HAVE a problem with my tamarillo tree. The new leaves grow well
but as they get bigger they become mildewy and drop off. I keep
it well fed with compost, washed seaweed and occasional banana skins.
The fruit used to be very gritty but it has improved. Can you help
with the mildew?
problem is powdery mildew, of which there are several different
species, each affecting a specific range of plants. Powdery mildew
spores germinate in warm, humid weather, so the disease is at its
worst during summer. With tamarillo, it usually starts as white
powdery spots which spread, eventually causing black patches, leaf
yellowing and leaf drop.
As you can't control
the weather, the next best way to control powdery mildew is to spray
in spring before the first infection gets established and follow
up with regular sprays at 2-3 week intervals. There are many fungicides
you can choose from, including Fungus Fighter, Super Sulphur, Bravo
and Fungus & Mildew Spray. Some gardeners use a home-made remedy
by mixing 1 teaspoonful of baking soda in 1 litre of water and adding
1ml of dishwashing liquid, though you need to apply this at weekly
intervals for it to have much effect. There are also reports that
spraying regularly with seaweedbased foliar fertiliser may reduce
the severity of powdery mildew attack.
With all these sprays
you need to get good coverage over the upper surface of the foliage,
particularly the new leaves which, with a large tamarillo tree,
can be quite difficult. But don't despair, even if you don't spray,
you should still get reasonable quantities of fruit, and in some
years the effects of the mildew will be much less than others. You're
keeping the tree well fed and watered, which will also help reduce
the effects of the disease.
Gardener, Issue 183, 2005, Page 31
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.