PROGRESS REPORT – 2002
TITLE: Mite Management in Nurseries and Production Fields
NAME: Kenneth A. Sorensen, Principal Investigator, Department of Entomology, North
Carolina State University, Box 7626, Raleigh, North Carolina 27695-7626
OBJECTIVES:
1. To determine source and species of mites on strawberries.
2. To evaluate miticides and predatory mites in plant nurseries.
3. To encourage mite management adoption.
JUSTIFICATION:
North Carolina State University Plant Disease and Insect Clinic records continue to
document the importance of mites on strawberries. Grower reports and observations
support problems with mites and their management. Most growers reported at preplant
meetings that they had mites in 2002. They also used up to 6 applications with most
making at least 2 applications. Only a very few use predatory mites. Also plant nurseries
remain unaware or do not report their mite management strategies and tactics.
METHODOLOGIES:
Mites collected from plant nurseries and grower fields were identified in the plant disease
and insect clinic. Growers were encouraged to submit tips and plugs as well as mite
samples for identification. Miticides were compared in grower’s fields and new miticides
were introduced into production and resistance management systems. Growers were
requested to obtain spray records from plant production nurseries. Predatory mites were
also released into grower fields to evaluate method of application and various rates.
Predatory mites were also introduced into plant production nurseries.
RESULTS:
Mite identifications indicated the predominant mite species to be the two-spotted spider
mite. Indications remain that mites come on plants and move into plantings from
adjacent vegetation and weed hosts. Lack of rotation of land and planting continually in
the same field sites promotes mite establishment. Resistance to miticides also exists as a
result of limited crop, land and class of miticides used and rotated. Predatory mite
establishment was difficult in the plant nursery due to excessive misting. Spider mites
were present in one shipment to Florida. The subsample in North Carolina contained no
plant feeding or predatory mites. A large planting will be tracked in Florida as well as
subsample small plantings in Florida and North Carolina.