Can We Eradicate the Invasive Beach Vitex?

by Rick O'Connor | Nov 24, 2022

If you read the introduction article to this series you would know that yes – based on comments from Dr. Simberloff, we can.  But your best chance at doing so is when the species is early in its invasion of the area – Early Detection Rapid Response (EDRR).  This can be seen again on the invasive species curve (pictured below). 

Have we jumped on the beach vitex issue quick enough? 

I am not sure.  Based on the records provided to EDDMapS (www.EDDMapS.org) there are 677 records in the United States.  97 of those are in Florida.  80 are in the Florida panhandle with another 5 records in Baldwin County AL.  44 of those records are in the Pensacola Bay area, another 34 in the Choctawhatchee Bay, and 5 records near Apalachicola.  This certainly sounds doable.  There are not that many records, and we should be able to easily remove plants from 80 sites.  However, I am also certain this is much underreported.  In my spreadsheet from our local surveys in the Pensacola Bay area I have 97 records – over double what EDDMapS has reported – and you could assume the same for the others. 

From EDDMapS, in the Pensacola Bay area there are three records from Perdido Bay, one from NAS Pensacola, 18 from Pensacola Beach, 3 from Navarre Beach, and 22 from Gulf Islands National Seashore.  Within Gulf Islands 20 of these are from Naval Live Oaks, 1 from Ft. Pickens, and 1 from Opal Beach. 

From my survey records I have 3 records from Gulf Breeze, 2 from Perdido Bay, 2 from Perdido Key, 7 from Navarre, 26 from Gulfs Islands National Seashore, and 57 from Pensacola Beach.  I should add here that 1 of the 3 in Gulf Breeze, 1 of the 2 in Perdido Bay, and 25 of the 57 on Pensacola Beach are currently “green” on my spreadsheet indicating that have been treated, removed, and have not returned (“eradicated”) – that is 28% of the known records – 70 records (72%) are still out there. 

When you look at the Choctawhatchee Bay area, 32 of the 34 records are on Eglin AFB property and are being controlled.  I am not sure how many have been eradicated, but they know where they are and are on top of the problem.  Two additional records are in Okaloosa County proper, one on Hwy 98 between Ft. Walton and Destin, the other in Henderson State Park near Destin.  Likewise, I am not sure of the status of these two sites.  Further east there is a record in Gulf County, and four in Franklin County.

These numbers suggest that yes… we have jumped on this plant soon enough and that eradication is possible.  But… do we have all of the records?  Are there really only these in the counties reported?  Are there no plants in Walton and Bay counties?  One would feel that there are more out there. 

Step 1 – we need GOOD surveys conducted. 

To date, all of the records have been coastal along the Intracoastal Waterway.  The seeds are viable in saltwater for up to six months.  Any seed that makes into the ICWW can easily be dispersed to new locations.  But it will take diligent work from community partners to survey these areas and update all of the records.  If interested in doing a survey, let me know. 

Step 2 – treatment. 

When treating invasive plants there are three methods you can choose.  (1) biological, (2) mechanical, and (3) chemical.  Currently, there are no biological controls for beach vitex approved by the Department of Agriculture, and I am not aware of any studies testing one.  So… this is not an option at the moment.  Many prefer not to use herbicides and that means mechanical removal.  There are plenty of records in the Pensacola Beach area where this has been successful.  In each case the plants where young, herbaceous vines and we could easily pull the taproot out.  In some cases, we did have to dig to remove all of the plant, but – based on annual surveys after treatment – they have not returned.  But in many cases mechanical removal was not an option due to the depth of the taproot, the extent of secondary roots extending from the spreading stolons, or the sheer mass and area in which the plant had invaded.  As beach vitex grows it becomes woodier, and more of a shrub with extending vines running in all directions.  At this stage you will need chemical. 

Based on studies conducted at Clemson University, the most effective chemical herbicides are those with the active ingredient IMAZAPYR.  This chemical showed success within one year in many cases but has its problems.  (1) The chemical is non-select, many it will kill any plant it comes in contact with – and they could be very undesirable.  (2) it has a long soil activity life – meaning it is active in the soil for several months.  Nothing will grow in the location and re-planting with native plants could be unsuccessful.  TRICLOPYR is a chemical used for Chinese Tallow and Poison Ivy.  It seems to be very effective on beach vitex however, it too is non-select and though its soil activity is not as long as imazapyr, there is a period of time when re-planting will not be successful.  A third chemical tested was GLYPHOSATE.  This product is also non-selective but its soil activity is only a few days, allowing from re-planting within a week.  However, because it is not as effective as the previous chemicals, re-treatments each year may be required (one study suggested up to five years of re-treatment may be needed). 

The chemical we are currently using is glyphosate.  Though it does mean that many of our records have not been eradicated yet, we can re-plant with native plants very soon and this has been desirable for a variety of reasons.  You must be careful to reduce over spray so that you do not kill neighboring plants.  In most cases, we remove all of the above ground biomass and then cut and treat the taproot.  Returning the following year to see how it has done.  NOTE: the seeds are numerous and working with the plant while it is in seed could spread the problem.  It is in seed during the fall and winter.  We recommend waiting until spring to do removals and summer to do chemical treatments. 

Step 3 – monitoring. 

