Once again, we are experiencing a prolonged heat wave in the Salinas Valley.  Maximum air temperature in the King City area reached 112 °F earlier in the week (Fig. 1).     Recent maximum air temperatures in South Salinas have been far greater than the average temperatures recorded for the same period during previous years (2015 through 2019).

Figure 1. Maximum air temperatures recorded at the South Salinas, Soledad, and King City CIMIS weatherstation from August 20 – September 6, 2022. Average maximum air temperatures for the same period during years 2015-2019 for South Salinas are also shown

Although this heat wave will probably wane in the next several days, the central coast region will likely experience periods of record setting temperatures in the future.  There are several concerns about how prolonged elevated temperatures affect cool season vegetables.  Heat can cause immediate damage to plant tissue when temperatures of the plant surfaces become too high and cause cells to die (Fig. 2).  In addition, sustained high temperatures can affect plant growth and development. For instance, in lettuce damage can vary from obvious burning on the edges of leaves from too much heat load (Fig. 3) to more physiological issues that result in poor head formation in iceberg (e.g. puffy heads). In broccoli, if heat damage occurs when heads are forming, it can result in uneven bead sizes when the head matures (Fig. 4).  Excessive heat can result in wilting in cauliflower (Fig. 5) during high temperatures and expose curds to sunburning or cause discoloring (Fig. 6.)  In the past two years, we have observed that excessive heat can stress lettuce plants and make them more susceptible to infection with Pythium Wilt (Pythium uncinulatum). That was particularly evident in the 2020 heat spells. If there is inoculum Pythium Wilt in the soil, stress caused by heat on the plant can set off infection (Fig. 7).  

Figure 2. Heat damage on broccoli leaves

Figure 3. Burning along the edges of leaves on romaine

Figure 4. Heat stress during the development of the broccoli heads can result in uneven bead sizes when heads mature.

Figure 5. Insufficient soil moisture during hot periods can lead to severe wilting of cool season vegetables such as cauliflower.

Figure 6. Sun exposure during a period of wilting in cauliflower can cause discoloration and sunburning of curds.

Figure 7. Pythium wilt infection in lettuce set off by excessive heat.

A previous article presented strategies for maximizing evapotranspiration rates to keep crops cool.  Evapotranspiration (ET) is the process in which liquid water vaporizes from plant leaves and moist soil surfaces and is lost to the surrounding air.  As liquid water vaporizes, heat is also lost from the surfaces of leaves and soil and from the surrounding air, which cools the crop. Assuring that crops have adequate soil moisture during the hottest period of the day (generally 11 am to 4 pm) can keep plants as cool as possible.  Insufficient moisture to meet crop water requirements can result in stomates of the leaves closing and decrease transpiration rates.  Limiting transpiration would raise leaf temperatures, potentially to temperatures greater than the surrounding air.  

Hence, a good strategy to prevent heat damage to vegetable crops is to water fields that have not been recently irrigated.  Also, keep in mind that during the last few days daily reference ET increased substantially due to the high air temperatures and so more water is needed than normal to replace the amount of moisture that crops transpiration.  In South Salinas, for example, the CIMIS station showed that daily reference ET increased from 0.18 inches per day in late August to 0.25 inches per day during the heat wave, approximately a 40% increase in water demand (Fig. 8). 

Figure 8. Daily reference evapotranspiration recorded at the South Salinas, Soledad, and King City CIMIS weatherstations from August 20 – September 6. Average daily reference ET for the same period during years 2015-2019 for South Salinas are also shown.

Irrigations do not need to be very long, as much as they should supply the crop with enough water to refill the soil profile to the depth of the root zone.   Irrigating more frequently for less time would be a better strategy than irrigating less frequently for more time, since the soil has a limited capacity to store water in the root zone. Over-saturating the soil during high soil temperatures through heavy irrigations could worsen infections from soil-borne pathogens.

The CropManage online decision support tool can assist with determining the amount of water to apply and frequency to irrigate for most vegetable crops produced in the Salinas Valley.  The software allows one to customize the recommendations for the development stage of the crop, soil type, and irrigation system characteristics.     

Finally, for crops irrigated by sprinklers, short irrigations during the hottest time of the day can reduce air temperatures.  This might be a good strategy for vegetables that are in a stage of development that is very susceptible for heat damage, such as cauliflower close to harvest.  

Date: Tuesday, May 10th, 2022

1pm – 5pm
Location: Watsonville Public Library

275 Main St., Suite 100, Watsonville, CA  95076

We will hold a hands-on training on CropManage.  CropManage is a free online decision-support tool for water and nutrient management of vegetables, berry, agronomic, and tree crops. Based on in-depth research and field studies conducted by the University of California Cooperative Extension, CropManage provides real-time recommendations for efficient and timely irrigation and fertilization applications while maintaining or improving overall yield. 

At this free workshop, we will provide hands-on training so that you can learn to use the newest version of CropManage. Crops currently supported include many vegetables (carrots, cabbage, celery, broccoli, lettuce, tomato, spinach, etc.), berry crops (raspberry and strawberry), tree crops (almond, walnut, and pistachio), and agronomic crops (alfalfa and corn). CropManage is also available in Spanish.

 
Who should participate? Growers, farm managers, other farm staff, crop advisors, consultants, and technical service providers are welcome. The workshop is for both new and current CropManage users. Spanish translation will be available.

What to bring? This is a participatory workshop. Please bring a tablet or laptop computer so that you can follow along and participate in the exercises. Each participant will need a user account for CropManage. Please set up a free user account at https://cropmanage.ucanr.edu/ before the workshop. Please arrive early to set up your laptop or tablet computer on the wifi and get logged on to CropManage.

