The Effect of Modifying the Microenvironment Among Geranium Stock Plants Within a Greenhouse on Botrytis Blight and Sporulation of Botrytis Cinerea Progress Report — March 1992
Date 2/28/92
Title of Project The Effect of Modifying the Microenvironment Among Geranium Stock Plants
on Botrytis Blight and Sporulation of Botrytis Cinerea
Institution where work is being conducted Michigan State University
Amount of Endowment Grant $ 25,000
Covering Period 1/1/92 to 1/1/93
Anticipated Date of Project Completion/Final Report 12/31/93
Individual(s) Conducting Project:
(List Project Leader First)
Dr. Mary K. Hausbeck – Title Visiting Assistant Prof.
Telephone Number (517) 355-4534
The Effect of Modifying the Microenvironment Among Geranium Stock Plants on Botrytis Blight
and Sporulation of Botrytis Cinerea
Mary K. Hausbeck
Michigan State University
- A. Project Objectives:
- The production of a cost-effective, high quality
product delivered in the quantities wanted and at the time they are
wanted will enable the floriculture industry to become revitalized. To
achieve this goal, the following two objectives must be met: (1)
pathogen-free planting stock, and (2) computerized plant growth
optimization strategies. This research research pertains to the
achievement of both of these goals.
temperature on germination of conidia of Botrytis cinerea as measured by
the occurrence and length of the germ tube when placed on geranium
leaves. A similar study has since then been completed at 20′C utilizing
geranium stems. Wounded stem surfaces of geranium stock plants were
inoculated with conidia and incubated in a dew chamber for 1, 3, 6, 9,
12, 24, and 48 hours. Stem sections were then prepared for examination
using the scanning electron microscope with the following results:
| INCUBATION TIME (hour) |
AVG. GERMINATION (%) |
AVG. GERM TUBE LENGTH (mm) |
| 1 | 0 | – |
| 3 | 48 | 3.8 |
| 6 | 47 | 5.5 |
| 9 | 68 | 11.0 |
| 12 | 63 | 14.7 |
- These data show that a large percentage of conidia (48%) germinate
in a relatively short time (3 hours) when placed on cut stems. The
conidia colonized the geranium tissue rapidly between 6 and 9 hours when
the germ tube length doubled. This suggests that conidial production
within the stock plant growing area must be minimized since only 3 hours
of moisture are necessary for nearly 50% of the conidia to germinate on
a newly-wounded stem.
- Further, our recently conducted studies demonstrate that modifying
the environment among stock plants using forced heated air can
negatively impact the occurrence of leaf blight among cuttings taken
from those stock plants. In our first study, an average of 74% of the
leaves became blighted due to Botrytis when cuttings were taken from
control plants grown in an environment that was not modified and exposed
to optimum conditions for disease development. In contrast, only 26% of
the leaves became blighted when cuttings were taken from geranium stock
plants exposed to forced heated air and treated in a similar manner.
Future plans include expanding these studies to further understand the
environmental parameters necessary for disease development.
- C. Anticipated Benefits for Floral Industry:
- The environmental parameters
necessary to deter Botrytis blight will be formulated into a forecasting
system to provide growers with an economical disease management tool
that improves plant quality by reducing disease and pesticide
applications.