It is important to re-visit each site (even it has been gone for over a year) to assess the status of these plants.  I am not sure how long seeds can be active in the soil.  There is a chance that though the plant you were working on was eradicated, the seeds it left the season before may sprout and re-treatment needed. 

YES – it is a lot of work, a lot of time, a lot of resources to manage invasive species.  Here again, finding the problems early and putting together a management plan can make the possibility of eradication possible and at a lower price.  Based on EDDMapS, there are four other records in the Jacksonville area.  If this is truly all there is out there, then we can – and should – eradicate this plant from the state.  But…

Let’s start with step 1 and go from there. 

If your community is interested in forming a survey/management team and needs help doing so, let me know.  We will do everything we can to make it effective and hopefully remove this plant from our area. 

Can We Eradicate Invasive Species?

by Rick O'Connor | Nov 17, 2022

I recently attended an invasive species conference, and this topic came up.  It seems strange that it would but those who work in the invasive species world have this in the back of our heads a lot.  I mean in a lot of cases we do not bring the word up when making presentations, what some call “the E word”, because we feel in the back of our heads, we will never eradicate them, and we should not lead people on that we might.  Lionfish management is a good example.  Everyone is aware that eradication is probably not an option and so we refrain from using the term when discussing this species. 

It came back a few years ago when I began working with beach vitex on Pensacola Beach.  It was a relatively new species on the radar in Florida and was not even listed as an invasive species in our state.  When we first heard about it in the Pensacola area, I checked EDDMapS to see how many records there were.  There was a total of three statewide; two in the Jacksonville area and one in Pensacola.  I conducted surveys of Pensacola Beach and found 22 additional sites where the plant existed and thought – MAYBE… if this truly ALL there was – we MIGHT eradicate this plant from the Florida panhandle.  There was a point after we had treated and removed the plants from those sites that we MIGHT have actually… dare I say it… eradicated beach vitex from Pensacola Beach.  I felt pretty good about stating this and there was even a little ceremony at a meeting to celebrated it.  Then… we found some on the north side of the Intracoastal Waterway in Gulf Breeze.  Then the plant popped in Navarre.  Then Perdido Key.  Then in Apalachicola.  And after a few years, the plant popped up again on Pensacola Beach.  We were too quick to use the term eradication and – like so many who try to manage these species – have refrained from using the term ever since. 

As I watched what was happening with beach vitex, watching what was happening with the brown anole, Chinese tallow, and what I saw in south Florida with Brazilian Pepper, I could see why many felt eradication is not part of the program.  I could see why most would immediately go into management mode and just skip the idea of eradication.  I could see why many would toss in the towel and find something else to work on. 

On the second day of the three-day conference the keynote speaker was Dr. Dan Simberloff.  Dr. Simberloff has been working with invasive species management since the late 1960s.  His talk was entitled Managing Invasions: What’s Worked, What Hasn’t, and What Might.  Early in his talk he asked a question… “What is our ultimate goal?”.  There was silence in the room for almost a minute.  Everyone was pondering.  In my head I was thinking “to control the species distribution as best we could and stop the introduction of anymore”.  But that was not the answer he was looking for.  After about a minute (because NO one responded 😊) he said – “our ultimate goal is eradication”. 

Again, there was silence.  He used the “E” word – out loud – in front of everyone.  I am guessing others were thinking what I was thinking.  “I didn’t think eradication was really possible?”  But his argument was that it is possible and began to run down a list of situations where it in fact HAS happened.  He also discussed new technologies that COULD allow for more. 

It was good to hear this honestly.  It felt like a locker room pep talk at half time and you are down by two touchdowns.  Your thought is that the other team has this in the box, and we should play for another half but really be thinking about how we are going to improve for the next game, so we are not in this situation.  Then “Coach Simberloff” gives his locker room talk, you go back on the field, and things turn around – you come from behind and win the game.  He made us feel like it was possible.  That we are out their fighting now but not to lose focus of the ultimate goal. 

I began to think about the beach vitex situation in the Florida panhandle again.  Maybe… just maybe…

But here’s the deal.  If you look at the invasive species curve (image provided here) you will see that your best chance at eradicating an invasive species is early in the invasion.  What people have termed EARLY DETECTION – RAPID RESPONSE (EDRR).  In my head, I think we MAY be there with beach vitex.  I do not feel the populations in the panhandle are beyond the level that eradication may now be actually achievable.  IF we know where all of the plants are.  In the back of my head, I still wonder if we have missed more than there is and that the populations may be further up the curve than we think.  BUT let’s look at this way – maybe we DO know where most of those plants are. 

The state is divided into regional management areas (CISMAS) and the western panhandle is part of the Six Rivers CISMA.  During the COVID period of 2020-2021, we developed a EDRR list for this CISMA and it is posted on our webpage (https://www.floridainvasives.org/sixrivers/).  Being a Sea Grant Extension Agent, my focus is on the coast.  The barrier islands and the waters that surround them.  We do have a few EDRR species that are popping up on, and around, our islands.  Have we detected them soon enough?  I am not sure but over the next few weeks I am going to post articles here to discuss some of them in hopes that the public will assist us in finding, reporting, and managing them.  The ultimate goal is eradication.  Let’s see if we can pull this off.