What Homeowners Should Know About Greening

The disease citrus greening, sometimes referred to as Huanglongbing or HLB is believed to be caused by the bacterium Candidatus Liberibacter asiaticus. Huanglongbing is Mandarin for “yellow dragon disease” which describes the yellow new shoots sometimes seen in infected trees.

This incurable disease has been in the news a lot over the past several years since it was first discovered in the Homestead area of Florida in 2005. HLB can be spread by an insect called the Asian citrus psyllid (ACP) or by humans through budding and grafting infected material. The ACP has piercing sucking mouthparts that allow it to acquire and transmit the greening pathogen from the vascular tissue of infected HLB hosts to healthy host trees. HLB host plants include all members of the citrus family including ornamental relatives the box orange and orange jasmine. The adult Asian citrus psyllid is widely distributed in tropical and subtropical Asia. Over recent years citrus greening has become a worldwide problem, significantly affecting citrus production in several countries including Asia, Africa, the Arabian Peninsula, and Brazil. Citrus producing areas of the world that remain unaffected by greening are Australia and the Mediterranean Basin.

Progression of citrus greening in Florida

To fully understand the history of progression of citrus greening in Florida we need to go back to 1998 when the ACP was first discovered here. It is believed that ACP arrived in Florida before the citrus greening pathogen did. From the time ACP was first discovered in Florida, it only took three years for the insect to find its way to 31 Florida counties. By the time greening was detected in south Florida seven years had passed. The perfect storm scenario had been created due to the extensive spread and establishment of the ACP throughout Florida. We have all the pieces in place for a tough fight against greening, we have the insect that spreads the disease, we have a favorable environment for the insect to reproduce, and we have plenty of greening infected host trees.

Adult Asian citrus psyllid. Spring 2008 Impact Magazine image. UF/IFAS File Photo.
Adult Asian citrus psyllid. Spring 2008 Impact Magazine image. UF/IFAS File Photo.
Scouting for psyllids and greening in your citrus

To scout for psyllids and greening in your citrus trees look for misshapen new leaves and the immature stage of the insect called nymphs along tender new shoots. The wingless flattened nymphs of ACP range in color from yellow orange to brownish. You will need a magnifying glass to see them well. The presence of immature nymphs can be a good indicator that your trees are being subjected to feeding and greening transmission. By the time you notice a tree is sick it is likely other trees in the area have already been exposed to feeding from infected psyllids. Early stages of greening could be confused with a general lack of vigor or nutritional deficiencies from not enough or the wrong type of fertilizer. Greening infected leaves have a mottled appearance that is nonsymmetrical, in other words if the leaf is folded in half one side is not the mirror image of the other. This is in contrast to nutritional deficiencies that are usually restricted to the interveinal areas of the leaf and match up when the leaf is folded in half along the midvein. Trees become stunted, suffer twig dieback, and produce off season blooms. During the final stages of the disease the fruit becomes misshapen or may remain small and green and taste bitter. When citrus trees quit serving the intended purpose of providing edible fruit or pleasing aesthetics they should be removed. For more information please visit http://edis.ifas.ufl.edu/pdffiles/PP/PP32600.pdf “Frequently Asked Questions About Huanglongbing (HLB; citrus greening) for Homeowners”, http://edis.ifas.ufl.edu/pdffiles/PP/PP32800.pdf “Huanglongbing (HLB; citrus greening) and Nutrient Deficiency Identification”, and For more information please visit http://edis.ifas.ufl.edu/pdffiles/IN/IN16000.pdf “Asian Citrus Psyllid, Diaphorina citri Kuwayama (Insecta: Hemiptera: Psyllidae)”

What homeowners can do to help citrus continue to produce well is pamper their trees by providing optimal growing conditions and supplying a well-balanced citrus fertilizer.

Citrus trees require well drained soil. This means proper site selection for planting and irrigations scheduling to account for rainfall can help prevent root rot pathogens. Homeowners should also consider using horticultural oils to treat to prevent insect infestations on their citrus trees. Horticultural oils work by suffocating insects by clogging their breathing spiracles. It is important to coat both sides of the leaves with oils for effective insect control. Horticultural oils can also prevent insects from laying eggs because their residue leaves leaf surfaces slippery. Horticultural oils are very safe, but caution should be exercised to avoid spraying oils during bright sunny days due to a risk of burning tender leaf tissue. Always follow the label instruction on any product very carefully. For more information please visit http://edis.ifas.ufl.edu/pdffiles/PP/PP33600.pdf “Citrus Tree Care for the Home Gardener in the HLB Era”

Not sure if you have citrus greening or a nutrient deficiency?

Check out this website for some helpful images.

