Russ Mizell and Xavior Martini, UF/IFAS Entomologists, NFREC, Quincy
Citrus production in North Florida is expanding rapidly in response to the devastation of citrus in Central and South Florida due to citrus greening disease. Citrus acreage in southern Georgia is also increasing. Florida’s climate is situated in the temperate (North) and subtropical (Central and South Florida) regions. Thus, non-native pests from other similar habitats around the world can and frequently do become established in Florida. For example, some non-native pests of citrus that are well established in subtropical Florida include Diaprepes abbreviatus, better known as the “Apopka weevil,” the sugarcane rootstook borer, and the Sri Lanka weevil, Myllocerus undatus. Both of these weevils feed on citrus leaves as adults and their immature stages feed on the roots. Both species also feed on a wide range of other plant species damaging leaves and roots.
The annual low temperatures observed in North Florida the last few years have been higher, possibly due to climate change, and as a result have enabled some pests usually restricted to the subtropical areas of Florida to expand their ranges into the North Florida temperate zone. In addition, expansion of citrus culture with the corollary acceleration of plant movements across the state increase the risk of pest introduction from southern parts of Florida.
Via this article, we are alerting extension personnel, home gardeners, and more specifically citrus growers and nurserymen that the Apoka weevil, Diaprepes abbreviatus has been detected for the first time in an established population in Jefferson County, FL. The Apopka weevil was found in a nursery in Jefferson County, and has not been found in citrus in North Florida to date. The Apopka weevil has several hundred known host plants including citrus, sugarcane, vegetables, fruits and many woody landscape plants. Sicklepod, Senna obtusifolia, and pokeweed, Phytolacca americana, appear to be favorite adult hosts in North Florida in August-September. The large black and white-striped and often orange colored adults (Fig. 1 – C and 1D) feed on fresh leaves where they place their white egg masses in pouches (Fig. 1 – A) made from 2 leaves connected together. The larvae (Fig. 1- B) hatch and fall to the ground where they feed on plant roots often at depths of 1-2 feet or more. There are 2 generations per year in southern Florida, but the number and timing of those that will occur in north Florida remains unknown. Adult weevils are easily detected, and often occur as mating pairs. They are not known to be great fliers; however, the larvae can be found in, and be spread around while infesting plant roots in containers.
Fig. 1: Diaprepes abbreviatus (A) eggs (B) larva, (C) orange form adult, and (D) white form adult. Picture by Tai Huang (A) and Lyle Buss (B, C and D).
This weevil is a quarantined pest, so nurseries in infested counties are required to follow specific insecticide treatments prior to shipping outside of the quarantine area. Producers of any potentially infested crops should monitor visually for the adult weevils by looking for feeding damage and adult weevils on the crop and associated weeds.
Further information on this insect pest can be found in the following UF/IFAS publication: Diaprepes Root Weevil, Diaprepes abbreviatus.
A buck chases a doe through plots of wildlife forages being evaluated at the University of Florida’s North Florida Research and Education Center. Photo Courtesy of Holly Ober
I know it feels too hot outside to talk about hunting season or cool-season food plots, but planting time will be here before you know it and now’s the time to start preparing. The recommended planting date for practically all cool-season forage crops in Northwest Florida is October 1 – November 15. Assuming adequate soil moisture, planting during the first half of the range is preferred. Between now and planting time there are several factors that need to be considered and addressed.
Invasive and/or Perennial Weed Control
Deer and other wildlife species utilize many soft/annual “weeds” as forage so controlling them is usually not a major concern. But from time to time unwanted perennials (grasses and woody shrubs) need to be controlled. An unfortunate and all too common example of and unwanted perennial is cogongrass – a highly invasive grass that should always be controlled if found. Effective control of perennial weeds, like cogongrass generally involves the use of herbicides. Late summer/early fall is a very effective time to treat unwanted perennials. Fortunately, this coincides well with the transition between warm-season and cool-season forages. If you have unwanted, perennial weeds in your food plots get them identified now and controlled before you plant your cool-season forages.
Typically the white, fluffy seadheads shown on the cogongrass above are not visible this time of year. Cogongrass is pale green and appears as leaves coming straight out of the ground – no visible stem. It typically has a white midrib that is slightly off-center in the leaves. The leaf margins are very rough/sharp especially when the felt from the top of the leaves downward. If you suspect you might have cogongrass, contact your county agent for conformation and follow their control recommendations.
