Allan Fulton, UC Irrigation and Water Resources Farm Advisor

Technology vs. Confusion

“Technology” has different meanings for different people (Figure 1). In irrigated agriculture, we look towards technology to meet our changing needs and sustain our industry in the long run; however, with technology, “confusion” and a sense of overload can hinder our ability to learn and apply it. This article considers the abundance of irrigation technology and the challenges with its adoption. Some ideas are offered to cope with a sense of confusion and overload.

Figure 1. Technology and confusion are often experienced together.

 

Why and Why Not Technology?

On one hand, there are many drivers that can cause us to look to technology for help with irrigation:

  1. Acquiring sustainable irrigation water supplies;
  2. Uniformly distributing water and nutrients to the crop;
  3. Proper timing and amount of irrigation for optimal production;
  4. Irrigating with limited labor yet improve execution and precision;
  5. Optimizing water and energy costs in relation to crop revenues; and
  6. Protecting groundwater and surface water from non-point source pollution.

On the other hand, there can be a variety of constraints to adopt irrigation technology:

  1. Technology is available from many origins and in many forms and, with this, comes a potentially steep learning curve to identify and understand whether a technology fits the need(s).
  2. No two farms are the same. Each has its unique challenges depending upon the variables (size, crops, human resources, microclimate, soils, water source, etc…)

Where to Begin?

When considering new irrigation technology, it’s probably best to start from the familiar “30,000-foot” perspective.  An orchard irrigation system has several components (Figure 2) and it’s necessary to determine what aspect may be the weakest link and provide the biggest return to investment in technology.  It’s helpful to recognize them all and not overlook something as you prioritize needs.

Water Well Technology

Well design and construction choices affect how efficiently water enters the well from the aquifer.  The less efficiently water enters into the well the deeper the pumping water level and the greater the yearly energy bill.

Figure 2. Schematic showing orchard irrigation system beginning with the well and pumping plant and extending out to the last lateral line and sprinkler or dripper.

If you are developing and securing a new groundwater supply, seek information on different techniques of well drilling, well design, construction, and development.  This can lead to a more reliable and affordable water supply and improve your understanding of the well you are buying.  Some information resources include: 1) Water well design and construction, UC ANR Publication 8086 http://groundwater.ucdavis.edu/files/156563.pdf); and 2) Water well design, construction, and development: Important considerations before making the investment (https://ucanr.edu/sites/Tehama/files/20593.pdf).

Pumping Plant Technology

Overall pumping plant efficiency affects the cost of pumping water.  The higher the efficiency the lower the cost of pumping an acre-foot of irrigation water.  Efficiency and cost of pumping are affected by power demand, flow rate, irrigation system pressure, and fluctuating groundwater pumping levels.   Flow meters to measure pump flow, pressure gauges or transducers that track irrigation system pressure, and well sounders or sensors to watch pumping levels are available to monitor pumping plant performance and costs.   If used, they can notify the operator when the pumping plant performance is veering too far from optimal and in need of attention.   They may also alert a manager of unexpected irrigation system failures such as a pump not turning on or off or a valve not opening or closing as expected.   Other technologies such as solar arrays and variable frequency drives (VFD) are also becoming more common to manage the costs of pumping water.  A solar system provides an alternative, renewable power source and a variable frequency drive (VFD) regulates the power to an electric motor to optimize demand and pumping plant performance.  This is particularly valuable to manage irrigation sets of different sizes and flow needs.  A VFD can also improve the consistency of flow and pressure to an irrigation system during pump start-ups, backflushing, and when pumping water levels fluctuate.

Figure 3. Magnetic flow meter (upper left), pressure transducer (upper right), acoustic groundwater level sensor (lower left), and VFD digital control panel (lower right).

Irrigation system technology

A wide range of technology is available and all aim to grow uniform orchards that produce efficiently and at a high level for many years.   This includes orchard site preparation schemes, choices among water filters, pressure regulators, drip emitters, micro-sprinklers, or mini sprinklers, and tools to help monitor and maintain irrigation systems.

Figure 4. Layered orchard soil considered for soil modification and/or zone irrigation management.

Land assessments using backhoe pits (Figure 4) to guide soil modification with excavators or other deep tillage equipment is one technique used prior to planting trees and installing an irrigation system.  Another approach uses non-invasive techniques to map and geo-reference soil variability.   This information is used to precisely design irrigation systems so that soils with distinctly different water infiltration and water holding characteristics can be irrigated in separate sets.  This approach is referred to as variable rate irrigation (VRI) or zone irrigation.  Refer to UC ANR Publication 3507, Prune Production Manual, Chapter 8 (https://www.youtube.com/watch?v=rz_ER49fZEA) and zone irrigation management articles found on the Sacramento Valley Orchard Source. (http://www.sacvalleyorchards.com/?s=zone+irrigation).

