Ae. Majule et al., THE ENVIRONMENTAL-EFFECTS OF DUSTING CASHEW (ANACARDIUM-OCCIDENTALE L.) TREES WITH SULFUR IN SOUTHERN TANZANIA, Tropical agriculture, 74(1), 1997, pp. 25-33
The effect of dusting elemental sulphur (S) as a fungicide for control
ling powdery mildew (Oidium anarcadii) disease in cashew (Anacardium o
ccidentale L.) upon soil fertility was studied in two agro-ecological
zones (AEZ), termed C2 and E5. Annual S dusting decreased the pH of to
psoil by up to 0.7 units over a period of four years dusting, reducing
pH values to less than the critical 5.5 level in some areas. At most
sites a decrease in pH was associated with the loss of major soil macr
onutrient elements from the topsoil due to leaching. An increase in Al
saturation to toxic levels also occurred, particularly in A C2. Preli
minary data showed that annual crop performance was also negatively af
fected by the increased soil acidity in some soils. From these results
it was concluded that the annual application of S dust to control pow
dery mildew disease is not environmentally sustainable and alternative
control strategies are needed with less damaging effects on environme
nt.