by Mary Salinas | Feb 16, 2016
As you have read in other articles in this blog, it is too early to fertilize your lawn; however, this is a good time to start fertilizing your citrus to ensure a healthy fruit crop later in the year.
Orange grove at the University of Florida. UF/IFAS photo by Tara Piasio.
Citrus benefits from regular fertilization with a good quality balanced citrus fertilizer that also contains micronutrients. A balanced fertilizer has equal amounts of nitrogen, phosphorus and potassium such as a 6-6-6, 8-8-8 or a 10-10-10. The amount of fertilizer to be applied will vary on the formulation; for example you will need less of a 10-10-10 than a 6-6-6 as the product is more concentrated. Always consult the product label for the correct amount to use for your particular trees. Fertilizer spikes are not recommended as the nutrients are concentrated in small areas and not able to be widely available to all plant roots.
The number of fertilizations per year will vary depending on the age of the tree. Trees planted the first year need 6 light fertilizations that year starting in February with the last application in October. In following years, decrease the number of fertilizations by one per year until the fifth year when it is down to 3 fertilizations per year. From then on, keep fertilizing 3 times per year for the life of the tree. Good quality citrus fertilizer will have accurate and specific instructions on the label for the amount and timing of fertilizer application.
Fertilizer should be spread evenly under the tree but not in contact with the trunk of the tree. Ideally, the area under the drip line of the tree should be free of grass, weeds and mulch in order for rain, irrigation and fertilizer to reach the roots of the tree and provide air movement around the base of the trunk.
If you have not in recent years, obtain a soil test from your local extension office. This can detect nutrient deficiencies, which may be corrected with additional targeted nutrient applications.
For more information:
Citrus Culture in the Landscape
by Matthew Orwat | Nov 17, 2014
Tuesday November 19th and Wednesday November 20th, substantial freezing weather is expected
How cold does it have to get before citrus in Northwest Florida needs to be protected? A concrete answer to this question does not exist. Growers and home gardeners alike must consider several factors including type of citrus grown and the location of the citrus.
Below are a few quick facts to assist growers and home gardeners in determining whether to protect or not to protect their citrus:
- Certain citrus trees such as lime, pomelo, grapefruit, sweet orange, lemon and citron will definitely need protection or need to be moved into a sheltered area. Individuals that grow these types on a consistent basis either wrap their trees with protective covers each season or grow them in containers and move them into greenhouses.
- The meyer lemon, which is in reality a lemon-sweet orange hybrid, is a tree that was introduced to the united states in 1908. Mature dormant meyer lemons can be hardy down to 20°F, with fruit hardy to 26°F. Immature trees, or those that have not reached dormancy, should be protected. Covers made of cloth should be large enough to touch the ground so that heat from the soil can help keep the tree warm.
- Generally, satsuma are cold tolerant down to 15° F, but young trees or trees yet to achieve dormancy are usually only tolerant to 26°F. Fruit should not sustain damage from freezing temperatures above 25°F. Extreme winds sometimes make the effects of freeze events worse, so it is always better to err on the side of protection if the trees are planted in an exposed site.
- Kumquats are the most cold tolerant citrus type grown in Northwest Florida, so protection is not required unless freeze events reach 20°F.
Additional facts to assist the grower or home gardener with citrus protection:
- Plant trees on a south-facing slope, south of windbreaks, on the south side of a structure or under a light canopy if possible. South facing slopes block harmful cold winds. Structures offer radiant heat which aids in the protection of citrus trees. Additionally, light over-story pine canopies allow sufficient sunlight through while reducing frost damage.
- Wrap the trunk with commercial tree wrap or mound soil around the base of the tree up to 2 feet. This will protect the graft of the young tree. Thus, if the branches freeze the graft union will be protected.
- Cover the tree with a cloth sheet or blanket. For additional protection, large bulb Christmas lights can be placed around the branches of the tree. This will increase the temperature under the cover by several degrees. Be sure to use outdoor lights and outdoor extension cords to avoid the potential of fire.
- Water citrus trees. Well watered trees have increased cold hardiness. Do not over-water. If the ground is moist, it is not necessary to water.
- Frames may be installed around young trees to hold the cover. This option keeps the blanket or sheet from weighing down the branches.
- For large production areas, micro-irrigation is an option. This practice will protect citrus trees up to 5 feet, but must be running throughout the entire freeze event. For additional information read this publication on micro-sprinkler irrigation.
- Always remember to remove cold protection once the temperature rises so that the trees do not overheat.
- Do not cover trees with plastic tarp, these will not protect the tree and can “cook” the tree once the sun comes out.
