Observations on the epidemiology and control of bacterial black spot in mango.
Kotzé J. M., Visser A. A.
Author Affiliation: University of Pretoria, Pretoria 0002, South Africa.
: 66-70
Abstract : Several experiments were conducted to obtain new information on the ideal conditions for infection and to determine the efficacy of different control conditions against bacterial black spot (BBS; Xanthomonas campestris pv. mangiferaeindicae) in mango. On susceptible mango cultivars, namely Keitt, Kent and Tommy Atkins, the effect of BBS goes further than fruit infection. The trees are weakened through loss of foliage, which eventually leads to lower yields. Copper compounds are bactericidal in the ionic form and toxicity to the pathogen is dependent on the concentration of copper ions and the time of exposure. Eradicants, i.e. calcium hypochlorite, work best when applied at doses up to 200 ppm, when the powder is dissolved in clean water without organic impurities at a pH of 6-6.5. Calcium hypochlorite was ineffective when applied to wounded leaves or fruits after the pathogen has already penetrated. Greenhouse experiments showed that BBS can be transmitted by pruning. In addition, wind inflicts wounds through which infection by the pathogen takes place.