2026 Christmas Tree Scouting Report June 18, 2026

Pest Information

Cryptomeria Scale

Cryptomeria scale development remains variable among locations. That being said, many Pennsylvania Christmas tree growers have already completed their first Cryptomeria scale management applications based on crawler activity observed earlier this season. In treated blocks, growers are reporting good control and increasing numbers of dead crawlers beneath female covers. However, delayed development at some sites reinforces the importance of continued scouting, as emergence timing can vary considerably based on location, elevation, host species, and microclimate.

Growers should continue monitoring susceptible plantings using tape traps and branch inspections. Additional crawler emergence may still occur over the coming weeks, particularly in fields where only eggs are currently present. The crawler stage remains the most vulnerable period for management and provides the greatest opportunity for control.

Management options during crawler emergence include horticultural oils, Centaur® (buprofezin), Safari® (dinotefuran), and Movento® (spirotetramat) where labeled.

Looking Beyond the First Generation

While much attention is focused on first-generation crawler activity, growers should remember that Cryptomeria scale typically produces a second generation in Pennsylvania. Based on observations from the August 13, 2025 Pennsylvania Christmas Tree Scouting Report, second-generation crawler emergence was observed at approximately 1,750–2,130 GDD (base 50°F).

Although most growers are currently focused on first-generation management, fields with a history of Cryptomeria scale should continue to be monitored through mid- and late summer. Effective management of the first generation often greatly reduces pressure later in the season, but growers should not assume that June treatments conclude management for the year.

Trees that appear relatively clean following spring applications may still experience renewed crawler activity later in the season. Monitoring with tape traps and periodic branch inspections should continue through August and September, particularly in blocks with historically high populations or where first-generation control was incomplete.

With Schuylkill County currently at 911.5 GDD, growers have likely completed only the first half of the Cryptomeria scale season. Based on 2025 observations, second-generation activity may not occur until an additional 800–1,200 GDD have accumulated. Maintaining records of crawler timing from year to year can help growers identify patterns unique to their farms and improve future management decisions.

Fletcher Scale

Fletcher scale continues to develop on Emerald Green arborvitae. Peach-colored eggs were observed beneath female covers this week. Additional scales contained active crawlers beneath the female cover, although crawlers had not yet emerged onto foliage.

These observations indicate that hatch is approaching rapidly. Growers should begin monitoring susceptible arborvitae closely over the next several weeks. Applications targeting newly emerged crawlers typically provide the highest level of control.

Bagworms

Bagworm hatch is underway. Newly emerged larvae were observed feeding outside overwintering bags while additional eggs remained inside. Hatch appears to be progressing slowly and remains variable among locations.

Bagworm hatch typically begins around 635 GDD, and many growers have now entered the early treatment window. Early instar larvae remain highly susceptible to treatment and are significantly easier to control before feeding damage becomes extensive.

Bacillus thuringiensis var. kurstaki (Btk) remains an excellent option for very small larvae. As larvae increase in size, growers may consider chlorantraniliprole, spinosad, acephate, bifenthrin, lambda-cyhalothrin, or other labeled products.

Spruce Spider Mites

Spider mite activity continues to decline at many locations. Only a few live mites were observed this week while most samples consisted primarily of eggs.

As temperatures increase, conditions become less favorable for spruce spider mite development. However, growers should continue monitoring fields with a history of mite pressure, particularly where populations were elevated earlier this spring.

Environmental Observations
Norway Spruce Frost Injury Becoming Apparent

Several Norway spruce samples submitted for diagnosis this spring have been attributed to freeze injury that occurred while buds were expanding and new shoots were elongating. Symptoms have become increasingly visible during the past several weeks as damaged shoots continued to develop.

Affected trees exhibit browning and desiccation of current-season needles, often concentrated throughout lower and middle portions of the canopy, while leaders and upper growth remain relatively healthy. Injury may initially resemble needle cast disease or general decline, but follows a pattern consistent with exposure during late spring freeze events. We have fielded many calls and messages with similar symptoms across the state.  To be sure you do not have a secondary infection, samples can be sent to the plant diagnostic lab for confirmation.

Many areas of Pennsylvania experienced unusually warm temperatures during April, followed by freezing conditions during critical stages of bud development. Trees that had advanced further in growth were particularly susceptible. As damaged needles expanded during shoot elongation, symptoms became increasingly visible.