For additional information, contact your local extension office.
by Roy Carter | Oct 28, 2014
Split citrus fruit. Image credit UF / IFAS
Citrus trees require a lot of care and attention to produce good quality fruit, yet even the most careful gardeners may run into the problem of split-fruit on their citrus trees. Split-fruit is a condition which strikes citrus trees in September and October and can wipe out a hundred or more fruit on a single tree. Researchers at the University of Florida have been studying fruit splitting for many years. Clear cut causes or solutions have not been found. My information on fruit splitting was provided by Extension Fruit Crop Specialist, Dr. Pete Andersen with IFAS located at Quincy, North Florida Research and Education Center.
Researchers have found that certain varieties of citrus tend to split more often than other. “Sweet Oranges” Tangelos” and certain varieties of Satsuma’s tend to split more than citrus which is not sweet. Grapefruit and acid fruits, such as lemons and limes rarely split.
The condition is known to be more common in seedlings and young trees than in older, more settled trees. However, split-fruit can be a very serious problem when it occurs on mature trees, because they usually have more fruit to lose.
Another condition which will cause fruit to split is insufficient copper in the soil. This used to be a much greater problem than it is today, due to the wide-spread use of copper in most fertilizer and spray programs. Potassium deficiency results in small, firm fruit with thin peels and increased fruit splitting. However, added potassium doesn’t correct splitting related to citrus varieties.
The most commonly held belief is that fruit splitting is caused by climatic conditions, since it only seems to occur at one time of the year. During the late summer and high humidity, followed by periods of drought. After a series of heavy rains, the trees absorb a great deal of moisture and force it into the fruit. Since the fruit is near maturity, the rind becomes less pliable and can’t expand rapidly enough to absorb the great volume of water from the trees. As a result the fruit splits.
Despite these findings, there are numerous cases of fruit splitting that doesn’t appear to be related to any of the above conditions. When the cause of the split is not fully understood, there is not absolute method of control. Also, there is no way to stop fruit splitting while it is occurring. The problem must be prevented before it starts. Attempts to control splitting through irrigation practices, fertilization and growth regulators have met with some success.
Fertilizer and irrigation practices won’t cure splitting, but may help to avoid large increase in the number of split fruit. In addition, growth regulators are available which can thicken the peel of the orange. Thicker peels have been found to split much less often that the thinner peels, due to their ability to withstand extra water pressure during the critical moths of the year.
If fruit splitting is a problem this year follow a recommended fertilizer program next year. This will insure a good supply of minor nutrients, especially copper. Make sure to keep the trees well watered during the dry periods of late summer and early fall. This will keep the fruit from swelling too rapidly, and splitting as a result.
by Mary Salinas | Mar 12, 2014
Delicious citrus! Photo by UF IFAS Thomas Wright.
All varieties of citrus – grapefruit, lemon, tangerine, kumquat and orange – are a vital part of our lives here in Florida. We love to grow citrus in our yards so that we can harvest the fruit fresh from the tree. On a wider scale, the citrus industry has a $9 billion annual impact on our economy providing over 76,000 jobs statewide.
But there are threats to our dooryard and commercial citrus from pests and disease. Only vigilance will help to combat the challenges so that we may continue to grow and enjoy our beloved citrus trees.
What can we do to protect our citrus?
- Learn about how to properly care for citrus and the pests and diseases that occur.
- Report any serious diseases like suspected citrus canker or citrus greening to the Division of Plant Industry by calling toll-free 1-888-397-1517.
- Purchase citrus trees only from registered nurseries – they may cost a little more but they have gone through an extensive process to remain disease and pest free. That will save you $$ in the long run!
- Don’t bring plants or fruit back into Florida – they may be harboring a pest!
- Citrus trees or fruit cannot move in or out of the State of Florida without a permit. This applies to homeowners as well as to the industry in order to protect our vital dooryard trees and citrus industry.
For more information please see:
Save Our Citrus Website
UF IFAS Gardening Solutions: Citrus
Citrus Culture in the Home Landscape
UF IFAS Extension Online Guide to Citrus Diseases
Your Florida Dooryard Citrus Guide – Common Pests, Disease and Disorders of Dooryard Citrus
by Larry Williams | Jan 27, 2014
This week, Northwest Florida is once again receiving some bitter cold temperatures. The freezing weather two weeks ago resulted in some cold damage to some local citrus trees. Cold injured citrus trees can take a while to become evident.
Citrus in freezing weather, under protective microsprinkler irrigation. Image Credit Doug Mayo UF IFAS
What appears to be damage will not always be permanent. Never be in a hurry to remove cold injured tissue from a citrus tree. Citrus, especially Satsuma, can be very resilient and will often re-sprout on injured tissue. Pruning before this can happen can remove fruit producing branches. Leaves on a freeze-damaged citrus tree will be hard and brittle.
