Abstract:
In this research work, digital image analytical techniques were used with the objectives to
detect and calculate disease severity and to estimate and optimize volume of fungicide. The
mancozeb fungicide was sprayed on tomato leaves two times to see the progression of
treatment to optimize the volume of fungicide. Total area of leaves and area of diseased
region of leaves were extracted from 1350 tomato-leaf images captured in three rounds.
First round was before spraying fungicide, second round was after the first spray of
fungicide and third round was after the second spray of fungicide The data were collected
from fifteen groups of tomato plants. Each group of plants had three pots as replications.
Each pot had one plant after thinning was performed. Control group was the one on which
fungicide was not sprayed. On group 8, 71.8 ml of fungicide was sprayed and it was the
recommended estimated volume. On groups 1-7, the applied volumes of fungicide were less
by 30, 25, 20, 15, 10, 5 and 0%, respectively, than the recommended volume of fungicide
was used. On groups 9-15, the applied volumes of fungicide were more by 5, 10, 15, 20,
25, 30 and 100%, respectively, than the recommended fungicide volume . In all rounds,
the disease severity of groups (1-8) increased rapidly. The groups 11-14, on which 15-30%
(approximately 82.8-93.66 ml) additional volume of fungicide was sprayed, showed almost
no change. As the volume deviated from this volume, the disease severity increased slightly. From the results, it can be concluded that the volume of fungicide sprayed on
group 11 was found to be the optimum volume of fungicide to be sprayed against early
blight of tomato.
