de Bie, Kees 
  
INCIDENCE AND CONTROL OF PESTS AND DISEASES 
All orchards suffered from stem boring caterpillars and several from beetles, flies 
and fruit piercing moths. Diseases affecting mango were not reported. To control 
caterpillars, 34 farmers used pesticides, viz. Lannate (12x), Azodrin (9x), Civin-85 
(7x), Furadan (4x), Folidol (5x) and Thiodan (3x). 
Regression showed that only Azodrin application had a positive moderately 
significant effect on yields (Figure 9°). The method of pesticide application was 
either by knapsack or by motor sprayer. Use of a motor sprayer had a highly 
significant impact on yields (Adj.- -R? of 15. 896), which might be explained by the 
fact that pesticides were sprayed deep into the tree canopy. The regression 
equation, derived is: Ln(Yield+1) = 1.17 + 1.88 (if a motor sprayer is used); see 
Figure 9°. Motor sprayers were almost exclusively used for application of Civin-85 
(4x), and Azodrin (3x). Spraying was practiced throughout the year. Besides 
spraying, farmers cut branches that showed signs of caterpillar damage. Several 
orchards were badly damaged by this practice. 
  
  
  
  
  
  
  
  
  
    
  
  
6 T T 6 T T 6 T T 
5r x 5r : zl [1 A 
c4 4 24r 4 A4F 4 
$ 3 3 
£9 1&9 jS 3 
= LX ol J 
37x 
1+ d Ar Jie al " 
9 Used b 9 Not used Used o None Applied 
a. Azodrin . Motor sprayer C. Supplementary irrigation 
Figure 9. a: Effect of Azodrin on caterpillar control. 
b: Effect of motor sprayer of pesticide efficiency. 
c: Effect of supplementary irrigation on yields. 
IRRIGATION 
Eighteen farmers reported experiencing water shortage during the fruit bearing 
stage (end of dry season). This number includes five (out of twelve) farmers who 
were able to apply supplementary irrigation water when available. Note that wells 
etc. dry-up when irrigation water is most urgently needed. Irrigation infrastructure 
present within or in the direct proximity of orchards included water reservoirs / 
dams (8x), ground water wells (10x), canals (6x), underground irrigation pipes with 
taps above the surface (5x), and hose-pipes / tubes for irrigation purposes present 
within the orchard (7x). 
Water shortage during the fruit bearing stage or the presence of irrigation 
structures did not visibly correlate with yields. Supplemental irrigation led to higher 
yields (Figure 9°) and significantly explained 796 of the overall yield variability. The 
equation is: Ln(Yield+1) = 1.20 + 1.17 (if ability to apply supplementary irrigation 
water exists). 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 
331