Post Winter Storm Elliott: Ambrosia Beetles in Citrus

Post Winter Storm Elliott: Ambrosia Beetles in Citrus

Winter Storm Elliott brought freezing temperatures to the Panhandle on December 24th that lasted through December 28th, 2022. While we’ve seen freezing temperatures in years past, none remained below freezing for as long as Winter Storm Elliott did, resulting in significant injury to citrus in our region. Those trees that received significant freeze damage are more vulnerable to pests and diseases. One such pest we are seeing as a result of Winter Storm Elliott, are ambrosia beetles.

Granulate Ambrosia Beetle, Xylosandrus crassiusculus Photo credit: David Almquist.

Ambrosia beetles are a group of wood-boring insects that live in dead or severely stressed trees or dead wood. They are attracted to the odor that the dead/dying trees give off, which is why you may be seeing them now in freeze damaged citrus trees. Once they locate a sick tree, they bore into the lower part of the tree (about 2-3 feet from the ground), creating a tunnel or a gallery. You’ll likely notice sawdust from the galleries at the base of the tree or you may notice a toothpick like protrusion of sawdust at the base of the gallery.

Toothpick like protrusions from ambrosia beetles. Photo credit: Danielle Williams.

Several species of ambrosia beetles are considered true pests that attack living trees, but most species are secondary to another issue. Because ambrosia beetles generally prefer dead or dying trees, they are not typically a problem for citrus trees. If you are seeing signs of ambrosia beetles on your trees, the beetles are likely targeting trees that sustained major freeze damage from Winter Storm Elliott.

Unfortunately, there are no effective strategies to control ambrosia beetles once they attack a tree, so the best line of defense is to keep your trees healthy. Consider the first three UF/IFAS Florida-Friendly Landscape principles for maintaining tree health:

#1 Right Plant, Right Place: Select plants that match the site’s soil, light, water, and climatic conditions. Plants that are well adapted for our region will be lower maintenance and have a better chance of flourishing as opposed to those that aren’t. For information on citrus varieties adapted for our region, please visit: UF/IFAS Evaluating Cold-Hardy Citrus Varieties for the Panhandle | Panhandle Agriculture (ufl.edu)

#2 Water Efficiently and #3 Fertilize Appropriately: Proper irrigation and fertilization enhances plant growth. Over watering or over fertilizing can do more harm than good so it is best to follow UF/IFAS recommendation rates and application timing.

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Choosing the Right Dooryard Fruit Varieties

Choosing the Right Dooryard Fruit Varieties

We have many choices of fruit that can be grown in the Florida Panhandle. For us hobby or dooryard growers, fruit trees can be an interesting crop to manage and most find it to be a beautiful addition to home landscapes. However, temperature and variety selection are key.

Blueberry Crop at UF/IFAS Plant Science Research & Education Unit. Photo Credit: Tyler Jones, UF/IFAS

Most fruit trees grown in the Panhandle are more temperate varieties, rather than tropical and subtropical fruits. Depending on the variety, winters in northern Florida may be too cold or may be too long for some fruit trees. Cold hardiness is a term used on fruit tree labels and reference guides. This refers to the plant’s ability to survive cooler or even freezing temperatures. In contrast, summer heat can also play a role in survivability. Some varieties are intolerant to excessive heat and humidity. The U.S. Department of Agriculture has developed a Plant Hardiness Zone Map that is helpful in selecting a variety of fruit tree: http://planthardiness.ars.usda.gov/PHZMWeb/. This is a standard by which gardeners and growers can determine which plants will thrive in their location. Northern Gulf County is in Zone 8b (15 to 20 degrees F), while coastal Gulf is in Zone 9a (20 to 25 degrees F).

Chilling requirement is another important topic when deciding on variety. Temperate zone fruit go through a “rest period” during the dormant months. For these fruit trees, a minimum length of time of cooler weather is needed for proper flowering to occur once favorable temperatures arrive. This rest period is essentially a reset. For the Panhandle, temperatures below 45 degrees F are known as chilling temperatures. The number of hours during the fall and winter that reach below this temperature equals the total chilling hours. For the Panhandle, this is rarely fewer than 500 hours. A plant that does not receive ample chilling will most likely be slow in bud and leaf development. Leaf expansion will be in increments throughout the year instead of in one period. On the other hand, colder, longer winters can cause fruit trees to end the rest stage early and begin to bud as soon as warmer temperatures arrive. This circumstance can cause cold injury later, as the Panhandle is historically known for late cold spells.

Citrus is a dooryard fruit, however it’s a subtropical fruit tree and not technically temperate. However, there are some varieties that thrive in the Panhandle. Another key to growing citrus, is to select varieties with different fruit maturity seasons. This way you can enjoy citrus year-round.

Some examples of dooryard fruit trees and varieties that are suitable for northern Florida are:

Apple: ‘TropicSweet’, ‘Anna’, ‘Dorsett Golden’

Blueberry: ‘Rabbiteye’, ‘Climax’, ‘Highbush’

Grapefruit: ‘Marsh’, ‘Ruby Red’

Lemon: ‘Myer’

Nectarine: ‘Suncoast’

Orange/Mandarin: ‘Navel’, ‘Parson Brown’, ‘Valencia’, Satsuma

Peach: ‘Gulfcrest’, ‘Gulfking’, ‘Gulfprince’

Pear: ‘Ayers’, ‘Baldwin’, ‘Kieffer’

Pecan: ‘Elliot’, ‘Stuart’, ‘Moreland’

So, where do I find information on varieties? The UF web publication “Dooryard Fruit Varieties” is a great resource. Also contact your local county extension office for more information.