Sol Looker is the Residential Horticulture Extension Agent and Master Gardener Coordinator at the Flagler County Extension Service, University of Florida. For more information email him at lookers@ufl.edu


Posted: January 30, 2018

Category: Fruits & Vegetables, Home Landscapes, Pests & Disease
Tags: Citrus, Greening, Planting, Psyllids


Mimi Vreeland

June 18, 2021

Thank you for your feedback, Frank. Here are a couple of links to our EDIS documents on beneficial insects. The following links include more of the commonly seen beneficial insects: https://edis.ifas.ufl.edu/topic_beneficial_insects and https://mrec.ifas.ufl.edu/lso/BANKER%20IST/Beneficial%20Insects%202.pdf that you can cut and paste into your browser. Though not an exhaustive compilation, they are a good start for identifying beneficial insects in your garden. Have a great day!

Frank Ebersold
June 18, 2021

Many thanks, that information is a real eye opener and I'm sure there are more beneficial insects out there. Do you have a reference guide, thanks, Frank..

Ilana Shimmel

December 8, 2020

Hello! Participants must be a member of 4-H or FFA to show in the fair.

Nancy Swinderman
December 7, 2020

Do you have to be a member of 4H to enter chickens in the fair? My granddaughter raises hens and would like to participate

Maia McGuire

November 19, 2020

Hi Lauren, I've checked with some of our plant restoration experts and they say there probably isn't anything that you can do to improve the chances of recovery, but that the plants are surprisingly resilient, so hopefully most will do just fine given a little time...

Lauren Levy
November 17, 2020

I am a homeowner in Pinellas County. We lost about 40% of our summer planting during Tropical Storm Eta. Is there anything you recommend we do for the remaining plants to help them recover, or is best to leave them alone, and let Mother Nature take care of it?

November 7, 2020

Leroy was a household name in global aquaculture in the 1980s and 90s, serving as President of the World Aquaculture Society in 1994 when I was a graduate student in Germany and in the UK. Someone who knew so much and gave so much his whole life. Rest in Peace, Leroy!

Carol Roberts
November 7, 2020

LeRoy joined our St. Lucie Extension office in the year 2000 and was an instant fit with our crew. He amazed us with all the projects he was involved in already and then he added more. He made sure we all got some of the farm raised shrimp from the IRREC project next door! He always spoke so proudly of his wife and daughters. He will be missed.

Bob Glazer
November 7, 2020

LeRpy was a colleague but even more importantly, a very close friend. I find myself constantly thinking that I need to call him to talk about something that just happened. He has left a hole in my heart that will be there forever. Sleep well, amigo.

Maia McGuire

August 10, 2020

I'm afraid we are not able to help you find buyers for the saw palmetto berries.

Cheyanne Jones
August 8, 2020

Who do i sale these berries to

Mimi Vreeland

July 13, 2020

Hello, Marilyn. Yes, we do! Please go onto our website at flagler.ifas.ufl.edu and look for the updated blog posting about our Thursday Plant Clinic. There is a zoom registration link at the top of the announcement just below the title. Just click on that live link and a Meeting ID and password will be sent to you. This is the same ID and password for the whole month of July. We look forward to seeing there and please pass the word on to other friends or neighbors that would like to attend our virtual plant clinic.

Marilyn Munoz
June 29, 2020

do you have a zoom class for July?

Maia McGuire

June 23, 2020

Sorry, I do not know of any opportunities for obtaining free sea oats or other dune plants...

Robert La Barbera
June 23, 2020

does the state provide free plants

Maia McGuire

February 3, 2020

Hi Gerry, I am going to forward your question about funding to my colleague Erik Lovestrand in the UF/IFAS Extension Franklin County Office (elovestrand@ufl.edu) as he may be more aware of support that might be available in your area. The manual "Dune Restoration and Enhancement for the Florida Panhandle" might also be of interest--you can find it at https://edis.ifas.ufl.edu/pdffiles/SG/SG15600.pdf. It recommends planting sea oats between December and April, with preferred dates being in March and April. Maia McGuire

February 2, 2020

We are also trying to restore the dunes and sea oats on a section of Carrabelle Beach on the Gulf Coast near Apalachicola after Hurricane Michael leveled the dunes and the sea oats. Are you aware of any local, state or federal programs to help on the purchase of the sea oats. We have already done a lot of work on the first steps to reestablish the sand dunes. Also, what is the best time to plant? THANKS for any suggestions you might have.

Maia McGuire

September 21, 2019

Hi Jack, sorry for the delay in responding--we are in the process of hiring a new horticulture agent. I am not sure why the link did not work for you--it is correct. Flagler County is considered to be outside the growing area for mangoes, although that could change as temperatures warm. Currently the northern limit for growing is Merritt Island (Brevard County). See https://edis.ifas.ufl.edu/pdffiles/MG/MG21600.pdf for more information.

Jack Kimball
August 10, 2019

Link for growing peach trees doesn't work. Also, how do you grow mangoes ? This is for Flagler county - central Fl. Jackkimball126@gmail.com (757) 693-1207 Thank you, Jack Kimball

Maia McGuire

July 30, 2019

Great to hear that!

