108 Papaya
intensity and types of scare devices to improve their effectiveness. Supplement
frightening techniques with shotguns, where permitted, to improve their effective-
ness in dispersing crows. Ultrasonic (high frequency, above 20 kHz) sounds are not
effective in frightening crows and most other birds because, like humans, they do
not hear these sounds. Cassette tapes used with pyrotechnics can be very effective.
Your neighbours may not like it as it will make the crows move elsewhere. Tapes can
also be used to attract crows for hunting purposes. Again this is a short-term solu-
tion testing up to a year. Repellents are also an option. Essentially, it is a chemical
that is fogged and sent up into the trees. One problem with repellents is that we may
not be able to use them in situations where fruits are grown for eating or marketing.
Shooting the crows is safe and legal. Trapping can be an effective option (Yahner
and Wright 1985).
9.11.1.1 Phytotoxicity
Papaya-growing regions have to combat a number of major and minor pests and
diseases, and the extent of damage depends upon agroecological regions. The com-
mon strategy for pest management, sometimes, is prevention through the applica-
tion of pesticides at regular intervals. Proper timing, deposition and coverage of the
pesticides’ application are critical for the effective control. Reproductive precocity,
high photosynthetic rates of short-lived leaves, fast growth and high reproductive
FIGURE 9.7 (See colour insert.) Symptoms of phytotoxicity.