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Pear Psylla Phenology Update

June 7, 2021

Pear Psylla’s Current Status: Old nymphs (hardshells) from the first generation are still present but declining. Summerform adults and eggs are rapidly building in cooler locations (Cashmere) and nearing peak at 1500DD in warmer ones (Medford). Early instar nymphs of the second generation are building in all locations, and will peak at 1750DD. Hardshells of the second generation are just starting in all locations.

Fig 1. Pear psylla life stages (curves) by degree days (x-axis) for three pear growing regions. Each life-stage curve shows relative abundance of the total predicted population. Adults and eggs are combined because the summer generations occur almost simultaneously. The vertical line shows where we are as of June 2, 2021. (Model created by Dr. Vince Jones. Graphic visualization by Dr. Robert Orpet)

Pear psylla IPM Recommendations (by Category):

 

Particle Films

A particle film should have been applied at 800DD, but if not, do so ASAP to help deter further egg-lay. Our experiments have shown that spraying particle films after egg-lay provides some control of nymphs, however, it is less effective than spraying before egg-lay. It is still early enough that particle films will not leave problematic lasting residues on fruit; however, past the first week in June there could be issues, especially for early harvested red pear varieties.

Conventional IPM Insecticides

Two Ultor sprays should occur after petal fall, one at 1000DD and a second 14 days later. If your populations are consistently above 1 psylla adult per tray, you can apply Ultor + Esteem together. Neither Ultor or Esteem will reduce adult numbers but will prevent nymph development. While it may not be immediately gratifying, this slow kill is much better for promoting natural enemies.

*Both Ultor and Esteem can only be used twice per season, and consecutive sprays cannot be applied less than 14 days apart.

Organic Management

Cinnerate and/or neem products (but no neem on Comice) are effective on psylla, but may need to be sprayed as tank mixes and repeatedly from 1000 to 2200DD (around July 1) to keep populations suppressed. Monitor populations to determine spray frequency and tank mixing needs. The goal is to keep your population at or below one psylla per tray. Stop spraying after 2220DD, because these products will not control hardshell nymphs.

Cultural Strategies

Two main cultural strategies can be used for pear psylla: 1. Summer pruning and 2. Honeydew washing.

Summer Pruning: The removal of vegetative shoots (water sprouts) from trees. This not only improves spray penetration, it can reduce the psylla population and amount of honeydew in trees if timed correctly. Aim for 20002200DD to maximize psylla removal. Summer pruning can occur later in the season at 3100DD as well, however, there is a greater a risk of sunburned fruit.

Honeydew Washing: The process of washing honeydew from trees by overhead sprinklers or airblast sprayer. This method is different from overhead irrigation because it is only used to remove honeydew (we highly recommend performing general irrigating with under tree sprinklers to reduce the risk of diseases). Because washing too often and for too long can cause disease issues, it is important to only wash when there is enough honeydew to cause injury. Wash near the end of the hardshell stage for each generation, around 1400, 3000, and pre harvest if honeydew is high. These timings are not exact, but research to determine thresholds and timings for washing is currently underway. If using overheads to wash, we recommend about 6 hours of runtime for a system delivering ~70 gallons of water per acre per minute. A nonionic surfactant like Regulaid can be mixed in halfway through the cycle to improve honeydew removal. For airblast sprayer washes, use at least 800 GPA for smaller trees, and increase gallonage with tree size; the goal is to make water run off all leaves.

Codling Moth

Remember, a soft codling moth program is critical to conserve natural enemies that control pear psylla. Mating disruption and first sprays should have already occurred by this point. Soft codling moth spray materials include: oil, granulosis virus, Intrepid (methoxyfenozide), Esteem (pyriproxyfen) and Altacor (chlorantraniliprole).

Natural Enemies

All the methods suggested above will have low impacts on natural enemies. Natural enemies like lady beetles (Fig. 2A), predatory bugs (Fig. 2B), and parasitoid wasps (Fig. 2C) are critical to prevent psylla and mite population explosions closer to harvest, and they do it for free! So avoid broad spectrum materials, especially multiple products at a time.

