Plant Diagnostic Lab — Page 5 — Plant & Pest Advisory

March 23, 2023 Steven K. Rettke

Some Early Spring Insect Pests of Christmas Trees

The accumulation of heat units (Growing Degree Days (GDD) will soon begin to increase rapidly in New Jersey as we approach the early weeks of April. If past histories or present-day monitoring indicate the need for interventions, then the best control windows for numerous insect/mite pests are beginning to occur. The following is an incomplete listing of a handful of some of our early-season Christmas tree insect pests that may need to be scouted & possibly controlled. Those included in this blog are the European pine sawfly, Eastern spruce gall adelgid, Cooley spruce gall adelgid, Nantucket pine tip moth, Pales weevil, White pine aphid, & Pine bark adelgid.

After many years, these slow growing Colorado blue spruce trees are close to reaching their peak selling growth stage as Christmas trees. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

March 13, 2023 Steven K. Rettke

White Pine Weevil: Overwintering Adults Become Active in March & April

Many arborists & landscapers often find it difficult to prevent white pine weevil pests (Pissodes strobi), because they are typically applying fertilizer & dormant oil treatments during the control window. In the state of NJ, the control window against feeding white pine weevil adults occurs in March & April. Adults over-winter in the duff beneath trees. The WPW adults will often crawl or sometimes fly to the top terminal leaders of pine, spruce, or Douglas-fir trees. Eastern white pine & Norway spruce species are the most severely attacked & the death of the terminal leaders of these trees will often occur.

Treatment timing is critical with this pest and controlling the adult female before egg laying is necessary. Apply preventative sprays (e.g., pyrethroids) only to the terminal leaders during this time. Before mating & egg laying, adults will feed by chewing holes within the central leader & cause a characteristic pitch flow that becomes white in color when dry. Then females will lay eggs in new cut-out holes within the top 12 inches of the leader just below the terminal bud. This blog will describe with the help of photographs the 7-stage lifecycle of this native weevil borer. Control & management options will also be provided.

White pine weevil adults are about 1/4+ inch long & have a long snout with two white spots on back of wing covers. Adults feed at terminal leaders during March & April. Most eggs will then be laid during April & May. (Photo Credit: Michigan State University)

Severe white pine weevil infestations to terminal leaders can destroy two or more years worth of growth to pine, spruce, & Douglas-fir trees. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

January 26, 2023 Steven K. Rettke

Nostoc in Nurseries: Herbicides to Control the Slippery Slime Threat

Nostoc is a cyanobacterium and is one of the oldest organisms on earth (over 3.5 billion years). It is a primitive growth, like algae, moss, and liverwort. Many years ago, it was incorrectly identified as blue-green algae. Nostoc has no roots, no vascular tissues & is not a plant but it is photosynthetic. It can be found growing within gravel, stones, limestone chips, granite, saturated soils & on-ground cloth within container nurseries. It can tolerate long periods of desiccation but requires plentiful amounts of water for establishment. This cyanobacterium growth can become common & persistent at certain nursery/greenhouse sites where long-term overhead irrigation is done.

Nostoc growing in front of container bay opening. The opening allowed the overhead irrigation to saturate the soil/gravel at entrance. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Nostoc growing on ground cloth within a nursery container bay. Creates a serious slipping hazard for nursery personnel. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

Nostoc is not toxic & does not directly compete with nursery/greenhouse crops or landscape plants, but it can harbor fungus gnats & snails. Nostoc first became a growing concern in nurseries approximately 30 years ago. Slipping hazards are the primary threat this organism poses to nursery & greenhouse personnel. It forms gelatinous masses composed of filaments linked together by protective jelly-like coverings. This creates a surface as slick as wet ice. Nostoc can occasionally be found growing within turf or landscape settings but is not common.

This blog will show with photographic images how Nostoc can be identified & will also review available control options.

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Filed Under: Nursery, Plant Diagnostic Lab

October 12, 2022 Steven K. Rettke

Autumn Pest Review: Soft Scales, Leafminers, Aphids, Mites & Adelgids

AUTUMN PEST REVIEW: Although the season is beginning to wind-down, there are still a number of insect & mite pests that require scouting during the fall weeks. The pests discussed in this blog include soft scale nymphs, boxwood leafminers, white pine aphids, spruce spider mites, southern red spider mites, hemlock rust mites, eastern spruce gall adelgids & hemlock woolly adelgids. The use of low %-rates of horticultural oils this fall can be especially valuable against controlling many of these pests.

