Figure 1: Research plots in 2017 affected by peanut collapse. Photo by B. Tillman
Shannon McAmis, De Broughton, Nick Dufault, Ian Small, Zane Grabau, Barry Tillman, and Diane Rowland, UF/IFAS Extension
In 2017, peanut growers of the Panhandle and North Central regions in Florida, and many areas in Georgia faced a number of issues. In addition to high disease, insect pests, nematodes, and Hurricane Irma’s aftermath, growers were faced with a new problem: peanut collapse or decline. University scientists hypothesized that abnormal weather patterns, including low solar radiation and decreased night-time temperatures during an important part of plant development, may have contributed to the collapse. Late in the season, growers noticed yellowing or necrosis of leaf margins, premature defoliation, plant stunting and weak pegs, all adding up to digging losses and reduced yield. This phenomenon was named peanut collapse or peanut decline by many growers and researchers (Figure 1: Peanut collapse). An estimated 25,000 acres fell victim to peanut collapse and experienced yield reduction of more than 1,000 pounds per acre. (retrieved from: Peanut Season has Begun in North Florida). UF/IFAS Extension Agents and researchers teamed up with University of Georgia and regional producers and scrambled to find the cause, but no main culprit was found.
Figure 2: A region-wide tour of peanut collapse took place with researchers, extension agents, and producers present.
In 2018, a team of Extension Agents and scientists are hoping to uncover more of this mystery and begin to gather the data needed to predict problems for harvest this year and into future years. They are using the help of a mobile app combined with drone flights. Researchers are using FieldX, an iOS app that is available through FieldX, Inc. that allows users to map field borders and upload geolocated pictures and notes conveniently on one platform.
Figure 3: Screenshot of the desktop app FieldX Dashboard.
FieldX is able to map and display multiple farms and fields at one time while individually tracking the geolocation of pictures and notes taken in the field. The app can track the exact path taken while scouting the field as well as record the specific location where pictures or soil and plant samples are taken.
Figure 4: Screenshot of the mobile app FieldX GeoNotes.
The FieldX app will allow for any incident of peanut collapse to be mapped, photographed, and described all on one convenient platform that can be shared with other users. This will help the team visualize the effect of peanut collapse for the entire region, and allow researchers to collect data about what happened when and where.
Recording the occurrence and progression of peanut collapse (and other diseases) will allow researchers to begin tracking symptom progression and begin to formulate models to assess risk in the future. Researchers will also combine drone or Unmanned Aerial Systems (UAS) images from identified fields to help develop early warning signals for the possible onset of collapse. Although the main focus of this work is to better understand peanut collapse, this technology can also be used to record and document other issues that may come up in the field, to better identify and predict risks to peanut production in the future.
The Peanut Decline Research Team encourages growers to report appearance of possible decline. If you suspect peanut decline may be an issue in one or more of your fields, contact your local county agent or De Broughton, Suwannee County Extension, who is coordinating this effort in Florida.
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.
Photo taken by Andrew Sawyer, UGA Wilcox County Extension of false white mold.
This article is from an educational update email from Dr. Bob Kemerait, UGA Plant Pathologist. Dr. Kemerait gave permission for Panhandle Ag to use this to share with the growers of Florida.
Andrew Sawyer, UGA Wilcox County Extension, sent me these great pictures yesterday afternoon. They are images of what we call “false white mold” which is caused by the fungus Phanerochaete. This is NOT the white mold, aka stem rot, that causes so much damage to our peanut crop and growers SHOULD NOT spray anything for it. False white mold does NOT harm the plant; in fact the real damage false white mold can cause is that growers spend money unnecessarily fighting it.
Picture of false white mold, taken by Andrew Sawyer, UGA Wilcox County Extension.
False white mold is most often found in fields planted using conservation tillage, where the white fungal growth covers both the limbs of the peanut crop and the associated crop debris. Early in its growth and development, the Phanerochaete fungus appears nearly identical to the white mold/stem rot pathogen and all-around bad guy Sclerotium rolfsii. However, as False white mold ages it begins to turn a yellow-orange color and takes on a toothed or hairy appearance. False white mold NEVER produces BB-sized sclerotia like Sclerotium rolfsii does.
A final difference, no lesions form beneath the fungal growth of Phanerochaete; they often form beneath the fungal growth of Sclerotium rolfsii.
Recent reports of salmonella sickness by the Center for Disease Control (CDC) has caused an increased focus on animal-human interaction. According to these reports, over 100 people in multiple states have been ill with salmonella. The CDC states that the most likely cause is their interaction with live poultry in backyard flocks. More recently, there have been at least 18 outbreaks of Virulent Newcastle Disease in Southern California. This disease is a highly contagious and often fatal virus that affects the respiratory, nervous, and digestive system of birds and poultry. It is important to note that no human cases of Newcastle have been reported from the consumption of poultry products (proper handling and cooking is always important.)
