- Author: Ben Faber
Caught with Your Water Down
Another type of disorder which arises presumably from water stress is one of the fruit pedicel (stem) termed ring-neck. This disorder was first described afflicting the Fuerte variety by J. Elliot Coit in 1928. Horne (1934) provides a good description of this disorder:
It is a blemish, usually on the fruit-stem or pedicel, consisting of irregular areas of superficial dried tissues which become more or less separated from the living tissue. It is particularly likely to affect the thickened segment of the pedicel next to the fruit. Sometimes a complete ring of surface tissue dies,separates from the pedicel,and peels off, leaving a scar. The upper end of the pedicel is slightly fleshy and enlarged, and a small ring-neck spot sometimes occurs on it. Occasionally lesions which have somewhat the appearance of ring-neck develop on the fruit, and where extensive, may give it a grotesque appearance through curling up of the dead surface layer from the edges.
It was originally believed that ring-neck could be caused by a pathogen. Early attempts failed to identify the causal organism. Work in South Africa eliminated pathogen involvement in the development of this disorder. This shows up along the coast where extremes of temperature can occur with Santa Ana conditions. With increased plantings in the Central Valley, it has shown up, as well. Temperature extremes and changing water demand need to be watched in order to avoid this abiotic disorder.
Examples of ring-neck. A. Slight damage to the fruit pedicel. B. Note the peeling of the pedicel tissue.
C. Note that only one fruit (left) is affected with ring-neck.
- Author: Ben Faber
What is allelopathy?
Allelopathy literally means “death to others.” In its simplest sense, allelopathy is the ability of one plant species to affect the growth of another through their chemical exudates. While early researchers narrowly defined the relationship to include only the influence of living plants on other living plants, more recently the definition has been expanded to include interactions within the soil environment. Such “soil-mediated chemical interference” is arguably a more relevant definition, as roots of adjacent plants share the same soil environment. Competition for water and nutrients, soil microbial activity, and other environmental conditions should be considered separately from any possible “chemical warfare” among plants. Therefore, allelopathy is currently understood to involve living or dead plant parts that release chemicals into the soil which have an effect on other plants—positive or negative. And no allelopathic chemical is better known—and feared— than juglone.
Read this interesting treatise on juglone and its history as a bogey for poor plant performance by Linda Chalker-Scott –
Do Black Walnut Trees Have Allelopathic Effects on Other Plants?
And once you have had your myth revealed, check out these other horticultural myths that Chalker-Scott and team have worked over:
Horticultural Myths
Image: Impatiens struggling, think it's the juglone?
- Author: Ben Faber
What Are the UC Ag Experts Talking About?
For 2023
| Event Name | Date |
|---|---|
| UC Ag Experts Talk: Vegetable IPM in the Sacramento Valley | 2/22/2023 |
| UC Ag Experts Talk: Insects in the Vineyard | 4/19/2023 |
| UC Ag Experts Talk: Flatheaded borer concerns in California walnuts | 5/31/2023 |
What is involved in the webinars?
A series of usually 1-hour long webinars, designed for growers and pest management professionals, highlighting various pest management and horticultural topics for citrus, avocados, and other subtropical crops. Master Gardeners can benefit from participating, but the pest management methods presented, especially the pesticides, are not to be followed without a clear understanding of their legal use by homeowners.
During each session, a UC Expert on the subject makes a presentation and entertains write-in questions via chat during and/or after the presentation. As we develop this program, we may expand to other crops.
What are the topics and how do I register?
Register for webinars using the links above.
Vegetable IPM in the Sacramento Valley by Dr. Amber Vinchesi-Vahl (February 22, 2023)
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Dr. Amber Vinchesi-Vahl will discuss IPM on vegetables in the Sacramento Valley, with a focus on tomatoes. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Insects in the Vineyard by Dr. Cindy Kron (April 19, 2023)
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Dr. Cindy Kron will discuss the importance of proper insect identification in IPM and discuss many insects that are beneficial in vineyards. She will also discuss economic thresholds for pests that cause damage and vector diseases and include a pest to be on the lookout for: spotted lanternfly. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Flatheaded Borer Concerns in California Walnuts by Dr. Jhalendra Rijal (May 31, 2023)
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Dr. Jhalendra Rijal will discuss flatheaded borer and how it is an old pest but has become a new problem in California walnuts. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Are there Continuing Education units?
