- Author: Ben Faber
Dogs can detect agricultural diseases early
Study shows dogs can sniff out laurel wilt-infected avocado trees well in advance
A study out of Florida International University evaluates the use of scent-discriminating canines for the detection of laurel wilt-affected wood from avocado trees. Julian Mendel, Kenneth G. Furton, and DeEtta Mills have ferreted out a possible solution to a serious issue in one corner of the horticultural industry, and then ascertained the extent to which this solution is effective.
The results of this study are presented in their article "An Evaluation of Scent-discriminating Canines for Rapid Response to Agricultural Diseases" published in the latest issue of HortTechnology.
Laurel wilt disease has resulted in the death of more than 300 million laurel trees in the United States alone. One affected plant is the commercially important avocado tree, the second-largest tree crop in Florida behind citrus. This disease has had a devastating effect on the industry in South Florida in past harvest seasons, and two larger avocado industries in Mexico and California are naturally worried that this disease, if it hits their crops, could spread fast enough to destroy their seasons.
Once affected by laurel wilt disease, trees succumb soon after infection. Once external symptoms are evident, this disease is very difficult to control and contain as the pathogen can spread to adjacent trees via root grafting. Until now, there has been no viable, cost-effective method of early diagnosis and treatment.
Laurel wilt is the consequence of an invasive species--the redbay ambrosia beetle--originally from Asia, which was inadvertently introduced into the United States in untreated wooden packing material.
But as with so many ailments, early detection can be instrumental in deterring a widespread infection. The use of scent-discriminating dogs has shown to offer the avocado industry legitimate signs of hope in their fight against the spread of such a profit-crusher throughout their groves.
Three dogs were trained and studied for their ability to detect the early presence of laurel wilt by scent. At present, canines are extensively used in law enforcement and forensics in the location of missing persons, explosives, drugs, weapons, and ammunition. More directly applicable, dogs have demonstrated the ability to detect invasive species of spotted knapweed, brown tree snakes, desert tortoises, and various cancers.
The highly sensitive canine olfactory system is capable of detecting odor concentrations at exceedingly minute 1 to 2 parts per trillion. The authors believe it likely, with properly directed training, that these dogs could use their natural talents to service the protective needs of the potentially ailing avocado industry.
During the course of the study, 229 trials were performed, and only 12 of those yielded false alerts. It was observed that dogs are indeed capable of high levels of relevant performance, even in harsh weather conditions such as high heat and humidity. The study provided proof that dogs can detect agricultural diseases such as laurel wilt and can be a powerful management tool if the disease is caught in its earliest stages.
About the valuable service provided by these dogs, Mills adds, "It is the best 'technology' so far that can detect a diseased tree before external symptoms are visible. The old saying that 'dogs are man's best friend' reaches far beyond a personal bond with their handler and trainer. It is depicted in their excitement every day as they deploy to the groves. Man's best friend may even help save an industry."
The complete article is available on the ASHS HortTechnology electronic journal web site: http://horttech.
Also a great article on dog-sniffing bee hives for foul brood. Go DOGS!
Image:
Cobra, a 3-year-old Belgian Malinois, is trained to detect laurel wilt-diseased trees before the visible symptoms are seen. She and two other Dutch Shepherd canines detect asymptomatic, but infected trees. Once a diseased tree is identified, these "agri-dogs" will sit, indicating a positive alert.
/h1>- Author: Ben Faber
The Latest on Florida's LW Disease
Recommendations for Laurel Wilt in Commercial Groves
Jonathan H. Crane, Tropical Fruit Crop Specialist1, Daniel Carrillo, Entomologist – Tropical Fruits1, Edward A. Evans, Agricultural Economist1, Randy C. Ploetz, Plant Pathologist – Tropical Fruits1, and Jeff Wasielewski, Commercial Tropical Fruit Crops Extension Agent2; 1UF/IFAS, TREC, Homestead, FL and 2Miami-Dade County Extension-UF/IFAS, Homestead, FL Website: http://trec.ifas.ufl.edu
Laurel wilt is a lethal disease that spreads rapidly among root-grafted avocado trees and for this reason necessitates frequent scouting to detect symptomatic trees and immediate tree removal to stop spread to adjacent trees. The research on the management of the laurel wilt pathogen and several ambrosia beetle vectors is continuing, therefore, recommendations for mitigation and control may periodically change.
