Contamination rates are often high when explants from
field-grown trees are used. From observation, I
discovered that suckers were easier to get
contaminated compared to male buds. The
contamination rate in suckers was higher compared to
that of male buds because the suckers originated from
soil. Improper sterilization procedure cannot kill some
of the soil microorganisms that might attach to the
suckers and this may results in exogenous infection of
bacteria.