When the subject discusses pest or disease management, continuing education units (CEU) will be requested from DPR (1 unit per session) and when relevant also Certified Crop Advisor (CCA) continuing education units will be requested. To qualify for the CEU make sure to
- register separately with your own email address and log in from your own device
- participate in the entire hour session
- complete and pass a final test with 70% or higher; if not passed, the test can be retaken
If you are connecting by smartphone and need CEUs, be sure that you are using the zoom app (Android, iPhone) so that you have access to the presentation and we can track your presence in the webinar.
Certificates of completion will be emailed within one week to those who meet those requirements above.
The webinars are recorded and linked from this web site for future study. However, continuing education units are awarded only to the participants who attend the live version of the webinar.
Make a gift to support UC Ag Experts webinars
Your gift furthers UC's Integrated Pest Management's mission to help California residents, growers, land managers, and other professional pest managers prevent and solve pest problems with minimal impact on people and the environment by developing and promoting the use of integrated and ecologically sound pest management programs. Make a gift and use the Comment field to specify that your gift is for UC Ag Experts Talk webinars.
Who is involved in the UC Ag Experts webinars?
This webinar series is brought to you by Ben Faber (UC ANR Ventura Advisor) and Dr. Beth Grafton-Cardwell (Emeritus Entomology UCCE Specialist) with the technical support of Petr Kosina (UC IPM Content Development Supervisor) and Cheryl Reynolds (UC IPM Interactive Learning Developer).
- Author: Ben Faber
New Educational Materials: Commercial HLB Detection Response Guide
To ensure California citrus growers are well prepared in the event of a potential commercial grove detection of Huanglongbing (HLB), the deadly citrus plant disease that can be spread by the Asian citrus psyllid (ACP), the Citrus Pest and Disease Prevention Program (CPDPP) has developed a response guide for growers to utilize and educate themselves on the California Department of Food and Agriculture's (CDFA) action plan.
Related
The Response Guide for a Confirmed HLB Positive Detection in a Commercial Grove details the steps taken by CDFA and actions required of the property or grove owner, as outlined in CDFA's Action Plan.
The actions in the response guide represent the most effective tools known to the citrus industry at this time and are meant to protect California's citrus groves and support CDFA's current required regulatory response. While, as of today, there have been no positive detections of HLB in a commercial citrus grove, the CPDPP recognizes the importance of proper preparation.
In addition to the requirements outlined in the guide, growers are encouraged to use as many methods as feasible for their operation in order to limit the spread of the ACP and HLB.
To read or download the response guide, please click here. If you have any questions or would like to order physical copies of this response guide, please visit our Resources page.
Response Guide for a Confirmed HLB Positive Detection
- Author: Ben Faber
Dr. Roger Baldwin, Cooperative Extension Specialist in Human-Wildlife Conflict Resolution in the Department of Wildlife, Fish, and Conservation Biology at UC Davis, discussed the management of voles, rats, and mice in agricultural fields with a particular emphasis on an IPM approach. He covered a variety of management tools including biocontrol, habitat modification, trapping, rodenticides, and fumigants. The webinar was recorded on October 26, 2022 and targeted to growers and pest management professionals. For Master Gardeners and others serving home environments, please note that management methods, especially any pesticides mentioned, are not to be used without a clear understanding of their legal use. Continuing Education credits are not available for recorded webinars. Closed captions are being reviewed for accuracy and will be corrected as necessary. Speaker: Dr. Roger Baldwin, University of California Cooperative Extension Specialist, UC Davis.
Watch other recorded webinars https://www.youtube.com/playlist?list... Visit https://ucanr.edu/sites/ucexpertstalk/ for information about webinars. Visit http://ipm.ucanr.edu/training/ for information about UC IPM online courses.
Image: Vole damage to tree trunk