This document describes the current recommendations to limit or prevent of the spread of the laurel wilt pathogen among avocado trees and to control the ambrosia beetle vectors of the disease. In addition, alternative management strategies concerning re-establishment of productive groves are discussed.
If you have trees symptomatic for laurel wilt please contact Don Pybas, LW Coordinator, (305- 247-0848; pybas@ufl.edu) or Jeff Wasielewski, Commercial Tropical Fruit Crops Extension Agent, (305-248-3311, ext. 227; jwasielewski@ufl.edu) for more information.
Disease symptoms of laurel wilt
The earliest external symptom of LW is green wilted leaves in sections of the canopy.
However, green-leaf wilting is quickly followed by desiccation and browning of these leaves, which remain attached to the plant stems for up to 12 months. Stem and limb dieback follow and eventually additional sections of the tree decline and the tree dies. Underneath the bark, the normally cream- white sapwood may have dark blueish-black streaks. Frequently, trunks and/or limbs may have numerous small diameter holes with sawdust tubes (toothpick-like protrusions from the bark), and/or sawdust clinging to the bark which is evidence of ambrosia beetle activity (i.e., boring into the tree).
Two main strategies for controlling the spread of the laurel wilt (LW) pathogen
- Frequent scouting to detect trees with green leaves beginning to wilt (i.e., early symptoms of LW) and their immediate uprooting and destruction.
- Infusion or injection of Tilt® fungicide into all the trees in a grove before a LW outbreak occurs. Repeated applications at an 8 to 18 month interval are necessary.
Of the two strategies mentioned above, the early detection-immediate destruction method is the most economical. Repeated infusion of fungicides may cause damage to the trees at the infusion sites and therefore may not be sustainable. In contrast, there is antidotal evidence that repeated injections are less damaging to the trees but there is a lack of information on the long-term sustainability of this method.
Primary strategy: early detection and tree sanitation (rouging)
A helicopter survey implemented by the Avocado Administrative Committee was important in alerting the industry and growers to new areas of potential LW infestation and is now important for monitoring on-going infestations. However, helicopter surveying is expensive and not frequent nor detailed enough to detect early green-leaf wilting caused by laurel wilt.
Scouting frequently is key in detecting LW affected trees at the green-wilt stage. Ground-based scouting by driving through groves via equipment (e.g., tractors, mowers, and spray equipment), trucks, and ATVs is possible. However, detecting early symptoms of LW in the tops of trees may be difficult by just driving. An alternative is the use of drones, which can cover large areas quickly, and in detail. However, there are Federal Aviation Administration requirements and regulations that must be met in order to operate commercial drones. Canine detection of LW is an additional detection method. The canines detect the LW pathogen in pre- and fully symptomatic (e.g., desiccated leaves, tree dieback) trees. In many cases, fungicide infusion of infected but pre-symptomatic (no outward signs like wilting) trees allows these trees to remain productive, however fungicide re-treatment is necessary. In addition, early detection by canines provides time to remove pre-symptomatic trees to prevent further root graft spread of the pathogen to healthy trees. The number of available trained canines and for some producers, the cost, may limit the use of canines.
The major component of LW control is to remove and destroy LW affected trees at the green- wilt stage. Do not hesitate to remove and destroy a green-leaf wilted tree – waiting to see if more of the tree canopy develops symptoms or turns brown allows time for the pathogen to spread to adjacent trees through their connected root systems. Waiting to remove and destroy the LW affected tree reduces the chance tree removal alone will stop the spread of the LW pathogen to neighboring trees.
