3 A vegetable grower uses both organic and chemical methods to manage pests on a tomato farm. (a) State what is meant by integrated pest management (IPM). [...

(a) Integrated pest management (IPM) is the use of a combination of different pest control methods - chemical, biological, cultural and mechanical - rather than relying on a single approach. [1] Its goal is to keep pest numbers below the economic injury level (the point at which pest damage costs more than the control measures), while reducing dependence on chemical pesticides alone. [1]

(b) Two cultural methods of pest control (each described): [4]

1. Crop rotation: growing a different crop (such as onions or legumes) in the field after the tomato season. This breaks the life cycle of pests that are specific to tomatoes, because their host plant is absent and pest populations cannot build up in the soil between seasons. [2]
2. Removal and destruction of infected plant material: collecting and burning or burying crop residues and fallen fruit after harvest eliminates breeding sites and overwintering refuges for pests, reducing the population that attacks the next season's crop. [2]

Other acceptable methods include using resistant varieties, adjusting planting dates to avoid peak pest activity, and intercropping with pest-repellent plants.

(c) Rotating different chemical groups of pesticide is important because pests can develop resistance to a chemical if the same group is used repeatedly. Surviving individuals that carry genes for resistance pass those genes to their offspring, increasing the resistant proportion of the population each generation. [1] When the farmer switches to a different chemical group with a different mode of action, pests that are resistant to the first group are still killed by the second. [1] This rotation delays or prevents the build-up of a resistant pest population, ensuring that the pesticides remain effective over multiple seasons. [1]

(d)

Advantage (any one): Biological control does not leave chemical residues on the harvested tomatoes, making the produce safer for consumers. [1] (Alternatives: it is more environmentally friendly as it does not pollute soil or water; the control agent can reproduce and provide ongoing, self-sustaining pest suppression.)

Disadvantage (any one): Biological control is slow to take effect and does not provide the immediate knockdown that chemical spraying delivers, so pest damage may continue while the control agent establishes. [1] (Alternatives: the biocontrol agent may not survive in the local environment; it may be difficult to obtain; it targets only specific pests and has no effect on other pest species.)