Fig 2. Natural enemies of pear psylla; i.e., your friends! A) Lady beetle feeding on psylla nymphs (L. Nottingham). B) Deraeocoris brevis feeding on psylla nymph (B. Higbee). C) Trechnites insidiosus parasitizing psylla nymph (R. Schmidt-Jeffris).

Psylla Phenology and Recommendations

June 1, 2021

Pear Psylla’s Current Status:
Some old nymphs from the first generation are still present but declining. Summerform adults and eggs are building in orchards (about 25-30% of the peak population are now present). Adults and eggs will increase until the peak at 1500 DD. Early instar nymphs of the second generation are beginning (10-15% of total population are present). No late nymphs of the second generation should be present.

Pear psylla life stages (curves) by degree days (x-axis) for three regions. Each life-stage curve shows relative abundance of the total predicted population. Adults and eggs are combined because the summer generations occur almost simultaneously. The vertical line shows where we are as of May 26 2021. (Model created by Dr. Vince Jones. Graphic visualization by Dr. Robert Orpet)

Pear psylla IPM Recommendations (by Category):

Particle Films: If you have not applied a postbloom particle film yet, you can still do so to help deter egg-lay, but it should be done immediately because egg-lay is getting closer to peak. Our experiments have shown that spraying particle films after egg-lay provide some control of nymphs, however, it is less effective than spraying before egg-lay. It is still early enough that particle films will not leave lasting residues on the fruit.

Conventional IPM Insecticides: The first Ultor (spirotetramat) application may have already occurred, but it can still be made at this point if not. Perform the first spray now if you have moderate pressure (around 1 adult per tray on average). If you have consistently more than 1 adult per tray, you can apply Ultor + Esteem (pyriproxyfen, which is also a soft and effective codling moth material). Apply a second Ultor spray 14 days after the first if pressure remains high or increases. Neither Ultor nor Esteem will reduce adult numbers, so this should not be expected. Instead, they will prevent nymph development. While it may not be immediately gratifying, this slow kill has the benefit of providing food to grow predators while suppressing the psylla population.
*Both Ultor and Esteem can only be used twice per season, and consecutive sprays cannot be applied less than 14 days apart.

Organic Management: Now is an excellent time to use Cinnerate and/or neem products (but no neem on Comice) at high label rates. These products should be applied at least twice, if not 3 to 4 times during this generation; ideally, at least one spray would have already been applied. If adult pressure is moderate (around 1 adult per tray on average), either product alone may be effective, especially if a particle film was already used. If pressure is high (greater than 1 adult per tray), these products can be tank mixed to improve efficacy.

Cultural Strategies: Two main cultural strategies can be used for pear psylla: 1. Summer pruning and 2. Honeydew washing. Summer Pruning: The removal of vegetative shoots (water sprouts) from trees. This not only improves spray penetration, it can reduce the psylla population and amount of honeydew in trees, if timed correctly. Aim for 2000-2200DD, before the 3rd generation of adults have begun emerging and all psylla will be in nymph stage and on the shoots. Summer pruning can occur later in the season at 3100DD as well, however, there is a greater a risk of sunburned fruit. Honeydew Washing: The process of washing honeydew from trees by overhead sprinklers or airblast sprayer. This method is different from overhead irrigation because it is only used to remove honeydew (we highly recommend performing general irrigating with under tree sprinklers to reduce the risk of diseases). Because washing too often and for too long can cause disease issues, it is important to only wash when it is necessary. We recommend targeting old nymphs of the second and third generations, so 1600 and 3000 DD. But remember, there is no need to wash if you do not have a fair amount of visible honeydew. If using overheads, we recommend about 6 hours of runtime for a system delivering ~70 gallons of water per acre per minute. A nonionic surfactant like Regulaid can be mixed in halfway through the cycle to improve honeydew removal. For airblast sprayer washes, use at least 800 GPA for smaller trees, and increase gallonage with tree size; the goal is to make water run off all leaves.

