Evaluation of Elevated CO2 for Control of Greenhouse Whiteflies on Poinsettias During Transit Progress Report — march 1993
Date Feb. 23, 1993
Title of Project Evaluation of Elevated CO2 for control of Greenhouse Whitefly on Poinsettias
Institution where work is being conducted University of Massachusetts at Amherst
Amount of Endowment Grant $ 7, 000
Covering Period Jan. 93 to Dec. 93
Anticipated Date of Project Completion/Final Report June 1995
Individual(s) Conducting Project:
(List Project Leader First)
Dr. Susan S. Han - Title Assistant Professor
Telephone Number 413-545-5228
Jennifer Nobel - Title Technical support
Evaluation of Elevated CO2 for control of Greenhouse Whitefly on Poinsettias
Susan S. Han and Jennifer Nobel
University of Massachusetts
- A. Project Objectives:
- Whitefly infestation on poinsettias arises frequently from cuttings that wereinfested at the start of the season. The main objective of this project is to find a
means to disinfest the cuttings, thereby, preventing the outbreaks of whitefly later in
the growing season. Use of controlled atmospheres (CA) with O2 levels below 1%
and/or CO2 levels higher than 50% have proved effective in killing various species of
insects on edible commodities, thus may be referred to as ‘insecticidal controlled
atmosphere’. These treatments leave no chemical residues, are safe to handle, and
are environmentally safe. The objectives of this study are to test (1) the effectiveness
of short-term insecticidal controlled atmospheres in eradicating whitefly; and (2) the
effects of these treatments on the growth and development of poinsettias.
- B. Results to Date:
- We had previously reported (Sept. 1992 Progress Report) that adult greenhousewhitefly (Trialeurodes vaporarium) are highly susceptible to elevated CO2 (25% or
50%) and had proposed to continue testing the efficacy of this technique for whitefly
disinfestation. However, we, subsequently found that eggs and pupae are more
resistant than adults to the elevated CO2 and that the same treatment had little effect
on these stages. Further investigation revealed that low-oxygen treatment has a
greater effect on whitefly and we are currently focusing our effort on the use of no or
low-O2 CA. Anoxic conditions, created by venting 100% nitrogen, resulted in mortality
of all stages of greenhouse whitefly. All adults were killed with 2 hr of anoxic
treatment. Sixty percent and 30% of the adult whitefly exposed to 1/2hr and 1 hr of
anoxia revived after being transferred to the atmospheric conditions. Those reviving,
however, do not remain vital for long and were dead in less than 24 hr. Other stages
of greenhouse whitefly require a longer treatment time where 4 hr and 8 hr of anoxia
killed 90% and 80% of the nymphs and eggs, respectively. Preliminary trials also
indicated that 8 hr of anoxia prevent emergence of most of the pupae into adults. We
are currently beginning to test the effect of this technique on sweet potato whitefly
(or silverleaf whitefly). Results to date indicate that the use of no or low O2
atmospheres is thus a promising method for eliminating whitefly from plant materials.
- C. Anticipated Benefits for Floral Industry:
- The success of this method would greatly reduce the outbreak of unwanted”imported” insects and the economic losses resulting from the infestations. Because
atmospheric air consists of 80% N2, the proposed approach would provide growers an
environmentally-safe means of preventing the spread of whitefly. Use of clean plant
materials, as an integral part of an integrated pest management, will drastically
reduce the hazards and expense of pesticides currently used by greenhouse growers.