The LW pathogen can survive in declining and dying trees and the only way to stop movement of the pathogen to adjacent trees is to remove (uproot) affected trees immediately. Just stumping or hatracking LW affected trees will not stop the pathogen from moving to adjacent trees through root grafts among adjacent trees. In addition, trees that are affected by LW are very attractive to ambrosia beetles. If these ambrosia beetles come into contact with the LW pathogen inside the tree, these beetles and their offspring may be contaminated with and spread the pathogen to more trees and groves. Therefore, proper destruction of LW affected trees is an important component for reducing the spread of this disease by root grafts and by ambrosia beetles.
Steps for properly removing and destroying LW affected trees
- Remove the entire tree by pulling or pushing. Pushing trees over before tree destruction is easier than trying to dig or uproot stumps from the ground.
- Once the tree has been removed, it should be chipped or burned. High powered front-end grinders are now in use which quickly chip the entire tree including the trunk area. Alternatively, wood may be chipped and wood too large split then chipped or burned. Call FDACS-Div. of Forestry at 305-257-0875 or 954-475-4120 for permission to burn (burn permit). Wood cut into smaller pieces will burn faster and more completely. The large wood may need to be burned more than one time (restack to expose non-burned wood) in order to be destroyed.
- Treating the tree stump (or stumps) with insecticides does not prevent the emergence of ambrosia beetles, which are already inside the tree and after a few weeks does not prevent further ambrosia beetle infestation. Thus, the best method to prevent beetle emergence from this wood and new boring into the wood is to dispose of the wood by chipping and/o rburning.
- Ambrosia beetles are attracted to avocado wood chips and leaving them untreated or not burned results in increased activity of ambrosia beetles in the grove. Wood chips should be spread out, not mounded, and thoroughly sprayed twice, 7-days apart, with an approved insecticide (e.g., Hero®, Talstar®, Malathion, Danitol® or Agrimek®), plus adjuvant (i.e., NuFilm®, Vapor Gard® or Pentrabark®). Some biopesticides (e.g., BotaniGard) have also been shown to kill ambrosia beetles as well. Avocado groves under organic production should chip and burn all wood.
Secondary strategies for preventing the spread of LW by root grafts among adjacent trees
Prophylactically treat entire planting with systemic fungicide
At present, there are no fungicides that cure LW-affected trees. The fungicide Tilt® (propiconazole) can be used, but it must be inside the tree before they are infected with the laurel wilt pathogen. Currently, Tilt® is the only labeled fungicide approved for laurel wilt control on avocado trees. Tilt® can only be used in commercial operations and is not approved for use by homeowners in their landscapes. When using Tilt®, growers must have in their possession the Section 18 special local needs label (SLN); go to http://www.syngenta-us.com/ or contact Jeff Wasielewski, Commercial Tropical Fruit Crops Extension Agent, (305-248-3311, ext. 227; jwasielewski@ufl.edu).
Infusion. Infusion consists of diluting the Tilt® with water and either passively or under pressure infusing the mixture into the flare roots at the base of the tree. Infusion of Tilt® must be repeated every 8 to 18 months. While effective, the infusion method causes damage to the flare roots making re-treatment difficult. Therefore, this application method may not be sustainable.
Injection. Injection consists of injecting the tree along the trunk and the major scaffold limbs using undiluted (or slightly diluted) Tilt®. Injection of Tilt® must be repeated every 12 to 16 months. Although a substantial number of groves have been treated in this manner, whether this method is sustainable in the long-term is not known.
Prophylactic treatment of groves, whether by infusion or injection, can be costly. As such this strategy if chosen is best suited for groves with varieties that generate relatively high returns.
Spot treatment. This is a combination strategy of early detection of LW symptomatic trees and treating by infusion one to two healthy trees adjacent a LW affected tree in an effort to prevent root movement of the LW pathogen to healthy trees. However, the key to success with the spot fungicide treatment is early detection of trees with symptoms of LW, their immediate uprooting and destruction and immediate infusion with Tilt® fungicide to the healthy adjacent trees. Although the spot treatment method is generally less costly than treating an entire grove approach, it may not be sustainable because of the damage to the flare roots caused by the necessity of repeated fungicide applications.
