What are pesticides?
Pesticides are tools that are designed to help farmers to safely deter or manage pests – such as insects, fungi and weeds – that can threaten the health or quality of their crop. Along with other plant science innovations, pesticides help farmers grow crops more efficiently and sustain-ably than ever before.
Types of pesticides
There are three main types of agricultural pesticides:
Herbicides:control weeds so that crops can flourish without unwanted plants competing for vital nutrients, space, water and sunlight.
Fungicides:protect plants from disease-causing organisms that can spread quickly and destroy fields of crops.
Insecticides:control insects that could damage crops by eating them or infecting them with diseases.
Pesticides are also used in urban settings to protect public green spaces from pests.
The importance of using pesticides
Plant protection is the practice of managing weather, weeds, pests and diseases that damage or inhibit the growth of fruit, vegetable and other horticultural crops. Proper crop protection is important to produce higher quality crops with minimal wastage. This increase in productivity leads to less land, water and labour being required for food crops. With less land being used biodiversity is preserved and less greenhouse gases are emitted. It also ensures more food reaches the shops and markets in good condition, which helps to keep the prices down.
The importance of using pesticides at the right time
It might seem that the best time to use a pesticide is right when you see pesky insects. However, a few rules do apply and timing is also an important issue. Every pesticide use has its own timetable, but within that schedule, the best way to maximize effectiveness is by applying chemicals at the right time of day.
The proper timing of pesticide use depends on the following factors:
- Plant Behavior
- Air Movement
- Insect Activity
- Drying Time
Just as plants absorb water best early in the morning, they will absorb chemicals most effectively between 3 a.m. and 8 a.m., and again around dusk. Stomata, the pores on plant leaves, are open during these hours, absorbing water vapor and dew during the coolest time of the day and when sunlight is not stimulating food production through photosynthesis. Pores can absorb foliar spray easily at these times.
A second reason to spray chemicals early in the morning or at dusk is that air is more apt to be still than at other times of day. Some chemicals, horticulturalists caution, must be applied when air movement is low, both for effective application and for personal protection.
Many insects are most active early in the morning and around dusk, making very early morning and early evening the most effective times for insecticide application. Insecticides can have undesirable consequences if they are applied at the wrong time.
Pesticide sprays require between one and 24 hours of drying time to maximize benefits. This may mean adjusting an automatic watering system or changing a watering routine to allow drying on leaves. Ideally, spraying is done on a clear day at the beginning of 24 rain-free hours. In humid climates, applying pesticide in the evening, thus leaving plant leaves wet at night, can increase plant vulnerability to disease.