Khalil I. Al-Mughrabi
Partner: Potatoes New Brunswick
Abstract: A field trial conducted in New Denmark, New Brunswick in 2010 was setup to compare different strategies to manage powdery scab of
potato (cv. Cal White; E1). The experimental field had a history of powdery scab and the soil is heavily infested with the scab pathogen S. subterranea.
Seed and in-furrow application of single or double doses of fluazinam or mancozeb; and single doses of fludioxonil, cyazofamid, boron, sulfur, nitrogen
or mustard meal were applied. There was no treatment effect on plant emergence or vigor. Seed and in-furrow treatments of mancozeb, in-furrow applications
of 2-4 kg fluazinam/ha, 816 g of cyazofamid/ha, 2.7 kg of boron/ha and 1055 kg of mustard meal/ha significantly reduced powdery scab severity. Particularly,
25 g of fluazinam/100 kg seed; in-furrow application of mancozeb at 7.5 kg/ha and 15 kg/ha significantly reduced powdery scab by 33.2%, 59.7% and 57.1%
respectively and significantly increased the marketable yield by 32.99%, 43.78% and 43.1% respectively, solely due to the control of the disease. Boron
significantly reduced the disease, increasing the marketable yield which was not significantly different from the control due to low total yield recorded in
the treatment. Mustard meal at 1055 kg/ha reduced the disease by 52.6%, increasing the marketable yield by 12.71%. Seed treatments with mancozeb and in-furrow
application of fluazinam were best in managing powdery scab in infested fields. The investigation however is required to be repeated using more combinations
of treatments for precise information on the management of powdery scab of potato in this region.