Mites Reference Page
Top: Crops: Mint: Mites:
Two Spotted Spider Mite in
Mint Reference Page
Mint—Spider
mites
Twospotted spider mite Tetranychus
urticae ID photos: 
fact page (pdf):
Strawberry spider mite T. atlanticus
fact page (pdf):
Strawberry spider mite T. atlanticus
Pest description and crop damage
Spider mite adults are small, eight-legged, spiderlike animals associated
with webbing and round eggs on the undersides of leaves. They are pale green,
yellowish to reddish, with two large, dark spots on each side of their bodies.
They suck plant juices, causing
leaves to yellow, bronze, dry, and fall under heavy infestations. They reduce
oil yield and probably quality.
Biology and life history
Mites overwinter as mature females found at the bases of mint stems and
underground. In spring, feeding begins on new growth soon after emergence
from soil. Populations are delayed a few weeks in fields flamed for wilt in
the fall and/or rust in the spring.
Females lay eggs associated with
silk webbing. Egg to adult may take as little as 14 days during the hot part
of summer. There are multiple generations each year.
Scouting and thresholds Sequential sampling procedures are given in PNW 182.Average numbers of mites per leaf are determined throughout a field on a weekly basis. Take 45 leaf samples (3 leaves per stem, 15 stems per site), and use the presence or absence of mites on leaves to estimate a mean number of mites per leaf at a site in a field. Stable and increasing populations of spider mites beginning at levels of 5 mites per leaf can reduce oil yields if not controlled.
Management—cultural controls
Fall plowing and fall and spring
flaming tend to delay by 3 to 4 weeks spider mite buildup early in the season.
Management—biological controls
Predator mites naturally occuring
in the field as well as those bought from suppliers and released into fields
early in the season can maintain spider mite levels sufficiently low to
avoid miticide applications.
Management—chemical control
1. M-Pede (potassium salts of
fatty acids) at 2% solution; see label for gal/a. PHI zero days.
2. Kelthane MF at 0.9 to 1.25
lb ai/a. PHI 30 days. Do not make more than one application per crop per
season. Do not feed treated hay or spent hay to livestock. Very toxic to
predator mites.
3. Dicofol 4 E at 1 lb ai/a.
PHI 30 days. Same restrictions as for Kelthane.
4. Omite at 1.5 to 2.25 lb ai/a
or Comite at 1.6 to 2 lb ai/a. PHI 14 days for each. Do not make more
than a total of two applications (either or both products combined) per
year. Ground and aerial applications are allowed. Do not feed treated mint
to livestock.
5. Metasystox-R at 0.75 lb ai/a.
PHI 14 days. Two applications allowed per year. Label allows chemigation.
6. Malathion at 0.9 lb ai/a.
PHI 7 days.
Note: Use of carbamate and some OP insecticides may stimulate or increase spider mite populations by killing predator mites or even stimulating spider mite reproduction. Certain miticides, even though they initially control spider mites, may result in a subsequent rapid increase in numbers due to the effect on predator mites that contribute to biological control.
Utility of Metasystox-R and malathion
as miticides has diminished through the years with development of tolerance
and/or resistance in some mite populations.
Source: 2003 PNW Insect Management Handbook
- Integrated Pest Management Information:
-
Two Spotted Spider Mite Management
May, 2003-jn