Pear Psylla Phenology Update

May 18, 2021

A phenology model for pear psylla was recently developed by Dr. Vince Jones. This model predicts the relative number of pear psylla from each life stage occurring as degree days are accumulated. Below is a graph showing the psylla degree day model and the status of psylla development on May 6th 2021. Degree days were averaged among weather stations in Medford, OR, Hood River, OR, Wapato, WA and Cashmere, WA; the difference from the coolest to hottest location was approximately 110 DD.

Click the graph for the full article.

 

Sustainable Control of Pear Psylla

mostly white slide with drawing of tree fruits in the lower left corner, a small video feed of the speaker in the upper right corner and the title be brave pear psylla management

February 22, 2021

Be BRAVE: Pear Psylla Management

On Thursday, February 18, 2021 as part of an OSU/WSU webinar, Stijn van Laer gave a talk on pear psylla management in northern European pear orchards.  Stijn is a crop consultant that works for company called FruitConsult based in Belgium.  They are a private consulting firm that does not sell products (i.e., chemicals), just management recommendations. Stijn discussed management of pear psylla in European orchards with conservation biological control (i.e., only using soft insecticides and at economic thresholds) and by augmentation of earwigs.  He also discussed the importance of proper sprayer calibration and how this can make or break effective management.

Evaluation of IPM for central WA pear orchards

article title and abstract in the journal biological control

February 9, 2021

IPM for Central WA Pear Orchards

Pear psylla and honeydew marking to fruit cause significant economic damage to pears in Washington, a key pear growing region of the United States. The goal of this project is to compare an integrated pest management (IPM) program using materials which selectively target pests and relies on large natural enemy populations to grower standard conventional and organic pear pest management.

Dupont, T., C. Strohm, L. B. Nottingham and D. Rendon. 2021. Evaluation of an integrated pest management program for central Washington pear orchards. Biol. Control. 152: 104390.

Prebloom Management of Pear Psylla with Particle Film

February 8, 2021

Psylla will soon be on the move!

Louis Nottingham and Robert Orpet wrote an article in the February 2021 edition of ‘Tree Fruit News’ reminding growers to start preparing dormant sprays of kaolin clay (Surround) to deter pear psylla colonization in the orchard. A dormant Surround spray will provide the first line of defense to keep psylla from entering your orchard. The optimal time to make this first Surround application depends on weather, but here is a good rule of thumb: if it is warm and dry enough for you to safely spray, go for it – psylla are probably colonizing your orchard!

Click the pic to learn more.

closeup of two pear buds in the orchard
Picture taken on 3/24/20 of a pear bud just before burst, sprayed at dormant (3/16/20) with Surround CF at 50 pounds/acre. This bud remains protected against oviposition until fresh green tissue ‘bursts’ from within the hard exterior scales.

 

Reflective mulch for pear psylla

two people working in a pear orchard with reflective mulch

November 19, 2020

New Publication!

Pear psylla, Cacopsylla pyricola (Förster), has remained the most challenging pest of commercial pears in Washington and Oregon, the top producers of pears in the United States. The lack of effective integrated pest management tactics for this pest has been a major barrier to effective management. In this study, we examined the potential for reflective plastic mulch affixed beneath pear trees to suppress pear psylla. In 2017 and 2018, single pear tree (cv. Bartlett) plots of reflective plastic mulch, black plastic mulch, and no mulch (check) were established in a research orchard to compare their effects on pear psylla.

Nottingham, L. B. and E. H. Beers 2020. Management of pear psylla (Hemiptera: Psyllidae), using reflective plastic mulch. J. Econ. Entomol. 113:2840-2849.

screenshot of publication in the journal of economic entomology

Surround applied in the fall for pear psylla management

November 19, 2020

Orpet and Nottingham article in ‘Fruit Matter’s Newsletter’ about potential for Surround applied in the fall for pear psylla management.

Kaolin clay (Surround WP) is a white sprayable powder that discourages pear psylla from laying eggs on pear trees by creating a physical barrier over the tree’s surface. If sprayed early in the season, the white coating could also deter psylla from colonizing orchards, possibly due to repellency of reflected UV light to insects. Kaolin is more persistent on trees than most insecticides, especially when used with a spreader-sticker (check labels for compatibility and mixing instructions), and it has low risk of harming natural enemies because it is non-toxic.

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