July 30, 2019

Thank you for this article. St George Island here. I followed your suggestions, including the use of hydrating polymer (despite having been discouraged from using this material by others). Planted 1200 liners over about 1 month. Last plantings dome about 6-8 weeks ago. 97-98% survival rate with great majority thriving!

Jim Kasserman
July 7, 2019

Your article here is the helpful I've found anywhere. Thank you.

Maia McGuire

April 8, 2019

The answer somewhat depends on the quantities you will be needing--there are a few wholesalers listed on the Florida Association of Native Nurseries' website. However, they only sell wholesale. If you are looking for a retail outlet, there are a few retailers listed here. You may also be able to work with a local nursery and have them purchase from a wholesaler and then re-sell them. The sources listed on the websites may not be the only ones (the websites only list members of the Association of Native Nurseries), but they are a good starting point. I hope this helps!

Maia McGuire

April 8, 2019

Pages 77-78 of the publication, Dune Restoration and Enhancement for the Florida Panhandle​, might be helpful!

Jim Kasserman
April 8, 2019

Any advice on propagation from local seeds to replenish hurricane depleted dunes ?

April 7, 2019

I am looking to purchase sea oatsplants for doing restoration in Gulf County, Fl. affected by hurricane Michael if you know of any suggestions where I could purchase these, thanks

Wendy Mussoline

March 7, 2019

Hi...Thanks for the heads up...I'll pass that on to our website team...

March 7, 2019

Hello there, I do think your site could possibly be having internet browser compatibility issues. Whenever I liok at your web site in Safari, itt lookjs fine but when opening in Intfernet Explorer, it's ggot some overlapping issues. I merely wanted to give you a quick head up! Besides that, wonderful website!

Maia McGuire

January 7, 2019

Hi Janet--you might want to check out some of the activities on the K-12 page at www.plasticaware.org. Unfortunately there is no simple answer, and there is always the risk of making the problem seem so big that people may feel hopeless to do anything. I think it's best to focus on small acts--if every student in the class did not use one straw a week, for example. In a year, each student would have prevented 52 plastic straws from being thrown away. For a class of 20 students, that's 1,040 straws! This may help them realize that one person can make a difference, and if they can get others to take simple actions, their efforts will be multiplied greatly! Feel free to contact me directly at mpmcg@ufl.edu.

janet stull
January 7, 2019

I'm an elementary art teacher in central Pennsylvania and would love some hints, tips or classes on how to reach our kids about the need to act. I talk about it and we recycle and make art using recycled objects - I just feel that I could use some ideas. Thank you, Janet

Maia McGuire

October 6, 2018

Hi Jack. That's a great question. The thought seems to be that the population of pteropods increases based on food availability. Winds and currents can affect where the pteropods are located and whether (and when) the shells will get washed up on beaches. It isn't an uncommon occurrence in Florida (considering the state as a whole), but often occurs over a relatively small stretch of beaches at a time. The shells can wash back into the ocean with subsequent tides, so they may only be apparent on a particular beach for a few days.

Jack Putz
October 5, 2018

Great explanation, but why are there so many on the beach...I've never seen them before...what happened or what is happening?

Maia McGuire

September 7, 2018

Whether or not you need a permit (in Florida, the permits come from the Department of Environmental Protection) depends on the size of the area to be planted, whether or not a sprinkler/irrigation system will be installed, etc. You may be required to coordinate with the local sea turtle patrol if planting will be done during sea turtle nesting season (to ensure no damage is done to nests that may be in or near the area to be planted. You can find your local DEP contact at https://floridadep.gov/water/coastal-construction-control-line/content/district-field-representatives-contact-list. That person will be able to advise you as to whether or not you need a permit (and if so, how to go about obtaining one).

Mary bruce
September 6, 2018

Do you have to have a permit to plant sea oats?

Maia McGuire

August 7, 2018

Hi Nancy, There is one retailer near you listed with the Florida Association of Native Nurseries (www.afnn.org). 7 Pines Native Plant Nursery is in Defuniak Springs, and it sells sea oats in gallon pots, according to the website. There may be other retailers who carry sea oats but are not members of that association. Hope t his helps!

nancy Roberts
August 5, 2018

I live in okaloosa county and would like to get some sea oat plants...where would that be possible?

Anna Eppinger

February 9, 2018

It is worth the trip! Be sure to get there early - it fills up fast and you'll see lots of other wildlife in the morning :)

Maia McGuire

February 7, 2018

I am glad you found it useful :)

February 6, 2018

Maia, Thank you so much for this valuable information.

Amy Taff
February 2, 2018

Wow! I’m packing my bag for a visit. I had no idea you would be able to see so many manatee in such a short distance. It’s also so exciting to hear about our youth being able to see these creatures in person. Certainly this experience will be a meaniful memory. Thank you for the post!

Maia McGuire

February 2, 2018

Thanks for your question, Cindy. We have added a link at the bottom of the post to a website that has some images. Hope that helps!

Cindy Triay
January 31, 2018

Thank you very much for all this information. Can you provide pictures of what you describe of on the infected trees?

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