The 5 Most Challenging Invasive Species of 2020

The 5 Most Challenging Invasive Species of 2020

(For the Garden Industry)

For months, I’ve been publishing content hinting at the end of the year. Well, it’s finally arrived, the actual end of the year. So here I am, participating in the annual moment of reflection for perhaps the most controversial and difficult year in recent history. As l look back, all I can think of is how much we’ve overcome. 

This year was nothing short of a challenge and being here today feelings like nothing shy of a miracle. But, looking back at all of the hard work our industry put in to thrive and stay afloat it’s not surprising that more growers and sellers saw upsides rather than downs.

With the ever present threat of invasive species, disease, and pests learning from this past year’s challenges will be just what we need to tackle 2021.

Let’s take a look back at this year’s 5 Most Challenging Invasive Species

#1. The Emerald Ash Borer (Agrilus planipennis Fairmaire)

This pest officially became so widespread this past year, that the USDA has ruled to roll back the quarantine efforts of the invasive species.

This pest officially infests all but 13 states of the contiguous United States of America.

Despite best efforts to quarantine and control the pest, the spread of the beetle has left many states with no other option but to remove the coveted Ash trees from their lands, and discontinue efforts of regulations. 

The new USDA approach hopes to reserve funding and efforts currently used for quarantining the Emerald Ash Borer, so that more effective management can be developed and executed. [1]

#2. Asian Citrus Psyllid (Diaphorina citri Kuwayama or ACP)

This particular pest is always at the top of our list when it comes to terrible, no good, invasive species. As we’ve discussed in some of our previous blogs, the Asian Citrus Psyllid spreads the Huanglongbing (HLB) disease, also known as Citrus Greening, that currently has no cure.

Citrus Greening is responsible for a 21% decline in the fresh citrus fruit market, as well as a 72% decline in the production of oranges as of 2019. [2] The pest and its disease is currently found in 9 states throughout the contiguous United States, all residing within the citrus belt of the U.S. 

The ever growing threat of this pest and the disease it carries is the root of the numerous citrus agreements, certifications, and licenses that are necessary for the Green Industry. Maybe in 2021 we’ll finally be able to get rid of this sucker for good!

#3. Gypsy Moth (Asian & European) 

Besides being my least favorite invasive pest to look at, this pest sure is a doozy!

 It has many technical names. The Asian Gypsy Moth is scientifically identified as “AGM, including Lymantria dispar asiatica, Lymantria dispar japonica, Lymantria albescens, Lymantria umbrosa, and Lymantria post¬alba[3]. The European Gypsy Moth is scientifically identified as “lobesia botrana or EGVM” [4].

See? A doozy. 

But what’s more frustrating about this pest is the way that it invades its host trees and does just enough damage before leaving and making way for more dangerous diseases and pests to kill it off. Some of their trees of choice are Oak trees, Sweet Gum trees, Willow trees, Birch trees, Apple trees, and Boxelder trees. However, there are plenty of other trees they seek. The Asian variety of the gypsy moth eats both evergreen and deciduous tree varieties, while the European variety only targets deciduous trees.

But as if their damage wasn’t enough, these apparently evolved species of moths also are difficult to prevent and control. Their unique “ballooning” method of transfer that their egg sacs can have, allows for them to be carried by wind instead of just flight. 

It was estimated back in 2011 that for the 20 years prior this pest had caused $30 million dollars in damages A YEAR! [5].

#4. Spotted Lanternfly (Lycorma delicatula)

If you follow us on social media @PlantSentry, or frequent our blogs, you’re probably familiar with this pest!

This pest has been around since it was first found in Pennsylvania in 2014. Since then, management efforts against the pest have been challenging to say the least. Part of the difficulty in managing this pest is that their eggs, larvae, and adults easily travel undetected through contaminated material. These materials can include your shoes, firewood, and really anything else they can attach themselves to.

Educational efforts such as Play Clean Go help provide guidance to many of us who unknowingly transfer this pest in our outdoor activities. 

This pest favors grape vines, hardwoods, and fruit trees, but will devor just about any plant. The fruit industry has been particularly impacted by this [6]. So far their cost in damages has resulted in a $50 Million dollar decline throughout the state of Pennsylvania. [7]

Part of this economic decline as a result of the pest has also been 500 jobs lost throughout the state of Pennsylvania. [7]

#5. Kudzu (Pueraria montana var. lobata)

Ah, finally #5, Kudzu! Now here’s a real handful of an invasive species. This guy has been in the U.S. for years, all the way back to 1876, and was an introduced species originally used to help control erosion. Since its arrival this invasive species has become perhaps the most invasive plant species in the U.S.

