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SPOTTED WILT
A SERIOUS DISEASE IN
TOMATOES
Suggested Methods of Costra)
(By H. A. Pittman, Plant Pathologist,
Department of Agriculture.)
Spotted or bronzy wilt ¡a at prä-
sent the most serious disease te
which the tomato is subject, nat
only in Western Australia, but in
all the other States of the Com-
monwealth.
The disease is due to a very small
parasite, known as a virus, which
lives In the sap ol affected plants, and
which is transmitted from plant to
plant by means of very small insects
known as "th ri ps," in much the sante
way as malarial fever is distributed
from one diseased human being to an- j
other, by thc anophellne mosquilu. "
These insects (thrips) are about
one twenty-iifth ot an inch in length,
and are frequently to be found tn
garden flowers, such as ca niano ie,
roses, gladioli, etc.. as weil as In tlx:
ubiquitous Cape weed. in ad<l>liun
to harboring thrips. it has bown (onad
recently that a number of t;iir« -n
flower plants, such as Iceland uoi'p.cs.
I<ef"iias. zinnias. nasiurnui.is. danlu*.
ranunculi, anemones. English mari-
golds, cosmos, etc.. may become i>
fected with thc spolU-d wilt virus. tn«l
serve lo breed up the disease for the
tomato crop, or other plants later or
For many years the disease has bi-on
so serious round the metropolitan a:u
that most people have given up at-
tempting to grow lon.iitnes bf f..rc
Christmas time. Planted after t tis
time, tomatoes do not generally inlier
to anything like the &ajne exlci.t as
those planted earlier.
There is, unfortunately, no certain
way to prevent this disease, but
the following control measures will
all assist In keeping the disease, to
some extent at least, in check:
(1) Do not grow tomato plants near
flower gardens.
(2) Grow the Early Dwarf lied
variety, which is less susceptible than
most of the others commonly grown.
Do not on any . account grow thc
Dwarf Champion, which is about Ute
most susceptible variety.
(8) When planting out the seed-
lings, plant out two or thrr« slight ly
separated in each place Instead of
one.
(4) Pull out diseased plants as soon
as they are noticed, and destroy by
burning or burying deeply. Thc di-
sease does not spread at ul', rapidly hy
contact from diseased to healthy
plants.
(5) Do everything possible to keep
down thrips. such as splaying fre-
quently with Black ¿¿caf 40. ken s'-ne
emulsion, or some similar mat-rfu I.
and by using overhead watering if
possible, as the thrip ls very much en-
couraged by dry atmospheric condi-
tions. The spraying with Black Leaf
40. etc. should be commenced before
the disease appears.
There is a variety now being sold
in Perth which appears to be fairly
resistant to spotted wilt.
It is being grown in consldei ab>
quantities by several of the leading
tomato growers at Balcatta, where it is
variously known as Arbuckle"«, Rich-
ter's, and so on. It might be worth
while to obtain a packet of these seeds
and try them out- This variety, how-
ever, is very susceptible to fusarium
wilt, so that seed and seed bed disin-
fection, etc, as Indicated in leaflet
336 should always be carried out.
As the disease is not due to any
fungal parasite, lt ta lmpossiblo to
prevent this trouble by spraying with
Bordeaux mixture or any similar
fungicide. »
Leaflet No. 836, "Seed and Seed Bed
Disinfection," can be obtained free of
charge on application to the Depart-
ment of Agriculture,
$