Registration is free: Please register at https://surveys.ucanr.edu/survey.cfm?surveynumber=37233 by May 9th, 2022. Seats are limited to the first 25 registrants.

 
Continuing Education Units (CEU) for Certified Crop Advisors (CCA) have been requested

Questions: Contact Michael Cahn at mdcahn@ucanr.edu / 831-214-3690 or Sacha Lozano at  slozano@rcdsantacruz.org / 831-224-0293                                                                                              

Agenda

1:00 – 1:20  Registration and computer set-up

1:20 – 1:40  Introduction

1:40 – 2:50  Getting started with CropManage

2:50 – 3:05  BREAK

3:05 – 3:50  Using CropManage for decision support and record-keeping

3:50 – 4:15  Group exercise

4:15- 4:40  Advanced features

4:40 – 5:00  Discussion / Q&A/ wrap up

NOTE: The following COVID-19 guidelines will be applied to this training workshop.

1. Wearing a face covering during the workshop is required.
2. Stay at home if you have COVID-19 symptoms, tested for positive, and/or close contacts with or exposure to others who have been tested for COVID-19.
3. Face masks and sanitation items will be provided at the workshop.

CropManage 2.0 Workshop: Hands-on training

Monterey County Agricultural Center Conference Room

 1432 Abbott St, Salinas CA 93901

Thursday, March 31 2016

(8:30 am – 12 pm)

We will offer a hands-on training to learn in depth about the features of CropManage 2.0, a free online decision support tool for water and nutrient management of coastal crops.  CropManage was recently revised with a new user interface and additional capabilities, and now supports iceberg and romaine lettuce, spinach, celery, broccoli, cauliflower, cabbage, and strawberries.  

Considering that the drought may continue into a 5th year, and water quality regulations continue to be linked to nutrient management, efficiently using water and nitrogen fertilizer is a high priority for Central Coast growers. CropManage can be a useful tool for providing quick decision support on water and nutrient management on a field-by-field basis. This training will provide an opportunity to learn how to use CropManage for improving the efficiency of your farming operations or for adding value to your consulting services. 

The workshop will take you step-by-step on how to navigate and use CropManage for assisting with fertilizer and water management decisions and record keeping. Wi-Fi internet access is available at our conference room so please bring a laptop or tablet computer so that you can follow along as we tour through the features of the software.   There should be sufficient time to answer questions as we cover the following topics: 

Agenda:

8:30 – 9:00      Registration and Refreshments

9:00 – 9:30      Introduction and update on CropManage 2.0

9:30-10:15      Getting started with CropManage

10:15  (Break)

10:30 – 11:15 Strategies for using CropManage for decision support and record keeping

11:15- 11:45  Advanced features and interfacing sensors with CropManage

11:45-12:00   Discussion of new features or changes needed

Certified Crop Adviser CEU hours (1 hr soil and water management, 1 hr nutrient management, 0.5 hrs professional development)

To keep the group size manageable so that we can provide individual help, we would like to limit the workshop to 30 participants.  If you have attended previous workshops and or feel proficient in using the on-line tool, then you are welcome to just attend the second half of the workshop (10:30-12 pm).  Whether or not you plan to attend the entire or part of the workshop, please RSVP in advance by sending an email to larriaga@ucanr.edu with the subject heading “CropManage workshop” and let us know the number of participants in your group.  We will email you a confirmation. Alternatively, you can contact our office at 831-759-7370.  Thank you, and I hope to see you soon.

Michael Cahn

Please feel free to contact us if you need special accommodations 

CropManage Workshop: Hands-on training

Monterey County Agricultural Center Conference Room

 1432 Abbott St, Salinas CA 93901

Thursday, April 2nd 2015

(8:30 am – 12 pm)

We will offer a hands-on training to learn in depth about the features of CropManage, a free online decision support tool for water and nutrient management of coastal crops.  In addition to head and romaine lettuce, CropManage now supports broccoli, cauliflower, cabbage, and strawberries.  

Considering that the drought is continuing into a 4th year, and nutrient management continues to be linked to water quality regulations, efficiently using water and nitrogen fertilizer is a high priority for Central Coast growers. CropManage can play an important role in providing quick decision support on water and nutrient management on a field-by-field basis.

This training will provide an opportunity to learn how to use CropManage for improving the efficiency of your farming operations or for adding value to your consulting services.  We will provide in depth hands-on training so that you can learn step-by-step how to navigate and use CropManage for assisting with fertilizer and water management decisions and record keeping. Wi-Fi internet access is available at our conference room so please bring a laptop or tablet computer so that you can follow along as we tour through the features of the software.   There should be sufficient time to answer questions as we cover the following topics: 

Agenda:

8:30 – 9:00 Registration and Refreshments

9:00 – 9:30 Introduction and update on CropManage

9:30-10:15 Getting started with CropManage

10:15  (Break)

10:30 – 11:15 Strategies for using CropManage for decision support and record keeping

11:15- 11:45 Advanced features and interfacing sensors with CropManage

11:45-12:00  Discussion of new features or changes needed.

To keep the group size manageable so that we can provide individual help, we would like to limit the workshop to 30 participants.  If you have attended previous workshops and or feel proficient in using the on-line tool, then you are welcome to just attend the second half of the workshop (10:30-12 pm).  Whether or not you plan to attend the entire or part of the workshop, please RSVP in advance by sending an email to larriaga@ucdavis.edu or mdcahn@ucdavis.edu with the subject heading “CropManage workshop” and let us know the number of participants in your group.  We will email you a confirmation. Thank you, and I hope to see you soon.

Respectfully,

Michael Cahn, Irrigation and Water Resources Advisor

Certified Crop Adviser CEU hours requested (1.5 hrs irrigation management, 1.5 hrs nutrient management)