Handiseni M., Sibiya J., Ogunlela V., Koomen I.
Abstract
The production and use of methyl bromide, a traditional soil biofumigant in vegetable nurseries in being phased
out because it depletes the ozone layer in the stratosphere. An affordable and effective alternative method,
preferably a non-chemical one, for seedbed sterilisation is needed. On-farm seed-bed trials were established
in Chinyika Resettlement Area, Zimbabwe in 2001-2003 cropping seasons to evaluate the effectiveness of some
non-chemical alternatives to methyl bromide for soil sterilization. Methyl bromide, soil solarisation and dry
heat by burning cow dung, maize cob, and brushwood (twigs) as a source of heat were evaluated for sterilisation
of paprika nursery seedbed soil. Burning of brushwood and cow dung treatments resulted in highest soil temperatures
at the two sites and in both seasons. Area under disease progress curve for disease incidence was least in the
brushwood treated seedbeds. Methyl bromide and use of brushwood had a seedling emergence which 61% and 57.3% higher,
respectively than non-sterilised control in 2001/2002 season. The inconsistencies associated with dry heat methods
in controlling soil microbes and weeds requires a combination of them with other sterilising agents such as
chloropicrin, methyl iodide and dazomet, if they have to match the efficacy of methyl bromide treatment for soil
sterilisation.
Key words:
Capsicum annuum L., sterilisation, methyl bromide, seedbed, dry heat