- Author: Ben Faber
In many ways our pest and disease management of fruit tree crops are exacerbated by our cultural practices. Avocado and citrus offer some very clear demonstrations of how we manage our trees can lead to reduced pesticide use. From the beginning, our selection of rootstock and scion can help lessen pest and disease problems. In both avocado and citrus we have good rootstocks which can handle problems, such as root rot more effectively than seedling rootstocks. So it is imperative that if you know that drainage will be a problem, starting off with the right, healthy rootstock helps. Also scion selection can have a major impact, as well. For example, ‘Lamb' avocado is much less prone to persea mite than is ‘Hass'. This pest can significantly impact a spray program and planting ‘Lamb' could mean virtually no sprays for this pest. Selling the ‘Lamb' fruit is then the challenge There are similar examples in citrus where one variety is more prone to a pest or disease than another.
Irrigation is probably the most important cultural factor in managing tree disease. Over, under and improperly timed irrigations are the conditions necessary for many root diseases. The Phytophthora spp. fungi are looking for distressed root systems brought on by waterlogging and other stressful situations. Other conditions, such as wetted trunks can also bring on some trunk diseases, like gummosis in citrus and crown rot in avocado. Simply preventing irrigation water on the trunks can limit these diseases. Other diseases, such as black streak, stem blight and bacterial canker in avocado are bought on by soil moisture stress.
Nutrients, especially nitrogen management, has been long known to affect levels of insects, such as scale, mealy bug and aphid. Encouraging lush growth helps sustain these insects, so reducing this growth tends to lower their numbers. Managing when canopy growth occurs can affect pest severity. Avocado thrips build their populations in the spring and moves easily from leaf to fruit causing significant scarring. By promoting leaf growth at flowering time with a nitrogen application, keeps the insect on the leaves and reduces fruit scarring. This also promotes growth that replaces leaves that have been damaged by persea mite. Likewise the incidence of citrus leaf miner damage can be reduced if spring pruning is avoided so that a flush of growth does not occur at the same time as the population is building. Timing of pruning is important in lemons to avoid wet periods of rain and fog to reduce the spread of hyphoderma wood rot fungus when its fruiting bodies are active.
Pruning can change pest pressure by changing the humidity in the canopy, introducing light and changing the climate supporting disease and pests. By making spray coverage more thorough, it also makes for a more effective application. Modified skirt pruning can have significant effects on mealy bug and scale control, fuller rose weevil incidence, ant colonization and snail damage. It's important that the trunk be protected as an avenue of movement for snail and ant control to get the best effects of this pruning. Skirt pruning also reduces problems with such weeds as bladder pod and the ladder effect of brown rot in citrus – fungal propagules splashed from the ground onto low-hanging fruit, which in turn is splashed to higher fruit.
Keeping a canopy clean of dust and fire ash also makes for more efficient biological control. Because predators are slowed in their search, they are less efficient. They also spend more time grooming their sensory organs, and this also slows them down. Parasites such as wasps are actually slowed by the physical abrasion to their tarsi. Dust also creates a drier environment, which is more hospitable to our pest mites. Watering picking rows, roads and even the trees themselves can lessen mite populations. Use of cover crops can also reduce dust and potentially provide pollen and nectar for predators and parasites. Of course cover crops create a whole new set of management issues, such as colder winter orchards and snails.
Finally harvest timing to avoid pest and disease is often overlooked. In avocado, fruit is often set in clusters. Greenhouse thrips love the microclimate created, and if in a size-pick the cluster is reduced, greenhouse thrips will often not be a problem. Harvest timing is also important in citrus. Fruit left too long on the tree can often develop septoria fungal spot. Picking in a timely manner reduces the incidence of this disease.
These are just a few examples of how cultural practices at the right time can reduce pest and disease problems.
- Author: Ben Faber
Loquat is an evergreen tree with delicious fruit. Too bad some varieties have big seeds, but in some countries like Spain and China they are a big deal. At one point, Orange County had 500 acres of trees – ‘Big Jim', ‘Gold Nugget', ‘Victory', ‘Mammoth'….. Now it's more of a pleasurable backyard shade tree that gets immense quantities of fruit twice a year. Too good to be true.
But it may be troubling to hear that a new bark beetle pest of loquats has been identified in China by the University of Florida's Forest Entomology Lab. A new paper describing the beetle has just been published in the journal Insects.
