TROUBLESHOOTER
Q Why do the leaves look mottled?
A Flecks on the leaves and tiny mites on the underside point to red spider mite. The mites tend to be green rather than red, but heavy infestations lead to leaf fall and you may find a fine white webbing over the plant. Red spider mite is worse in a dry atmosphere, so check plants, damp down the greenhouse and mist plants daily. Use biological control Phytoseiulus persimilis, which eat the mites and their eggs.
Q How do I get rid of whitefly?
A Whitefly appear as tiny white flies on the leaves that fly up in clouds when disturbed. They feed on plant sap and excrete honeydew, which can encourage sooty mould. Spot problems early by putting up yellow sticky traps. If there’s an outbreak, order the tiny parasitic wasp Encarsia formosa as a biological control.
Q Why do some flowers fail to form fruit?
A Low temperatures or erratic watering can affect fruit set, so aim for consistent warmth and moisture. Mist with tepid water and ensure there’s a gentle breeze in the greenhouse to help pollination; carefully tapping plants also helps to move pollen around.
Q When’s the fruit ready to harvest?
A Pick the fruit when it’s young, firm and shiny, but note that not every cultivar is shiny. Leave them on the plant for too long and the flesh can become bitter. To reduce any bitterness, salt your aubergine slices for half an hour, then rinse before cooking.
Cut away fruits with secateurs when you harvest rather than twisting or pulling, as yanking them off will damage the stems.