Christmas Trees Edition
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Seasonal pest alerts and news about insects, diseases, and weeds impacting Christmas Tree production including Commercial Ag Updates (meetings and marketing); and Pesticide Program updates from the Rutgers Pest Management Office News Blog.
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Rutgers Weather Forecasting - Meteorological Information important to commercial agriculture.
Private Applicators: NJDEP August Mailing of 2024 Invoices & Recertification Credit Status
Bilingual Labeling: Parts of Pesticide Labels Will be Required to Also Be In Spanish
Christmas Tree Pest Notes for July 2023
Cooley Spruce Gall Adelgid (1850-1950 GDD = galls open): Colorado spruce (especially green forms), Sitka and Oriental spruce, and Douglas-fir share this pest’s two host life cycles. Mature adult females lay eggs at the tips of branches. These eggs hatch and the immatures move to new growth and start feeding. The combined feeding and salivary secretions induce the development of a bright green, oval “pineapple” gall on the terminals (as opposed to galls at the base of new growth on Norway spruce from the Eastern spruce gall adelgids). By midsummer, the gall will turn brown and crack open, as the adelgids within mature and emerge as adults. These winged adults migrate to Douglas-fir (or another spruce) and spend the remainder of the summer feeding on the needles, covered with cottony wax.
During late July or early August the adult Cooley spruce gall will emerge from the opened brown pineapple shaped galls. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Sometimes Douglas-fir is so heavily attacked that needles are spotted, bent, or distorted. Two or more generations can occur on Douglas-fir through the following season (Christmas tree growers will treat Douglas-fir when new growth is 3-4 inches). By next fall another winged generation flies back to spruce and lays eggs for the cycle to repeat itself.
Adelgid nymph within protective cottony wax feeding on Douglas-fir needle. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Control by pruning out galls when seen; place sticky traps out in late summer (Douglas-fir or spruce) (1850-1950 GDD) to determine the timing to spray adults with insecticidal soap (+ sticker). Some of the tip “pineapple” galls on spruce have already opened up, and the winged adults have emerged. Except to improve the aesthetic appearance of the trees, there is nothing to be gained by picking off the galls after they have opened. Future control windows will occur during the fall or early spring months, against the overwintering females located at the bases of terminal buds. Some possible treatments include horticultural oil, carbaryl (Sevin), insecticidal soap, or imidacloprid (Merit).
The Christmas Tree Pest Notes Blog for July 2023 also contains a few additional insect pests. Those included below are pine needle scale, pitch mass borer, white pine weevil, & some comments regarding cicada killer wasp predators.
2023 Spotted Lanternfly Tracking Survey
Rutgers NJAES Wine Grape Extension, in association with Penn State Extension Grape and Wine Team, is calling on those who own, operate, or manage a farm or vineyard in the New Jersey region to participate in a survey that aims to track the spread and severity of nymph and adult spotted lanternfly populations during the 2023 season. The data collected will provide insights into the distribution patterns of both nymph and adult SLF within and outside vineyards, enabling growers and researchers to better understand this invasive pest’s potential impact on agriculture in the Mid-Atlantic region. [Read more…]
Beware of Cryptomeria Scales on True Firs within Christmas Tree Farms
Armored scales are generally regarded by green industry plant managers as being one of the more difficult insect pests to control. The Cryptomeria scale (Aspidiotus cryptomeriae ‘Kuwana’) is an armored scale that is notorious for being especially difficult to detect because of the translucent waxy cover. The elongate hemlock scale species resembles this scale, but it has a waxy cover that is caramel brown in color. Although the hosts of Cryptomeria scale can potentially include numerous conifer species, they are most typically found on hemlocks & pines in the landscape and on true firs in production situations such as Christmas tree farms. The damage potential is especially high on true firs.
Signs of Cryptomeria scales beneath needles. (Photo: Steven K. Rettke, Rutgers Coop. Ext.)
Chlorotic banding & mottling symptoms produced by Cryptomeria scales on Fraser fir (Photo: Steven K. Rettke, Rutgers Coop. Ext.)
Get ready for bagworms…NOW
Days-old bagworm = critical management target – T. Waller – RCE
Bagworms should begin hatching NOW through – 4 weeks in NJ, beginning in the southern regions. Now is an optimal time to get this pest on your radar and prepare materials or approaches to attack first/second instar caterpillars. The control window for this pest is typically between 600-900 GDD50 when they begin to hatch and become airborne, i.e. the “ballooning” phase. It is important to check for egg-hatch prior to applications for greatest chemical efficacy, and to continue scouting as they often hatch and develop at asynchronous rates.
It is critical to target these insects EARLY!
Bagworm management – mechanical: If eggs have not hatched: hand-remove sacs/bags. Typically female/egg filled sacs are higher in the canopy so keep that in mind while scouting. This removes the problem from the field or landscape.
Treatment options for Lepidoptera (caterpillars) to have at the ready – containing: B.t. (Bacillus thuringiensis), spinosad , bifenthrin ), cyfluthrin, carbaryl, chlorantraniliprole, cyclaniliprole, cyclaniliprole + flonicamid, Lambda-cyhalothrin, cyantraniliprole, Indoxacarb. NOTE – Lethal pesticide doses are important, as sub-lethal doses can trigger early pupation, making the pest all but invincible to chemical or biological treatments. Follow label exactly.
IT IS CRITICAL TO ROTATE MATERIALS (Rotate between IRAC groups)
DISCLAIMER: The label is the law, always refer to it for allowable host crops, use-restrictions, application rates, reapplication intervals, re-entry intervals (REI), and mix compatibility information. Production and pesticide information on this site are for private/commercial pesticide applicators and landscape professionals only, and are NOT for home gardener use. Provided materials represent examples and do not cover all possible control scenarios. Please contact your local agent or chemical sales representative for more information or to discuss additional pest management options.
| BAGWORMS (600-900 GDD) (Bagworm hatch prediction as of 5/24/23) | ||||||
| Crop type | Common Name | Scientific Name | GDD Min (50F) | GDD Max (95F) | Reference | Developmental / Target Stage |
| Conifer mostly, many minor hosts | Bagworm | Thyridopteryx ephemeraeformis | 600 | 900 | RU | Larvae (early instars) – ONLY CONTROL WINDOW |
| Region | Location | Station | Date (600 GDD) | Date (900 GDD) | *Treatment window | *Bagworm Hatch – Predictions only, SCOUTING is critical! Treat as soon as larvae detected. |
| South | Upper Deerfield | NJ50 | 31-May | 14-Jun | 14 days | |
| Central | Howell / Freehold | NJ10 | 9-Jun | 23-Jun | 14 days | |
| North | High Point | NJ59 | 15-Jun | 2-July | 17 days | |
Please download and print the Rutgers Nursery and Landscape Pest Scouting Guide or Conifer and Christmas Tree Pest Scouting Guide and refer to this post “Obtaining your local growing degree-days (GDD)” for additional information. (See pest scouting guides for complete list of references – cited within lists below)
Please SHARE what you SEE!! If you see a pest, disease, otherwise interesting or troublesome issue please report it to the Working Group by following the QR Code on the front of the Pest Scouting Guides or by filling out this reporting form.
