- Author: Ben Faber
Our latest edition of our Newsletter is available on-line, where you can also subscribe to future editions
https://ceventura.ucanr.edu/news/Topics_in_Subtropics/
Enjoy
TOPICS IN THIS ISSUE – Sandipa Gautam, Editor
- California inundated with invasive fruit flies
- Satellite-based irrigation tools to manage irrigation water more precisely in avocado groves
- Managing citrus mealybug – does ant control help?
- Phytoplasma Diseases of Palms in the USA
- Understanding fruit fly quarantines
- Cultivating Citrus Resilience to HLB in California
- Phenology and the Avocado
- The Annual California Avocado Society Meeting
- Pre-bloom foliar boron application on olive may improve yield
- Author: Ben Faber
A repeat post from the recent past
- Author: Ben Faber
What Can Happen With Too Much Rain? Watch that Mulch!!!
Rain is wonderful stuff. If it comes and washes the accumulated salts of the last several years out of the root zones of citrus and avocado, that's a good thing. But what happens if there is a little too much of the good stuff? In the winter of 2005, Venture got over 40” of rain, which is 200% of what is normal. The last time big rains occurred prior to that was in the winter of 1997-98. That year the rains were evenly spaced on almost a weekly basis through the winter and into the late spring and over 50" fell. That year we had major problems with both citrus and avocados collapsing from asphyxiation. The same occurred in 2005, but not so pronounced.
Rain is good, right?
In 2003 we had a lot more rain than we normally see and in Carpinteria it rained 4 inches in July!!!!!! In some young trees with poorly developed root systems, we have seen some collapse from asphyxiation. Avocados tend to be more susceptible than citrus, and some rootstocks more than others. Even big trees collapsed.
Asphyxiation is a physiological problem that may affect certain branches, whole limbs or the entire tree. Leaves wilt and may fall, the fruit withers and drops and the branches die back to a greater or lesser extent. The condition develops so rapidly that it may be regarded as a form of collapse. Usually, the larger stems and branches remain alive, and after a time, vigorous new growth is put out so that the tree tends to recover. Young trees can be harder hit, but sunburn damage from lack of leaves may be more of a problem.
Asphyxiation is related to the air and water conditions of the soil. The trouble appears mainly in fine-textured or shallow soils with impervious sub-soils. In 1997-98, this even occurred on slopes with normally good drainage because the rains were so frequent. When such soils are over-irrigated or wetted by rains, the water displaces the soil oxygen. The smaller roots die when deprived of oxygen. When the stress of water shortage develops, the impaired roots are unable to supply water to the leaves rapidly enough and the tree collapses. The condition is accentuated when rainy weather is followed by winds or warm conditions.
It doesn't take standing water to have asphyxiation occur.
- Author: Ben Faber
California Avocado Growers Seminars Series 2024
Scheduled Topics
February 15 (10 - 12 AM)
HOW TO MANAGE THE TREES IN A WET YEAR
Topics and Speakers
By Hamutahl Cohen, PH.D. Entomology Advisor, UC Cooperative Extension
PCA Panel on Thrips Management Under Different Weather Scenarios
Moderator Dr. Hamutahl Cohen
Caloptilia Updates
By Bodil Cass, Extension Subtropics Entomologist, UCR
Panel on Cultural Practices in a Wet Year
Moderator Dr. Ben Faber, PH.D. Advisor, UC Cooperative Extension
Hybrid Meeting
- Author: Ben Faber
LAUREL WILT AND PHYTOPHTHORA ROOT ROT SURVEY
BACKGROUND
Despite the importance of laurel wilt (LW) and Phytophthora root rot (PRR) in avocado producing states, and the research conducted to date, there are still major gaps in our knowledge. Specifically, little is known about grower decision-making about management and the economic costs and benefits of management options. Understanding grower decision-making, economic costs, and the benefits of management options to growers is crucial to the establishment of rational and sustainable disease management strategies. That's why in this project we are organizing a multi-state survey to collect data about management, to understand the situation and highlight effective management strategies for each state.
Note: Laurel wilt (LW) disease is not Fusarium dieback. (Fusarium dieback is the disease spread by the invasive shot hole borers.) Laurel wilt is currently reported only in the eastern and central US.
And here's the survey that we are asking growers to complete:
https://ufl.qualtrics.com/jfe/form/SV_6fEn9M00UGmnwXA
Thank you.
University of CA, Florida, Hawaii and TAMU (Texas) personnel working on avocado disease
- Author: Ben Faber
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