The beetle, newly named Cryphalus eriobotryae, was first observed in April of 2018 in a tree nursery near the city of Suzhou in Jiangsu, a coastal province of China. Loquat trees were dying for unknown reasons. There are no other insect pests known either to specialize in loquat trees or to kill them. But when the problem spread to other areas during the summer of 2018, it became clear that a real problem had emerged.
Chunrong Chu, a technician with Suzhou's forest service, and Sizhu Zheng, an entomologist with Suzhou's customs agency, sent photos and specimens of the beetles to the UF Forest Entomology Lab for identification, led by Dr. Jiri Hulcr. The lab has staked out an unusual specialty in the entomology world. Having already built the world's largest cryo-collection of bark and ambrosia beetles, Hulcr's team established a volunteer service for the global identification of bark and ambrosia beetles.
Dr. Andrew Johnson, a research scientist in the UF Forest Entomology Lab, was studying the genus. He quickly realized that he was looking at an entirely new species. He named the beetle eriobotryae in reference to the name of the genus of plants to which loquats belong. "By giving this a name and recognizing it as a potential threat, we can encourage further work," said Johnson. "Before giving it a name, it is difficult to coordinate and to work on this species."
The work has barely started. The beetles' DNA has recently been sequenced and analyzed via a method that examines one very specific part of a genome in order to determine its identity. But a full pre-invasion assessment has not been conducted. It is still not clear exactly where the beetle came from, what its potential is as an invasive species, or what means can be used to prevent and fight future outbreaks.
Bark beetles are a group of insects including thousands of species that chew holes through the bark of a tree and feed on the phloem just beneath the bark. They live most of their lives invisibly, breeding and rearing their young in tunnels called galleries. Most bark beetles only colonize recently dead trees, but some species may turn their attention to living trees and can kill them, sometimes on a massive scale, as with the Southern pine beetle.
In affected areas of Jiangsu, the threat of the loquat beetle is not an obscure issue. Loquats are as economically and culinarily important as, say, oranges in Florida or avocados in Mexico. "Local people really want to know how to control and kill this pest," says Dr. You Li, a scientist with the UF Forest Entomology Lab who also contributed to the paper. "That's why they are happy we could tell them more about this beetle."
So far, the loquat beetles have all been found in nurseries, which may be a clue to the origins of the beetle and the means of its spread. Transportation of live plants from one location to another is a frequent vector for movement of invasive species that can hitch a ride.
The process of loquat death begins when beetles make tiny holes at the base of the tree. This progresses up along the trunk as the offspring of the initial beetles mature and start tunnels of their own. As the galleries of beetles become more dense, eventually, the tree may be girdled around its circumference. At that point, it is no longer able to move water and nutrients from the roots to the leaves. The leaves rapidly turn brown and die while remaining attached to the branches.
So it looks like we can add another beetle to the list that is causing problems around the world.
Get the low down on bark beetle spread:
Peter H.W. Biedermann et al. Bark Beetle Population Dynamics in the Anthropocene: Challenges and Solutions, Trends in Ecology & Evolution (2019). DOI: 10.1016/j.tree.2019.06.002
Photo: Loquat orchard under netting in Spain:
Read on:
https://www.mdpi.com/2075-4450/10/6/180
Cryphalus eriobotryae sp. nov. (Coleopetera: Curculionide: Scolytinae), a New Insect Pest of Loquat: Eriobotrya japonica in China
(A) Tree killed by Cryphalus eriobotryae; (B) teneral adult; (C) adult outside a newly excavated gallery; (D) larva; (E) pupa; (F) cankers on the trunk; (G) adults made the canker; (H) tree recovered after failed beetle attack; (I) galleries on the underside of peeled bark.
The newly-identified loquat beetle. Credit: Dr. Andrew Johnson
/span>- Author: Ben Faber
Snails and Slugs (May 22, 2019 from 3-4pm)
Presenters: (!) Dr. Cheryl Wilen (UC IPM), (2) Dr. Rory Mc Donnell and (3) Dr. Dee Denver (Oregon State University), (4) Dr. Adler Dillman and (5) Dr. Irma De Ley (UC Riverside). The webinar will cover an overview of snail and slug biology, damage and management with emphasis on brown snail and Italian white snail, and current research on slug biocontrol using nematodes. One DPR CE unit (other) and one CCA CE unit (IPM) are approved.
