Christmas tree IPM update 5.27.20

Happy summer for a few days anyway.  Sure sped up the plants (and weeds!) in my garden.

 

First report of gypsy moth larvae that I have heard.  Get ‘em while they are small!

 

Even though I could use a little more breeze today, it isn’t helpful when spraying pesticides. Rutgers has advice on reducing the potential for drift when applying pesticides.

https://plant-pest-advisory.rutgers.edu/10-best-management-practices-to-avoid-herbicide-drift/

 

And thinking of herbicides, some paraquat labels now require EPA training. Check the label and if it is required, you can find it here:

https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators

Don’t forget – Paraquat is a restricted use pesticide so you must be a certified pesticide applicator to use it.

 

I had 2 emails about root aphids this spring, so I thought I would give everyone the information. Root aphids are small and white and live on the roots of the trees (bet you saw that coming).  They usually don’t cause much trouble but with high populations on small trees, they can. (The threshold I saw was 100 on a seedling).  Since they feed on the fine feeder roots, effects of drought or too much water could be exacerbated.

 

You might see ant activity in the same area.

 

Flagship (thiamethoxam) 25WG and 0.22G are labeled for aphids (25WG) specifically for root aphids) and soil application.

I wouldn’t treat everything just the young trees in the area with the issue.

 

I don’t know that it is this species for sure but some information….

* section updated 6/2009 by James Young A Conifer Root Aphid, Prociphilus americanus (Walker), in True Fir Jack DeAngelis Department of Entomology, OSU 6/19/98

 

A few years ago some Christmas tree growers in Washington state found an aphid feeding on the roots of young true fir (Abies sp.) trees that were stunted, yellowed and in obvious decline. The aphid was subsequently identified as Prociphilus americanus (Walker), a conifer root aphid (no common name). While reported earlier feeding on the roots of true fir, often attended by ants (Lazius sp.), the aphid has never been reported to injure its host tree. In the last 2 years some Oregon growers of true fir have reported this aphid as well, again associated with young trees showing signs of stress (stunted and yellow tops, reduced root development). In fields where the infested trees are found one can also find apparently healthy trees (normal growth and color) also with aphids feeding on their roots, although usually at lower density.

APHID FEEDING. Aphids feed by piercing host tissue (leaf, stem or root) and sucking plant sap through tube-like mouthparts. While removing plant sap, aphids may also inject toxins, plant growth regulators or pathogens along with saliva to aid feeding. Feeding may therefore cause abnormal growth, disease and even terminal dieback. Aphids excrete large amounts of honeydew which is essentially unprocessed plant sap. Many insects use honeydew and therefore are attracted to these colonies.

LIFE HISTORY. Like some other aphids, P. americanus has a life history that alternates between two different host plants. The primary host harbors the sexually reproducing form while the secondary host harbors an asexually (parthenogenetic) reproducing form. For P. americanus the primary host is ash (Fraxinus sp.). Here it forms dark brown to black colonies in curled terminal new growth in early spring. These colonies may form on suckers or at the base of the tree as well. During late April through early June a winged form leaves the primary host and searches out its secondary host, true fir. Here the aphid feeds on the roots and reproduces asexually during the summer months. These wax-covered colonies may be visited by ants collecting honeydew. Honeydew-collecting ants sometimes defend their honeydew providers and may even move aphids around. During late August through October a winged form returns to ash to continue the sexual cycle. The asexual form may continue to develop on fir throughout the year. Therefore, eliminating the ash, the primary host, or even controlling the winged aphid is not likely to be an effective control for P.americanus.