Photo Credit: Mark Mauldin
Soil Fertility Management
In my experience, the most common cause for poor plant performance in food plots is inadequate soil fertility. Before planting, collect and submit soil samples from each of your food plots. Laboratory analysis of the samples will let you know the fertilizer and lime requirements of the upcoming cool-season crop. It is very important to have the analysis performed prior to planting so performance hindering issues can be prevented. Otherwise, during the growing season, by the time you realize something is wrong, it will likely be too late to effectively address the problem. This is particularly true if the issue is related to soil pH. To affect soil pH in a timely manner lime needs to be incorporated into the soil. Incorporation is impossible after the new crop has been planted. Soil analysis performed at the University of Florida’s Extension Soil Testing Lab cost $7 per sample. Your county’s UF/IFAS Extension Agent can assist you with the collection and submission process as well as help you interpret the results.
Variety Selection & Seed Sourcing
It takes time to find the best products/varieties. Just because forage seeds are sold locally, doesn’t mean that the crop or specific variety is well suited to this area. The high temperatures and disease pressure associated with Florida, even in the “cool-season” mean that many products that do very well in other parts of the country struggle here. Below are some specific forages that are favored by wildlife (specifically white-tailed deer) and generally well adapted to Florida. You may discover that these varieties are not sitting on the shelf at the local feed & seed. Often local suppliers can get specific varieties, but they must be special ordered, which adds time to the process. Hence the need to start planning and sourcing seed early.
If you are debating trying food plots on your property for the first time, please carefully consider the following. Food plots are not easy. Making productive food plots that provide a measurable, positive impact to the wildlife on your property takes considerable time, effort, and money. Considering this, food plots really only make sense when viewed as habitat improvements that provide long term benefits to multiple wildlife species. If you are looking for nothing more than a deer attractant during hunting season, food plots are not a very practical option. For more information on getting started with food plots contact your county’s UF/IFAS Extension Office and check out the reference below.
June 6th is a great day to learn about all types of invasive species that threaten natural areas in Northwest Florida! The UF/IFAS Extension Bay County office will have multiple educational exhibits with living samples of species of concern from 9:00 a.m. – 5:00 p.m. central time, on Wednesday, June 6th. This is a multi-agency effort to inform citizens about the impact of invasive plants and animals and how they can help reduce introduction and spread. For full details see the Bay Invasive Workshop Flyer
We are pleased to announce our partners Florida Fish and Wildlife Conservation Commission (FWC) and Science and Discovery Center of Northwest Florida will be on hand to share information about caring for exotic pets and current management plans for invasive species such as Lionfish, Aquatic Weeds, and how to surrender an animal on designated Pet Amnesty Days.
Dr. Steve Johnson, UF/IFAS Associate Professor of Wildlife Ecology will be the featured speaker.
At noon there will be a special guest speaker for a bring your own lunch & learn “Exotic Invaders: Reptiles and Amphibians of Concern in NW FL.” Dr. Steven Johnson, UF/IFAS Associate Professor of Wildlife Ecology, will talk about exotic reptiles and amphibians we should be aware of that may occur in our area.
In the morning, we will be focusing on the invasive air potato vine with the distribution of air potato leaf beetles for biological control. Need air potato leaf beetles to manage the air potato vine on your property? Please register to receive beetles using the following link: http://bit.ly/bayairpotato They will be distributed from 9 a.m. to noon on June 6th.
Learn more about the success of the Air Potato Biological Control program at http://bcrcl.ifas.ufl.edu/airpotatobiologicalcontrol.shtml
Adult grass carp, Ctenopharyngodon idella Val. Credit: Jeffrey E. Hill, University of Florida
Florida has hundreds of aquatic plant species, and they are an often-overlooked feature of Florida’s landscape. Overlooked that is, until the growth of non-native (even some native) species interferes with use of our waters. Some aquatic plant species can become problematic in Florida waters when their growth interferes with fishing, flood control, navigation, recreation, livestock watering, or irrigation. For these reasons, being knowledgeable about properly managing aquatic plants is important to the many uses of Florida’s waters, whether it be a state managed public waterbody, or your own backyard farm pond.