This plant currently inhabits mostly the Southeastern portion of the country but can be found in 30 states throughout the U.S. 13 of the 50 contiguous states currently list this plant as a noxious weed, although it is no longer a federally listed noxious weed. [8]

With the ability to overgrow even trees in a forest, this plant overcrowds existing vegetation and prevents healthy growth of native species in their regions. It is currently estimated that this plant covers about 20,000 to 30,000 square kilometers of land throughout the U.S. [9]

Nationwide this invasive species contributes to roughly $500 million dollars lost in cropland and control efforts. [9]

Looking Forward in 2021

So there you have it, the 5 most challenging invasive species that we faced in 2020 throughout the Garden Industry.

It’s difficult to look at this list without concern for the future and wonder what combative steps we might take as an industry against these species. At Plant Sentry™ we ask these same questions and we have these same concerns. This is why as a company we’ve set the standard to provide the best possible guidance not just for ourselves, but for those we serve in resolving the challenges that invasive species bring. 

Our company, Plant Sentry™, started out as a small idea, but it has turned into a component for much greater change. Throughout our industry companies and clients are showing more interest in working to resolve the challenges and issues that invasive species bring. As we greet the new year of 2021, we’re confident that our community will continue to encourage a brighter future with less invasive species.

Until then,

Happy New Year from Plant Sentry™












The Silent Struggle of the Citrus Industry

The Silent Struggle of the Citrus Industry

Throughout the world, there are a number of afflictions that can plague plants of all shapes and sizes. As time continues to pass, plants continue to change. Each change will often lead to an evolution that will potentially combat their native threats. But, there is one plant family that seems to be increasingly in danger with each passing year, that time and evolution can’t protect. 

The citrus family.

Last month we took a deep dive into what makes the two most powerful citrus states in the U.S. move. Now, we’re going to take you into the constant struggles these states face, as they combat a disease that has almost all but wiped out the global citrus supply. 

This month, we’ll be talking about Huanglongbing (HLB), also known as Citrus Greening Disease. This disease has been responsible for compromising every citrus species throughout the globe. With an immense workforce behind the industry, it wouldn’t just be our countertops that could be left empty if the fruits simply disappeared, but also the stomachs and wallets of the millions of people it employs.

So, What is Citrus Greening?

Citrus Greening Disease, or Huanglongbing (HLB), is a far-reaching citrus disease that has impacted the entire world of citrus growing. Once a tree has contracted the disease, its fruit will appear misshapen and green, while having a bitter taste. Within a few years of the disease infecting the tree, it will die.

The name Huanglongbing means “yellow dragon” and pays tribute to the yellow offshoots that the tree will develop as a response to the disease. The name also recognizes the yellowing and greening effects that the disease will have on the fruits.

While the disease is not contagious to human beings, the threat that this disease presents is a threat to the citrus family itself. It is currently identified that Citrus Greening has the capacity to infect every type of citrus on the planet. 

The disease is believed to have first emerged in 1919 in the Southern part of China. [1]  From there the disease will continue to spread all the way to the United States by 2005 when it is first identified in Florida. 

Since its arrival, “citrus greening has been responsible for a 90% reduction to the production of Florida’s most valuable crop” [4].

The active bacterium that infects the citrus plant is the Candidatus Liberibacter asiaticus (Las). Through the Asian citrus psyllid (Diaphorina citri), the bacterium is spread infecting citrus plants or contracting the disease themselves. 

Once the psyllid has contracted the bacterium for the disease from an infected tree, it will then infect healthy trees with the disease-causing their decline and the spread of Citrus Greening. 

With few treatments available for the disease and no proven cure, conversations that surround Citrus Greening often focus on slowing the disease, and the extent of the damage that it has caused.

Measuring the Impact of the Disease

The impact that the disease has had on citrus trees has been overwhelming and dismal. In 2016, the USDA National Institute of Food and Agriculture released a Fact Sheet that recognizes that as a direct result of Citrus Greening, we could see the destruction of the citrus industry within our lifetime. 

Most severely hit, is perhaps the citrus state of Florida where they’ve seen a decrease in orange trees by 20 million, since 1966. In addition to oranges, the grapefruit trees have also drastically declined, to roughly a third of the 14 million that they used to be.

With a recognized impact of serious proportions, the USDA and citrus community fear that the devastation the disease can cause to California, would be just as grave. 

California produces 80% of citrus fruits sold throughout the United States.

In response to the seriousness of Citrus Greening, regulatory efforts surrounding the citrus communities have amplified in hopes of slowing down the spread, and prolonging protection against it for those who have yet to be exposed. 

The states that have confirmed Citrus Greening are: California, Florida, Georgia, Louisiana, Puerto Rico, South Carolina, Texas, and the U.S. Virgin Islands.

