Insecticidal Controlled Atmosphere for Management of Sweetpotato Whitefly Progress Report — September 1994
Date August 22, 1994
Title of Project Insecticidal Controlled Atmosphere for Management of Silverleaf Whitefly
Institution where work is being conducted University of Massachusetts-Amherst
Amount of Endowment Grant $ 6,000
Covering Period Jan. 94 to Dec. 94
Anticipated Date of Project Completion/Final Report Dec. 95
Individual(s) conducting Project:
(List Project Leader First)
Susan S. Han - Title Assistant Professor
Telephone Number (413) 545-5228
Insecticidal Controlled Atmosphere for Management of Silverleaf Whitefly
Susan S. Han
University of Massachusetts
- A. Project Objectives:
- We have previously reported that reduced-O2 controlled atmospheres (CA) effectively control various stages of
greenhouse whitefly (Trialeurodes vaporarium) as well as the adult stage of silverleaf whitefly (see previous progress
reports). This method leaves no chemical residues, is safe to handle, and is environmentally safe. The objectives of this
study were to test (1) the effectiveness of short-term reduced 02 controlled atmospheres on various stages of the more
damaging silverleaf whitefly; and (2) the effects of controlled atmospheres on different developmental stages of
poinsettias.
leaves were collected from the greenhouse at the University of Massachusetts at Amherst. Leaves were then placed in
vials containing water and treated with a constant flow of air or with factory-mixed N2 (containing =2ppm O2).
Following the gas treatments, leaves were maintained in a 20′C growth chamber with 12 hour of light (17 ¬± 3 uMOL*s-1
m-2) provided by cool-white fluorescent lamps. Results showed that a 4-hr reduced-O2 treatment resulted in limited
control of the eggs, nymphs and pupae of silverleaf whitefly (Fig. 1). In comparison, an 8-hr treatment prevented 20%
of the eggs and pupae from further
development and killed 80% of the
nymphs.
no differences in growth and
development of rooted cuttings
treated with air or reduced O2 for 8 hr
at 20′C. In our present studies, we
have found that repeated treatment of
rooted cuttings (up to 3 times), did
not affect the growth of the cuttings
(data not shown). In addition,
unrooted cuttings of 6 cultivars were
treated to determine if the reduced-O2
treatment would affect the rooting
potential. Treatments were also
performed on the flowering stage in order to explore the possibility of using this technique to quarantine saleable
plants. Four weeks after the CA treatment, no differences in root or vegetative growth were detected between unrooted
cuttings treated with air or with low O2 (data not shown). Considerable differences, however, existed between cultivars
when plants were treated at the flowering stage (Table 1). Symptoms of phytotoxicity, evident as areas of discoloration
on the bracts, typically appeared 24 to 48 hours after the treatment. Of the six cultivars tested, ‘Annette Hegg’ was
most sensitive to the treatment followed
by ‘Freedom’. Minimal phytotoxicity
occurred on the other cultivars.
Experiments conducted to date thus
indicate that low-O2 CA can be used for
disinfestation of both greenhouse and
silverleaf whitefly on unrooted and rooted
cuttings of poinsettias. However,
selection of plants for their tolerance to
the low-O2 treatment would be necessary
if the technique is to be employed on
fully-colored plants.
low-O2 treatment. The degree of phytotoxicity was visually estimated, at
10% increments. as the percentage of total bract area with discoloration.
Data were collected 2 days after the treatment and are means +/- SE.
| Cultivar | Phytotoxicity | Cultivar | Phytotoxicity |
| (%)^z | (%)^z | ||
| Celebrate II | 0.1c^y | Pink Peppermint | 0.3c |
| Freedom | 7.Ob | Supjibi | 4.1c |
| Hegg. Red | 31.4a | V-14 Glory | 1.1c |
| ^z Percentage of area with symptoms of phytotoxicity. | |||
| ^y Means separated by Duncan’s multiple test, P=0.05. | |||
- C. Anticipated Benefits for Floral Industry:
- The proposed method of
reduced-O2 insecticidal CA would provide the greenhouse industry with an environmentally-safe means of controlling
the spread of whitefly through infested plant material. The integration of this technique with an IPM program would
drastically reduce the use of hazardous pesticides, and would increase profitability to the greenhouse industry by
reducing pesticide costs and increasing the quality of the product.
