by Erik Lovestrand | Feb 27, 2017
Fruits on HLB infected trees ripen prematurely, are small, and often drop from tree. Photo credit: Erik Lovestrand
If we look at the big picture when it comes to invasive species, some of the smallest organisms on the planet should pop right into focus. A microscopic bacterium named Candidatus Liberibacter asiaticus, the cause of Citrus Greening (HLB), has devastated the citrus industry worldwide. This tiny creature lives and multiplies within the phloem tissue of susceptible plants. From the leaves to the roots, damage is caused by an interruption in the flow of food produced through photosynthesis. Infected trees show a significant reduction in root mass even before the canopy thins dramatically. The leaves eventually exhibit a blotchy, yellow mottle that usually looks different from the more symmetrical chlorotic pattern caused by soil nutrient deficiencies.
HLB, referred to as “Yellow Dragon” in China, causes an asymmetrical pattern of chlorosis in citrus leaves. Photo credit: Erik Lovestrand
One of the primary vectors for the spread of HLB is an insect called the Asian citrus psyllid. These insects feed by sucking juices from the plant tissues and can then transfer bacteria from one tree to another. HLB has been spread through the use of infected bud wood during grafting operations also. One of the challenges with battling this invasive bacterium is that plants don’t generally show noticeable symptoms for perhaps 3 years or even longer. As you would guess, if the psyllids are present they will be spreading the disease during this time. Strategies to combat the impacts of this industry-crippling disease have involved spraying to reduce the psyllid population, actual tree removal and replacement with healthy trees, and cooperative efforts between growers in citrus producing areas. You can imagine that if you were trying to manage this issue and your neighbor grower was not, long-term effectiveness of your efforts would be much diminished. Production costs to fight citrus greening in Florida have increased by 107% over the past 10 years and 20% of the citrus producing land in the state has been abandoned for citrus.
Many scientists and citrus lovers had hopes at one time that our Panhandle location would be protected by our cooler climate but HLB has now been confirmed in more than one location in backyard trees in Franklin County. The presence of an established population of psyllids has yet to be determined, as there is a possibility infected trees were brought in.
Another symptom of citrus greening is small, lopsided fruit that are often bitter. Photo credit: Erik Lovestrand
A team of plant pathologists, entomologists, and horticulturists at the University of Florida’s centers in Quincy and Lake Alfred and extension agents in the panhandle are now considering this new finding of HLB to help devise the most effective management strategies to combat this tiny invader in North Florida. With no silver-bullet-cure in sight, cooperative efforts by those affected are the best management practice for all concerned. Vigilance is also important. If you want to learn more about HLB and other invasive species contact your local UF/IFAS Extension office.
by Jennifer Bearden | Feb 27, 2017
Aliens are invading our forests, pastures, fields and lawns. Well, okay, not aliens but invasive species are invading our beautiful landscapes. Invasive species are non-native or exotic species that do not naturally occur in an area, cause economic or environmental harm, or negatively impact human health. These invasive species have become the number one threat to biodiversity on protected lands. However, invasive species do not know boundaries, and as a result, public, private lands, natural and man-made water bodies, and associated watersheds are affected. National Invasive Species Awareness Week (NISAW) is February 27-March 3, 2017.
It is estimated that Florida Agriculture loses $179 million annually from invasive pests (http://www.defenders.org/sites/default/files/publications/florida.pdf). Generally, eradication of an invasive species is difficult and expensive. Most of the mitigation efforts focus on control rather than eradication.
EDDMaps (Early Detection and Distribution Mapping System), a web-based mapping system for reporting invasive species, currently has 667 different invasive plants reported in Florida. Many invasive insects, animals and diseases have also landed in Florida. Some famous invasive species in Florida include cogongrass, wild hogs, red imported fire ants, Chinese tallow, and lionfish.
For National Invasive Species Awareness Week, the University of Florida IFAS Northwest Extension District will highlight new invasive species each day. There are a couple of ways to receive this information during NISAW:
You can help us control invasive species in several ways. First, always be cautious when bringing plants or plant materials into the state. Plants or even dead plant material can harbor weeds, insects and diseases that can become invasive in our state. Second, when you see something suspicious, contact your local extension agent for help identifying the weed, insect or disease. Third, you can volunteer your time and effort. Invasive species control is difficult and requires a cooperative effort for funding and manpower. The state has several Cooperative Invasive Species Management Areas (CISMA) in which public and private organizations work together to control invasive species in their area. These CISMAs hold work days in which volunteers can help remove invasive species from the environment.
For more information about NISAW or invasive species, contact your local county extension agent.
by Jennifer Bearden | Feb 4, 2017
Despite efforts by public and private land managers, feral hog populations continue to rise in many areas in Florida. Feral hogs damage crop fields, lawns, wetlands, and forests. They can negatively impact native species of plants and animals. Their rooting leads to erosion and decreased water quality.
