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J.C. Stephenson
Mites
continue to be one of the major pest groups on ornamental crops.
Chemicals remain the preferred method of control in nursery situations.
Due to the ornamental horticulture industry being minor in comparison
to other areas of agriculture in the pesticide market, new materials
are slow to be developed. This along with a reluctance of companies
to re-register current products makes chemical control challenging.
The Southern Red Mite, Oligonychus ilicius, is
a common pest on ericaceous plants, primarily azaleas, and camellias.
This mite occurs in greatest abundance during the cooler months
of the year. Feeding produces a bronze or brownish plant appearance
followed by leaf drop, which is more pronounced with cooler temperatures.
METHODS
This efficacy test was a recommended rate evaluation of foliar-applied
miticides with a current outdoor nursery label. Infested Robin
Hill ‘Redmond’ azaleas growing in trade gallon containers with an
amended pine bark-peat moss medium were used in this study. Treatments
consisted of a single foliar-applied spray to all leaf surfaces
to the point of runoff with the materials and rates listed in
the table. Plants were grown in full sun and irrigated with overhead
impact sprinklers as needed. Live mite counts were recorded at
7, 14, and 28 days after treatment (DAT). Eggs were not counted.
A Llanfair Orchard Leaf Brushing Machine was used to brush mites
from three, 4-inch terminal shoots per plant onto a biocular
microscope counting disc with grid.
|
Live Mite Counts from
Brushed Azalea Terminal Shoots |
|
Treatment1 |
Rate 100 gallons |
Live mites/ terminal
shoots2 |
|
|
7 DAT |
14 DAT |
28 DAT |
|
Kelthane T/O |
16 oz |
25.5 |
47.5 |
43.3 |
|
Sunspray 6E |
128 fl oz |
20.0 |
51.0 |
50.5 |
|
Orthene TTO 75SP |
10.7 oz |
60.3 |
109.3 |
30.3 |
|
Tame 2.4EC |
16 fl oz |
64.5 |
106.5 |
42.3 |
|
Avid 0.15EC |
4 fl oz |
61.5 |
97.5 |
60.8 |
|
Hexygon 50WP |
2 oz |
28.0 |
8.8 |
4.3 |
|
Talstar F |
38.4 fl oz |
44.5 |
88.3 |
69.0 |
|
Untreated |
-- |
87.5 |
125.5 |
50.8 |
1Treatment
application March 24, 1998.
2Mite counts are a mean of four plants. |
RESULTS
At 7 DAT, plants treated with Hexygon 50WP, Kelthane T/O, Sunspray
6E, or Talstar F had fewer mites than the untreated check. At
14 DAT, similar trends were observed, except Talstar F failed
to provide significant control. Plants treated with Hexygon 50WP,
an ovacide/larvicide, had considerably lower mite numbers than
any other treatment. At the last evaluation (28 DAT), Hexygon
50WP was the only chemical to provide significant control. Mites
counted at this time on plants treated with Hexagon 50WP were
almost all adult females.
In summary, this test indicates that a single application of
the miticides tested is not sufficient to eradicate a preexisting
infestation of Southern Red Mites. Kelthane T/O, Sunspray 6E,
and Hexygon 50WP appear to be the most effective treatments with
Hexygon 50WP providing the longest control.
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