The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
o t-t- L.
o /2- Phytotoxicity Evaluations of Dycarb on Selected-F1-4a:g"4 ..
2 C;n!ral Science
L. S. Osborne and A. R. Chase Library
University of Florida, IFAS
Agricultural Research and Education Center ApkP 1 7 ri
AREC-Apopka Research Report, RH-86-12
I ;, t t of Florida
One of the most critical needs for the ornamental foliage-4-ds-try=4-'
a safe and reliable method of controlling mealybugs. Dycarb (bendiocarb)
is one of the most effective materials registered for mealybug control.
The label recommends that 12 to 20 ounces of product (by weight) be mixed
with 100 gallons of water and then sprayed to "glisten" for the control of
citrus mealybugs. The labeled rates of this pesticide range from 12-40
oz/100 gal for the control of certain pests including aphids, mites and
some scale insects. This pesticide is not thought to have systemic
activity, but it appears to be as effective as other pesticides that have
systemic activity. Because of reports that Epipremnum aureum (Linden &
Andre') Bunt. (Golden pothos) and other plants have been damaged by sprays
and drenches of this material, phytotoxicity studies were initiated. In
the following studies, foliar sprays and a soil drench were tested for
phytotoxicity on a range of foliage plants. The drench treatment was
included to simulate excessive runoff from a spray application; a practice
that has been implicated in many of the most severe cases of phytotoxicity
The following plants were used for phytotoxicity studies:
1. Aglaonema commutatum Schott 'Silver Queen'
2. Aphelandra squarrosa Nees 'Dania' (Zebra plant)
3. Brassaia actinophylla Endl. (Schefflera)
4. Chamaedorea elegans Mart. (Neanthe bella palm)
5. Cissus rhombifolia Vahl 'Ellen Danica' (Grape ivy)
6. Codiaeum variegatum (L.) Blume 'Norma' (Croton)
7. Dieffenbachia maculata (Lodd.) G. Don 'Perfection'
8. Epipremnum aureum (Linden & Andre') Bunt. (Golden pothos)
9. Ficus benjamin L. (Weeping fig)
10. F-icus retusa 'Nitida' Thunb.
11. Hedera helix L. 'Curly Locks' (English ivy)
12. Hoya carnosa (L.f.) R. Br. (Wax plant)
13. Nephrolepis exaltata (L.) Schott. 'Fluffy Ruffle' (Boston fern)
14. Philodendron scandens subsp. oxycardium (Schott) Bunt.
15. Spathiphyllum 'Bennett'
1This research was partially supported by grants from the Florida Foliage
2Association and Mallinokrodt, Inc.
Associate Professor of Entomology and Associate Professor of Plant
Pathology, respectively, Agricultural Research and Education Center, 2807
Binion Road,'Apopka, FL 32703.
Rooted cuttings or seedlings of 13 plant species (Table 1) were
transplanted into 4-inch standard square pots containing Vergro potting mix
(Verlite Co. Tampa, FL 35680). Tests were conducted on raised benches in
the greenhouse at AREC-Apopka. Temperatures were maintained between 65 and
86F. Ten plants from each species were allocated to each of 5 treatments:
1) Control water spray; 2) Drench with 50 ml of 15 oz Dycarb/100 gal;
3) Spray to glisten with 15 oz Dycarb/100 gal; 4) Spray to glisten with 30
oz Dycarb/100 gal; 5) Spray to glisten with 45 oz Dycarb/100. Sprays were
applied with a 1 gal hand-sprayer (Flat fan 8002 nozzle) maintained at 40
psi. Each treatment was applied three times at weekly intervals.
Applications were made in the morning before each application with the
final evaluation taking place 2 weeks after the last spray. Epipremnum
aureum, Ficus benjamin, and Ficus retusa 'Nitida' were used to test
various drench rates for phytotoxicity. The rates tested were 0,2,4,8 oz
Dycarb/100 gal. The damage rating scale used was: 0 = no phytotoxicity; 1
= very slight; 2 = slight; 3 = moderate; 4 = severe; 5 = very severe.
Phytotoxicity was noted on all plants sprayed with Dycarb except on
Philodendron scandens subsp. oxycardium, Chamaedorea elegans and Hoya
carnosa (Table 1). Damage was evident after the first application on the
most sensitive plant species such as Cissus rhombifolia. The symptoms
which developed on most plant species were necrotic spots, tip necrosis,
leaf cupping, and leaf distortion (Table 2). Symptom severity and speed
with which they developed increased with increased rates of Dycarb. Plants
drenched with Dycarb developed the most severe damage and symptoms appeared
sooner than in any spray treatments. Drenches applied at low rates to
Epipremnum aureum and Ficus sp. caused no observable phytotoxicity.
The results of these studies are disturbing because Dycarb is one of
the most effective pesticides for control of mealybugs and scales and
because nine of the plants sensitive to Dycarb are among the 120 plants
presently listed on the Dycarb label. Two of the most sensitive plants
tested, Epipremnum aureum and Ficus benjamin exhibited no sensitivity to
drench rates up to 8 oz. There are indications that lower rates of this
chemical are effective in the control of mealybugs. Therefore, there is
the potential for using lower rates on sensitive plants. Secondly, greater
intervals between applications may allow good control of the pest insects
and minimize phytotoxicity.
Table 1. Phytotoxicity of Dycarb drenches and sprays to foliage plants.
Treatment (oz Dycarb/100 gal)
0 15 15 30 45
Aglaonema commutatum O.Oa 1.2 1.3 1.8 2.6
Aphelandra squarrosa 0.0 5.0 3.2 3.1 3.9
Brassaia actinophylla 0.0 5.0 3.2 4.5 5.5
Chamaedorea elegans 0.0 0.0 0.0 0.0 0.0
Cissus rhombifolia 0.0 5.0 3.2 5.0 5.0
Codiaeum variegatum 0.0 4.8 1.2 2.0 5.0
Dieffenbachia maculata 0.4 5.0 2.1 3.1 3.9
Ficus benjamin 0.0 5.0 1.4 2.8 5.0
Hedera helix 0.0 4.0 2.2 2.5 2.9
Hoya carnosa 0.0 1.0 0.0 0.0 0.0
Nephrolepis exaltata 0.0 5.0 3.4 3.4 5.0
Philodendron scandens oxycardium 0.0 0.0 0.0 0.0 0.0
Spathiphyl lum 0.0 2.0 3.0 2.7 3.2
aThe damage rating scale used was: 0 = no phytotoxicity; 1 = very slight;
2 = slight; 3 = moderate; 4 = severe; 5 = very severe. These ratings are
from the final evaluation taken two weeks after the last application of
Table 2. Phytotoxicity symptoms observed on selected host plants as a
result of treating plants with Dycarb drenches or sprays.
Philodendron scandens oxycardium
Necrotic spots, leaf cupping,
& deformity, stunting
Margihal & tip necrosis,
Necrotic spots, leaf deformit
Necrotic spots, leaf cupping,
Necrotic spots, tip necrosis
Leaf cupping, necrotic spots,