Christmas Tree Scouting Report: July 3, 2025

Weekly scouting report compiled by Kelly Piccioni, Penn State Extension, Schuylkill County. This week's scouting data contributors: Kelly Piccioni, Penn State Extension, Don deMackiewicz, Sarah Pickel and Cathy Thomas (PDA), Jim Fogarty (Schuylkill County), Rick Geissler (Berks County), Gerrit Strathmeyer II (Adams and York County).

Pest Information

More rain and extreme heat! Every possible scenario of a weather-induced stressor has been thrown our way this growing season. 

Sunburn

Douglas Fir in our scouting areas experienced burning during those early extreme heat days last week.  Damage started to present itself on Friday and through the weekend.  This week, sun damage also appeared on a few Fraser Fir along the edges of fields and roads.  Evergreens are most likely to experience sunburn during intense sun exposure and limited moisture. South- and west-facing slopes receive the most direct afternoon sun, making them especially prone to needle burn. Exposed hilltops or open fields without shade or wind protection also create conditions where trees dry out quickly and are vulnerable to photodamage. Trees located along the edges of newly cleared or thinned fields may be at risk as well, particularly if they were previously shaded and are suddenly exposed to full sun. Sites with sandy or shallow soils that hold little moisture can worsen the effects, as roots struggle to keep up with water loss during hot, dry periods. Additionally, fields with bare ground, mowed strips, or minimal vegetation between rows can reflect sunlight back onto lower branches, increasing heat stress. Sunburn typically appears as browning or bleaching on the sun-facing sides of the needles and may lead to needle drop or dieback if the stress is prolonged.  Growers have sheared trees with severe damage and will share updates on their recovery at the end of the summer. 

Cryptomeria Scale 

Eggs are still being found under cryptomeria scale on Fraser Fir in some areas. In most areas, dead crawlers and a couple of live crawlers that have settled down and shielded themselves, so no longer crawlers. Cryptomeria scale has two generations per year in Pennsylvania. If a spray was applied in the last week of June to target first-generation crawlers, growers should begin monitoring for the second generation by the third or fourth week of July. Crawler emergence for the second generation typically begins in late July and can extend through mid-August, depending on weather and site conditions. Crawlers are the most vulnerable stage and look like small, yellowish flattened specks. To detect them, use double-sided tape or black electrical tape (sticky side out) wrapped around twigs or branches in previously infested areas, particularly the undersides of needles where scale populations are highest. Once active crawlers are observed, a well-timed insecticide application can help suppress the population. Products such as horticultural oil, insect growth regulators like buprofezin, or systemic options like dinotefuran are effective when applied during crawler peak. Good coverage is essential, and in some cases, a follow-up application 7 to 10 days later may be warranted to catch extended emergence. Regular scouting in late July will help ensure timely and effective treatment.

Fletcher Scale 

Fletcher scale has been found on arborvitae in Schuylkill County in small numbers. This soft scale insect typically has one generation per year, with crawler emergence occurring in mid to late June. By early July, many crawlers have already settled and begun feeding, making them less susceptible to contact insecticides. Since current populations appear low, treatment may not be necessary unless populations increase or noticeable honeydew and sooty mold begin to appear. Growers should continue to monitor known problem areas by inspecting branch tips for settled nymphs and sticky residue. If management is needed, horticultural oil or insecticidal soap can help suppress young crawlers if applied during peak emergence, while systemic options like imidacloprid may be considered for larger infestations.

Arborvitae Leafminer 

Emerald Green Arborvitae in our scouting areas in Berks and Schuylkill have arborvitae leafminer. Arborvitae leafminer is a small moth whose larvae feed inside the foliage of arborvitae, causing the tips of branches to turn yellow or brown. This damage often looks like winter burn or drought stress, but a closer inspection reveals hollowed-out or papery foliage. If you gently pull apart a browned tip, you might find a small larva or its sawdust-like droppings. In Pennsylvania, adult moths typically emerge in late May to early June. After mating, they lay eggs on the foliage, and the newly hatched larvae quickly tunnel into the leaf tissue, where they remain hidden while feeding. The larvae overwinter inside the plant and resume feeding in early spring. Infestation is often scattered and easy to miss until symptoms are widespread. Growers should scout in late May and June, watching for tip dieback and checking suspect foliage by holding it up to the light to detect internal feeding. For management, removing and destroying heavily infested tips during the dormant season can help reduce the population. Insecticide applications are only effective when timed to adult flight, before larvae bore into the tissue. Products containing spinosad, bifenthrin, or permethrin are commonly used, and growers can monitor adult emergence by tapping foliage to dislodge moths or using yellow sticky traps. Proper timing and thorough coverage are key to control.

Other

Continuing the investigation, but an update to some growers having flagging and shoot dieback on Canaan Fir.  Samples are currently at the Plant Lab, so results are inconclusive. Scouting this week, thrips and springtail were found at the branch collars of shoots that had total dieback. The damage to the branches is not typical of thrip damage, and appears to be an opportunistic infestation of the thrips. Springtails are loving this hot and wet weather, but are merely a nuisance pest. Once again, the extreme heat and rain can cause environmental stresses on trees, especially trees that have been previously stressed.  We will update on this issue once lab results are reported.  If any growers are experiencing this in large numbers, we ask that you contact Kelly Piccioni at keg200@psu.edu. 

Botrytis Blight has been observed in several counties. The combination of tight spacing, recent heat, and heavy rainfall creates ideal conditions for this disease to develop. When planning your cutting this season, consider selectively harvesting or thinning rows to open up the field and improve air movement between trees. This can help reduce future disease pressure and promote better drying conditions for the canopy.

Many mite species thrive in high heat. Warm, dry conditions are especially favorable for spider mites, including those found on evergreens like spruce spider mite or two-spotted spider mite. While spruce spider mites are typically more active during cooler spring and fall weather, hot, dry summers tend to favor warm-season mite species. Heat accelerates their life cycle, leading to faster population growth, especially if natural predators are disrupted. If mite pressure is suspected during hot weather, it's important to scout regularly by tapping foliage over white paper and looking for movement. Early detection is key to avoiding heavy damage.

The IPM Hotline is now accessible for Christmas Tree Scouting Information! Dial 1-800-PENN-IPM (736-6476), option 5 (Christmas Trees) to hear the latest update.

We appreciate the feedback and look forward to more site visits! Contact Kelly Piccioni at keg200@psu.edu to schedule a site visit to your farm. Always rotate products by mode of action and confirm they're labeled for use on Christmas trees in Pennsylvania.