Figure 5. Pressure transducer on irrigation line (top) and flow meter on injection pump (bottom).

Pressure gauges or transducers (Figure 5) can be installed in drip or micro-sprinkler lines intermittently across an irrigation system to verify the system is operating as designed and according to schedule.  Small flow meters can be installed on injection pumps to verify chemigation and fertilization efforts are going as planned.  It is becoming easier to collect and analyze pressure and flow data from an irrigation system.  This allows a quick response if needed, or the option to save the historical data for management consideration at a later time.

Irrigation scheduling technology

Decisions on when to begin irrigating, how frequent and long to irrigate, and when to stop irrigating an orchard is often based on experience.  However, there is growing interest in information and technology that enables a manager to adjust to site-specific weather, soil, and crop conditions (Figure 6).  The technology varies considerably ranging from manually operated, partially automated, or fully automated. The delivery of information can range from infrequent snapshots in time to hourly or more frequent delivery so that trends in crop water balances, soil moisture, or tree water status can be observed, evaluated, and used to guide the next irrigation scheduling decision.

Figure 6. Irrigation scheduling technology. ET station (top left), plant water status sensor (top right), and soil moisture sensor (bottom).

Remote data and information acquisition

Remote implies “from afar” and not actually being there in person.  Data acquisition is a process of collecting signals from various sensors that measure real-world physical conditions.  “Telemetry” (Figure 7) is the means of gathering and transmitting the data to a collection point.  After the signals are received they are then converted to useful numerical values that can be analyzed on a computer and interpreted to answer questions and guide management decisions.

Being able to collect quantitative data and information and respond based upon it while reducing labor and management time spurs interest in irrigation technology.  It represents opportunity and hope as we strive to irrigate orchards as efficiently and productively as possible.

Find your place on the technology continuum

Irrigation technology is best viewed as a “continuum” … something that changes constantly but gradually without clear dividing points.  It will continue to have a level of uncertainty and choosing to pursue technology is not always necessary, rather it is contingent on need.

Figure 7. Parts of a telemetry system. Cell tower and gateway next to pump controls (top left), gateway connection to the internet (bottom left), orchard cell tower connected to sensors in the field (top right); and node connection to field sensors (bottom right).

When considering irrigation technology, it’s probably best to step back and try to view the irrigation system in its entirety.  By doing this, it will provide an opportunity to appreciate the improvements that have already been made and identify those parts of the system that are in greatest need of attention in the future.   This should help ensure investments are focused on improvements with less risk and the largest opportunity for return.

Once some needs have been identified and prioritized, it may make sense to try the technology on a partial scale or even manually to establish proof of concept, robustness, and effectiveness on the way towards automation and broader adoption.

 

PRUNE (DRIED PLUM): CONVENTIONAL FUNGICIDE EFFICACY

 

Fungicide

Resistance risk

(FRAC#)1

Brown rot

Russet scab Rust
Blossom Fruit2
Bumper/Tilt2 high (3) ++++ ++++ —- +++
Elite/Tebucon/Teb/Toledo2,7 high (3) ++++ ++++ —- +++
Fervent Medium (3/7) ++++ ++++ —- +++
Fontelis high (3) ++++ +++ —- +++
Indar2 high (3) ++++ ++++ —- +++
Inspire Super high (3/9)   ++++   ++++ —- +++
Luna Experience medium (3/7)4 ++++ ++++ ND ++++
Luna Sensation2 medium (7/11)4 ++++ ++++ ND ++++
Merivon medium (7/11)4 ++++ ++++ ND ND
Pristine2 medium (7/11)4 ++++ ++++ ND ND
Quash 2 high (3) ++++ ++++ —- +++
Quadris Top2 medium (3/11)4 ++++ ++++ ND ++++
Quilt Xcel/Avaris 2XS 2 medium (3/11)4 ++++ ++++ ND ++++
Rovral5 + oil low (2) ++++ NR —- NR
Scala6 high (9)3,4 ++++ +++6 —- ND
Topsin-M/T-Methyl/Incognito/Cercobin+ oil2,4 high (1)4 ++++ ++++ —- —-
Vangard6 high (9)3,4 ++++ +++6 —- ND
Elevate2,7 high (17)4 +++ +++ ND —-
Rhyme/Topguard** high (3) +++ +++ —- +++
Rovral5/Iprodione /Nevado low (2) +++ NR —- NR
Topsin-M/T-Methyl/Incognito 2,3 high (1)4 +++ +/- —- —-
Abound high (11)4 ++ + —- +++
Bravo/Chlorothalonil/Echo/Equus8,9,10 low (M5) ++ ++ ++ —-9
Captan7,8,10 low (M4) ++ ++ +++ —-
Gem7 high (11)4 ++ + —- +++
Oso high (19) ++ ++ —- ND
Rally2 high (3) ++ ++ —- —-
Sulfur10 low (M2) +/- +/- —- ++

