Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1916-07-31
cckiy Bureau Of In
formation for All Who
Till the Soil or Are In
terestcd in Making Homes
TOMATO DISEASES
PECULIAR TO VIRGINIA


1T seems advisable at this time SAYS
w. +. Thomas, assistant i'm plant path
ology aud bacterioloEy OF tho Virginia
experiment station, TO call the att"n'
ton OF tomato growers in Virginia &c
some OF the most important diseases
which arc usually observed in this
state. During recent years tomato
blights and rots have become SO Sc
rious a problem as to cause a consid
cradle number Of growers to abandon
tho culture OF tomatoes entirely. While
control measures have been worked
out to a fair degree OF satisfaction,
these diseases arc still formidable on
rr;lics of the tomato growing industry.
There arc three diseases of sufficient
economic Importance to be carefully
considered. There are Il number OF
less important troubles which occur
locally in less vigorous forms.
Black spot. or rust tmacrosporum),
is more common in the states further
South sometimes running entire crops.
1t is not uncommon in virginia and
has been reported widespread in
Botetourt County. This is a true leaf
blight. II begins as small dark spots
which later show concentric rings. Tho
spots often become one fourth inch or
ami cause the margin and tin OF the
leaf 10 curl ny. The love- leaves are
first attacked.
The carly blight. or leaf spot tsep.
toria) is more common and more de-
structive in Virgin Like the black
spot, IL attacks the lower leaves first.
and may continue upward until practi
cally all the leaves have shrivclred.
Tho leaf FIRST shows small dark spots
which later become light iii the center.
The spots rarely become as large as
small pea. No concentric marking is
seen us IN the black spot The leaves
usually wilt and remain attached to
tho stem fol some time. The two di-
seases just described usually appear
about the middle OF July and Inst until
cool weather. Warm, wet weather is
favorable 10 their development
The late blight downy mildew
(phytophthora) is the most serious
disease found on tomatoes in this State
1t does not usually appear until the
latter part of July. This is more
typical blight. attacking leaves, fruit
and stems and causing death quickly.
The fungus usually attacks the tip
of the leaf and works inward. giving
IT the appearance of having been FROST
cd When dry, it is brownish; when
wet. II is almost black, often showing
purple tint. The underSidc OF the
leaf will often show Il white. downy
covering OF the fungus threads. There
is no definitely marked spottnG as
in the black spot and leaf spot The
disease passes through the leaf to the
stem, and in damp. warm weather, will
kill All entire plant in few days
Very warm weather tends to check
the progress of the fungus. On the
fruit the effect of the disease appears
soon after il is seen on tho leaves and
stems. The stem end turns dark and
l.,-I,. at- IL, to Co., l.
duce wet rot. When not treated, this
disease frequently destroys the entire
crop.
Fortunately, all these diseases re-
spond 10 the same general program
OF treatment None OF them are known
10 live over in the seed. However. it
is easy and desirable to plant seed
from healthy fruit. especially in the
ease OF late blight. The destruction
Of old diseased plants is OF great i'm
por;ancc in preventing heavy infec-
lions from these diseases. Rotation OF
crops has not proven as valuable as
il would seem. 1t is advisable. how
ever, when II can be done conveniently
BY far the most thorough and re-
liable control is obtained by spraying
with standard Bordeaux mixture
C+-5-50 formula). which can hc pre-
pared cheapiy on any farm.
When a heavy infection is expected,
spraying should begin with the seed
bed As rule three thorough sprays
at Intervals OF fifteen 10 eighteen DAYS
Will give good control. The first spray
should hc applied n Virginia from the
10Th to the 18th OF july.
: number of varieties Of tomatoes
such as stone and Buckeye State, have
shown considerable resistance OF fun
Euous attack. Il is expected that care
ful breeding aAl' selection will produce
varieties of tomatoes which Will with
stand succcsstuNy The ravaEcs of these
diseases.