Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES
Fletcher Scale
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Identification.
In the
past, Lecanium (Lecanium fletcheri) spp. of scales found on Taxus have been assumed to be L. fletcheri.
However, Lecanium fletcheri is reported to have only one
generation per year; while a common Lecanium scale found on Taxus
plants has two generations per year. In some places in Michigan
and nearby a Lecanium spp. on Taxus
has one generation per year.
Host Plants.
All Taxus species. Also, a similar scale is found
on arborvitae.
Life Cycle.
The
first generation crawlers emerge from June 10-30, settle on the needles and
twigs and feed until August when they are nearly mature. A second generation of
crawlers emerges in September. These young scales will mature in May.
Scouting.
Look
for small (3-5 mm), brown hemispherical scales on inner foliage and twigs of Taxus plants. Young immature scales are even smaller, flat
and clear.
Management.
Only
apply insecticides to Taxus if the scale population
is too high (greater than 15% of samples. are infested). Parasites and
predators regulate scale populations. Parasites are most effective along field
borders. Biological control has good potential in production nurseries as well. .
Apply.
Dursban or Talstar in early October if
scales can be found on more than one of 10 leaf samples examined in August. If
an unacceptable level of live scale is still found in April or early May,
another application can be made at that time. Early July is the next best time
to apply an insecticide. However, because of a second generation, a July spray
without an October spray is risky.
Information obtained through Michigan State Extension,
Landscape CAT Alert 61094006
Insect
and Disease Fact Sheet Compliments of New Century
1-877-79TREES