Rating:    ++++= excellent and consistent, +++= good and reliable, ++= moderate and variable, += limited and erratic, +/- = often ineffective, —- = ineffective, ? = insufficient data or unknown, NR=not registered after bloom, and ND=no data

* Registration pending in California.

1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode-of-action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode-of-action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action Group number.

2 Fruit brown rot treatments for fungicides in FRAC Groups 1,2, 3, 17, 7/11 are improved with the addition of 1-2% light summer oil. The oil is “light” summer oil (1-2% vol/vol). If applied in summer, the fruit will lose its waxy bloom and look red. They will dry to normal color. Use of a sticker such as NuFilm-P (8 to 16 fl oz/A) and high gallonage (120-150 gal/A) applications will provide effective control and fruit will retain their waxy bloom.

3 Strains of Monilinia fructicola and M. laxa resistant to Topsin-M and T-Methyl have been reported in some California prune orchards. No more than two applications of Topsin-M or T-Methyl should be made each year. Resistant strains of the jacket rot fungus, Botrytis cinerea, and powdery mildew fungi have been reported in California on crops other than almond and stone fruits and may have the potential to develop in prune with overuse of fungicides with similar chemistry. Subpopulations of both Monilinia spp. have been shown to be resistant to AP (FRAC 9) fungicides on prune in CA.

4 To reduce the risk of resistance development, start treatments with a fungicide with a multi-site mode of action; rotate or mix fungicides with different mode-of-action FRAC numbers for subsequent applications, use labeled rates (preferably the upper range), and limit the total number of applications/season.

5 Blossom blight only; not registered for use after petal fall.

6 High summer temperatures and relative humidity reduce efficacy.

7 Registered for use on fresh prunes only.

8 Do not use in combination with or shortly before or after oil treatment.

9 Do not use after jacket (shuck) split.

10 Do not use sulfur, captan, or chlorothalonil in combination with or shortly before or after oil treatment.

 

 

PRUNE (DRIED PLUM): ORGANIC FUNGICIDE EFFICACY

 

Fungicide

Resistance risk

(FRAC#)1

Brown rot

Russet scab Rust
Blossom Fruit2
Dart low +++ ++ —- +
EcoSwing low +++ ++ —- +
Problad1 low +++ —- —- —-
Oso1 low ++ ++ —- ND
Double Nickel 552, Serenade ASO/Opti, Serifel, Taegro, etc. low ++ —- —- +
Aviv3 low ++ —- —- +
Sulfur4 low (M2) +/- +/- —- ++

Rating:    ++++= excellent and consistent, +++= good and reliable, ++= moderate and variable, += limited and erratic, +/- = often ineffective, —- = ineffective, ? = insufficient data or unknown, NR=not registered after bloom, and ND=no data

1 Pending registration in CA.

2 Strains of Bacillus amyloliquefaciens.

3 Strains of Bacillus subtilis.

4 Do not use sulfur, captan, or chlorothalonil in combination with or shortly before or after oil treatment.

  

PRUNE (DRIED PLUM): TREATMENT TIMING

Note: Timings listed are effective but not all may be required for disease control. Timings used will depend upon orchard history of disease, length of bloom, and weather conditions each year.

 

Disease Green bud White bud Full bloom May June July
Brown rot1 +++ +++ +++ —- + ++
Russet scab2 —- —- +++ —- —- —-
Rust3 —- —- —- + ++ +++

Rating:   +++ = most effective, ++ = moderately effective, + = least effective, and —- = ineffective

1 Flowers are susceptible beginning with the emergence of the sepals (green bud) until the petals fall but are most susceptible when open.

2 A physiological disorder; no pathogens involved.

3 More severe when late spring rains occur.