Ambrosia beetle suppression - insecticide applications in the immediate area (1 acre) surrounding LW positive avocado trees
The largest portion of the ambrosia beetle population is inside infested trees. Contact insecticides will not prevent ambrosia beetle emergence from already infested trees or wood.
Chipping and burning wood are the only ways to eliminate ambrosia beetles inside tree stumps and wood and stop their reproduction. To suppress ambrosia beetles active in the environment after chipping and/or burning infested trees, applications of contact insecticides and/or biopesticides to about one acre of trees surrounding a LW affected tree is recommended. After removing LW affected trees, make two applications of insecticide directed to the trunk, scaffold limbs and medium to large wood (not the foliage) of adjacent trees at a 10-15-day interval. The spray should be bark directed spray to the lower part of the tree and not the leaves and upper canopy. Malathion, Danitol® and Agri- Mek®SC are registered for bearing avocado trees. In order to reduce the chances of beetle resistance these products should be rotated (Table 1). For Malathion and Danitol® use an adjuvant such as NuFilm® to prolong the efficacy of the insecticide. Do not use sticker-type adjuvants like NuFilm with Agri-Mek®SC use a non-phytotoxic, non-ionic activator type wetting, spreading and/or penetrating spray adjuvant or horticultural oil (not dormant oil) – see label for details. Do not use Vapor Gard® and Pentrabark® adjuvants as they may cause phytotoxicity on leaves. For non-bearing avocado trees, Talstar®-S and Hero® may be applied (Table 2); use an adjuvant to prolong their efficacy.
The biopesticides BotaniGard® ES and Mycotrol® (the active ingredient is Beauveria bassiana
or Bb) are registered for avocado and have been shown to provide some ambrosia beetle control. The strategy is to attempt to suppress the ambrosia beetle population increase, which occurs during the spring. Research has shown trunk directed applications of Bb are capable of killing ambrosia beetles and the time-line for application of these materials is February through May when average temperatures are lower and beetle populations are increasing. However, proper trunk and major limb directed application is paramount for Bb to be effective. The concept is to place live Bb spores on the main trunk and scaffold limbs where ambrosia beetles may contact the live Bb spores.
- First, compatibility of Bb with other spray materials varies. A general recommendation is to clean spray tanks prior to tank mixing. Bb is not compatible with some fungicides (e.g., Abound® and Switch®) and insecticides (e.g., Danitol® and Malathion) (Table2).
- Spraying Bb too close to an application of a non-compatible spray material application will reduce the effectiveness of ambrosia beetle control. Therefore, time Bb applications toh ave the most time before and after any potential non-compatible spray material is used.
- Only purchase what will be used immediately. Do not leave these bio-insecticides in the tank for prolonged periods since it will kill the active Bb spores. Also be sure to store BotaniGard® ES and Mycotrol® in a cool, dry place that stays between 40°F and 85°F – otherwise the Bb spores will be killed.
- Mix the BotaniGard® ES and Mycotrol® in sufficient water to ju st wet the trunk and major limbs. Do not spray to run-off as this causes the Bb spores to wash off the bark. A light but thorough wetting is ideal.
In general, ambrosia beetles are attracted to areas of low light levels (i.e., shade). To reduce the potential for ambrosia beetle attack, selective pruning and/or annual or biannual topping and hedging should be practiced to increase light levels within the grove and tree canopies.
Summary
Ambrosia beetle control is a part of the strategy to control laurel wilt. However, it is imperative to implement early scouting for laurel wilt symptomatic trees and for tree removal and destruction to occur quickly. Strategies to suppress the ambrosia beetle population include selective pruning and/or regular topping and hedging to reduce the shading within and among avocado trees. This may reduce the attractiveness of trees to ambrosia beetles. Actively controlling ambrosia beetles in the immediate vicinity of an active laurel wilt outbreak may reduce new laurel wilt outbreaks.
