Abstract:
Using high-quality initial planting materials ensures the production of high-quality seed potatoes.
Under polytunnels, the Department of Agriculture maintains a program for producing high quality seed potatoes. Very recently it was reported that infection of powdery scab pathogen
caused by Spongospora subterranea f. sp. subterranea in the soilless potting media used for that
program. It is a quarantine pathogen, and there are currently no effective management techniques
in place for it. As a result, this study was designed to investigate fumigants and fungicides for
managing this infection. Powdery scab infected soilless media were collected from the G1 seed
potato production polytunnel. Those were treated with fumigants; methamsodium (40 mL/L),
formalin (100 mL/L), hydrogen peroxide (0.25 mL/L), and fungicides; mancozeb (2g/L),
amisulbrom (0.5 mL/L, 1.0 mL/L, 1.5 mL/L) and kept for two weeks by covering a black polythene.
The treated media were filled into grow bags and sprouted seed potato (var. Redlasoda) were
planted one tuber per bag. For control untreated media was used. Three replicates for each
treatment were kept according to the completely randomized design. Plants were maintained
following the DOA recommended agronomic practices. Number of root galls per plant was
recorded in weekly intervals from the age of two months to three months. At the end of the
experimental period, no of infected tubers per plant and total yield per plant were recorded. The
lowest mean number of root galls per plant (1.93±0.02, p≤ 0.05) was observed in amisulbrom
(1.5mL/L) treatment followed by methamsodium and amisulbrom (1.0mL/L) while untreated
growing medium showed the highest (7.49±0.02). The lowest percentage of infected tubers per
plant was also recorded in amisulbrom 1.5 mL/L treatment. But it was not significantly different
from that of methamsodium, mancozeb and other two amisulbrom treatments. The highest yield
per plant was observed in methamsodium treatment, but it was not significantly different with
other treatments and the control. Our results highlighted that fumigation of soilless medium with
1.5 mL/L amisulbrom and 40 mL/L methamsodium has the potential to reduce powdery scab
infection. However, further investigations are required by monitoring pathogen inoculum level,
medium condition and environmental factors.
