We found that Carbofuran and Deltamethrin were the two most frequently
mentioned pesticides in rice farming, i.e., 34 rice fields were applied
with Carbofuran and 32 rice fields with Deltamethrin. Carbofuran is one
of the most toxic Carbamate pesticides and it is used to control aphids,
stem borers, and golden snails. Deltamethrin is used to control insect
pests such as cutworm and diamond back moth (Fabro & Varca, 2012). The
usage of rodenticides (Brodifacoum) and herbicides (Metsulfuron-methyl)
in UCRB rice fields was low compared to the insecticides. Brodifacoum is
typically used to control rats, while Metsulfuron-methyl is typically
used to control weeds (Derbalah et al., 2019).
Profenofos and Mancozeb were widely used in vegetables cultivation, e.g.
in chili and tomato fields (Fig. 2 ). 26 chili fields were
treated with Profenofos, and 24 fields with Mancozeb. For tomato, 15
fields were treated with Profenofos and 14 fields with Mancozeb. From
the 13 types of pesticides which were used on tomato, 10 pesticides were
also used on chili. It is because most tomato farmers also grow chili in
this area. The result revealed that farmers generally used the similar
pesticides for different vegetable types; only the frequency and amount
applied varied based on area and vegetable types.
To estimate the amount of pesticides used, the concentration or weight
percentage of each pesticide and its frequency of application are
needed. These parameters vary per pesticide, crop type and farmer. The
survey results show that farmers in the UCRB have developed their own
dosage regimes, application frequencies and recipes for pesticide
mixtures for their crops based on their experience. Almost all of them
mixed multiple pesticides in the application, except for lettuce,
chayote, cassava, and bitter gourd. The application frequency of each
pesticide per crop type is depicted in Figure 3 .