Wild boar Photo Credit: Florida Fish & Wildlife Conservation Commission
There are several options for controlling feral hogs. Choosing the right option depends on the situation.
Options include:
- Hunting with dogs,
- Hunting with guns,
- Box Traps,
- Corral Traps.
Let’s talk about these options.
Hunting with dogs is really not very effective for removing enough hogs to control populations. Dog hunting can move sounders of hogs from areas where damage is occurring for a period of time. This can be helpful when crops need to be protected from hog damage until they can be harvested.
Shooting hogs also is not effective for removing large numbers of hogs. Situations where it is successful include protecting crop fields and for taking hogs that will not go into a trap. Shooting success depends the education level of the hogs and the sophistication of the shooting equipment available. Hogs learn quickly to avoid danger. They learn by watching other hogs who get shot or trapped. Hunting pressure can disrupt hog patterns and make them harder to trap or hunt.
Box traps can be effective at trapping young hogs that are not trap smart. A study conducted by a graduate student, Brian Williams, at Auburn University looked at the efficacy of different trap styles. Young hogs entered box traps and corral traps at similar rates. The study also found that adult females were 120% more likely to enter corral traps than box traps and adult males were more reluctant to enter either trap style but were more likely to enter the corral traps. (Williams et al, 2011)
Corral traps are shown to be most effective for eliminating complete sounders. By eliminating a sounder at once, populations can be reduced. Corral traps are also more economical. In the Auburn study, the trapping cost per pig for box traps was $671.31 and for corral traps was $121.28.
Corral traps are best for capturing whole sounders. Box traps can be effective for capturing young hogs. When trap smart adult females or males are in an area, shooting or hunting with dogs are options. Just remember that hunting pressure often just moves the hog problem onto another property. In order to eliminate hogs from a given area, we must employ several of these strategies. For example, we may be able to trap a sounder in a given area but still have a group of boars that will not go into a trap. In this case, we may set up to shoot them after trapping the rest of the hogs in a corral trap. By using these two techniques, we can drastically reduce the number of hogs in an area.
[youtube https://www.youtube.com/watch?v=FsGJP_HjR60]
For more information about feral hogs, go to http://articles.extension.org/feral_hogs.
Reference: Brian L. Williams, Robert W. Holtfreter, Stephen S. Ditchkoff, James B. Grand Trap Style Influences Wild Pig Behavior and Trapping Success. Source: Journal of Wildlife Management, 75(2):432-436
by Rick O'Connor | Oct 14, 2016
Most coastal residents along the panhandle are aware of the invasive lionfish and the potential impacts they could have on local fisheries and ecosystems. Since they were first detected in this area in 2010, there have been tournaments, workshops, and presentations, to help locals both learn about the animal and ways to control them. Existing non-profits have joined the fight and new non-profits have formed. In 2015 FWC and local organizations began hosting the Lionfish Removal and Awareness Day (LRAD) events. These are held the weekend after Mother’s Day. During the 2016 event in Pensacola, 8,089 lionfish were removed. In 2016 FWC introduced the Lionfish Challenge. This program began at the conclusion of the LRAD event and ran through September 30. Lionfish, or lionfish tails for those who wanted to keep the animal, could be turned into local collection sights and submitted for state awards and recognition – a Hall of Fame was created and King Lionfish. Over 16,000 lionfish were logged during this event. But has any of this helped? Are we getting control of this invasive species?
The Invasive Lionfish
Maybe… having conversations with local divers who work with researchers and remove for profit, it appears that the 2016 Pensacola LRAD may have made an impact. If you review the literature it states that to control an invasive species a minimum of 25% of the population should be removed annually. Others say you need to remove 75% and others still say it should be 25% each month. The problem here is that we do not know how many lionfish are actually out there. We know how many we are bringing in but is it enough?
One report, submitted by the non-profit REEF (from Key Largo) a few years ago, indicated they had removed about 70% of the lionfish in their area during one tournament. Based on this, the argument that tournaments are effective was supported. The recent Pensacola LRAD suggest the same. Local divers who remove lionfish with researchers, tourists, and as a commercial venture for themselves told us that their “sweet spots” – where high numbers of lionfish can be found – are not so sweet anymore. They are finding lionfish, but prior to LRAD it was not uncommon for some locations to have 50-100 lionfish around them. These same locations may yield 10-20 now. Though this information is anecdotal; it does suggest that these intensive tournaments may be having an effect on managing them. Of course a quantitative study is needed to confirm these observations, but it is encouraging none the less.
It is believed the tournaments alone will not solve the problem. With their high reproductive rates, continuous removals are needed. To encourage this divers can obtain a Saltwater Products License from FWC and sell what they catch. Some dive charters are now making it a tourism trip – “lionfish hunting”. As long as it marketed properly (as in they are not going to find tons of them – but will enjoy shooting a few) customers seem to be happy and are enjoying it. Of course they are still working on an effective trap so that non-divers can participate in control programs. It is also important to note that you should not get into a commercial venture on lionfish as your main source of income. To do so would lead to the argument “we do not want to get rid of lionfish because they are my livelihood”. The objective is to make them uncommon and reduce their impact on our marine resources.
