I received this small booklet with my subscription to Organic Gardening
awhile back. It has 300 super tomato tips.
Tomato Disease Troubleshooting;
BACTERIAL WILT, BROWN ROT
Range: Most of the southern US, from MD to TX.
This bacterium can live in your soil for six years and may infect only a few
plants at a time, leaving the others unaffected. The disease enters through
the roots, causing the whole plant to wilt, beginning with the top leaves.
The plant stops growing, the insides of its stems become dark brown and
water soaked and the main stem near the soil line starts to decay.
Observe a long, 4-5 year rotation, and destroy infected plants promptly,
Plant early in well-drained soil to avoid the disease's most encouraging
conditions; young plants with wet feet. Venus and Saturn varieties are
CURLY TOP, WESTERN YELLOW BLIGHT
Range: Normally, the western US, especially arid and semiarid regions, and
wherever sugar beets are grown.
This virus overwinters in perennial plants. Beet leafhopper larvae pick up
the virus and transmit it to tomatoes when they mature. The new growth on
infected plants will be twisted and curled. The leaves become yellow and
stiff, and the flowers are malformed. The small amount of fruit produced
will ripen prematurely.
In warm climates, pull the infected plants and try a second crop. Avoid
planting the second crop (or next year's tomatoes) near beets. Wrap tomato
plants in cheesecloth or fabric row cover, leaving the tops open, to
Range: Most of the US, especially the New England, central, mid-Atlantic and
southern states. The optimal temperature for the spread of the disease is
Fungal spores, which can remain viable for more than a year, overwinter on
host weeds and plant debris. Tomatoes are most susceptible to infection
when they begin to set fruit. One-half inch, brown to black spots develop
on lower leaves. The lesions may be round or angular in shape, with shadowy
concentric rings. As these spots produce new disease spores of their own,
leaves wither and die. The damage often continues until the entire plant is
Full sun and ample space between plants are essential. Rotate crops and
keep new plantings at least 200 feet away from previous years' plantings.
Avoid early maturing varieties, which are very susceptible. You can slow
the progress of the disease by picking off the bottom leaves as they brown.
The plants will continue to bear, and there's nothing wrong with eating the
Range: Most of US, especially the central and southern states (east of the
Mississippi and south of the Ohio rivers). Hot weather (80-95 degrees)
The fungus overwinters in the soil and can remain there for several years.
It enters tomatoes through root wounds. Lower leaves turn yellow, wilt and
drop off. Just after fruit set, the entire plant may turn yellow and die.
The fruit usually decays and drops. The roots appear discolored and rotted
and dark streaks develop inside the lower stem and roots.
If the plant continues to produce fruit that ripens, you can eat it. But if
your soil has fusarium fungus in it, it probably always will. Your best
recourse is to plant resistant varieties - designated by the letter "F"
after the variety name. Choose plants and seeds that are certified disease
free, and plant in fertile, well-drained soil. Low potassium coupled with
high nitrogen can encourage the disease.
LATE BLIGHT, BUCKEYE ROT
Range: Most severe in the eastern US during periods of cool, damp weather.
Generally occurs when temps range from 60-70 degrees.
The fungus overwinters in soil that contains plant debris. Potato
volunteers (or infected potato seed pieces) can spread the disease to
tomatoes. In early summer, spores become windborne. The first symptoms of
disease include dead, brown areas on the leaves near the base of the plant.
When plants are more mature, circular or oval-shaped, greasy looking rot
spots appear on the green fruit. By late summer, the plants have only a few
As with early blight, you can slow the disease (but not much) by picking off
infected leaves. And the plants will produce some fruit, which is edible.
To avoid the disease next year, don't plant tomatoes near potatoes or in
soil where potatoes were grown the year before. Provide lots of air
circulation and full morning sun. Stake or cage plants to keep fruit high
off the ground. Wet only the root zone when watering plants.
SEPTORIA LEAF SPOT
Range: Almost everywhere tomatoes are grown. Thrives in damp weather, when
temps are 60-80 degrees.
The fungus overwinters on tomato debris and weeds. At first, one-sixteenth
to one-eighth inch light spots with dark margins will appear on lower
leaves. The spots are smaller and more numerous than those of early blight.
Later, a sprinkling of black dots appears within the spots. Affected leaves
eventually wither and die.
As soon as you see these signs, break off infected leaves to keep the spores
from spreading, especially during cool, wet periods. When the weather turns
hotter, the disease usually is checked naturally. Space plants widely to
improve air circulation. Maintain a one to two year rotation. Control host
weeds (including jimsonweed, horse nettle and morning glory) and grow only
varieties that are suited to your climate.
TOBACCO (TOMATO) MOSAIC VIRUS
Range: Most of the US.
The virus overwinters in weeds and soil and can be seedborne. It is readily
transmitted by human activities such as suckering and tying tomato branches.
Infected leaves become mottled with yellow green and dark green mosaic
patterns, and they also may become wrinkled. Plants become yellow and
stunted. Long dark streaks may develop on the stems, along with brown
sunken rings on the fruit.
Destroy infected plants promptly. To avoid the disease next year, use
certified disease free seeds and transplants. If you know the disease is
present in your garden, dip your hands in a half and half mixture of milk
and water when transplanting, trellising or touching tomatoes, suggests the
staff at PetoSeed, a plant-breeding company in Saticoy, California.
TOMATO SPOTTED WILT
Range: Particularly serious on the West Coast, it is increasingly seen in
the southern, central and eastern US.
A virus that overwinters in weeds, tomato spotted wilt is picked up by onion
and other thrips and transmitted to tomatoes, especially in hot, damp
weather. Bronze, ringlike spots appear on leaves, and plants become
stunted. Yellow mosaic patterns may appear on leaves, and fruit may show
rings of pale red, yellow or white.
You can prevent the disease by wrapping tomato cages loosely in fabric row
cover to discourage feeding by thrips. Thrips are also discouraged by
aluminum - surface mulch.
Range: Most of the US, especially the northern states. Optimal temps are
The fungus overwinters in soil and enters plants through breaks in the
roots. When first affected, plants will wilt in midday, but perk up at
night; each day the wilting becomes worse. Large stems near the base of the
plant will show dark streaks inside. Plants usually wither and die shortly
after fruit set.
As with fusarium wilt, if the plant continues to produce fruit that ripens,
you can eat it. Also, as with fusarium, if your soil has verticillium, it
probably always will. Grow one of the many resistant tomato varieties
designated by the letter "V" after the variety name. Rotations are useful,
but the benefits are limited because many plants host the fungus. Since
strawberries, peppers, eggplants, and potatoes are well-known alternate
hosts, do not follow these crops with tomatoes in your rotation scheme.
Hope this helps some in identifying tomato diseases.
Zone 7b - North Carolina
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