Hi, my passionfruit vine is covered with fruit and flowers but the leaves are turning yellow and falling off. What could be causing this?

Hi Michelle, passionfruit are a short lived vine, fruiting for 5-7 years, then it is a good idea to replant a new vine. Not sure how well established the vine is or how old it is and whether it has done well in the past or is newly planted?

There are several things that can cause yellowing leaves so it is a process of elimination. One could be sap sucking insects such as aphids or passionvine hopper, look on the underside of the leaves and you should see castings from insects or even the insects on the leaf. Talk to your local garden centre for a suitable control if you do find insect pests are the problem.

Another reason is a sudden change in temperature from hot to cold, passionfruit are subtropical fruit vines that are fussy about where they grow - a sunny sheltered spot in well drained soil is best. Overwatering to poorly drained soils can also cause leaves to yellow and drop, this leads to root rot disorders which show up as yellowing, falling leaves. Regular copper based sprays through winter and early spring until flowering starts is beneficial, but if it is a root disorder due to poor drainage or heavy clay soils then consider relocating the vine in winter.

Passionfruit put on a lot of growth in a small amount of time so need regular feeding, fertilise with either Tui Citrus Food or Tui General Garden fertiliser every 4-6 weeks throughout the growing season, if plants don't get enough nutrients the leaves will yellow. Make sure the vine is planted in a free-draining soil, water regularly in the growing season to keep the vine actively growing. Regular applications of Tui Seaweed Plant Tonic will be beneficial, mix 70-100ml in a 9L watering can and apply every 2 weeks to stimulate root growth and to improve overall plant health. Collect up the fallen leaves and dispose of in the rubbish in case they there are any insect pests or disease which can overwinter in the soil. Lianne.