Abstract:
Anthurium (Anthurium andreanum Linden) suffers from a serIOUS
disease viz., bacterial blight incited by Xanthomonas axonopodis pv.
diefJenbachiae (McCulloch and Pirone) Vauterin et al.
A survey was conducted in Thiruvananthapuram district and
information on disease intensity and varietal reaction of the disease was
studied from randomly selected thirty anthurium gardens. Plants with
disease infection upto 50 per cent was noticed in most of the gardens.
Generally pink varieties exhibited tolerance while red varieties were
susceptible. Both foliar and systemic symptoms were observed.
The bacterium was a gram negative, motile, short rod. Potato
Sucrose Agar was the best solid medium for growth of the bacterium.
Morphological, physiological and biochemical characters of the ten
isolates were compared and some characters like nature and rate of
growth, virulence and hydrolysis of starch were found varying.
Aglaonema sp., Alocasia sanderiana, Anthurium ornatum, Colocasia
esculenta, Dieffenbachia spp., Philodendron spp., Syngonium sp. and
Xanthosoma sagittaefolium of Araceae family and ornamental plants like Orchid
spp., Dracaena spp. Heliconia sp., Sterilitzia reginae and Maranta arundinaceae
were hosts of the pathogen.
Among the fifteen botanicals tested under in vitro conditions crude
extract and 2 : 1 dilution of Allium sativum and Tagetes erecta, crude and
two per cent concentration of neem cake extract and one and two per cent
neem oil and coconut oil were 'effective in inhibiting the growth of the
pathogen.
The relative efficacy of five ecofriendly management practices viz.,
application of A. sativum, T. erecta, neem oil, coconut oil and neem cake
extract, at two levels and 100 ppm streptocycline were tested on seven
month old tissue culture plants. Pre and post inoculation sprayings with
crude extract of neem cake and T. erecta reduced the disease by 85 per
cent.
When the same spraying schedule with these two botanicals and 100
ppm streptocycline was given on flowering plants, crude extract of neem
cake was the most effective followed by crude extract of T. erecta. The
effect of streptocycline 100 ppm was on par with T. erecta. The study
thus indicates that botanicals could be used as a substitute for antibiotics
in the management of bacterial blight of anthurium.
