Please print or download the two resources of this post (click on them):
- Printable Pest Scouting Guide 25-60 GDD
- Expanded Pest Scouting Guide 25-60 GDD with CLICKABLE links
- (Zoom in and click directly on the links within this document)
The information provided in the downloads gives early season scouting ranges (in growing degree days, base 50F) for specific insect pests harming nursery crop production and maintenance. Additionally, forecasting predictions (GDD50 accumulation) for calendar dates of multiple regions of New Jersey (S,N,C) are provided.
To determine your local growing degree-days, please review this post “Obtaining your local growing degree-day information”
Scouting Ranges:
- This document supports scouting, it does not replace it. Keeping good notes on pest development will help dial in scouting and treatment efforts at your local level.
- It is important to note that these GDD50 are not exact, rather provide a range of GDD and subsequent calendar dates that can be used to scout for, and treat for, insect pests.
- The pests listed here will be listed again in future scouting range announcements as they undergo further developmental life stages or are vulnerable to management options.
- If you need more information, OR you are regularly seeing specific pest development stages at growing degree-days different than those listed here, please contact Tim Waller at twaller@njaes.rutgers.edu
| Projected GDD50 accumulation as of | ||||||
| NJ – Region | Location | March 1st | April 1st | May 1st | June 1st | July 1st |
| Southern | Upper Deerfield (NJ50) | 0 | 48 | 157 | 564 | 1241 |
| Central | Howell / Freehold (NJ10) | 0 | 26 | 107 | 455 | 1076 |
| Northern | High Point (NJ59) | 0 | 5 | 11 | 224 | 676 |
| Forecast: NOAA NCEP Coupled Forecast System model version 2 (CFSv2) forecast system (3.5 months) (USPEST.ORG) | ||||||
| Pest Scouting – Growing Degree-day Ranges | (25-60 GDD50) | |||||
| CROP TYPE | Common Name | Scientific Name | GDD Min (50F) | GDD Max (95F) | Reference | Developmental / Target Stage |
| Conifer | Eastern spruce gall adelgid | Adelges abietis | 25 | 100 | 3 | Spring control of overwintering stage |
| Conifer | Northern pine weevil | Pissodes approximatus | 25 | 100 | 4 | 1st adults active |
| Conifer | Zimmerman pine moth | Dioryctria zimmermani | 25 | 100 | 3 | 1st larvae active |
| Conifer | Cooley spruce gall adelgid | Adelges cooleyi | 25 | 120 | 3 | Spring control of overwintering stage |
| Conifer | White pine weevil | Pissodes strobi | 25 | 220 | 4 | 1st adults active |
| Shade trees | European fruit lecanium | Parthenolecanium corni | 35 | 145 | 2 | Spring control of overwintering stage |
| Many, evergreen | Euonymus scale | Unaspis euonymi | 35 | 120 | 2 | Spring control of overwintering stage |
| Conifer | European pine sawfly | Neodiprion sertifer | 35 | 145 | 1 | Hatched larvae |
| Conifer | Fletcher scale | Parthenolecanium fletcheri | 35 | 148 | 2 | Spring control of overwintering stage |
| Conifer | European pine shoot moth / borer | Rhyacionia buoiana | 50 | 220 | 4 | 1st larvae active |
| Maples | Maple bladdergall mite | Vasates quadripedes | 58 | 148 | 2 | Spring control of overwintering stage |
| Honeylocust | Honeylocust plant bug | Diaphnocoris chlorionis | 58 | 246 | 2 | Nympths / adults active |
| Conifer | Pine tortoise scale | Toumeyela parvicornis | 58 | 148 | 2 | Cralwer activity |
| Conifer | Pine bark adelgid | Pineus strobi | 58 | 618 | 2 | Spring control of overwintering stage |
| Conifer | Balsam twig aphid | Mindarus abietinus | 60 | 100 | 4 | Egg hatch |
| References | RU | Rutgers Cooperative Extension – IPM Notes | ||||
| 2 | http://ccetompkins.org/resources/using-growing-degree-days-for-insect-management | |||||
| 3 | https://extension.psu.edu/ipm-basics-for-christmas-trees#section-2 | |||||
| 4 | https://www.canr.msu.edu/ipm/agriculture/christmas_trees/gdd_of_conifer_insects | |||||
| 5 | https://www.agriculture.nh.gov/publications-forms/documents/landscape-pests.pdf | |||||
| 6 | https://extension.umd.edu/ipm/pest-predictive-calendar-landscapenursery | |||||
(Please note: we will be providing pest GDD ranges regularly throughout the season for our green industries)
Important notes about growing degree-day models:
- These models do not replace scouting. They should guide scouting efforts and pest management programs, once the vulnerable life stage or economic threshold of a pest is recorded. Observations at a local level for specific pests is critical to IPM efforts and further refinement of degree-day-based predictions.
- GDD50 values for pest development are not exact, rather they should be viewed as a range.
- The growing degree-day model (GDD50) is general by design. Some insect pests have specific formulas for their growth and development (some examples here). However, the GDD50 model is useful for many pests and plant species.
- Many GDD50 target values were developed in other parts of the country and should be ‘ground truthed’ at a local level. Blind applications of pesticides, without truthing pest development, may not deliver desired outcomes.
