have a question for the Plant Doctor regarding blight and tomatoes.
Last year I had quite bad blight on my tomatoes and was wondering
if I should not use my old wooden tomato stakes and buy new ones.
Can blight remain on the wooden stakes and infect plants the next
year? Also, is it worth adding copper to the soil when planting
tomatoes to fight against blight or is this an old wives' tale?
had exactly the same problem as you did last summer so I
asked our head of Horticulture, Ingrid Ennis (my boss!) what she
suggested. Her advice was to try to prevent the pathogen from infecting
the plants in the first place. So this year, I've avoided planting
other members of the potato family (which tomatoes are in) nearby
so no more potatoes. The neighbour's potato jasmine has also
had a good chop back, so it isn't too close to my new tomato plants.
Members of the same family can often harbour the same diseases.
I've also been growing other different vegetables in the area that
was affected, in an attempt to reduce the disease in the soil (like
a mini crop rotation). In my case, I planted lettuces, rocket, silverbeet,
and spring onions, all of which I could harvest before the tomatoes
went in. To replenish the nutrients in the soil I added compost
and sheep pellets.
Like you, I was also
worried about the stakes possibly harbouring fungi or bacteria,
so I am using new stakes this time. I am also putting down a nice
layer of pea and lucerne straw around my tomato plants not
only does this cut down on watering needs in summer, but it will
stop pathogens being splashed onto your plants when it rains or
when you water them. You can buy this straw from most garden centres.
The only drawback is that nesting birds tend to rake it up for their
I wouldn't put copper
into the soil. Too much copper is toxic to plants and it can build
up in the soil. However, a good copper spray on the foliage every
now and then is a good preventative for blight, so I will be trying
that soon (most garden centres stock several choices of spray).
Different tomato cultivars
have different levels of resistance to blight. I personally found
last summer that cherry tomatoes, such as 'Sweet 100' seemed to
have more resistance than some of the larger cultivars I was growing.
I hope this helps.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH