Tag: Newsletter

As we transition from winter to spring, crucial phenological processes begin in avocado orchards, particularly the Flowering and Fruit Set. These stages are critical precursors to the next harvest. To optimize tree health and productivity during this period, implement the following cultural practices: 

Fertilization 

• Initiate fertilizer application to support flower development and fruit set 
• Adjust fertilizer quantities based on flowering intensity 
• Consider foliar applications of micronutrients to boost tree health 

Irrigation Management 

• Maintain adequate soil moisture during flowering, fruit set, and early fruit development 
• Monitor soil moisture levels regularly and adjust irrigation schedules accordingly 
• Implement deficit irrigation strategies if water resources are limited, but avoid water stress 

Pollination  

• Monitor flowering progression closely 
• Introduce honeybee hives when approximately 10% of flowers have opened 
• Consider supplemental pollination techniques in areas with insufficient natural pollinators 

Crop Load Management 

• Assess fruit set and consider early thinning of excess fruit 
• Remove small or damaged fruit to improve overall crop quality 
• Balance crop load with tree vigor to prevent alternate bearing 

Pest And Disease Control 

• Implement Avocado Thrips and Persea Mite control measures based on monitoring results 
• Be vigilant for symptoms of root rot, which is most stressful to trees in spring 
• Apply appropriate treatments if root rot is detected 
• Monitor for other seasonal pests and diseases, such as fruit spotting bug or anthracnose 

Weed Management 

• Control weeds to reduce competition for water and nutrients 
• Use mulch or cover crops to suppress weed growth and improve soil health 
• Time weed control to avoid competition with avocado flowers for pollinating insects

Orchard Floor Management 

• Maintain a clean orchard floor to facilitate harvest operations 
• Consider cover crops to improve soil structure and beneficial insect populations 
• Manage ground cover to balance ecosystem services with practical orchard management 

By implementing these practices, growers can optimize tree health and productivity during the critical spring transition period, setting the stage for a successful avocado harvest.

By Gerardo Aldunate, Agronomist, Index Fresh 

While avocado trees may appear dormant during winter, the winter season is crucial for the accumulation of carbohydrates, or energy , which supports the next growth cycle and fruit crop. Despite the apparent inactivity, both leaves and roots remain functional, and fruit continues to grow, albeit at a slower rate.

Optimizing tree conditions during this period is essential for achieving peak performance in the following spring. To ensure the best outcomes, growers should implement the following cultural practices:

Fertilization

• Review the current fertilizer plan and analyze leaf sample results 
• Develop and adjust the upcoming fertilization strategy as necessary 
• Apply mulch to conserve soil moisture and provide organic matter

Pruning

• Conduct maintenance pruning in frost-free areas to improve light penetration 
• Remove dead wood before the rainy season to prevent disease spread

Irrigation

• Adjust watering schedules to account for lower tree water demand
• Perform irrigation system maintenance to ensure efficiency 
• Implement leaching irrigations to prevent salt buildup in the soil

Frost and Rain Protection

• Inspect and service wind machines for frost protection 
• Enhance natural air circulation within the orchard
• Assess and improve water drainage to prevent waterlogging

By focusing on these key areas, avocado growers can help their trees weather the winter months and set the stage for a productive spring season.

By Gerardo Aldunate, Agronomist, Index Fresh

In October, the Index Fresh team took its show on the road, bringing experts in automated irrigation and Integrated Pest Management (IMP) to California growers. We held our annual seminar in San Luis Obispo, Ventura and Temecula, providing over 150 growers with an opportunity to learn about new tools to improve their growing practices and ultimately increase yield and revenue.

Read on for a taste of the irrigation automation presentations at Seminar 27. To learn more about Pest Control Advisor Tom Roberts’ detailed presentation on Avocado 1PM and for additional information about automated irrigation, watch the video recording at indexfresh.com/seminar/seminar-27/

Automated irrigation, why bother? “In my mind the number one reason to consider automation is to save time and money,” California avocado grower John Cornell told an audience of avocado growers at the Index Fresh Grower Seminar on Oct. 24.

Technology gains in agriculture in recent years have reduced the cost of installing and implementing automated irrigation. A number of companies offer automated systems, and the products range from relatively straightforward to highly sophisticated. What they all have in common is the ability to improve precision and reduce labor – both of which benefit the grower’s bottom-line.

Research conducted by Andre Biscaro, Irrigation and Water Resources Advisor with U.C. Cooperative Extension, demonstrates that most growers over-irrigate early in the season and under-irrigate late in the season. This trend is a product of guesswork related to how much and how often to irrigate. Sensors and automation help to reduce the guesswork and allow for application of the proper amount of water and fertigation at the proper time. As a result, stress is reduced, health improves, and yield increases.

Labor savings can be significant when irrigation is automated. By programming and remotely monitoring irrigation with a smartphone, growers can tailor timing and volume of water applications to parts of their grove with different needs. “An automated system saves a tremendous amount of time compared to having workers running around turning water off and on,” Cornell noted.

Automation doesn’t mean full time farming from your phone, but its two-way communication can prevent costs associated with some of the unpredictable aspects of farming. Cornell relies on a system that shuts down immediately when there’s a break in a line. “You’re not going to wake up surprised at 5 a.m. to find that 10,000 gallons of water have washed away,” he said.

Climatic data from weather stations can be programmed into many of the automated systems available to growers, and Biscaro pointed out that weather stations inform irrigation rates specific to climate and soil conditions across various avocado growing areas. Soil type is also taken into account to ensure that transpiration rate and water holding capacity are both factored into irrigation rates.

By assisting growers in finding the sweet spot for irrigation- not too much and not too little – automated systems conserve water and reduce fertigation costs. When the tree is provided the right amount of fertigation, wasteful fertilizer run-off becomes a non-issue.

Along with improved yield and lower costs, a major benefit of automated systems is enhanced record keeping. Abundant data is available through many of the systems on the market today, and this information, particularly when captured over time, can instruct decisions that further benefit tree health and productivity.

Technological improvements have made irrigation automation more affordable, and Cornell stressed that the benefits quickly outpace the cost. “I’m a bit of a penny pincher,” he said, “so I really do my research.”

The California Avocado Commission (CAC) has announced important changes to the assessment rate for the 2024-25 season. Here’s what you need to know:

Assessment Rate Change

The CAC Board of Directors has approved a new assessment rate of $0.005 (half a cent) per pound on all California-grown avocado varieties. NOTE: THE 2024-25 CAC ASSESSMENT IS A FIXED RATE PER POUND (not a percent of value). The 2023- 24 assessment was 2.25% of the value.

Who Needs To Pay?

All avocado producers in California are required to pay this assessment, with one exception. Growers who have produced an average of less than 10,000 pounds of avocados annually over the past three marketing years are exempt.

If you have any questions concerning the assessment for the 2024-25 crop year or the reporting and payment procedures, please contact CAC Accounting at: accountspayable@avocado.org or call (949) 341-1955.

Avocado growers in California have long grappled with the devastating effects of root rot, a disease caused by the soil borne pathogen hytophthora cinnamomi. This insidious fungus can significantly reduce tree health, fruit quality, and yield, ultimately leading to tree death.

After playing the role of villain in the California avocado industry for decades, P. cinnamomi is finding itself outmatched by a product that hit the market in 2021 called Orondis. A cutting-edge fungicide by Syngenta, Orondis is proving highly effective in controlling root rot.

When our Index Fresh staff presented the 2024 Cultural Seminar Series, they fielded numerous requests from avocado growers seeking more information about Orondis. The following information relies primarily on direct input from Syngenta, as well as experts in the avocado industry.

Why has root rot plagued the avocado industry for so long?

P. cinnamomi thrives in areas of excess soil moisture and poor drainage and can survive adverse conditions as persistent spores in the soil. Avocados didn’t evolve alongside the pathogen, which is thought to have originated in New Guinea, thus never developed resistance to P. cinnamomi. As Farm Advisor-Emeritus Gary Bender pointed out in his recent article in the California Avocado Society’s Avocado Quarterly, “California growers have developed an efficient way to harvest fruit and get it to the packinghouse, but that system also moves the fungus from grove to grove via dirty bins, dirty ladders, truck tires and on the boots of pickers who move from grove to grove.”

How Does Orondis Work?

Orondis, with its active ingredient oxathiapiprolin, operates through a unique mode of action. It targets a specific protein essential for the survival and reproduction of Phytophthora, effectively disrupting its life cycle. By reducing the pathogen’s population in the soil, Orondis promotes healthier root systems, improved water and nutrient uptake, and increased tree vigor.

“Orondis works directly against the Phytophthora propagules in the soil, rather than against the pathogen in the tree, effectively eradicating the pathogen from treated soil for a period following application,” stated Tim Spann in the winter 2021 edition of the California Avocado Commission’s “From the Grove” magazine.

Key Considerations for Orondis Application

Timing: Apply Orondis during periods of root flush, typically in spring and late summer. Note that Orondis has a restricted entry interval of 4 hours and a pre-harvest interval of 30 days.

Method of Application: Soil should be  pre-wetted  before  application. Orondis should be applied through the irrigation water (micro-sprinkler or drip). A general recommendation, using drip irrigation as a guide, would be to allow for at least 6-8 hours (but no more than 10-12 hours of water) to be run after the injection of Orondis.

Rate: Labeled use rates are 4.8 fl oz/A – 9.6 fl oz/A. When establishing a new grove, or for heavy/severe infections, the higher end of labeled rates is recommended on a 6-month retreatment program for the first year. If soil testing confirms a significant reduction in Phytophthora propagules following treatment, you can consider switching to a maintenance program of 4.8 fl oz/A on a 6-month retreatment interval, or 9.6 fl oz/A on a 12-month retreatment interval.

Rotation: Resistance Management guidelines  on  the  Orondis  label instructs growers to limit sequential use of Orondis to two applications before rotating to a fungicide with a different mode of action.

Integrated Pest Management with Orondis

“While Orondis is extremely effective at reducing Phytophthora populations in the soil at low use rates, there is no silver bullet, and incorporating things like cultural controls are also imperative for long-term management of the disease,” states Dr. Jeannette Rapicavoli, Agronomic Service Representative for Syngenta.

Optimal results rely on combining various strategies, including:

Cultural Practices: Help minimize disease pressure by irrigating appropriately (duration and amount), no wetting of trunks, planting on berms, applying organic mulch and ensuring proper tree nutrition Resistant Rootstocks: Using resistant rootstocks can provide a strong defense against the pathogen.

Sanitation: Prevent soil or water movement from infested areas.

Fungicide Applications: Timely applications of Orondis can effectively control Phytophthora.

At this stage of the season, we are completing the flowering and fruit set, a process in which the tree spends a lot of energy (sugars, starch, water, nutrients, etc.). Now is the time to recover all resources used by the tree. Your avocado trees now need: 

Fertilizer: Adjust nutrient amounts based on fruit load and the stimulation of new growth (next year’s floral shoots). Aim to make healthy leaves, fruiting wood, and strong roots. 

Irrigation: Water is the basis of the photosynthesis process (energy for the tree). Increase the amount of water and/ or irrigation frequency. 

Pruning: Control the height of tall trees, regulate alternate bearing, control regrowth, and remove “dead” wood. It is important to keep a good balance between reproductive and vegetative growth. Reduce sunburn by painting the branches with a mix of white paint and water. Remember to disinfect pruning tools between each tree. 

Pest control: Monitor pest populations, such as persea mite, to evaluate need for control. 

Mulching: Add mulch to improve conditions for better root growth.

By Gerardo Aldunate, Agronomist, Index Fresh

Scorching heat across interior Ventura County this July spelled trouble for avocado growers. When the mercury climbs over 100 degrees for days, it can mean total crop loss. Growers across California’s avocado growing region who are vulnerable to high heat have applied old-fashioned farming ingenuity and novel techniques to combat the worsening threat caused by extreme heat. 

“It’s definitely getting hotter,” said Dr. Ben Faber, a farm adviser with UC Cooperative Extension. “Just 10 years ago, 110 degrees was unheard of, and since then we’ve had three summers in Santa Paula and Fillmore when it’s gotten 110 degrees and hotter. It’s gotten to 120. It’s not supposed to happen, but it’s happening.” 