One challenge in diagnosing frost injury is the delay between the weather event and symptom development. Many trees appeared normal immediately following the freeze, but developed visible browning weeks later. This delayed symptom expression can make it difficult to associate the injury with the original weather event.

Management is largely supportive and includes maintaining adequate soil moisture, minimizing additional stress, and monitoring for secondary pest or disease issues throughout the remainder of the growing season.

Weed Management Corner

Summer Cleanup and Planning for Next Year

As summer progresses, many growers are beginning to notice escaped grasses, yellow nutsedge, Canada thistle, and perennial broadleaf weeds in tree rows. Weeds compete directly with Christmas trees for water, nutrients, light, and space, and can interfere with scouting, spraying, shearing, and harvest operations. Effective weed management requires both summer cleanup and planning for next year's residual herbicide program.

For annual and perennial grasses, clethodim products remain among the most effective postemergence options available when applied to actively growing grasses. Common trade names include Select Max®, Arrow®, TapOut®, Intensity®, Shadow®, Trigger®, Section Three®, Clethodim 2E®, and numerous generic formulations. Clethodim provides excellent control of many annual and perennial grass species but will not control broadleaf weeds or sedges. Clethodim is often considered one of the safest postemergence herbicides available to Christmas tree growers because it controls grasses without injuring most labeled conifer species. This allows for over-the-top applications in many Christmas tree plantations, making it an excellent option for managing grass escapes where directed sprays would be difficult or time-consuming.

Yellow Nutsedge

Yellow nutsedge continues to be one of the most challenging weeds in Christmas tree production. Halosulfuron products such as SedgeHammer® and ProSedge® provide some of the best postemergence suppression of nutsedge, while Basagran T/O® (bentazon) and Reward® (diquat) can provide suppression of emerged plants. However, growers should recognize that these treatments will not eliminate the underground tubers responsible for future infestations. Although this Penn State Extension article is more turf focused, there is more information on Nutsedge.

For fields with recurring nutsedge pressure, now is the time to plan for next spring. Pennant Magnum® (S-metolachlor) and equivalent S-metolachlor formulations remain among the most effective residual herbicides for suppressing yellow nutsedge emergence while also providing excellent annual grass control. The goal is not simply to control nutsedge after it emerges, but to reduce emergence from established tubers before the problem expands further. Growers battling nutsedge this season should strongly consider incorporating an S-metolachlor product into next year's preemergence herbicide program.

Goal® (oxyfluorfen) remains an excellent companion herbicide for broadleaf weed control and suppression of newly emerged seedlings but should not be relied upon for nutsedge management. Growers may want to consider combinations that include Goal®, S-metolachlor products, and a residual grass herbicide such as pendimethalin when developing next year's weed management program.

One important distinction between grass herbicides such as clethodim and herbicides used for nutsedge management is crop selectivity. While clethodim is commonly used over labeled Christmas tree species for grass control, products used to manage nutsedge may have different application restrictions, species sensitivities, and potential for crop injury. Growers should carefully review product labels for approved tree species, tree age restrictions, application methods, and precautions before use. Applications should be made in a manner that minimizes contact with desirable foliage and actively growing shoots unless specifically permitted by the product label. As always, label directions should guide all application decisions.

Canada Thistle

Canada thistle is becoming increasingly noticeable in some plantations. Clopyralid products such as Stinger® and Lontrel® remain among the most effective selective herbicides available for thistle management and also provide control of ragweed, horseweed, clover, knapweeds, and several other troublesome broadleaf weeds. Because clopyralid moves throughout the plant and into underground rhizomes, it often provides better long-term suppression than contact herbicides alone.

For growers managing thistle along field edges, fence rows, roadways, and other non-crop areas, Crossbow® (triclopyr + 2,4-D) can also be an effective option. Crossbow provides control of Canada thistle as well as many woody brush species and perennial broadleaf weeds. However, growers should exercise caution around Christmas trees and other desirable broadleaf plants, as off-target movement can cause injury. Always consult the label regarding approved use sites and application restrictions before use.

As with many perennial weeds, treatment timing is critical. Applications made while thistles are actively growing and before flowering generally provide the best results. Fall applications can be particularly effective as plants begin moving carbohydrates into underground root systems for winter storage, improving the movement of systemic herbicides into rhizomes.

