1. I am losing
about half of my tomato crop because of fruit rot. Sunken round spots develop
over the ripening fruit. The spots enlarge rapidly in warm weather. What can be
done?
Answer: There are a
number of tomato fruit rots. The majority, including anthracnose which you
apparently have, can be controlled by staking the plants or using a tomato cage
in the spring and mulching with grass clippings or leaves, to get the fruit off
the damp ground.
In addition, spray at seven to ten day intervals using maneb, zineb,
captan or a multi-purpose vegetable or tomato spray containing one of these
fungicides. Follow the manufacturer’s directions.
These materials will also control the common and destructive foliage
blights. Spraying should generally start when the first fruit clusters are the
size of walnuts.
2. The older and
lower leaves on my tomato plants are spotted, turning yellow and dropping off.
I’m afraid the fruit will sun scald. What sprays do you recommend?
Answer: Tomato
blights are often controlled by spraying at seven to 10 day intervals
throughout the season, starting when the first fruits are about one inch in
diameter.
Use a maneb or zineb fungicide. You can also buy a multi-purpose
tomato or vegetable spray containing one of these materials. Sprays are more
effective than dusts. Be sure to spray the undersides of the leaves. In
addition:
- Buy certified, disease-free
transplants.
- Keep down weeds.
- Space plants for good air
movement.
- Destroy or bury plant
refuse in the fall since the blight-producing fungi overwinter in this
refuse.
- Stake and mulch plants
3. About a month
ago I planted tomato seed which I kept in the basement until germination took
place, then moved the container to a kitchen window. When the seedlings were
about 2 inches high they all flopped over. JW, PA
Answer: Your
seedlings were affected by what is called “damping-off“, prevalent where there
is too much moisture and poor ventilation.
Sow seeds in a mixture of equal parts loam, leafmold, and sand or
buy a good bagged seed starting mix.
A simple method of sterilizing soil before sowing is to fill the
containers with the mixture. Water with boiling water a day or two before
sowing the seed. Containers should be well drained.
4. For several
years we have had blight on tomato plants. The leaves curl under and the fruit
has white spots. What could he causing this? LR, Kansas
Answer: Tomatoes are
attacked by fruit spots, wilts and blights. One of the most prevalent and
hardest to control is fusarium wilt.
At first the leaves curl, later turn yellow and die. This disease
usually appears about the time the first fruits are ripening and starts at the
base of the plant. The wilt moves up the plant finally destroying the entire
plant and the fruit.
Nothing can be done once a plant is infected by wilt. Another season
plant the tomato plants in a new location, using so-called wilt resistant
varieties.
5. Why do
tomatoes grow good vines but bear no tomatoes? For two summers this has
happened in my garden on ground where strawberries were formerly grown. LV,
Iowa.
Answer: Too much
nitrogen in the soil, too much shade, plants too close together and inferior
seed are some causes of a scarcity of fruit on tomatoes.
If the temperature is low and the weather wet when tomatoes start
blooming the blossoms are not pollinated and the fruit does not set. Later if
the temperature becomes hot, above 100 degrees, the pollen is killed and fruit
does not form.
Usually there is sufficient good weather for the plants to set a
crop of fruit sometime during the blooming period.
6. The leaves on
my tomato plants are mottled with a yellowish green to dark green pattern. The
leaves are curled, crinkled and puckered. The plants as a whole appear stunted
and bunchy. Have I done something wrong?
Answer: Your tomatoes
appear to have a virus disease – probably one in the mosaic complex. Sometimes
the symptoms closely resemble 2,4-D injury with narrow, spindly,
shoestring-like leaves.
Fruits are often reduced in size and number. Check mosaic by controlling
the aphids (plant lice) which transmit the causal virus (es). Destroy the first
infected tomato plant when found.
Keep down all weeds growing in and around the garden area. Set out
disease-free certified transplants, when possible. If a smoker, wash your hands
thoroughly with soap and hot water before handling healthy plants. The same
viruses may be in the tobacco you smoke!
7. The last two
years I lost nearly half of my tomatoes because of a kind of dry rot. The
bottom of the tomato would start rotting while it was still green and by the
time it was ripe it was rotten all over. Is this a disease or a soil
deficiency? What can be done?
Answer: This disease
is called blossom-end rot. Its appearance is first noticeable around the dried
up blossom and gradually enlarges, taking on a black colour.
The disease is caused by conditions adverse to the normal growth of
the plant. An uneven water supply seems to be the cause of this trouble.
Irrigation will completely control it if properly used.
It is most troublesome in a year of moisture extremes and affects
plants that have been pruned and staked more than plants left undisturbed.
8. Last spring I
grew fine tomato plants with lots of bloom but they all fell off. What caused
that and what can be done for it?
Answer: Bud drop of
tomatoes may be caused by either extremely hot or cold weather just at
blossoming time. Then too, excessive rains may actually wash away the pollen.
These causes for bud drop are not controllable. Another common cause
of this trouble is excessive nitrogen. Under ideal growing conditions, on a
soil that contains excessive nitrogen, tomatoes make a heavy vegetative growth
and refuse to set fruit.
The remedy is to plant tomatoes on soil that is not too rich.
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