Economic considerations
Rogue (remove and destroy) and replace
Economic modeling indicates that early detection and removal of the infected avocado tree (primary strategy) plus replacement (i.e., replanting) provides the best option for the operation to remain profitable. Immature trees are less likely to be attacked by ambrosia beetles and are not root grafted to adjacent trees. Harvesting can commence from third or fourth year.
Stumping and top-working trees
Stump healthy trees to 3 to 5 ft in height (~$25/tree) and allow trees to resume production.
Alternatively stump trees and topwork (~$35/tree) trees to a more profitable cultivar. Production may resume in 2-4 years depending upon cultivar and production practices. Their production level will be at a higher level than young (1-3 years-old) trees. The drawback for maintaining these older trees is they remain root grafted to adjacent trees and LW could move from tree to tree via the root system. It is not recommended to stump LW affected trees to topwork.
Replanting
Remove a block or grove of old avocado trees (~$50/tree) and replant avocado trees (~$30/tree) with a more profitable cultivar. To establish a new grove estimated to be ~$8,000/acre. The advantages to removing mature root-grafted avocado trees and replanting to young avocado tree includes: (1) young trees are less attractive to AB (small diameter trunks and lots of light in grove) and (2) young trees are not and will not be root grafted to adjacent trees for years – so LW pathogen cannot spread tree to tree by the roots. This strategy buys time to find better control solutions to LW-AB. The disadvantages to remove and replanting with young trees is the cost of removing old trees and replanting with young trees, fruit production will not begin for 3-4 years, and will not be substantial until 7-8 years.
Alternative options for LW affected groves
Remove trees (~$50/tree) and enter an alternative agricultural business or fruit crop.
Table 1. Contact insecticides for ambrosia beetle control. Direct applications to the trunk and medium to large wood to about one acre of trees surrounding the LW affected tree. Rotate pesticides products reduce the potential for insect resistance. MixDanitol®,Malathion and Hero® with anadjuvant (e.g.,NuFilm®) to prolong their efficacy. ForAgri-Mek®SC do not useNuFilm® or similar, use a non-phytotoxic, non-ionic activator type wetting, spreading and/or penetrating sprayadjuvant or horticultural oil (no a dormant oil) – see label for details. The biological control insecticidesBotaniGard® ES andMycotrol® do not need anadjuvant and should be stored in a cool (<85°F), dry place.
Product |
Rate per acre |
Spray interval |
Potential # of applications allowed per year per acre |
Comments – estimated days of efficacyz |
Danitol® 2.4 EC (fenpropathrin) |
21.3 oz |
14 |
1 |
14-21 |
Malathion 5EC (malathion) |
24 oz/100 gallons |
7-10 |
Open |
10-14 |
Hero® (liquid)y (zeta-cypermethrin+ bifenthrin) |
10.3 |
14 |
6 |
14-21 (non-bearing trees only xy) |
Agri-Mek®SC (abamectin) |
4.25 oz |
30 |
2 |
Do not mix with NuFilm or similar; see label for details |
Talstar®S (bifenthrin) |
40 oz |
NA |
1 |
Not known; non-bearing trees onlyy; may not need adjuvant |
BotaniGard® ES (Beauvaria bassiana) |
32 oz |
7-14 |
Open |
Not known |
Mycotrol-O® (Beauvaria bassiana) |
32 oz |
7-14 |
Open |
Not known; organic production |
x, Special Local Need (SLN Section 24C): y, Only for non-bearing trees; do not apply within 1 year of harvest; z, The estimated days of efficacy is influenced by numerous factors including weather conditions (e.g., rainfall, temperature, and UV light intensity). |
Table 2. Compatibility of fungicides, insecticides, adjuvants and foliar nutrients with BotaniGard® |
||
Fungicide |
BotaniGard |
|
Pre-application |
1 h |
6 h |
Abound |
NC |
NC |
Cuprofix-Ultra 40 Disperss |
C |
C |
Flopan 80 |
NC |
NC |
Kocide 2000 |