Any pest, whether plant, animal, or insect, is best managed using “IPM” or Integrated Pest Management. IPM involves using a variety of available “management tools” to control pests in an economically and environmentally sound manner. As in any IPM effort, the first thing to do is identify what is causing the problem. Next, define what your management goals are. Then, research what tools are available for you to manage the problem. And finally, devise and implement your management plan.
In this article, we will look at one of the “IPM tools” used to manage aquatic plants – the grass carp (Ctenopharyngodon idella Val.). The use of grass carp to manage problematic levels of aquatic plants falls under the general management term of “biological control.” Biological control essentially uses one living organism to control another living organism. Grass carp have become one of the most widely recognized examples of biological control.
The Grass Carp
As the name implies, the grass carp is an herbivorous fish that eats plants. It is native to eastern Russia and China, living in large muddy rivers and associated lakes, and is actually one of the largest members of the minnow family. According to the Florida Fish and Wildlife Conservation Commission, the largest triploid grass carp taken in Florida was 15 years old, 56″ long and weighed 75 pounds! The grass carp has been introduced into more than 50 countries and is used as a food item in many places around the world. They are used in nearly all states of the USA to manage aquatic plants.
Introduction into the United States
“The grass carp was considered for introduction into the U.S. primarily because of its plant-eating diet, which was thought to have great potential for the control of aquatic weeds. In 1963 the U.S. Bureau of Sport Fisheries and Wildlife Fish Farming Experiment Station, Stuttgart, Arkansas, in cooperation with Auburn University, imported grass carp for experimental purposes; in 1970, this fish was introduced into Florida primarily for researchers to study its ability to control hydrilla.” (Grass Carp: A Fish for Biological Management of Hydrilla and Other Aquatic Weeds in Florida). “Early release of diploid fish led to reproductive populations in several US drainage systems, including the Mississippi River and major tributaries” (Grass Carp, the White Amur: Ctenopharyngodon idella Cuvier and Valenciennes (Actinopterygii: Cyprinidae: Squaliobarbinae))
Development of the Sterile Triploid
According to the UF/IFAS publication, Grass Carp, the White Amur: Ctenopharyngodon idella Cuvier and Valenciennes (Actinopterygii: Cyprinidae: Squaliobarbinae), “Use of the fish was limited from 1970 until 1984 due to tight regulations surrounding concerns of escape and reproduction, and the potential impacts that colonization of the fish could have on native flora and fauna. These concerns led to research that developed a non-reproductive fish, which was equally effective in controlling hydrilla.” This non-reproductive fish is known as the triploid grass carp. Through a process of subjecting fertilized grass carp eggs to heat, cold, or pressure, the resulting fish have an extra set of chromosomes rendering the fish sterile. Triploid carp have the same herbivorous characteristics as the normal diploid carp, but they are unable to spawn and reproduce. Their inability to reproduce is what makes them a viable tool to manage aquatic plants, and that is because their numbers and feeding pressure can be controlled, they cannot overpopulate a waterbody, nor if they escape, will they overpopulate un-managed areas.
The growth of invasive aquatic plant species can interfere with the many uses of Florida’s waters. This is invasive hydrilla mixed with water lilies in a Florida lake. Photo by Judy Biss
What kinds of aquatic plants do they eat?
The grass carp grazes on many types of aquatic plants, but it does have its preferences. Its most preferred aquatics plants are hydrilla, chara (musk grass), pondweed, southern naiad, and Brazilian elodea. Its least favorite aquatic plants are species such as water lily, sedges, cattails, and filamentous algae. It will, however, graze on many types of plants, even shoreline or overhanging vegetation in the absence of its preferred foods. Another reason the grass carp is an effective plant management tool is because it eats many times its body weight in plant material. As stated in Grass Carp, the White Amur: Ctenopharyngodon idella Cuvier and Valenciennes (Actinopterygii: Cyprinidae: Squaliobarbinae), “every 1 lb. increase in fish weight requires 5–6 lbs. of dry hydrilla (Sutton et al. 2012), which—considering hydrilla is 95% water—is a great deal of live plant material.”