The avocado tree is sensitive to temperature fluctuations in both directions, and the aftermath of heat damage looks a lot like the aftermath of frost. After extreme heat, the orchard needs to be evaluated for damage. Fruit can drop — in severe cases, most of it — and if the leaves start to get crunchy from heat damage, the first step is to reduce irrigation and fertilization. The damaged tree cannot process the irrigation like a healthy tree, so excess water, even from regular irrigation, could lead to root rot on impacted trees. Another tell-tale sign of heat damage is browning of the stem where it connects to the fruit. Avocados with browning stems will eventually drop.  

“Leaves are crispy. The fruit is on the ground. You’ll know heat damage when you see it. It’s really obvious,” Faber said. In the event that the leaves drop, apply whitewash to exposed branches to prevent sunburn. Otherwise, avoid pruning until there is new growth in order to protect the tree from sunburn. 

It could take six months to a year to observe the extent of the damage to each tree, whether it’s a matter of temporary fruit and leaf damage for the season or if the tree is severely impacted and might never recover. 

Beware Of Forecasts Over 90 Degrees 

Finicky avocado trees react to temperatures over 90 degrees. The stomata on the leaves, which open to allow transpiration under normal circumstances, close to retain moisture, but a side effect is causing the tree’s internal temperature to accelerate upward. If the forecast predicts that the temperature at your orchard will exceed 90 degrees throughout the day, consider that as being in the avocado tree heat advisory zone. 

“We’ve had to advise Index Fresh growers on recognizing and preparing for ever-more-frequent extreme heat,” said Keith Blanchard, California Field Manager for Index Fresh. “The good news is there are measures to take that can protect the crop and trees from extreme heat.” 

Faber, a specialist in subtropical horticulture, pointed out that avocado trees are at home in tropical weather, but the tree evolved to live under larger trees in the forest. Cultivators have taken avocados out of their natural shaded setting, so we must apply farming tools to protect them. “Avocado trees were naturally accustomed to hot weather, but also being shaded,” he said. 

Preparing For Extreme Heat 

As they have adapted to extreme heat, growers have developed game plans with mainly two proven techniques, advanced irrigation and overhead sprinklers. 

Overhead sprinklers can reduce ambient temperatures by 10 degrees through evaporative cooling in the orchard. If the forecast calls for 100 degrees, it is possible to bring temps down to about 90 degrees in the orchard, or right at the threshold before the trees close their stomata and enter the danger zone where internal temps spike. 

Even before it becomes time to switch on the overhead sprinklers, growers should prepare by irrigating ahead of time. Trees that are hydrated will withstand greater heat and suffer less damage, even if temps climb over 90 degrees. “Sometimes, the grower says, ‘Oh, it’s hot. I’m going to turn the irrigation on.’ But by then it’s too late,” Faber said. “If you can anticipate it and hydrate the tree, that’s when you are helping, because when it’s too hot, water isn’t going anywhere.”

In addition to overhead sprinklers, growers can reduce ambient temperature through adding moisture and evaporation to ambient air. The added overhead shower is most helpful when the water settles on the leaves or other surfaces, because that water will cool the tree down immediately, Faber said. 

Anecdotally, growers in hot temp zones have been able to install overhead sprinklers for about $1,200 per acre by laying them over existing irrigation systems. Growers will use overhead sprinklers in blocks during heat events, and it is important to monitor and rotate sprinkler locations frequently enough to keep trees moist throughout hot weather. 

Different Results On Different Trees 

Orchards in the same climate can have wildly different outcomes from extreme heat events. A recent event in Santa Paula caused nearly 90% fruit loss at one avocado orchard but others that were nearby withstood temperatures with far less damage. 

“Really, it’s a carpet of fruit on the ground,” Faber said of the badly hit orchards. 

Heartier trees where the fruit sets inside the canopy seem to handle extreme temperatures better. Also, some growers are finding that GEM trees, shaped so fruit sets inside the canopy, tend to fare better in hot or cold temps. The added protection from the elements was a primary reason for selecting the GEM to commercially cultivate. 

Note Of Caution 

Faber advises against using products marketed as Antistress 550/2000 on avocado trees. The products, which are applied to the canopy, can do more harm than good on avocados.