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Pear IPM Case Studies: Honeydew Washing at Four Orchard Locations

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Pear IPM Case Study: Honeydew Washing at SC Orchards

By Tianna DuPont, Chris Strohm, WSU Extension; Louis Nottingham, WSU Entomology

Honeydew washing systems offer another tool for the pear IPM toolbox. The following case study is one example of a honeydew washing system used to reduce pear fruit marking in combination with a full IPM program.

View of the orchard showing the overhead washing system riser.

System Specifications

  • 75 GPM/Acre
  • 0.16 in/hr
  • Tree spacing: 10′ x 20′
  • Sprinkler spacing: 30′ x40′
  • Sprinkler head: R2000 K4 15deg #14 Nozzle (Green)
  • Tie Into Existing 3/4″ valve risers
  • Installed in 2020

image showing how the system connects to the existing sprinkler with separate shutoff valve.

Schematic diagram of the experimental honeydew washing riser.

Impacts

Split image showing shoots with leaves effected by psylla honeydew pre- and post-washing where the pre-wash sample shows a glob of honeydew.

Chart showing the effect of washing on the amount of Honeydew present pre- and post-washing as measured by Brix scale. Shart also compares two different times during the season when the washing occurred. The first timing was in July with 24hr washing interval that decreased the Brix from slightly over 2.0 pre-wash compared to under 0.5 for post-wash. The next timing was in August suing 12hr interval where the pre-wash Brix was well below 0.5 and post-wash even less.

Costs

  • Parts: $760 per acre
  • Labor: $180 per acre
  • Total: $940 per acre

Grower Comments

Infobox: In 2020, we did two 24-hour sets after install then switched to 12 hour sets for washing and irrigation. Trees were allowed 2 days drying before spraying. Washing improved organic and conventional pesticide efficacy against psylla by removing "honeydew armor". The cold water from washes also appeared to keep mite populations down.
View of sprinkler riser in action spraying water from above the orchard canopy.

Pear IPM Case Study: Honeydew Washing at Kiehn Orchards

By Chris Strohm, Tianna DuPont, WSU Extension; Louis Nottingham, WSU Entomology

Honeydew washing systems offer another tool for the pear IPM toolbox. The following case study is one example of a honeydew washing system used to reduce pear fruit marking in a conventionally managed orchard.

Image shows an irrigation riser above the tree using a Rainbird sprinkler head.

System Specifications

  • 50 – 65 GPM/Acre
  • 0.11 – 0.14 in/hr
  • Tree spacing: 10′ x 20′
  • Sprinkler spacing: 60′ x 40′
  • Sprinkler head: mix of R2000/Rainbird
  • Under-tree to over-tree switch in July
  • Installed in 2018

Images show the placement of the under-tree sprinkler with the R200 head.

Image shows both the under-tree and over-tree components in place and indicates the parts used at each potion of the setup.

Impacts

split image comparing pre- and post-washing of shoots where the pre-wash shoot has multiple psylla and globs of honeydew present which are not seen on the post-wash shoot.

Two charts showing the results for the August and September wash timings. The August chart shows that the honeydew level measured on the Brix scale is about 0.5 at Pre-wash and and less than half of the that after washing. The second chart, Septermber timing, shows the pre-wash honeydew level just above 1.5 Brix compared to roughly 0.25 for the post-wash shoot.

Cost

  • Parts: $480 per acre
  • Labor: 4180 per acre
  • Total: $660 per acre

Grower Comments

Quote box: (quote 1) Installed 2018 in problem areas for psylla. (quote 2) We use this as a targeted system for honeydew during the late summer period leading to harvest. (quote 3) In years when psylla gets out of control, this system is saving our workers and our fruit quality. (quote 4) About 50% grower returns can be lost from bad psylla marking. (quote 5) We believe our wash is removing honeydew bubbles around the insects and improving spray efficacy several days later.

image showing an overhead riser in the pear orchard spraying out over the canopy.

 

Pear IPM Case Study: Honeydew Washing at Schmitten Orchards

By Chris Strohm, Tianna DuPont, WSU Extension; Louis Nottingham, WSU Entomology

Honeydew washing systems offer another tool for the pear IPM toolbox. The following case study is one example of a honeydew washing system used to reduce pear fruit marking in a conventionally managed orchard.

Image showing the placement of the overhead sprinkler in relation to the top of the tree canopy.

System Specifications

  • 60 – 70 GPM/Acre
  • 0.13 – 0.15 in/hr
  • Tree spacing: 10′ x 20′
  • Sprinkler spacing: 40′ x24′
  • Sprinkler heads: mix of R2000 / Rainbird
  • Dual system, valves switch between under-tree and over-tree
  • Installed in 2018

image showing the dual system in place with he valves that switch from under-tree or over-tree use.

Image shows a complete over-tree and under-tree unit in the orchard, labeling the R200/Rainbird sprinkler at the top and the 10' S40 3/4 inch PVC pipe used for the riser.

Impacts

Image of pre-washed shoot showing presence of psylla and honeydew globs.

Two charts showing the results of pre- and post-wash timings in July compared to August. In the July chart, the pre-wash honeydew level was just below 1.0 on the Brix scale compared to the post-wash level being well below 0.25. On the August chart, the pre-wash honeydew level was at 2.5 Brix and the post-wash was about 0.25.

Cost

  • Parts: $900 per acre
  • Labor: $200 per acre
  • Total: $1100 per acre

Image close-up of a post-wash leave showing psylla damage, but no honeydew.

Grower Comments

Quote text box: (quote 1) If there is a definite honeydew problem, the system is on for 8-12 hours. (quote 2) Shorter sets (6 hours) are used when honeydew is not problematic. (quote 3) I believe we are doing 1 less spray due to washing. That's saving us $300 to $600 per acre. The system pays for itself within 2 years. (quote 4) I want to get away from using as many pesticides as we do, if I can use the force of water to manage psylla that is a good alternative.
Image shows the riser and under-tree unit placement in the orchard.

Pear IPM Case Study: Honeydew Washing at Gale Orchards

By Chris Strohm, Tianna DuPont, WSU Extension; Louis Nottingham, WSU Entomology

Honeydew washing systems offer another tool for the pear IPM toolbox. The following case study is one example of a honeydew washing system used to reduce pear fruit marking in a conventionally managed orchard.

Image show the over-tree portion of the washing system used at this orchard.

System Specifications

  • 80 GPM/Acre
  • 0.21 in/hr
  • Tree spacing: 10′ x 20′
  • Sprinkler spacing: 45′ x 30′
  • Sprinkler heads: Rainbird impacts
  • Old system
  • Separate from under-tree irrigation

Full height image of the system used in this orchard showing its relationship with the trees.

Impacts

pre- and post-washing images showing the the pre-wash shoot with visible honeydew.

Chart showing the level of honeydew present pre- and post-washing in August. The pre-wash Brix level was less than 0.25 and the post-wash level being well below that.

Costs

  • Old System
  • Install cost-prohibitive

Grower Comments

Quote text box: (quote 1) I go back and forth between irrigating over- or under-tree. Generally, I will do one pass of the overheads before applying a spray. (quote 2) Very helpful if trees get sticky but I have not had difficult psylla pressure in recent years.
This image is from a more distant vantage to show the full height of the over-tree sprinkler in ration to the surrounding trees.

Contact

Tianna DuPont

WSU Extension

tianna.dupont@wsu.edu

(509) 293-8758

Chris Strohm
WSU Extension Assistant
(509) 293-8792
chris.strohm@wsu.edu

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