Information for this article can be found in the UF/IFAS EDIS publication: “Dooryard Fruit Varieties” by J. G. Williamson, J. H. Crane, R. E. Rouse, and M. A. Olmstead: http://edis.ifas.ufl.edu/pdffiles/MG/MG24800.pdf

UF/IFAS Extension is an Equal Opportunity Institution.

Citrus Spotlight: ‘Parson Brown’, A Unique Sweet Orange

Citrus Spotlight: ‘Parson Brown’, A Unique Sweet Orange

The Sunshine State produces a wide selection of citrus, with a number of varieties that can be grown right here, in your Panhandle dooryard. And, what is more satisfying than picking fresh fruit from your very own trees? So, are you looking for a different variety to plant? The ‘Parson Brown’ sweet orange may be of interest. It can certainly add uniqueness to your dooryard citrus grove.

Originating in China, orange varieties began being introduced in Europe in the fifteenth century. As for introduction to America, Columbus brought orange seeds to the new world on his second voyage in 1493. The first plantings in Florida were around 1513 in the settlement of St. Augustine. For the ‘Parson Brown’, a chance seedling originated at the home of Reverend N.L. Brown near Webster in 1856. Sumter and Seminole counties are still home to some of the largest densities of ‘Parson Brown’ orange trees in the state.

Parson Brown Sweet Orange

Figure 1: ‘Parson Brown’ Sweet Orange. Credit: D.P.H. Tucker, Ray Bodrey, UF/IFAS.

The Parson Brown, however, is often overlooked. The most popular dooryard sweet orange varieties grown throughout Florida are Navel, Hamlin, Valencia and Pineapple. Availability of this variety in our region is not easily found either, as you may have to search to find a tree.

Unlike the short, round appearance of many citrus trees, the Parson Brown tends to grow tall and slim. The Parson Brown’s more upright tree structure is very distinctive. A specimen will certainly stand out in a grove. The fruit and yield rival a Hamlin orange, particularly when grown in heavy, hammock soils rather than sandy soils with low organic content. The variety is also not as marketable as the Hamlin on a commercial level, due to the heavier seediness. You can expect at least 10 seeds per fruit. Average diameter of fruit is between 2 ½” to 2 ¾”. Harvest season for fruit is generally between October and January. Evidence suggests that along with the ‘Sugar Belle’ variety, the ‘Parson Brown’ may be more disease resistant, specifically more tolerant to citrus greening. HLB or citrus greening is a disease that has devastated both commercial production and dooryard citrus across the state.

Contact your local county extension office for more information. Also, for more information on growing citrus in Florida, see the UF/IFAS Extension EDIS publication, “Citrus Culture in the Home Landscape” by Robert E. Rouse and Mongi Zekri.

UF/IFAS Extension is an Equal Opportunity Institution.

Citrus Choices for the Panhandle

Citrus Choices for the Panhandle

The panhandle of Florida is a great place to grow citrus with our plentiful sunshine and sandy soil. But some varieties do better than others. Here are some that thrive in the more northerly climes of Florida:

Nagami kumquat. Photo credit: UF/IFAS.

Nagami kumquat. Photo credit: UF/IFAS.

  • Satsuma mandarin is cold hardy to 15°F once established. There are a few different available cultivars with fruit ripening October through December. Fruit needs to be picked promptly when ripe.
  • Kumquat is cold hardy to 10°F once established. ‘Nagami’ and ‘Meiwa’ are the two common cultivars of the small tart fruits. Fruit matures in fall and winter and holds fairly well on the trees.
  • Calamondin is a lesser known variety that bears small fruit that resemble tangerines. The tart fruit is great for jams and chutneys. Fruit is borne all year.
  • Some of the sweet oranges that do well in the panhandle are Navel, Hamlin and Parson Brown. They are cold hardy to 14°F once established and are harvested November through January.
  • Minneola or Honeybell tangelo is also hardy to 14°F and harvested in January. This is a cross between a Duncan grapefruit and a Darcy tangerine. This bell-shaped fruit is very juicy and sweet. Unlike the other citrus varieties, it needs another citrus nearby for cross-pollination in order to produce an abundant crop.
  • Meyer Lemon is the choice to make if you would like to grow lemons in the panhandle. Other lemons may be damaged by our occasional freezes.

Grapefruit and lime can be grown – although unreliably – on the coast with protection from northwestern winter winds. They are much more susceptible to freezes in more northerly panhandle locations.

In order to have the healthiest and most productive trees, learn about how to properly care for citrus and how to recognize and combat the pests and diseases that occur.

Citrus canker symptoms on leaves, fruit and stem. Photo by Timothy Schubert, FDACS

Citrus canker symptoms on leaves, fruit and stem. Photo by Timothy Schubert, FDACS

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 citrus. What can we do to protect our citrus?

  • 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. Inspections and diagnosis are free. Citrus canker has been confirmed in south Santa Rosa County in the past 3 years.
  • 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. This rule protects 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