If freeze damage is severe, the leaves will collapse, dry out and fall from the tree. It’s normal for leaves to take on a wilted or drooping appearance during periods of low temperatures. Don’t confuse this with freeze damage. Frozen leaves will not be wilted – they will be hard and brittle. Freeze damage can also cause the trunk and larger branches to split and the bark to become loose. Twigs and branches may continue to die for up to two years following a severe freeze.
Unless the soil becomes dry, be careful to not water cold injured citrus trees during warm periods that often follow freezes. This will delay the tree’s growth and keep the tree in a more dormant state. However, it is important to not let citrus trees go totally dry, because this will increase freeze damage. Later on, if you see that the damaged tree is putting on new growth, it’s okay to give it a little water.
It is best to not prune or fertilize citrus trees during fall and winter.Delay pruning of damaged limbs until late spring or summer because it’s difficult to determine the extent of damage until spring growth takes place. Pruning also may encourage new tender growth during the cold season.
If it appears that you’ve lost half the tree in a freeze, you’ll only need to apply about half as much fertilizer. If you have the situation where many leaves were lost but twigs and branches were not injured, you’ll need to slightly increase the amount of fertilizer. Fertilization should begin after new growth has occurred come spring. It’s a good idea to make frequent light applications rather than one heavy application.
Fertilizing your lawn during fall and winter may not only be damaging to your lawn but it can potentially cause cold injury to your citrus trees, as well. The roots on trees (including citrus) extend two to three times beyond the tree’s branches. As a result, citrus tree roots grow out into the lawn. Tree roots in the lawn are shallow. So, late applications of lawn fertilizer will impact your citrus trees as well. Your lawn and citrus needs ample time to use the fertilizer but yet still have time to go dormant before cold weather arrives.
by Blake Thaxton | Nov 25, 2013
Citrus Canker lesions on leaves. Photo Credit: Beth Bolles, UF IFAS Extension – Escambia County
Authors: Blake Thaxton & Mary Derrick, UF/IFAS Extension – Santa Rosa Co. Mikaela Anderson, FDACS Division of Plant Inspection
Citrus canker is a serious disease of citrus trees that was recently confirmed for the first time in southern Santa Rosa County. Canker is caused by the bacterial pathogen Xanthomonas citri subsp. citri. Citrus canker has been a major pest of citrus in south and central Florida. It is economically damaging to the commercial industry and is also problematic to homeowners because it causes premature fruit drop, discolored fruit, and eventually causes the tree to become unproductive.
Canker was first introduced in 1912 into Florida and was declared eradicated in 1933. The disease was found again in the Tampa area on citrus in 1986. It was declared eradicated in 1994, but once again was found in 1995 in Miami. This time, the disease was not successfully eradicated in part because hurricanes made the disease too widespread to control. Despite its prevalence in south and central Florida, this disease has not been known in the Panhandle. The University of Florida and the Florida Department of Agriculture and Consumer Services’ Division of Plant Industry will be assessing the extent of the disease in Santa Rosa County in the coming months.
Lesions growing through the channels formed by the Citrus Leafminer insect. Photo Credit: Beth Bolles, UF IFAS Extension – Escambia County
How might you know if your citrus is infected by canker? One of the best indicators of canker is the presence of lesions, diseased spots, on the upper and lower surfaces of the leaves. The lesions will be raised and have a rough surface and will be surrounded by yellow halos. Similar lesions may be present on the fruit and stems as well.
[important]If you suspect that your citrus trees may have citrus canker please contact the Division of Plant Industry’s Helpline Center at 1-888-397-1517
before taking any action to reduce accidental spread of this disease. [/important]
Lesions formed on the stems. Photo Credit: Beth Bolles, UF IFAS Escambia County Extension
The disease is highly contagious to citrus only and spreads rapidly through wind, rain and via people on their hands, clothes, and tools. Do not transport any plant material that shows symptoms of canker. Decontamination practices should be used when going from one citrus tree to the next. Hand washing with soap and water for 20 seconds or more to eliminate bacterium on the skin should be practiced as well as using alcohol-based hand sanitizer. Pruning tools or other tools that come into contact with citrus should be disinfected by a fresh solution of 1 ounce of household bleach to 1 gallon of water. An old or dirty bleach solution is not able to disinfect because the chemical is no longer active.
[warning]Do Not Move a Plant Infected with Citrus Canker. Please Call your local Extension Office for further instructions[/warning]
For more information on citrus canker:
(The University of Florida IFAS Citrus Canker website provides a photo gallery of disease symptoms & information about the disease)
