Which of the following is NOT a reason chemical control may be necessary?

The choice that is not a reason chemical control may be necessary is the availability of resistant varieties. When resistant varieties of a plant are available, they have been specifically bred or engineered to withstand certain pests or diseases, which reduces the need for chemical interventions. Growers can select these varieties to manage pests naturally by making their crops less susceptible to those threats.

In contrast, inadequate crop management practices can lead to pest issues necessitating chemical control. Poor practices may allow pests to proliferate unchecked, which could prompt the need for chemicals to regain control. Similarly, if crop rotation is not feasible, a farmer may find themselves continuously planting the same crop in the same location, which can lead to increased pest pressure and potentially the need for chemical control to manage those populations. Lastly, a sudden unexpected disease outbreak can overwhelm a crop’s defenses and necessitate swift chemical application to protect the crop from extensive damage.