Evaluation of fungicides in managing Phytophthora root rot of - IR-4

IR-4 Ornamental Horticulture Program
Research Report Cover Sheet
Trial: 2007 FL
Researcher(s) Aaron Palmeteer
University of Florida
Affiliation:
Homestead
PhoneNumber: 305-246-7001
ajp@ufl.edu
Email:
ProjectTitle:
Phytophthora Efficacy
Protocol #:
07-001
FL
PR#
Research Target
Crop/Plant
Product
26386
Phytophthora palmivora
Bamboo Palm
Heritage
100-1093
Phytophthora palmivora
Chamaedorea seifrizii
Azoxystrobin
Syngenta
Phytophthora palmivora
Bamboo Palm
Insignia 20WG
7969-184
Phytophthora palmivora
Chamaedorea seifrizii
Pyraclostrobin
BASF
26385
Phytophthora palmivora
Phytophthora palmivora
Bamboo Palm
Chamaedorea seifrizii
Segway
Cyazofamid
28005
Phytophthora palmivora
Bamboo Palm
Phytophthora palmivora
Chamaedorea seifrizii
Phytophthora palmivora
Phytophthora palmivora
28004
26387
EPA Reg. # Production Site Status
Shadehouse/Lathe
C
Shadehouse/Lathe
C
71512-13
ISK
Shadehouse/Lathe
C
Stature SC
241-428
Shadehouse/Lathe
C
Dimethomorph
BASF
Bamboo Palm
V-10161
-
Shadehouse/Lathe
C
Chamaedorea seifrizii
V-10161
Valent
Evaluation of fungicides in managing Phytophthora root rot of Bamboo Palm
(Chamaedorea seifrizii), 2008
Several new and registered fungicides were compared for control of
Phytophthora root rot on one year old containerized bamboo palms
(Chamaedorea seifrizii) in a soilless media (peat core, pine bark, cypress dusk,
and perlite) produced under 70% shade cloth and weekly overhead
irrigation. Palms were divided into two categories (preventative and
curative) based on initial root necrosis ratings and evidence (isolation) of the
pathogen Phytophthora palmivora. Healthy palms not infected with P.
palmivora and roots showing < 20% necrosis (preventative) were separated
from those confirmed to be infested with P. palmivora and an initial root
necrosis rating >20% (curative). For both categories there were sixteen
replications of each fungicide treatment arranged in a randomized complete
block design.
A bamboo palm isolate of Phytophthora palmivora was grown on quarter
strength V8 agar plates. After two days of growth, the plates were flooded
with sterilized distilled water and placed under fluorescent light for 10 days.
The mature cultures were flooded with fresh water and gently brushed to
dislodge the sporangia. On 19 Dec, 7 Jan, 28 Jan, 19 Feb, and 4 Mar all
fungicide treatments were applied as a drench. One day following each
fungicide application of palms in the preventative group, a pipette was used
to inject 0.07 fl oz. of the zoospores and sporangial slurry into the soil at the
base of each palm. All palms in the curative group were not challenge
inoculated.
Symptoms of Phytophthora root rot developed on untreated bamboo palms
within 4 weeks of inoculation and progressed, resulting in plants susceptible
to lodging and moderate to severe root rot. All fungicide treatments in both
the curative and preventative trials significantly reduced percent root
necrosis. The low rate of Insignia gave the best control in the preventative
trial and percent root necrosis was significantly less than the high rate of V10161. Both rates of Segway gave the best control in the curative trial and
percent root necrosis for the low rate of Segway was significantly less than the
high rate of Insignia. Final ratings for percent root necrosis taken from the
control plants in the curative trial were so severe (51-86%) the majority of
plants were lodging and unable to stand without support.