of Vegetable Gardening publication includes a Microsoft Excel Cost Workbook to help answer some of these cost questions. This budget template is customizable, so it’s important that you consider all the costs for your vegetable garden. If you are looking for more detailed crop budgets, there are a lot of North Florida Enterprise Budgets available from UF/IFAS.
by Matt Lollar | Dec 16, 2021
Trees provide shade, aesthetics, and perspective to the landscape. However, they only serve as burdens if not properly selected and maintained. To help determine what trees do best under certain conditions and to provide information on tree care, this month’s Gardening in the Panhandle LIVE! was all about trees.
Florida maple beginning to exhibit fall color. Photo credit: Larry Williams, University of Florida/IFAS Extension – Okaloosa County
Tree Selection
Some trees grow faster than others. That’s not always a good thing, but if you’re trying to select a tree that grows fast and will provide shade in your yard then you might want to give the following species a try. Click on the links for more information.
A lot of times you’ll read a particular tree species prefers moist, well-drained soil. Some coastal soils are very well drained and require supplemental irrigation after establishment to keep some species alive. One tree that does well in sandy, well-drained soils without supplemental irrigation is the sand live oak. Another tree, that would never win a popularity contest, but does well in sandy soils is the sand pine. This tree has a gnarly growth habit, which would make it an interesting focal point in the landscape. Turkey oaks are another option for dry spots.
There are a lot of fruit tree species that can be grown successfully in the panhandle. The key to good fruit production is selecting trees that are adapted to the average number of chill hours (usually calculated by the number of hours between 34ºF and 45ºF) your yard receives on a yearly basis. Some peaches, plums, and nectarines have been developed for our climate. Citrus such as satsumas and tangerine hybrids grow well in the panhandle, but sometimes require cold protection. Persimmons, loquats, and pears are other fruit trees that grow well.
If you already have mature trees in your yard, then you may be looking for smaller, understory trees to enhance your landscape.
Living this far south, you often have to really seek out trees that change color in the fall. Dogwoods, Florida maples, and blackgum trees all have great fall color. Some of the red oaks also have nice fall color. Two that come to mind are the nuttall oak and the Shumard oak.
Trees can cause a lot of damage if planted too close to sidewalks or buildings. To determine if a tree will fit in a confined space, you will need to consider its mature trunk flare diameter.
Florida is the southern extreme for growing ginko trees. If you decide to plant a ginko tree, make sure to select a male cultivar to avoid stinky, slippery fruit.
To successfully plant a tree, you need to start with a healthy tree. If the tree you purchase was grown in a pot, make sure it isn’t rootbound and doesn’t have encircling roots. You also should inspect the tree’s form, branching structure, and look for the presence of included bark. Please read “Selecting Quality Trees from the Nursery” for more tips on what to look out for when purchasing a healthy tree.
Some trees are more tolerant than others of high winds and flooding. Please read this publication about tree failure from hurricanes to help determine what tree species are better adapted to these weather events.
Santa Rosa County Master Gardener Pruning a Stone Fruit tree at the WFREC. Photo Credit: University of Florida/IFAS Extension
Tree Maintenance
Armillaria is a common fungal pathogen that infects trees from their roots. Other major diseases are more specific to certain species. A more comprehensive list of tree and shrub diseases can be found on the Ask IFAS website.
Tree establishment period depends on a lot of factors. Once a tree is established, it’s roots can be equal to about three times the distance from the trunk to the dripline.
Part of the beauty of a bald cypress is its knees. However they can also be a nuisance for mowing and other yard maintenance. The purpose of cypress knees is a bit of a mystery and there are a lot of theories on the subject.
Fallen leaves can help add nutrients back to your yard. Even if you are trying for a manicured lawn, you may want to rake up the leaves and use them elsewhere in the landscape.
Regardless of the species, most fruit trees benefit from a good pruning. Deciduous fruit trees should be pruned to maintain good branch structure and form, while citrus may benefit from a light hedging.
Trees are a wonderful addition to any landscape, but it’s important you select the right tree for the right place. Hopefully this article provided some information to guide you in the right direction.
