by Matthew Orwat | Nov 18, 2013
On the night of November 13th, a mild freeze of 30°F occured in parts of Northwest Florida. Don’t be caught without a citrus protection plan !
Satsuma Tree protected with micro-irrigation. Image Credit: UF IFAS Jackson County Extension
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 Mary Salinas | Nov 4, 2013
For centuries, people annoyed with plant pests have used oils to control insects, mites, and even some fungal diseases. Current oil products are better than ever!
Sample oil products for pest control. Photo by Mary Derrick.
Commercially available horticultural oils are mineral oils from refined petroleum products. Impurities are removed and then an emulsifying agent is added that allows the oil to mix with water for application. Neem oil is a newer product that has become increasingly popular; the oil is an extract of the seeds of the neem tree.
What are some of the advantages of using an oil for pest control?
- Oils are inexpensive and easy to apply
- Oils can be used on most plants (check the label for a list!)
- Oils control a wide range of pests that feed on plants (again, check the label for a list of pests the product will control!)
- Oils pose a low risk to people, pets, and desirable beneficial predators
- Since oils kill pests by blocking their breathing holes (spiracles) and/or gumming up their mouthparts, there is no chance for resistance to develop
- One product can control both insects and some diseases like powdery mildew at once
- Oils can be combined with some other pesticides to provide greater control
[warning] Don’t combine with, or use within 30 days of, any sulfur based pesticide. The combination can harm your plants![/warning]
There are always drawbacks to a product. What are the drawbacks?
- Some plants (including cryptomeria, junipers, cedars, maples, and redbud) are damaged by oils – check the label!
- Ensure good coverage during spraying as pests must be contacted with the oil in order for the control to work
- Oils break down quickly and reapplication may be necessary
- Check the label for instructions on the temperature range when it can be used. Older formulations generally are safe when temperatures are in the 40 to 80°F range but ultra-fine oils can generally be safely applied during hotter weather.
For further information:
Natural Products for Insect Pest Management from UF IFAS Extension
Insect Control: Horticultural Oils from Colorado State University Extension
Less Toxic Pesticides from Clemson University Cooperative Extension
by Matthew Orwat | Feb 15, 2013
According to the National Weather Service a mild freeze is predicted for Northwest Florida this weekend, specifically Saturday night to Sunday morning. Washington County Horticulture extension agent Matthew Orwat says,” While mature, dormant Satsuma trees are cold hardy down to 14° – 18 °F, young trees need protection if temperatures dip into the upper 20s.”
Photo Credits David Marshall
Here are a few techniques to protect young citrus trees from late-season freezes:
- 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 may 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 your Satsuma trees. Well watered trees have increased cold hardiness.
- Frames may be installed around young trees to hold the cover. This option keeps the blanket or sheet from weighing down the branches.
- For homeowners with lemon, lime or other less cold hardy citrus, 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 click here.
- Always remember to remove cold protection once the temperature rises so that the trees do not overheat
- Do not cover trees with plastic tarps, these will not protect the tree and can “cook” the tree once temperatures rise.
Please see the following publications by retired UF / IFAS Extension agents Theresa Friday and David Marshall for additional information regarding freeze protection of citrus.