C |
C |
Ridomil Gold Copper |
C |
C |
Ridomil Gold SL |
C |
C |
Switch 62.5WG |
NC |
NC |
Tilt |
C |
C |
ProPhyt Phosphonate |
C |
NC |
C = compatible; NC = Not compatible |
|
|
Compatibility of insecticides with BotaniGard® |
|
Insecticide |
BotaniGard |
|
Pre-application |
1 hour |
6 hours |
Danitol |
NC |
NC |
Hero |
C |
C |
Admire Pro |
C |
C |
Malathion |
NC |
NC |
Permethrin |
C |
NC |
Agrimek |
C |
C |
Actara |
C |
C |
Talstar |
C |
C |
Mustang |
C |
C |
C = compatible; NC = Not compatible |
||
Compatibility of adjuvants with BotaniGard® |
||
Adjuvant |
BotaniGard |
|
Pre-application |
1 hour |
6 hours |
Banole oil |
C |
C |
Citrus oil |
C |
C |
NuFlim |
C |
C |
L1700 |
C |
C |
Pentrabark |
C |
C |
Compatibility of KeyPlex 350 with BotaniGard® |
||
Pre-application |
1 hour |
6 hours |
Keyplex 350 |
C |
C |
C = compatible; NC = Notcompatible |
|
(c://tree destruct and LW control recommendations 12-22-17.doc)
- Author: Sonia Rios
Controlling Pests in Avocados Round Table Meeting Sept. 28, 2017, 8:00 AM - NOON Fallbrook Public Utility District, 990 E. Mission Rd, Fallbrook, CA 92028 DPR Hours Upon Approval Light refreshments & pastries will be available Please Register for this free event:
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“Introduction to Avocado Integrated Weed Management” – Sonia Rios, UCCE Farm AdvisorsRound table Discussion 1 - Old challenges/new possible solutions - pesticide resistance, new pesticides, etc.- Mary Lu Arpaia & Sonia Rios“A Review: Redbay ambrosia beetle & Laurel Wilt Disease” – Tim Spann, California Avocado CommissionRound table Discussion 2- New challenges – Laurel Wilt Disease and other pest challenges - Mary Lu Arpaia & Sonia Rios
If you have any questions, contact Sonia Rios, UCCE Riverside/San Diego Counties sirios@ucanr.edu
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- Author: Sonia Rios
During the first week of August, the California Avocado Society, Inc., California Avocado Commission, University of California Cooperative Extension hosted six Laurel wilt researchers from the University of Florida. The speakers were Randy Ploetz, Jonathan Crane, Bruce Schaffer, Daniel Carrillo, Jeff Wasielewski and Edward Evans. In addition to talking at all three seminar locations, San Luis Obispo, Ventura, and Fallbrook, the researchers were also able to tour the major avocado growing regions.
Laurel wilt is a deadly disease of redbay (Persea borbonia) and other tree species in the Laurel family (Lauraceae), which includes the avocado tree. The disease is caused by a fungus (Raffaelea lauricola) that is introduced into host trees by a nonnative insect, the redbay ambrosia beetle (Xyleborus glabratus). Native to Southeast Asia, the ambrosia beetle has similarities to our current ambrosia pest, Polyphagous shot hole borer and the Kuroshio Borer. That is why this visit from our fellow extension researchers from the University of Florida. However the fungus associated with Laurel Wilt is unlike the disease here in California. Laurel Wilt is a disease that that causes a reaction in the tree to restrict water flow in the tree and the tree collapses rapidly. The tree dies so fast that it doesn't even have a chance for the leaves to fall of the dead branches.
The beetle has the ability to spread the specific pathogen to other ambrosia beetle vectors which happens when they feed on infected trees. Sanitation is the most effect way to manage this problem. Scouting for wilted branches and their rapid removal has been the key to early intervention and eradication. Dr. Ploetz suggests removing the tree immediately. By the time you see frass and streaks in the wood, the tree is already infected and has been for sometime. As soon as a growers see the wilt in the branches, its time to move quickly. This disease may be mistaken for Verticillium wilt or Phytophthora. It can spread throughout the grove by root grafting.