Fall Cleanup and Perennial Weed Management

September and October remain among the most effective times of year to control perennial weeds. During the fall, plants naturally move carbohydrates into roots and underground storage structures in preparation for winter. Systemic herbicides applied during this period move with those carbohydrates, often providing significantly better perennial weed control than comparable spring applications.

Directed applications of glyphosate after trees have fully hardened off can provide excellent control of perennial grasses, goldenrod, milkweed, hemp dogbane, pokeweed, and many other difficult perennial weeds. Triclopyr products such as Garlon 3A® and Vastlan® may also be useful where woody brush and perennial broadleaf weeds are becoming established.

Growers should remember that not all glyphosate products carry the same labeled uses. While many products contain glyphosate as the active ingredient, labels can differ considerably between manufacturers and formulations. Before making applications in Christmas tree plantations, growers should verify that their specific product is labeled for Christmas tree production. Products labeled for industrial sites, rights-of-way, or non-crop areas may not necessarily include Christmas trees on the label.

It is also important to understand the concentration of the product being used. Glyphosate formulations are commonly sold as 4 lb/gal, 4.5 lb/gal, and 5.4 lb/gal products. Substituting one formulation for another without adjusting rates can result in poor weed control or increased risk of crop injury.

Other Ornamental Pests 

Ash Clearwing and Lesser Peachtree Borer

Ash clearwing and lesser peachtree borer remain active in monitoring traps. Growers implementing preventative borer management programs should continue evaluating residual activity of previously applied insecticides and maintain protection intervals where necessary. For more information, see the Penn State Extension factsheet on lesser peachtree borer.

Red oak clearwing borer (Paranthrene simulans)

Oak clearwing borers continue to be active in many areas of Pennsylvania during the summer months. Adult moths resemble small wasps and are often detected using pheromone traps rather than direct observation. Larvae tunnel beneath the bark of stressed or injured oak trees, feeding within the cambium and disrupting water and nutrient movement.

Infestations are most commonly associated with trees experiencing drought stress, construction injury, soil compaction, root disturbance, or previous pest problems. Symptoms may include branch dieback, thinning canopies, roughened bark, sap flow, or the presence of small emergence holes on trunks and major branches.

While oak clearwing borer is not considered a direct Christmas tree pest, growers maintaining shade trees, landscape plantings, or farm woodlots may encounter this insect. Management is largely preventative and focuses on maintaining tree vigor, minimizing stress, and protecting susceptible trees during periods of adult flight.

Preventative trunk and scaffold branch applications containing bifenthrin remain one of the most commonly used management options during adult flight. Applications are intended to target newly hatched larvae before they enter the bark where they become protected from treatment. Timing applications to coincide with trap captures and peak adult activity generally provides the greatest level of protection. The grower who submitted this photo cut and burned the infected trees, and the tree would not be salvaged for sale. 

As with ash clearwing and lesser peachtree borer, continued trap captures indicate that adult flight remains active and growers monitoring susceptible hosts should continue scouting throughout the summer.

Looking Ahead

Continued warm weather will likely accelerate insect development while increasing drought stress on trees affected by spring frost injury. Growers should continue monitoring both pest activity and overall tree health as the season transitions into summer. 

PCTGA Summer Meeting: August 13 - 15, 2026.
Location: Mytrysak Family Tree Farm Fleming Rd. Indiana, PA
Website 

Kelly will be presenting on pest control strategies and a scouting with confidence interactive presentation. We hope to see you there! 

Next Report

As always, growers should carefully read and follow the most current product label before making any pesticide application. Labels can change; rates may vary by crop or application method, and specific restrictions regarding PPE, reentry intervals, pollinator protection, and seasonal maximums must be followed. The Pennsylvania Department of Agriculture reminds applicators that "the label is the law" and that all pesticide applications must remain in compliance with both federal and state regulations.

The next scouting report will be available on June 25, 2026. Reminder, please submit observations anytime prior to Tuesday, June 24 , 2026, by noon to Kelly Piccioni at keg200@psu.edu to be included in the next report. As a reminder, you may also call into the hotline weekly for updates: 1-800-PENN-IPM (1-800-736-6476) option 5