These reports are a good reminder that proper biosecurity by both small poultry flock owners and visitors should be exercised. It should come as no surprise that there are associated risks with livestock production, even in the smallest backyard flocks. Poultry are in constant contact with the outside world and their desire to scratch and peck the ground exposes them to numerous biological pathogens. Standard biosecurity practices within a home flock should become normal practice for poultry owners and can be easily implemented. Some steps you can take to best secure your flock include:
- Washing, rinsing and disinfecting feeders and waterers every week to 10 days. More often if heavily used
- Quarantine any birds that appear to have even slight to moderate symptoms of abnormalities
- Implement a pest control program, this should include rodents, insects, and snakes.
- Secure your poultry from natural predators, this may include a family pet like a dog or cat
- Limit the number of people who encounter your poultry, especially family or friends who own flocks
- Ensure you are acquiring birds from reputable sources. Most commercial hatcheries have stringent biosecurity measures at their facilities.
- Quarantine any new birds for at least 14-21 days before introducing them to your flock .
- Wash your hands before and after handling birds. A disinfectant by the coop can be handy as well.
Enjoying your backyard flock should be one of the delights of raising poultry on your own. They provide hours of entertainment and usually a few eggs each day! Ensuring that you and your animals are safe should be a top priority. As always, reach out to professionals, hatcheries, Extension agents, or other seasoned poultry owners for information.
These University of Florida publications are also great resources for additional information.
Crown gall symptoms on roses caused by the bacterium Agrobacterium tumefaciens (Rhizobium radiobacter) – Photo credit: Kamil Duman
Kamil Duman, Susannah Wright, Fanny Iriarte, Barron Riddle, Gary Knox and Mathews Paret, University of Florida – NFREC, Quincy, FL
For rose nurseries, and commercial landscapers, each of the many rose diseases are as important as the others. Crown Gall, however, is one of the most unsightly of the many rose diseases. The disease got its name from the large tumor-like swellings (galls) that typically occur at the crown of the plant, just above the soil line. Agrobacterium tumefaciens (updated scientific name Rhizobium radiobacter), is a bacterium that resides in the soil and causes crown gall disease.
In recent years, researchers at the University of Florida have been observing an increase in rose crown gall disease in Florida. To further understand how widespread this issue is on roses, a research team conducted multiple field surveys in 2017, which led to the discovery of many cases of crown gall disease on different rose varieties in both private and public facilities. Some of the key aspects nursery growers and landscapers should know about crown gall disease are summarized in this article.
Rose Crown Gall Symptoms
Galls range in size from as small as 1/4 inch to several inches in diameter. The gall is an overgrowth of host plant tissue that typically forms at the soil line, but can also form on branches or roots. Galls are initially white, spherical, and soft but darken with age as outer cells die. Galls can either be almost entirely on the surface of the plant and easily detected or almost indistinguishable from normal plant tissue except for its enlarged appearance. The bacterium, which causes Crown Gall disease, survives and persists in the soil for up to three years. It can invade recent wounds on the branches or roots. Swelling can be seen as early as 14 days to as long as 6 months following entry of the bacterium into the plant. The tissue near the gall can be damaged due to rapid cell enlargement. If vascular tissue is affected, wilting can result from the restricted water movement.
Early stage symptom of Crown Gall on roses can be noticed as the small white galls. Photo credit: Susannah Wright
The galls can enlarge to a quarter size in a short period of time from the initial small galls. Photo credit: Mathews Paret
The galls will turn dark in color as they age. Photo credit: Kamil Duman
The Bacterium that Causes Crown Gall
Agrobacterium enters the plant mostly from the soil through wounds on the roots, lower stem or from the branches during plant pruning. Symptoms are caused by the insertion of a small segment of DNA (known as the T-DNA), from a plasmid into the host plant cell, which is incorporated into the plant genome. Once the plasmid integrates with the plants own DNA, the altered plant cells start dividing rapidly and uncontrollably, and the root or stem develops a tumor-like swelling. Galls can range from pea size to softball size. Tiny cracks from freezing temperatures or wound sites can be the site of gall formation. Once the wound compounds are generated, the bacteria detach from the xylem cell walls and are carried upward with water during evapotranspiration to the wound site where they initiate galls. One of the common ways the disease spreads is by pruning nearby healthy plants with the same un-sanitized pruning tool used on an infected plant.
