MSc

The present study entitled “Management of fungal diseases of capsicum
(Capsicum annuum L.) under protected cultivation” was conducted in the Department
of Plant Pathology, College of Horticulture, Vellanikkara during June to February
2016-17. The major objective was to assess the incidence and severity of fungal
diseases of capsicum under protected cultivation and to formulate an eco-friendly
management practice.
A survey was conducted in three districts of Kerala, Thrissur, Palakkad, and
Thiruvanathapuram by selecting nine poly houses where capsicum is being cultivated
during August to February 2016-17. During the survey, incidence of fungal diseases
like powdery mildew, leaf spot, fruit rot, stem and fruit rot were noticed on capsicum
under protected structures at various locations. Incidence of powdery mildew was
observed in all the polyhouses except Vellanikkara, and the disease severity varied
from 5.3 to 90.23 per cent. Leaf spot was noticed in three poly houses, during rainy
season, the per cent disease severity varied from 2.97 to 5.36 per cent.
Symptomatology of fungal diseases of capsicum observed during the survey was
studied. The fungi associated with the diseases were isolated and the pathogenicity
was proved. Cultural and morphological characterization of the pathogens was
carried out and the fungi were tentatively identified as Leviellula taurica, Cercospora
capsici, Colletotrichum capsici and Fusarium sp. The isolates were sent to Rajiv
Gandhi Centre for Biotechnology, Thiruvanathapuram for DNA sequencing and
based on molecular characterization, it was confirmed that the leaf spot, fruit rot and
stem and fruit rot of capsicum are caused by Cercospora capsici, Colletotrichum
capsici, and Fusarium sp. respectively.
Field experiments were conducted simultaneously inside the poly house and
rain shelter for management of fungal diseases of capsicum with seven treatments and
three replications. The treatments included two biocontrol agents (Trichoderma viride
(asperellum) and Pseudomonas fluorescens) two systemic fungicides (tebuconazole
and
difenoconazole)
and
two
contact
fungicides
(mancozeb
and
copper
hydroxide).Among the treatments, T4 (soil solarisation + soil application of
Trichoderma asperellum +seed treatment with carbendazim+ mancozeb (2g.kg-1) +
foliar spray with mancozeb (0.2 %) was the most effective for management of
Cercospora leaf spot in both poly house and rain shelter, followed by T2(soil
solarisation+ seed treatment and foliar spray with Pseudomonas fluorescens(20g.L-1)
and T1(soil solarisation+ soil application of Trichoderma viride (asperellum)) and
these were statistically on par. Among the treatments, T5 (soil solarisation +soil
application of Trichoderma asperellum+ foliar spray with tebuconazole (0.1 %) was
the most effective for management of powdery mildew in rain shelter and poly house,
followed by T6(soil solarisation +soil application of Trichoderma+ foliar spray with
difenoconazole (0.05%) and these were on par. Correlation analysis was performed
with the meteorological data recorded during the experiment and per cent disease
severity (PDS) at periodic intervals and it was found that there is significant positive
correlation with RH in rain shelter and temperature in poly house in case of
Cercospora leaf spot. In powdery mildew, there was a significant negative correlation
with PDS and temperature inside the protected structures. Economic analysis of the
field experiments suggested that the soil solarisation with combination of biocontrol
agents and tebuconazole recorded the highest B:C ratio.
It was found that soil temperature at 10cm depth was higher in solarized soil
when compared to non-solarized soil by 6.350C and 4.50C inside poly house and rain
shelter respectively. It was also recorded that the population of soil microflora was
reduced due to solarisation in protected structures.
Analysis of population of phylloplane microflora proved that there was drastic
reduction in the population of phylloplane fungi, bacteria and actinomycetes after
spraying with chemical fungicides whereas the population increased after spraying
with biocontrol agents. Survival of biocontrol agents on the phylloplane of capsicum
was also studied and it was found that Pseudomonas florescens, survived on the leaf
surface up to 15 days after foliar application.
Thus, the study has confirmed the identity of causal agents of major fungal
diseases of capsicum. Cercospora capsici reported for the first time on bell pepper
from the country. It also suggested economical and effective management practices
against the diseases. Further, the results of the study prove that, timely application of
biocontrol agents gives satisfactory control of diseases without affecting beneficial
microbes