June 17, 2008

Christmas Tree Scouting Report #13 - June 17, 2008

This report is compiled by Sarah Pickel of the PA Department of Agriculture from the scouting recordings of Jim Fogarty and Kyle Halabura of Halabura Tree Farms, and Sandy Gardosik, Karen Najda, and Cathy Thomas of the PA Department of Agriculture.

The crawlers of Cryptomeria Scale have emerged in Dauphin, Northampton, Schuylkill and York Counties on Canaan, Concolor and Fraser Firs.  They can also be found on Douglas Fir and the spruces.  In Schuylkill County, crawlers were first noticed on Monday, at 700 Growing Degree Days.  In York County, the crawling nymphs have begun to settle on the undersides of the needles.   Once the nymphs have settled into one spot, they will begin to form their waxy covering.  To scout for this scale in your fields, look on the lower branches of the trees for a yellow speckling on the top sides of the needles.  Growers can begin their series of two spray treatments the week that they see crawlers emerge.  The second spray can be applied 7 – 10 days after the first spray.  Check your 2008 Insecticides and Miticides sheet in Insecticides & Miticides for PA Christmas Tree Pests for chemical products that can be used for this scale.  Horticultural oil can also be used on these crawlers.  Growers will want to use a super fine oil product that will be less likely to cause foliage burn.  Also, when using oil, growers may want to add a 3rd application to the spray series.

Last week, crawlers of Elongate Hemlock Scale were seen in Adams and York Counties.  A spay series lasting 12 weeks is recommended.  This may consist of 3 sprays, 4 weeks apart or 4 sprays, 3 weeks apart.  Penn State research recommends using Dimethoate.  Other chemicals with trans-laminar abilities will also work.  For the full list of recommend products, check the 2008 Insecticides and Miticides sheet (link above).  Hosts of this scale are true firs, Douglas fir, hemlock and spruces.  Damage caused by this scale can also be found on lower tree branches and resembles cryptomeria damage, but can have a white cast in heavy cases.  This white appearance comes from the shedding of the male scales’ white waxy covering.

Because Cryptomeria and Elongate Hemlock Scales are located on the lower branches of the trees, whatever pesticide growers choose to use, they should be directed toward the lower portion of the tree and at the underside of the branches.  Recently mowed rows will help to ensure that proper coverage is achieved. 

Last week Bagworm larvae were seen feeding on Douglas fir and Arborvitae in Dauphin and Schuylkill Counties.  Bagworms can infest any conifer species.  Growers can still spray for this pest if they did not get to it last week.  Only one spray may be necessary for bagworms.  If control is not achieved at this point in the season, growers can hand pick the bags that these larvae form later in the season.   Just make sure to remove them from the field.

For growers who also grow Arborvitae, juniper, cypress, yew or hemlock, another pest to be scouting for is Fletcher scale.  This soft scale can cause black sooty mold to form on the foliage thanks to the honeydew they secrete.  In Schuylkill County, crawlers were found under the adult scale coverings on Arborvitae.  These nymphs should be emerging sometime this week or next.  A registered insecticide can be used against this crawler stage.

Many growers may be beginning to shear their trees this week, usually starting with pine species.  It may be a good thing for employees to keep a note book close by to record any pest problems they see while they’re out shearing.  While it may be too late to treat for many of the pests this season, often a fall treatment is possible.  Employees could be recording useful information about pests that can be dealt with in the fall.