Gall formation at pruning sites indicates contamination of the plant during pruning. Photo credit: Kamil Duman
The crown gall bacterium is a soil pathogen, which means the main inoculum source is in the soil. The bacterium can overwinter in infested soils, where it can live for several years. The bacterium can spread easily during field preparation, pruning and irrigation. Insects, nematodes and grafting materials can also transfer the bacterium.
A plant with a mature gall that is potentially releasing the crown gall bacterium into the potting soil. Photo credit: Susannah Wright
Crown Gall Management Recommendations
- Plant only disease-free roses. Check very carefully before you buy plants for any kind of galls in the crown or branches
- Plant in clean soil (Avoid areas with a history of crown gall infestation)
- Avoid areas with heavy infestations of root-attacking insects and nematodes
- Select well-drained soil and irrigate from clean water sources
- Keep grafts and buds well above the soil line
- Destroy diseased plants as soon as you notice them to avoid cross-contaminating other plants.
- Do not keep infected plants with healthy plants, as the likelihood of accidental transmission through pruning is high
- Avoid mechanical injury to plants from tillage and hoeing
- Provide winter protection so that the bark does not crack
- Disinfect pruning tools between plants. Disinfest budding/grafting tools before and after use. Bleach (10%; equivalent to 0.6% sodium hypochlorite), or quaternary ammonium-based sanitizers are effective disinfectants. Make sure to prepare fresh stock routinely
- If crown gall plants are discovered, please contact your county extension agent for information. Agents can submit samples to the Plant Pathology Lab at the University of Florida-NFREC for disease confirmation and additional site-specific management recommendations.
Sliverleaf whiteflies (SLWF), also known as sweet potato whiteflies, are a major pest in many cropping systems. The SLWF has a broad feeding range of over 600 host plants, which includes ornamental, vegetable, and field crops. This season, large populations of silverleaf whiteflies have been reported in in cotton in Georgia, Alabama, and now Florida’s Panhandle.
Whitefly adults and eggs (photo credit James Castner)
Females deposit eggs on the underside of leaves. Once an egg hatches, the first instar in the SLWF life cycle is referred to as a “crawler.” As the name implies, during this stage the immature instar will crawl on the leaf underside until selecting a location to feed. Once settled, the remaining stages of its life cycle are immobile until it reaches adulthood. Both the adult and immature SLWF have sucking mouthparts, which they use to feed on plant juices. SLWF excrete honeydew, a waste composed largely of sugars. This honeydew provides a perfect enviroment for sooty mold development on the leaf tissue, which can impact photosynthesis, as well as cause the cotton lint to stick together making it difficult to gin. Feeding damage from SLWF can also result in premature defoliation. SLWF populations will increase and pose a threat to cotton until it is defoliated or the leaves drop from feeding injury.
University of Georgia Extension Entomologist, Dr. Phillip Roberts published the article Georgia Cotton: Whitefly Infestations Across the State – What Can You Do? a few weeks ago. The article discusses thresholds and other key management factors. A summary for most of his article can be found below. Dr. Ron Smith of Auburn University also published the article Silverleaf Whitefly Control in Cotton that also discusses SLWF management.
When scouting cotton for SLWF, select the fifth mainstem leaf below the terminal to check for infestations. Sample at least 30 random plants in the field, avoid edges by moving at least 25 paces into the field and then keep selected plants about 10 paces apart. Treatment is recommended when 50 percent of sampled leaves have 5 or more immature crawlers. Keep in mind that late planted cotton has a higher risk for SLWF infestations, as well as hairy leaf varieties in comparison to those with a smooth leaf.
Whitefly nymphs and pupae (photo credit Lyle Buss)
Insect Growth Regulators (IGRs) such as Knack and Courier are the main component of SLWF management programs in cotton. Their effects on SLWF populations are generally slow due to the stages they target in the insect life cycle, but these types of products have long residual activity. With large infested areas across the southeast, certain products are becoming harder to obtain due to treatment demand. Other products with whitefly activity include Assail, Sivanto, and Venom which target all stages of the insect’s life cycle. Oberon is another product used, which treats primarily nymphs.
It is important to note the role beneficial insects play in the field. Natural enemies of the SLWF include lacewings, minute pirate bug, and some species of ladybug. These types of insects can be conserved by avoiding use of broad spectrum insecticides such as pyrethroids, unless other pest thresholds are reached. Pyrethroids can be identified by looking at the active ingredient listed on a product label, their common name will end in -thrin or –ate. Examples of these types of products include Bifenthrin, Karate, and Orthene.
For more information consult the following articles, or contact your local Extension Agent.