Non-target effect of chemical sprays and population dynamics of the mango phylloplane microbial population.
Jager, E. S. de; Sanders, G. M.; Korsten, L.;
Yearbook - South African Mango Growers' Association Year: 1994 Vol: 14 Pages: 43-47 Ref: 28 ref.
1994
บทคัดย่อ
ABSTRACT :
The effect of chemical sprays, of infection with Xanthomonas campestris pv. mangiferaeindicae, seasonality and of leaf maturity and leaf surface (adaxial or abaxial) on microbial density and diversity of the mango phylloplane were studied. Bacterial, fungal and yeast numbers, as well as fungal and yeast diversity, were significantly reduced by chemical sprays. Both total number and total diversity were significantly lower in chemically sprayed trees. Infection with X. c. pv. mangiferaeindicae reduced fungal numbers and diversity as well as total diversity. Bacterial numbers and diversity remained unaffected. The lowest numbers and diversity of microorganisms occurred on the western side of the mango tree, and significantly more microbes were encountered on the adaxial leaf surface. Diversity on the adaxial and abaxial leaf surfaces was similar. More microbes were recorded in winter and spring. Bacterial numbers increased in autumn. Fungal and yeast numbers were highest in winter and spring, resp
ectively. Yeasts were the dominant microbe present, greatly exceeding fungal and bacterial numbers. Microbial and fungal diversity were not affected by season, whilst bacteria and yeast diversity were lowest in summer and autumn, respectively. Yeast diversity was lower than that of bacteria and fungi. Microbial numbers increased with leaf age, whereas microbial diversity increased during the initial stages of shoot development, and remained constant thereafter. It is concluded that this knowledge of the ecological situation can be used in further biological control programmes of pre- and postharvest diseases of mangoes.