The generation time for the beetle inside avocado trees takes about 40-50 days depending upon temperatures. Their flight activity is highest in the late afternoon and early evening. Dr. Carrillo mentioned that ambrosia beetles are notoriously difficult to control because they are inside the tree most of their life cycle versus being outside the tree. Contact herbicides will not work, because the insects are primarily inside the tree. One of the first goals to avoid infection, is to keep your trees healthy. A sick tree is more attractive
Scouting for laurel wilt in commercial avocado groves
1. Surveying for the symptoms of laurel wilt is a key component of limiting the spread of laurel wilt. Growers and their workers should survey their groves immediately and then weekly or more often if an infestation is detected in an adjacent grove. Pathogen sniffing dogs are currently being used, however there are less than half-dozen trained dogs for this purpose. Symptoms to look for might include:
i. Leaf and young stem wilting.
ii. Leaf color changing from light green to dark green, bluish-green or greenish-brown. Some leaves showing leaf mottling (dark and light green areas) and yellowing.
iii. Dead leaves curled hanging on the tree.
iv. A few stems and limbs with 2 to 4 ft of dieback or whole sections or entire limbs with dieback.
v. Inspection of the trunk and major limbs may show dried sap (white, crystalline powdery material) that indicates insect boring. In any case, on symptomatic limbs remove the bark down to the sapwood and look for dark streaking. Dark streaks in the sapwood may indicate fungal infection. Normally this sapwood should be white to yellowish with no dark staining or streaking. In addition, small, dark holes in the sapwood further indicate wood boring beetles are present.
2. If the tree shows only a few stems and limbs with 2 to 4 ft of dieback, wait for confirmation of laurel wilt before removing the tree. You can remove the dead part of the limb by cutting several feet below the dead area of the limb; burn or bury the infested limb.
- Author: Ben Faber
From The Packer:
South Florida university researchers are using dogs and drones to sniff out a disease that's killing the region's avocado trees.
The Florida International University researchers are sending dutch sheppards and belgian malinois into avocado groves to locate trees infected by the lethal laurel wilt disease, which is spread by the redbay ambrosia beetle.
Detection is a major problem and trees can start to wilt within two weeks.
By the time infected trees are detected, the fungus has likely spread to nearby trees via root grafting, said DeEtta Mills, a biological sciences professor.
She and Kenneth Furton, a university provost and forensic chemist, are leading research that trains and deploys five dogs into Miami-area groves.
Drones flying above the groves can detect symptomatic trees, which signal researchers to direct the dogs to infected areas.
The dogs run through the groves and with their powerful noses, have been 90% accurate in locating infected trees, Mills said.
Because of permitting paperwork delays by the Federal Aviation Administration, the researchers haven't been able to use the drones.
The researchers hope to receive approval for drones by August and are relying on growers to point them to infected trees.
The drones provide higher accuracy and can better cover larger areas because running the dogs too long can overheat them and wear them out, Mills said.
Their heavy panting can dull their sniffing senses so after about 20 minutes, the researchers return them to kennels in air conditioned vans, Mills said.
The dogs are trained with diseased wood and infected tree samples detected by the dogs are sent to researchers who examine DNA to verify contamination, she said.
“These dogs, they love to do this and it's amazing to watch them,” Mills said. “These ‘girls' come out of the kennels of the van and ask us where we would like to send them and what we would like them to do. They're extremely highly-driven dogs. If we can get permission to use the drones, it will help us identify areas we need to go in with the dogs and help us verify infection much faster so the dogs won't have to cover as much ground.”
Canine detection is another way of helping save the state's multi-million dollar avocado industry and ultimately, the North American industry.
Florida growers have lost about 4,000 of nearly 800,000 trees and the disease has spread throughout the Mid-Atlantic and into Mississippi.
If it travels farther west, the dogs and drones detection system could also help growers in California and Mexico protect their much larger production, she said.
The Miami university is also working with University of Florida researchers and growers.
N.B. These techniques could also be used to trace Polyphagous Shot Hole Borer infested trees, as well.