Use of Grass Carp as a Biological Control
Integrating the use of grass carp in aquatic plant management plans is usually cost effective. In many cases involving the use of grass carp, overabundant aquatic weed infestations are first treated with an aquatic herbicide to reduce biomass. The carp are then stocked to control regrowth and to extend the time between herbicide treatments. This can be up to 5 or more years, depending on the situation. One factor in long term control is the survival of the stocked grass carp. They are not without predators as largemouth bass, otters, birds, etc. readily prey on small grass carp. Stocked fish should be at least 12 inches long to help avoid predation and provide plant control. Other considerations to factor into your management plans are the long term, yet non-specific, control that grass carp can provide. If not stocked in the correct manner, they may end up eating aquatic plants that you wish to maintain. Also, if they eat all the aquatic plants, your once clear water may become dominated by algae instead.
How can I get grass carp for my lake or pond?
The Florida Fish and Wildlife Conservation Commission (FWC) administers the Grass Carp program for Florida. A permit is required before you can purchase carp, and only the sterile triploid carp are permitted for use in Florida. The FWC can answer many questions about the use of grass carp and if this aquatic plant management “tool” is the right one for you to use in your particular situation. In north Florida, the regional FWC office is located at 3911 Highway 2321 Panama City, FL 32409, Phone: 850-767-3638.
What do I need to know about triploid grass carp?
Cost: Triploid grass carp cost between $5 and $15 each and are usually stocked at three to ten fish per acre, resulting in costs as low as $15 per acre. In comparison, herbicides cost between $100 and $500 per acre and mechanical control may cost more than twice that.
Time: Grass carp usually take six months to a year to be effective in reducing problem vegetation, although they provide much longer term control than other methods, often up to five years before restocking is necessary. When used in conjunction with an initial herbicide treatment, control of problem vegetation can be achieved quickly, and fewer carp are required to maintain the desired level of vegetation.
Overstocking: Once stocked in a lake or pond, carp are very difficult to remove. If overstocking occurs, it may be ten years or more before the vegetation community recovers. Even after carp are removed, other herbivores such as turtles may prevent the regrowth of vegetation.
Water Clarity: Aquatic plants remove nutrients in the water. When plants are removed, nutrients may then be utilized by phytoplankton, turning the water green. Clarity may be improved by reducing or eliminating sources of nutrients into the lake such as road runoff and lawn fertilizer.
Inflows/Outflows: It is in the best interest of people stocking carp to keep them in the desired lake or pond. It is also a required condition of the permit. Any inflows or outflows through which carp could escape into other waters require barriers to prevent fish from escaping into waters not permitted.
For more information on this topic, please see the following resources used for this article:
Chinese Privet. Photo by Karan A. Rawlins, University of Georgia, Bugwood.org
This week’s featured video was produced by Alabama Extension to show the results of a Chinese Privet chemical control demonstration. This video shares the results for three techniques used for privet control: foliar (spraying leaves), cut stump, and basal bark treatment. There is also a companion fact sheet that provides more details on controlling Chinese Privet: ANR-1468 Control Options for Chinese Privet.
If you enjoyed this video, you might want to check out the featured videos from previous weeks: Friday Features
If you come across an interesting or humorous video related to agriculture, please send in a link, so we can share it with our readers. Send video links to: Doug Mayo
Chinese tallow tree (Sapium sebiferum L.) can be identified by its simple, alternate leaves with broadly rounded bases that taper to a slender point and dull white seeds that remain attached after leaves have fallen. Photo Credit: UF/IFAS
Chinese Tallow is an invasive tree that is now well established in the Southern United States. It first became a concern in natural areas, due to its invasive nature and adverse effect on native communities of plants. Chinese tallow was first recognized as an issue in the Carolinas in the 1970s, and since has spread through Florida’s flatwoods, strand swamps, floodplain forests, and other plant communities due to its growth habits, invasive characteristics, and extensive use as an ornamental plant. Not only are they an invasive, but Chinese Tallow trees are also toxic to livestock. (Poisonous Plants of the Southeastern United States page 28-29)
For help identifying weeds or developing a control plan for your operation, please contact your county extension agent.
For more information on this topic please see the following UF/IFAS Publication: Natural Area Weeds: Chinese Tallow