How do you prevent Blight? My tomato plant leaves are going brown?

Hi Lee-Ann, Early Blight appears as yellowing lower leaves, the foliage turns brown, shrivels and dies. If caught early enough Early Blight doesn’t usually affect flowering and fruiting later in the season, Early Blight occurs during warm, humid wet weather in early spring and affects stressed plants.

Late Blight is irregular greenish-brown soft spots on the edge of the leaf. Dark patches appear on the stem of the plant, the spots grow quickly and often there is a greyish mould on the underside of the leaves or on the stem. The leaves shrivel up and die. Late Blight also causes fruit to rot if the disease is not treated, it is prevalent in warm humid wet weather, especially in late summer.

To reduce the chance of Blight affecting plants, avoid planting tomatoes and potatoes in the same spot each year, rotate crops if able, pick up any fallen leaves and dispose of in the rubbish or burn, do not compost to prevent the disease spreading as fungal spores can remain in the soil. During warm humid weather protect plants with a copper based fungicide.

Stake plants to improve air circulation, remove the lower leaves up to the first tomato truss. Keep plants consistently watered throughout the growing season and avoid overhead watering and wetting the foliage as this spreads disease. Mulch around plants to help conserve soil moisture. Make sure any cutting tools are cleaned as disease can spread from cutting infected plant material.

Tomatoes are gross feeders, they do a lot of growing in a short space of time, feed them with Tui Tomato food or Tui Superfood Tomato Liquid fertiliser to keep them actively growing, flowering and fruiting.