The states that have confirmed the presence of the psyllid are: Alabama, American Samoa, Arizona, California, Florida, Georgia, Guam, Hawaii, Louisiana, Mississippi, Northern Mariana Islands, Puerto Rico, South Carolina, Texas, and the U.S. Virgin islands. [3]

So far the types of citrus that are identified to be at risk from the disease are: Chinese box-orange, Curry leaf, Finger-lime, Grapefruit, Key Lime, Kumquat, Lemon, Lime, Limeberry, Mandarin Orange, Mock Orange, Orange, Orange Jasmine, Pomelo, Sour Orange, Sweet Orange, Tangerine, and Trifoliate Orange.

But…Not All Hope Is Lost

With the disease continuing to spread and ravage the industry, citrus giants are beginning to see signs of hope through developments against the disease that could just possibly save their entire way of life.

While we previously mentioned that there is no known cure for the disease, we couldn’t bring anything to your attention, at this time, that didn’t come alongside a hopeful ending. 

So, here’s the good news:

Researchers around the country have been working non-stop for years to examine every possible avenue that can expedite the discovery, management, and treatment methods for Citrus Greening.

At the University of Florida (UF) researchers have discovered that citrus trees grown “under oak canopies or alongside Oak (Quercus) trees, are healthy” [4]. Whereas the citrus that is grown a few rows away from this structure often show signs of HLB. 

This observation led to further interest from scientists and researchers that brought them to identify the affect that Oak (Quercus) leaf extracts have as a combatant against the bacterium Candidatus Liberibacter asiaticus. Their findings identified that the leaf extracts from the Oak (Quercus) restored the leaves of the HLB infected citrus trees within their physiological parameters. This new discovery could quite possibly mean effective methods against the disease and perhaps greater longevity for the infected trees.

But, these discoveries and advancements haven’t come without a cost, and their own shortcomings. In August of 2019, the UF published an article that back pedaled the long believed “silver bullet” approach of antibiotic spray to fight against HLB. 

They acknowledged that the practice of spraying oxytetracycline and streptomycin solutions may not be as effective as originally believed in combating HLB. But, what they did find was that trunk injections of the bactericides resulted in access to the cellular structure of the trees and their fruit that allowed the oxytetracycline to effectively combat the HLB. 

But this isn’t all of the good news, finally, as we close out our article, we have one more amazing development against this deadly citrus disease. The first effective treatment, capable of controlling Citrus Greening. 

On the west coast, in Riverside California, University of California at Riverside (UC Riverside) has developed the first ever treatment method with curative properties through the use of antimicrobial peptides.[5] 

The peptides derive from a molecule extracted from the Australian Finger Lime. Through 2 years of grueling research Dr. Hailing Jin was able to identify the relationships between the citrus variety’s resistance to the disease and combative properties needed to be successful in other citrus varieties. 

Through the project’s successful trialing and development, UC Riverside has entered an exclusive, global licensing agreement to bring this treatment to market with the company, Invaio. The peptide treatments are needed a few times throughout the year, providing a cheaper and more effective solution in combating HLB than any other approach in the industry.  

Looking to the Future

While developments continue, and there are no guarantees of success, it is important to acknowledge how this disease came to be so difficult. While there were a number of variables that couldn’t have been controlled, there were a number of variables that could have.

The important takeaway from this disease is that while the challenges have been great, our efforts make a difference both in prevention and in treatment. 

As a plant lover, grower, protector, or admirer, it is our responsibility to ensure that our plants are being protected, and are protecting other plants.

When purchasing plants, be sure to ask what treatments your plant may have received before purchasing. Check to see if the plant is an invasive species to your region. And ALWAYS keep a watchful eye for signs of pests and disease. 

Diseases like HLB aren’t just won and lost in a single battle in contributing to its spread. The war is won through continuous combined efforts of regulatory compliance, and company’s like Plant Sentry stepping up to do the right thing. 

We’re always looking for new friends willing to do the right things for growers, consumers, and ultimately themselves. If you think you know one, or may be one of them, be sure to reach out to us below and tell us more about yourself!


[1] Bové, J. (2006). HUANGLONGBING: A DESTRUCTIVE, NEWLY-EMERGING, CENTURY-OLD DISEASE OF CITRUS. Journal of Plant Pathology, 88(1), 7-37. Retrieved September 30, 2020, from

[2] Citrus Greening FAQ. (n.d.). Retrieved September 30, 2020, from

[3]  Citrus Greening. (n.d.). Retrieved September 30, 2020, from

[4] Koestoyo, Posted:, 22, S., 23, J., 25, G., 22, A., . . . 18, E. (2020, February 12). Oak trees may hold antibacterial to help infected citrus trees. Retrieved October 01, 2020, from

[5] New tools in the fight against lethal citrus disease. (2020, August 25). Retrieved October 02, 2020, from