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Mites on Conifers
 ( Ophiostoma novo-ulmi )
Spider mites infest a variety of conifer species including pines, spruce, hemlocks, arborvitaes and others.  The mites pierce and suck nutrients from conifer needles. Spider mites are so tiny that the easiest way to diagnose infestation is to take a twig sample from your conifer and beat it against a white piece of paper.  Spider mites appear as moving brown specks on the paper. Spider mites create webbing at the base of needles and branches.

 

SYMPTOMS:
Needles will become mottled in color.  This will progress into needle discoloration and in severe infestations, needle loss.

PHOTOS:

A and B show adult spider mites on spruce.  C, D, and E show the symptoms of mite infestation on spruce.  Note the webbing in photo D.

Photos C, D, and E taken by John A. Weidhass, Virginia Polytechnic Institute and State University, www.forestryimages.org.

WHAT TO DO:
WHEN TO DO IT:
WHAT WILL HAPPEN:

Arborjet is working on the registration of a new insecticide for trunk Micro-infusion™ using the Tree I.V.  This new insecticide will be mixable with Arborjet’s micro-elements including MIN-jet IRON, PALM-jet, and ROOT-jet.  The Tree I.V. Micro-infusionTM system with the Arborjet Technology is the recommended trunk injection procedure for use in conifers. 

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Generally, the best seasons for micro-infusion™ are fall and spring. Uptake occurs when trees are transpiring. The environmental conditions that favor uptake are moderate temperatures, adequate soil moisture, and high humidity.  Soil temperature should be above 40 degrees for micro-infusion™.  Tree health will influence uptake time.  Generally, hot weather or dry soil conditions will result in a reduced rate of uptake.  If treating trees in the summer, micro-infuse in the morning for the quickest uptake. A dying tree is a poor candidate for treatment.  It is the responsibility of the arborist or tree custodian to assess tree health and its potential for recovery before undertaking treatment. 

 

Spider Mites prefer hot and dry conditions and infestation usually becomes an issue in the summer months. Arborjet recommends a program of monitoring during the summer.  In other words, keep one eye on the trees and another eye on the weather.  For fastest uptake rate, early morning is the best time to inject in the summer months. Uptake rates will be fastest early mornings during the coolest part of the day. If the infestation is present, AVA-jet can be injected for quick kill of mites.

This new injectable insecticide will be Micro-infused into the tree using the Tree I.V.  will provide a quick kill of the mites present.

PHOTOS:

Healthy Blue Spruce and Healthy Ponderosa Pine taken by: Dave Powell USDA Forest Service

E