SOFT SCALE NYMPH MIGRATIONS: Most soft scale species (exceptions include magnolia, tuliptree, and globose) have 1st instar nymphs that spend July and August feeding along veins on the undersides of leaves of their deciduous host (the use of a hand lens may be needed). During the weeks of late summer and early fall, these nymphs migrate off the leaves onto woody stem tissue and molt into the overwintering 2nd instar stage. The size of the nymphs increases 3-times after molting and their presence is usually observable even without magnification (they can be as large as lenticels). Typically, overwintering soft-scale nymphs have a dark coloration, to help absorb sunlight and maintain body warmth.

European elm 1st-instar nymphs settled along the main vein underneath elm leaf. During the early weeks of fall they migrate from leaves onto the bark to overwinter. (Photo Credit: Cornell University)

October 3, 2022 Steven K. Rettke

Spruce Spider Mites: A Key Cool Season Mite Pest

Spruce spider mite species (Oligonychus ununguis) are found in Christmas tree farms as well as landscapes & nurseries in the New Jersey region. The late weeks of September & early weeks of October are transition periods for this cool season mite. With the arrival of autumn & cooler temperatures, the spruce spider mites begin to “wake up” from their summer dormancy & will be observed feeding & laying eggs. Observations this past week in Christmas tree farms have shown increased activities of the spruce spider mites. This spider mite species will feed exclusively on various conifers including spruce, fir, Douglas-fir, hemlock, Cryptomeria, arborvitae, false-cypress, pine, & juniper.

This Christmas tree farm is an ideal site for potential spruce spider mite infestations. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

September 28, 2022 Melissa Bravo

Driving into High Path Avian Influenza Quarantine Zones in PA. Know the rules.

September 28, 2022. There has been a significant area placed under quarantine in Lancaster County East Lampeter Township. Read below to refresh on the rules when driving into a HighPath Quarantine Area.

For those traveling to Lancaster County for equipment, supplies and feed, be aware of the 20km zone that includes areas near Ephrata, New Holland, Gap, Quarryville, and Manhiem locations; and the 10km zone that includes Lancaster and Stroudsburg areas; and the epic-center 3km zone.

Secretary Fisher has sent along the PADLS quarantine map to Ag Agents, you can contact your Ag agent for a copy of the map. The map when it is updated, can also be found at: https://padeptag.maps.arcgis.com/apps/webappviewer/index.html?id=a9066a3d68a443a08043766cb84bf4ae

“Migration season is underway and the virus is obviously in the environment. Please ensure all your poultry caretakers are practicing their best biosecurity, especially regarding using clean and dedicated footwear when entering the poultry houses.”- PADLS

Earlier this year….

As of 5/11/2022: The PA Department of Agriculture, via communications from Kevin D. Brightbill, DVM | State Veterinarian | Director is requesting continued compliance of the agriculture industry at large with the General Quarantine Order; Virus Control for Highly Pathogenic Avian Influenza Poultry, Poultry Litter, Conveyances, Feed, Refuse, Containers and Material Standards for the existing control zones established in Lancaster and Berks County.

There is an Interstate (existing or carried on between states) and General Quarantine Order in effect in Pennsylvania; specific to Virus Control for Highly Pathogenic Avian Influenza Vehicle, Container and Material Standards that is critical to abide by to prevent introduction of High Path. The specifics of “following the conditions and requirements of this Interstate and General Quarantine Order Order related to vehicles and products being transported including other domestic animals” can be found in the Pennsylvania Bulletin Volume 52 Issue 18 52 Pa.B. 2597 General Quarantine Order; Virus Control for Highly Pathogenic Avian Influenza Poultry, Poultry Litter, Conveyances, Feed, Refuse, Containers and Material Standards.

https://www.pacodeandbulletin.gov/Display/pabull?file=/secure/pabulletin/data/vol52/52-18/637.html

New Jersey agriculture producers, please be mindful of these efforts as you travel in and out of the location of the current quarantine area (10 kilometer radius) as shown in the PA DEPT AG MAP https://padeptag.maps.arcgis.com/apps/webappviewer/index.html?id=a9066a3d68a443a08043766cb84bf4ae.

Elsewhere in the region, please consider how you can help reduce potential spread as you travel to and from agriculture service centers in the region.

To stay up to date on the quarantine restrictions and recommendations related to disinfecting transportation vehicles and conveyances, please join the weekly Pennsylvania High Path Avian Influenza call by contacting Jennifer Reed – Harry, Penn Ag Industries at Email: jrharry@pennag.com

NJ Poultry Producers. To participate in the next South-Jersey Poultry Association monthly webinar with guest veterinarians from either USDA or state agencies, contact Melissa Bravo at the Salem County Extension Office.