7 April 2026 - Talking Woolly Apple Aphids with Dr. Robert Orpet, More Scab Predictions

This week on scaffolds, I talk to Dr. Robert Orpet of Oregon State University, one of the few people in the US who has worked extensively on woolly apple aphid but in Washington state, about woolly apple aphid, Kerik gives us more scab forecasting, and anna gives us the state of the state update with a review of scouting, degree day accumulations and reminders for the very quick start to the season happening in the Hudson Valley.

Cox - Apple Scab Disease forecast predictions for New York as of 4-5-26 - Too cold for apple scab infections - refresh coverage as needed.

State of the State Show Notes

Historical Phenology and Average Degree Day Accumulation Base 43 (for reference)

- Silver Tip (McIntosh) || 58-106

- Green Tip (McIntosh) || 99-144

- Half Inch Green (McIntosh) || 150-201

- Tight Cluster (McIntosh) || 206-257

Phenology & DDs for NY NEWA Stations from 1/1 – 4/6

Station || Stage || DD 43F || DD 50F ||

Geneva || green tip || 175 || 90

Highland (HVRL) || 1/2" to early TC || 203 || 108

Clifton Park || first green || 136 || 67

Peru (Forrence) || silver tip || 84 || 34

Medina (Roberts) - Inland || first green || 161 || 76

Appleton North - Lake || first green || 118 || 55

Fairville (The Apple Shed) - Inland || first green || 181 || 91

Williamson (DeMarree) - Lake || first green || 147 || 72

*all DDs Baskerville-Emin, B.E

Upcoming Pest Events

Pest/Phenology Event || DD Base 43˚F || Approx. Date

STLM Traps set out || 1-Apr

Pear psylla – egg laying || 84 ± 44 || 33 ± 21 || 4-Apr ± 11 days

RBLR – 1st catch || 144 ± 32 || 60 ± 20 || 17-Apr ± 9 days

Rosy apple aphid – 1st nymphs present || 189 ± 55 || 86 ± 30 || 25-Apr ± 7 days

STLM – 1st adult catch || 168 ± 48 || 73 ± 28 || 20-Apr ± 9 days

STLM – 1st egg observed || 208 ± 65 || 94 ± 36 || 27-Apr ± 5 days

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Tight cluster (McIntosh) || 228 ± 27 || 105 ± 19 || 27-Apr ± 7 days

Tarnished plant bug – 1st observed || 222 ± 105 || 105 ± 62 || 25-Apr ± 15 days

OBLR – 1st overwintered larvae observed || 236 ± 78 || 112 ± 48 || 29-Apr ± 7 days

Black stem borer – 1st adult catch || 283 ± 50 || 137 ± 40 || 6-May ± 3 days

European red mite – egg hatch observed || 284 ± 53 || 134 ± 34 || 6-May ± 4 days

Cold Temperature and Frost Risk

Picture Table of Critical Spring Temperatures for Tree Fruit Bud Development Stages https://www.canr.msu.edu/resources/picture-table-critical-spring-temperatures-for-tree-fruit-bud-development-stages

Regional Weather Events page for NEWA weather stations, including a map of freeze events on 4/25 and 26. https://newa.cornell.edu/regional-weather-events/

Cornell Statewide Frost Protection webinar held on Friday April 12th recording now available online here: https://youtu.be/TIBEpfb98ws

Scouting and Monitoring Resources

Video: Apple Insect Targets and IPM Practices (including explanations of Degree Day calculations), https://youtu.be/NwyBAcvbpUs

NY Tree Fruit Pest Monitoring Network Blog

https://blogs.cornell.edu/treefruitpests/

Interested in collaborating and contributing trap capture data? Contact Anna Wallis aew232@cornell.edu

Quick Guide for Apple Insect Pests https://help.nysipm.org/hc/en-us/articles/23290226665751-NEWA-Quick-Guide-for-Apple-Insect-Pests

Virtual Orchard Scout Training webinar recording on the Cornell IPM YouTube channel

https://www.youtube.com/watch?v=OtyOWCL1Q2A

Apple IPM Intensive Workshop playlist https://www.youtube.com/playlist?list=PLoNb8lODb49vifrm9Tla4GmAVhlIL0527

Northeast Regional Climate Change Monthly Maps

https://www.nrcc.cornell.edu/regional/monthly/monthly.html

NEWA Help Desk Frequently Asked Questions and Table of Contents. https://help.nysipm.org/hc/en-us/categories/16994462926231-NEWA-Network-for-Environment-and-Weather-Applications

https://help.nysipm.org/hc/en-us/sections/17011505301783-Apple-Insect-Disease-and-Crop-Management-Forecasts