TY  - BOOK
AU  - Veena S S 
AU  - Peethambaran C K (Guide)
TI  - Distribution of species of phytophthora affecting coconut and pepper in Kerala
U1  - 632.3 
PY  - 1996///
CY  - Vellayani
PB  - Department of Plant Pathology, College of Agriculture 
N2  - The present investigation was undertaken to correctly 
identify the species of Phytophthora causing bud rot of coconut 
and foot rot of pepper in Kerala and to find out their 
comparative role in causing diseases on coconut and pepper. The 
study also aimed at isolation of viable antagonistic agents 
against the pathogen, so as to utilize them in future for 
biological control. 
The study was conducted during 1992-96 at College of 
Agriculture, Vellayani and Indian Institute of Spices Research, 
Kozhikode. Detailed symptomatology of both the diseases at 
different locations were studied. Periodic collections were made 
from diseased coconut and pepper from seven districts of Kerala. 
The morphological characters of the isolates were 
studied in detail. The length, breadth, L/B ratio, pedicel 
length and caducity of sporangia of coconut isolates were smaller 
than pepper isolates. The sporangial shapes differed 
considerably between and among the isolates. All the isolates 
except those collected from Kannur and Kasaragod districts 
(C7 - C16), produced abundant number of sporangia on carrot agar. 
Phytophthora are either heterothallic or homothallic. 
Generally P. palmivora and P. capsici are heterothallic. But ten 
 
coconut isolates obtained from Kannur and Kasaragodu districts 
produced abundant number of sexual structures on carrot agar, 
indicating their homothallic nature and this is the first report 
of homothallic Phytophthora causing bud rot of coconut in Kerala. 
All other 52 isolates were mated with known A1 and A2 mating type 
and all the coconut isolates produced oospores with A1 and all 
the pepper isolates produced oospores when mated with A2. 
Zoospore production was induced from sporangia using 
cold treatment. The number of zoospores in sporangia ranged from 
6-15 in number. Chlamydlospore production was a rare phenomenon 
in pepper isolates while all the coconut isolates and five pepper 
isolates produced chlamydospores. 
All the isolates were inoculated into pepper seedlings, 
coconut leaves, tender coconut and coconut seedlings and the time 
required for infection, variation in symptom expression by 
different isolates etc. were studied. All the sixteen coconut 
isolates produced foot rot in pepper. Fourty six isolates of 
pepper produced lesions on coconut leaves and nut rot in tender 
coconut, while, only six isolates of pepper produced bud rot in 
coconut plants. The cross infectivity of pepper isolates needed 
further confirmation to prove the point beyond doubt. Eight 
cultivated plants, 9 ornamental plants and 12 weed plants were 
tested for the host range of coconut and pepper isolates. Many 
plants belonged to the above three groups took infection 
successfully. 
 
The microorganisms found associated with healthy and 
diseased pepper and coconut plantations and microorganisms from 
soils of pepper and coconut gardens of different parts of Kerala 
were isolated. Out of more than 200 microorganisms, only 28 
fungi inhibited the growth of Phytophthora in vitro. On pepper 
plant, 12 isolates had inhibitory action. Three organisms, viz., 
Verticillium chlamydosporium, Aspergillus terreus and Chaetomium 
sp checked the pathogen completely even after seven days of 
spraying with the organisms. 


UR  - https://krishikosh.egranth.ac.in/handle/1/5810153237
ER  -