Evaluation of Elevated CO2 for Control of Greenhouse Whiteflies on Poinsettias During Transit Progress Report — September 1993
Date August 10, 1993
Title of Project Evaluation of Elevated C02 for Control of Greenhouse and Sweetpotato Whitefly on Poinsettias
Institution where work is being conducted University of Massachusetts, Amherst
Amount of Endowment Grant $ 7,000
Covering Period Jan. ‘93 to Dec. ‘93
Anticipated Date of Project Completion/Final Report Dec. ‘93
Individual(s) Conducting Project:
(List Project Leader First)
Dr. Susan S. Han - Title Assistant Professor
Telephone Number (413) 545-5228
Jennifer Nobel - Title Research Technician
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 were infested at the start of theseason. The main objective of this project is to find a means of disinfesting the cuttings, thereby, preventing the
outbreak of whitefly later in the growing season. Use of controlled atmospheres (CA) with reduced O2 and/or
elevated CO2 levels can effectively control various species of insects on various commodities. The time required
for 100% mortality depends on the insect species, its developmental stage, and the temperature and atmospheric
composition during the treatment. 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 controlled
atmospheres for management of greenhouse whitefly (Trialeurodes vaporarium); and (2) the effects of controlled
atmospheres on the growth and development of poinsettias.
- B. Results to Date:
- Results showed that greenhouse whitelly are highly susceptible to low-oxygen conditions. Anoxicconditions, created by venting with 100% nitrogen, resulted in mortality of all stages of greenhouse whitefly. All
adults were killed with 2 hr of anoxic treatment (Fig. 1a). Sixty percent and 30% of the adult whitefly exposed
to 1/2 hr and 1 hr of anoxia revived after being transferred to the atmospheric conditions. Those reviving,
however, were dead in less than 24 hr. Other stages of greenhouse whitefly require a longer treatment time
where 4 hr of anoxia killed 90% of the nymphs (Fig. 1b) and 8 hr killed > 80% of the eggs and pupae (Fig. 1c
and 1 d). These studies indicated that 8 hr of anoxia killed the majority of the whitefly, thus, a minimum treatment
time of 8 hr was tested on poinsettia cuttings. Nine cultivars of rooted poinsettia cuttings (Angelico, Celebrate
II, Dark Red Hegg, Freedom, V-14 Glory, Lilo, Pink Peppermint, Red Sails, Supjibi Red) from Paul Eche Range
were treated with 8 hr of air (control) or N2. Following the treatment, cuttings were potted in 10-cm plastic pots
and placed in the glasshouse under interrupted night (8 hr natural light plus night interruption with 3.6 umol*s-1*m-2
incandescent lamp between 10PM and 2AM). The height and weight of six replicate plants measured four weeks
after the treatment demonstrated that, with the exception of ‘Supjibi Red’ and ‘V-17 Angelica’, there were no
differences in growth between those treated with air or N2 (Table 1). We are currently evaluating the responses
of unrooted cuttings which, based on the development of phytotoxicity (necrotic lesions), appear to be more
sensitive to the anoxia treatment. These results suggest that the use of anoxia is a promising method for
disinfestation of whitefly on poinsettias.
- C. Anticipated Benefits for Floral Industry:
- The success of this method would greatly reduce the outbreak of unwanted, “imported” whitefly and theeconomic 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.