Of course it will take time to know for sure just how effective the tournaments have been. Several will be meeting this week in Ocala to discuss the 2017 tournament season. I have written a longer update on the lionfish, which can be found at the Escambia County Extension Marine Science page.
by Rick O'Connor | Sep 2, 2016
The Asian Tiger Shrimp (Penaeus monodon) have been reported across the northern Gulf of Mexico for several years now but unlike Cogon grass, Chinese tallow, and Lionfish they have not really made the press. We know they are there, but captures in shrimp trawls seem to be infrequent… it just does not look like a serious problem.
The Asian Tiger Shrimp can reach lengths of 12″
But now there is a study being conducted by Dr. Jennifer Hill (Louisiana Tech University) that sheds a little light on the impacts of this new invasive species. Working out of Dauphin Island Sea Lab, and funded by Mississippi-Alabama Sea Grant, her study is looking at the interactions between the tiger shrimp and our native species – the white and brown shrimp.
Tiger Shrimp as Predators
Dr. Hill has discovered that tiger shrimp do not prefer salt marshes, as our native species do. They are apparently too large, ranging between 8 and 10 inches – some as large as 14 inches, and prefer more open environments. Tiger shrimp may prefer seagrass beds, another haunt for local shrimp, but she is not sure at the moment. She has noticed that when tiger shrimp are around the native shrimp move towards structure. This is to avoid predation by tiger shrimp, which do try and catch them – but they are not very good at it. Her study indicates that 80-90% of the native shrimp survive such attacks, but forcing the natives towards structure could impact the catch by our shrimpers.
Tiger Shrimp as Prey
Preferring open environments leaves tiger shrimp at a higher risk of predation. One thought is that their large size and dark color may not be recognized as a shrimp by local predators. One species that has shown interest in them are redfish. Dr. Hill has found that redfish will not hesitate to go after them, and may actually prefer them over white shrimp, but – because of the size of the tiger shrimp – it must be a large redfish.
Five tiger shrimp captured by shrimpers in Pensacola Bay.
Shrimpers in Alabama and Mississippi are currently selling the tiger shrimp they capture to Dr. Hill for her studies. She found that very few were captured in 2014, possibly due to the cold winter that year, but had plenty submitted in 2015. The mild winter of 2016 may produce a large number this summer. If you are shrimper in the Pensacola area, and interested in selling live tiger shrimp at $30 each, contact Dr. Hill at (251) 861-2141 ext. 2179.
by Sheila Dunning | Jun 3, 2016
According to the Atlas of Florida Vascular Plants, there are more than 4,200 plant species naturally occurring in the state. Nearly 3,000 are considered native. The Florida Native Plant Society (FNPS) defines native plants as “those species occurring within the state boundaries prior to European contact, according to the best available scientific and historical documentation.” In other words, the plants that grew in natural habitats that existed prior to development.
Native plants evolved in their own ecological niches. They are suited to the local climate and can survive without fertilization, irrigation or cold protection. Because a single native plant species usually does not dominate an area, there is biodiversity. Native plants and wildlife evolved together in communities, so they complement each other’s needs. Florida ranks 7th among all 50 states in biodiversity for number of species of vertebrates and plants. Deer browse on native vines like Crossvine (Bignonia capreolata), Trumpet Creeper (Campsis radicans), Yellow Jessamine (Gelsemium sempervirens) and Trumpet Honeysuckle (Lonicera sempervirens). The seeds and berries of Black-eyed Susan (Rudbeckia fulgida), Flowering Dogwood (Cornus florida) and Dahoon holly (Ilex cassine) provide vital food for songbirds, both local and migratory. Saw palmetto (Serenoa repens) provides cover for numerous birds and small mammals, as well as, reptiles.
Non-native plants become “naturalized” if they establish self-sustaining populations. Nearly one-third of the plants currently growing wild in Florida are not native. While these plant species from other parts of the world may provide some of the resources needed by native wildlife, it comes at a cost to the habitat. These exotic plants can become “invasive”, meaning they displace native plants and change the diverse population into a monoculture of one species. Chinese privet (Ligustrum sinense), Popcorn trees (Triadica sebifera) and Cogongrass (Imperata cylindrica) have changed the landscape of Florida over the past decade. While Water hyacinth (Eichhornia crassipes) and Hydrilla (Hydrilla verticillata) have changed water flow in many rivers and lakes. These invasive species cost millions of taxpayer dollars to control.
By choosing to use native plants and removing non-native invasive plants, individuals can reduce the disruptions to natural areas. For more information one specific native plants that benefit wildlife go to: http://edis.ifas.ufl.edu/uw384
It learn which plants are invasive go to: http://www.fleppc.org/list/2015FLEPPCLIST-LARGEFORMAT-FINAL.pdf
