Date Feb. 28, 1992

Title of Project Evaluation of Elevated CO2 for Control of Greenhouse Whiteflies on Poinsettias

Institution where work is being conducted University of Massachusetts, Amherst

Amount of Endowment Grant $ 5,000
Covering Period Jan. 92 to Jan. 93

Anticipated Date of Project Completion/Final Report Jan. 93

Individual(s) Conducting Project:

(List Project Leader First)

Dr. Susan S. Han - Title Assistant Professor

Telephone Number (413) 545-5228

Nancy Woycicki - Title Graduate student assistant

Evaluation of Elevated CO2 for Control of Greenhouse Whiteflies on Poinsettias

Susan S. Han and Nancy Woycicki

University of Massachusetts-Amherst

Progress Report to the American Floral Endowment, 2/28/92

A. Project Objectives:

Elimination of whiteflies from poinsettias remains a major challenge for many growers. The problem

arises frequently from purchased cuttings that were infested with whiteflies in the propagation area.

Since prevention is known to be the best management strategy in controlling insect outbreaks, I proposed

to investigate means of excluding all stages of whitefly from plant materials prior to arrival at the

production area. The method combines results of past work in which elevated CO2 was effectively used

to control insects as Caribbean fruit fly and codling moth as well as studies showing the ability of

floricultural crops to tolerate elevated levels of CO2. The objectives of this project are 1) To determine

the effectiveness of elevated levels of CO2 in controlling variousstagesof whitefly. 2) To investigate the

effects of elevated levels of CO2 on further growth and development of plants.

B. Results to Date:

To date, a colony of greenhouse whiteflies has been established for the project. In addition, we are

constructing cages covered with fine screen in order to start and maintain plant materials in a whitefly-free

space. The availability of these clean plant materials will allow us to investigate the susceptibility

of various stages of whitefly to the elevated CO2 treatment. This can be accomplished by introduction of

adult whiteflies to the cages for one day. The adults will then be removed from the cages the following

day. All eggs will, therefore, be laid on the same day and further development of stages can be

coordinated. Treatments can then be applied separately to eggs, nymphs, pupae, or adults and the

survival rate of the various stages of whiteflies to the treatments can be assessed.

In order to collect adult whiteflies, we have assembled some custom-made aspirators. After collection

of the adults into the aspirator, the system can be connected directly to a constant flow of CO2 and used

to investigate the susceptibility of the adults to the CO2 treatments. The collected adults can also be

released into the cages for use in inoculation of clean plant materials. By allowing the eggs to develop

for various lengths of time, we will have all stages of insects needed to conduct the proposed studies.

The poinsettia cuttings needed for this project have been acquired from a local greenhouse grower. The

cuttings should arrive late April or early May at which time we will evaluate three commonly grown

cultivars for their tolerance level to the elevated CO2 treatments.

C. Anticipated Benefits for Floral Industry:

In recent years, there has been increasing pressure from many states restricting the amount and type of

pesticides that can be used in the greenhouse. These new regulations have forced the industry to explore

non-chemical methods for controlling common greenhouse pests. If our results show that elevated CO2

treatment is effective against whitefly, the technique would provide the floral industry a non-chemical

and safe way of preventing the spread of whiteflies. Using clean plant materials in conjunction with

integrated pest management will drastically reduce the hazards and expense of pesticide currently used

by greenhouse growers.

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