From Fox Weather by way of CA Avocado Commission, hot weather is forecast for mid- to late- June
This is a time to make sure that trees are adequately hydrated prior to the heat spell. Once trees start losing water through transpiration, it's hard for them to absorb water and heat stress and sunburn damage can result. The trees need to be fully water, so that they can continue to transpire to cool themselves during the heat spells.
And don't forget people in the field:
- Be sure shade is available on demand when the temperature is below 80 degrees F, shade must be provided at all times when the temperature exceeds 80 degrees F, as close as practicable to where employees are working;
- Shade must be provided to all employees on a rest or meal break,except those who choose to take a meal break elsewhere (editor's note: provision of shade as usual may not be consistent with social distancing recommended by various COVID-19 guidance; ag employers implementing heat illness shade requirements can ensure adequate shade consistent with social distancing requirements by staggering meal and rest breaks, but additional shade may be necessary);
- Fresh, pure, and suitably cool water must be made available in sufficient quantities (replenishment is permissible) to allow each employee to drink one quart per hour;
- Water is to be provided as close as practicable to location of work;
- Employees must be trained about heat illness and the Cal/OSHA Heat Illness Prevention (HIP) Standard before they work in conditions where they might be exposed to heat;
- Supervisors must be additionally trained in HIP compliance procedures, emergency responses, and ensuring effective communication to facilitate emergency response.
- A written copy of your HIP program in English and the language understood by the majority of the employees and be available to employees and Cal/OSHA inspectors on request — this is the most frequently-cited part of the HIP standard — and probably the most easily-avoided HIP citation!
- Remember: When temperatures exceed 95 degrees, employers must implement “high heat” procedures, including a mandatory 10 minute break every two hours (meal and rest periods can serve as these breaks, but if employees work beyond eight hours or waive meal or rest periods, you must still ensure the mandatory rest break occurs).
30-Day Weather Outlook for May 31, 2020, to June 22, 2020
Summary- The prevailing pattern is a high pressure ridge from N California westsouthwest or southwestward. Cold fronts coming S through California will tend to extend southwestward from southcentral-S California to the area SW – W of S California.
A long-lived pattern of troughing or low pressure will continue from southwest of Central California to about 25N then extend west toward Hawaii.
The MJO is showing a slow increase in activity over the next two weeks.
CFSDailyAI and CFSv2 suggest some rains primarily in northern California and the Sierras, and into Siskiyou Mountains and southern Oregon at times.
It is early for monsoonal showers and thunderstorms (TSTMS). However, the presence of upper lows may begin to bring tropical moisture northward into SOCAL and the Sierras, despite the lack of a usual summer monsoonal pattern.
Potential Dates of Precipitation (from Fox Weather's CFSDAILYAI system):
Salinas Valley-San Luis Obispo Co- S SierraNV:
Salinas Valley Showers: 6/2-3. Hot spells 6/4, 6/8-9, 6/11-12, 6/14-17, 6/22-27.
San Luis Ob/Edna: Hot spells 6/6, 6/9, 6/12, 6/15-17, 6/20-27th, 7/1.
Southern California Citrus/Avocado Area, San Luis Obispo Co to San Diego Co:
Southern California Citrus/Avocado Area: May 31-June 15.
Santa Barbara, Ventura to San Diego Co: No rainfall of consequence.
Santa Barbara Co: 6/6, 6/12. 6/16-17th, 6/22-26th.
Ventura Co: Hot 6/16-17th, 6/22-26th.
San Diego/Orange: Hot 6/16-17, 6/22-26.
Summary – June 15 – July 15… In Northern and Central California, Hottest: 6/14-17, 6/22,27, 7/1-2.
San Luis Obispo Co... Hottest periods 6/15-17, 6/22-27.
Southern California… Shallow marine layer and hot inland. Hottest: 6/16-17, 6/22-26, 7/1-3.
Seasonal Outlook July 15 – August 31... Northern and Central California overall pattern…. Near normal rainfall (minimal). Above normal temperatures occur during all of July and all of August. Usual thunderstorms (TSTMS) in the central and N Sierra and Plateau.
Southern California: San Luis Obispo Co, Santa Barbara Co, and Ventura to San Diego Counties east through Los Angeles to San Bernardino, Riverside and Imperial Counties…. Our latest guidance is suggesting a hot period in N and Northcentral California during mid-July, but near normal behavior of the marine layer at the SOCAL coast and valley areas. Although cloud amounts should be about normal, temperatures will drift above normal due to warmer sea surface off SOCAL and Baja. Weak troughs and upper lows will intermittently develop and deepen the marine layer as is normal for summer.
Looking further ahead into Sept – Nov, Dry and persistently warmer than normal conditions develop during the late Sept through Nov Santa Ana season.
Alan Fox...Fox Weather, LLC
Copyright © 2020, Fox Weather, LLC, Used by permission.
What are the effects of fire and smoke and ash and heat and all the other potential things that might affect plants and animal products that we eat?????? Can you simply wash off contaminants? What impact on the soil, itself? Does anything special need to be done to start producing food again? Come learn more.