And What Else Are the
UC Ag Experts
Talking About?
Event Name | Date |
---|---|
UC Ag Experts Talk: Snails and slugs | 5/22/2019 |
Uc Ag Experts Talk: Management of Weeds in Citrus Orchards | 6/19/2019 |
UC Ag Experts Talk: Citrus Dry Root Rot | 7/24/2019 |
What is involved in the webinars?
A series of 1 hour webinars, designed for growers and Pest Control Advisors, will highlight various pest management and horticultural topics for citrus and avocados. During each session, a UC Expert on the subject will make a presentation and entertain write-in questions via chat during and/or after the presentation. As we develop this program, we may expand to other crops.
Topics: pests and diseases of citrus, avocado and other crops
And Next up is:
Management of Weeds in Citrus Orchards (June 19, 2019 from 3-4pm)
Dr. Travis Bean, assistant weed science specialist in UCCE, will discuss the importance of weed management in citrus, tree age and variety considerations, scouting and weed identification, cultural and mechanical practices, and pre- and post-emergence herbicides. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Register in advance for the webinars by clicking on the event links above.
Are there Continuing Education units?
When the subject discusses pest or disease management, continuing education units will be requested from DPR (1 unit per session). Participants will pre-register, participate in the webinar and be awarded the unit. The sessions will be recorded and hosted on this web site for future study. However, continuing education units will be awarded only to the participants who attend the live version of the webinar.
Who is involved?
This webinar series is brought to you by Ben Faber (UC ANR Ventura Advisor) and Dr. Beth Grafton-Cardwell (Depart of Entomology UC Riverside Extension Specialist) with the technical support of Petr Kosina (UC IPM Contect Development Supervisor) and Cheryl Reynolds (UC IPM Interactive Learning Developer).
- Author: Beth Grafton-Cardwell
What Are the Ag Experts Talking About?
Event Name | Date |
---|---|
UC Ag Expert talks about citrus thrips | 10/17/2018 |
What is involved in the webinars?
A series of 1 hour webinars will highlight various pest management and horticultural topics for citrus and avocados. During each session, a UC Expert on the subject will make a presentation and entertain write-in questions via chat during and/or after the presentation. As we develop this program, we may expand to other crops. These programs are open to all, but are geared to those individuals, such as PCAs and Growers who need CEUs.
Topics: pests and diseases of citrus and avocados
What are the topics and how do I register?
Citrus Thrips - October 17, 2018 at 3 pm
Register in advance for this webinar by clicking on the event link above.
Are there Continuing Education units?
When the subject discusses pest or disease management, continuing education units will be requested from DPR (1 unit per session). Participants will pre-register, participate in the webinar and be awarded the unit. The sessions will be recorded and hosted on this web site for future study. However, continuing education units will be awarded only to the participants who attend the live version of the webinar.
Who is involved?
This webinar series is brought to you by Ben Faber (UC ANR Ventura Advisor) and Dr. Beth Grafton-Cardwell (Depart of Entomology UC Riverside Extension Specialist) with the technical support of Petr Kosina (UC IPM Contect Development Supervisor) and Cheryl Reynolds (UC IPM Interactive Learning Developer).
https://ucanr.edu/sites/ucexpertstalk/
Photo: The mighty citrusthrips - Scirtothrips citri
/table>/h1>
- Author: Ben Faber
Citrus: UC IPM Pest Management Guidelines
Publication Number: 3441 Copyright Date: Rev. 2017
Length: 234 pp.
Language: English
Inventory Type: PDF File
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This is a free publication if you access it as a web page or downloadable PDF document.
These official UC-approved guidelines for pest monitoring techniques, pesticide use, and nonpesticide alternatives for agricultural crops are essential tools for anyone making pest management decisions in the field. This 124-page guideline covers citrus fruit. Updated August 2015. A hard copy version of these guidelines can be purchased as Publication 3441P. The PDF version of this publication is best viewed using the free Adobe® Acrobat® Reader. You can download a free copy of the Acrobat Reader from Adobe Systems Incorporated. Some users have experienced problems using Preview with these documents; we recommend using the Adobe® Acrobat® Reader. |