Abstract:
The study was conducted to survey and identification of pathogenic diseases of gerbera
plant in and around Dhaka and isolation of associated causal organism and confimation
their pathogenicity during the period of April to October 2019, in the central laboratory
of the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka1207.
For survey total nine sites were visited of Agargaon, Savar, Gazipur and
Narayanganj. Based on symptomological study fungal diseases such as Alternaria leaf
spot (Alternaria alternata), Cercospora leaf spot (Cercospora sp.), Anthracnose
(Colletotrichum capsici.), Blight (Curvularia geniculata), Sclerotinia wilt (Sclerotinia
sclerotiorum), Gray mold (Botrytis sp.), Powdery mildew (Erysiphe sp.), Stem rot
(Fusarium oxysporum.) and the viral diseases such as Mosaic (Mosaic virus), Leaf curl
(Leaf curl virus) were identified. Among all identified diseases, Alternaria leaf spot
showed the highest disease incidence (66.67%, Gazipur) and Gray mold showed lowest
disease incidence (5.56%, Narayanganj). The reduction rate of plant height due to
Alternaria leaf spot, Cercospora leaf spot, Anthracnose, Blight, Sclerotinia wilt, Gray
mold, Powdery mildew, Stem rot, Mosaic and Leaf curl disease were 28.42%, 28.1%,
12.69%, 12.47%, 30.67%, 28.36%, 28.08%, 19.14%, 12.89% and 22.06% respectively.
Reduction rate of other plant part due to Alternaria leaf spot (leaf length 42.62%, leaf
width 26.79%), Cercospora leaf spot (leaf length 15.27%, leaf width 15.69%),
Anthracnose (stem length 10.94%), Blight (leaf length 22%, leaf width 33.33%),
Sclerotinia wilt (stem length 34.22%), Gray mold (flower size 42.86%), Powdery mildew
(leaf length 19.17%, leaf width 18.75%), Stem rot (leaf length 17.42%, leaf width
17.65%, flower stalk length 44.78%), Mosaic (leaf length 24.43%, leaf width 34.78%)
and leaf curl (leaf length 63.08%, leaf width 60.47%) were recorded. Following Koch’s
prostulate, pathogenicity test of Curvularia geniculata and Erysphe sp. were done on
healthy gerbera plants. Inoculated plant showed symptoms of Blight disease and Powdery
mildew disease after 9 and 6 days inoculation respectively. Whereas controlled plant
showed no symptoms of diseases. That confirmed the pathogenicity of Curvularia
geniculata and Erysiphe sp.
Description:
A Thesis
Submitted to the Faculty of Agriculture,
Sher-e-Bangla Agricultural University, Dhaka,
In Partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
IN
PLANT PATHOLOGY