For more information about the program for to:
In 2018 the Ojai Valley Land Conservancy (OVLC) accepted a grant from the Resources Legacy Fund on behalf of Watershed Coalition of Ventura County (WCVC) for a study of projected climate changes in Ventura County. OVLC contracted with Drs. Nina Oakley and Ben Hatchett, climatologists with the Desert Research Institute (DRI), to evaluate historic climate variability and projected changes in Ventura County. This information is needed to “paint a picture” of future climate in the watersheds of Ventura County (Ventura River, Santa Clara River, and Calleguas Creek) to support and inform climate change-related decision-making. This study provides important information for the amendment to WCVC's Integrated Regional Water Management (IRWM) Plan
You can find a copy of the report on the DRI website at: https://wrcc.dri.edu/Climate/reports.php.
To view presentations and other information from the two WCVC Climate workshops conducted with Drs. Oakley and Hatchett in October of 2018, and April of this year please visit: http://wcvc.ventura.org/documents/climate_change.htm
Some of those most interesting findings for me, are the historical data. For example, data for the years 1896 – 2018, show a tendency toward increasing maximum temperatures over the period, especially the last 10 years (Fig 1.2). But most interesting, is the increasing minimum temperatures (Fig 1.3) as compared to the maximum temperatures. Winter where is thy sting? The 2018-19 winter was the coldest in my memory, with the heater on full time at night, but there was no general frost damage this year. I can remember 1990 and 2007.
Precipitation in the South Coast region exhibits high interannual variability over the period examined. No notable long-term trends are observed (Fig. 1.4). Since approximately 2000, the 11-year running mean decreases, associated in part with the 2012–2019 drought. It is unclear whether this trend will continue in subsequent years.
There's a lot more information in the report. READ On.
But something to keep in mind, is that we had a terrible heat wave last July, and it could easily happen again. Growers who had their trees well hydrated before the heat arrived, sustain less or no damage to the trees and much less fruit drop. Trees that were irrigated on the day it started to get hot, never had a chance to catch up with the heat. Once the atmosphere starts sucking the tree dry, water movement through the soil, roots and trunk cant keep up with the demand. Weather forecasting is pretty accurate 3 days out, and if heat is forecast, get those trees in shape. You can run water to reduce the temperature and raise the humidity in the orchard to reduce transpirational demand which helps some.
Something we learned last year. What we saw and what to expect:
Map of elevational changes in Ventura County and how
Sometimes we don't see things that are not uncommon, but suddenly catch our eye. A recent lemon harvest of a trial in the Central Valley turned up lots of fruit with enlarged nipples on the stylar end. These are from a 'Limoneira 8A' rootstock trial. Not all of of the fruit was like this, but all of the rootstocks had these fruit, so it wasn't a rootstock effect.
On asking around it turns out, this happens in other places, for example on Spanish fruit:
And on Australian fruit:
And even in many normal years and orchards there is some of this special fruit
During the 2018 spring bloom there were several heat waves that hit citrus growing areas. Dr. Mary Lu Arpaia, UCR Fruit Specialist, surmises that high temperatures make for elongated fruit and quite likely impact cell division at the stylar end, as well. So the more heat spells during bloom, it's likely that we will see more of this fruit shape. It's still good to eat.
- Author: Jim Downing , UC Agriculture and Natural Resources Lucien Crowder, UC Agriculture and Natural Resou
California avocados often are exposed to high temperatures after harvest, either in the field or during preconditioning (ethylene treatment), especially in summer. It's been known that long periods of high temperatures can delay ripening time and reduce fruit quality, but a new study indicates pronounced effects after only short periods of high temperature following harvest. Authors of the study concluded that it's important to maintain avocados at temperatures below 25°C following harvest and that the ideal temperature to ripen the fruit is 20°C. The authors also found that ripening below 20°C resulted in significantly longer ripening times and resulted in poorer coloration of the ripened fruit.
Mary Lu Arpaia, UC Cooperative Extension specialist, Jim Sievert and Sue Collin, staff research associates (retired) in the Department of Botany and Plant Sciences at UC Riverside, working with David Obenland, research physiologist with the USDA Agricultural Research Service, Parlier, studied for two seasons holding avocados from multiple harvest times for the first 24 or 48 hours of the ripening period at high temperatures (20°C to 35°C), with and without ethylene. In the third season, they made a detailed assessment of ripening temperatures (15°C to 25°C) on ripening time and fruit quality.
Results from the first two seasons showed that even a 24-hour exposure to temperatures of 25°C and above inhibits ripening and increases postharvest disorders such as stem end rot and body rot. In season 1, the incidence of stem end rot increased from 9.7% at 20°C to 32.3% at 35°C, and body rot increased from 3.9% to 20.2% for the same treatment comparison. Ethylene applied during the exposure period was ineffective in preventing the disorders.
In the third-season trial, temperature was also shown to be critical. Fruit ripened below 20°C took slightly longer to ripen. Additionally, the authors found that the ripened fruit at either 15°C or 18°C remained more green then fruit ripened at the higher temperatures. Avocados ripened above 20°C were more likely to develop pink discoloration in the mesocarp. Ripening temperature had no effect on overall likeability, or ratings of grassy or rich flavor.