Tomatoes Q&A

Tomato (40 Questions)

1. Q. When should I start my seed indoors to produce tomato transplants for my garden?

A. Depending upon temperature and how the plants are grown, it takes from
6 to 8 weeks to produce a healthy, 6-inch tall transplant for setting out in
your garden. The plants should be grown in a warm area and receive 6 to 8
hours of sunlight daily or tall, poor quality, leggy plants will result.

2. Q. How do you select good transplants at nurseries or garden centers?

A. First, select the Extension recommended varieties of transplant
whether it be tomatoes, peppers, eggplant or broccoli. Also, look for plants
that appear healthy, dark green in color, and do not have any spots or holes in
the leaves. The ideal tomato, pepper or eggplant transplant should be just
about as wide as it is tall. Avoid tall, spindly plants.

3. Q. How often should my tomatoes be fertilized?

A. It is necessary to fertilize the garden before planting tomatoes.
Apply the fertilizer again when fruit first sets. From that point on, an
additional fertilization (sidedress) every week to 10 days is recommended.
Plants grown on sandy soils should be fertilized more frequently than those
grown on heavy, clay soils. A general sidedress fertilizer recommendation is
one to two tablespoons of a complete fertilizer scattered around the plant and
worked into the soil. If using a fertilizer high in nitrogen such as ammonium
nitrate or sulfate, reduce the rate to one tablespoon per plant.

4. Q. Should tomato plants be staked, caged or left unsupported?

A. Tomatoes should be supported. Whether you cage or stake them is
personal preference. Regardless of the method, plants with foliage and fruit
supported off the ground will produce more than unsupported plants. Caging has several advantages. It involves less work than staking. Once the cage is placed over the plant there is no further manipulation of the plant – – no pruning, no tying. The fruit are simply harvested as they ripen. In many areas, staking and pruning of the plant to a single or multiple stem results in sunburn when the developing fruit is exposed to excessive sunlight. Other advantages of caging over staking include protection of fruit from bird damage
by more vigorous foliage cover and less fruit rot. Caged tomato vines produce more fruit of a smaller size, but staked and tied plants produce less fruit which mature earlier yet are larger.

5. Q. My tomato plants look great. They are dark green, vigorous and healthy. However, flowers are not forming any fruit. What is the problem?

A. Several conditions can cause tomatoes to not set fruit. Too much
nitrogen fertilizer, nighttime temperatures over 70 degrees F., low
temperatures below 50 degrees F., irregular watering, insects such as thrips
or planting the wrong variety may result in poor fruit set. Any of these
conditions can cause poor fruit set, but combinations can cause failures. If
Extension recommended varieties are used , the main reason tomato plants do not
set fruit is because they are not planted where they can receive 8-10 hours of
direct sunlight daily. Any less direct sunlight will result in a spindly
growing, nonproductive plant with healthy foliage.

6. Q. Are there really low-acid tomato varieties?

A. There are some varieties that are slightly less acidic than others,
but this difference is so slight that there is no real difference in taste or
in how the tomatoes should be processed. Some yellow-fruited types are
slightly less acidic than the normal red varieties, but not enough to make any
difference. Research conducted by the USDA indicates that all varieties
available to the home gardener are safe for water bath processing as long as
good quality fruit are used. Flavor differences which exist between varieties
are not because of differences in acid content, but balances of the sugar to
acid ratio.

7. Q. Some tomato varieties are recommended because they are determinate and fast maturing. What does determinate mean and can you tell if a tomato is determinate by looking at it?

A. Determinate means the plant is small. Determinate tomato varieties
seldom are more than 5 to 6 feet tall. A determinate vine is distinguished by
a repeating pattern of two leaves followed by a flower or fruiting cluster. An
indeterminate vine has a repeating pattern of three or four leaves, then a
cluster.

8. Q. Can I save seeds from my tomatoes from next season’s plantings, and if so how?

A. You can save seed from tomatoes if the variety is not a hybrid.
Hybrid tomatoes do not come true from seed. The plants and fruit from seed
saved form your home garden may or may not resemble the parent. Chances are the
fruit will be poorer quality and the vine characteristics will not be the same
as the parent plant. However, for true breeding varieties, such as Homestead,
it is easy to save seed. To save seed from tomatoes or any other home
vegetable fruit crop, leave the fruit on the plant until it is mature, pull
it, squeeze juice with seed into a glass, let this ferment for two days
adding water if needed. Rinse the seeds two or three times to remove debris.
Seeds will settle to the bottom. After rinsing the seeds, blot them and place
them in the sun to dry. Store the seeds under cool, dry conditions.

9. Q. When caging tomatoes, how large should the cage be?

A. The diameter of the cage should be at least 18 to 20 inches. Smaller
cages often restrict plant growth and reduce yields. Height of the cage will
vary but generally 2 feet is sufficient for the recommended varieties.
However, if vining types such as Better Boy, Homestead or Terrific, are used a
cage 5 feet in height is preferred. Regardless of variety, the 2 foot tall
cage is sufficient for most fall garden tomatoes.

10. Q. How do you stake tomatoes?

A. Staking involves pruning or suckering the plant to either one or two
main stalks. Tomatoes grown without support develop a bush shape. However, if
the plant is to be trellised or staked, it must be pruned to a single or double
stalk. The small suckers which develop between the axil of the leaf and the
stem are removed to develop a vine structure rather than a bush. A wooden
stake an inch in diameter and 6 feet long is driven into the ground beside the
plant. Do not damage the root system when inserting the stake in the ground.
The stalk of the plant is loosely attached to the stake as it grows. The plant
can be attached to the stake with twist-ties, soft string, strips of cloth or
panty hose. The plant is sufficiently supported if it is attached to the
stake at 12 to 14 inch intervals. Continued suckering to prevent the plant
from developing more than one or two central stems. If a double-stalk plant
is desired leave the sucker produced above the first flower cluster since it
will be the most vigorous.

11. Q. What causes a tomato to crack? Is there anything I can do to prevent it?

A. Cracking is a physiological disorder caused by soil moisture
fluctuations. When the tomato reaches the mature green stage and the water
supply to the plant is reduced or cut off, the tomato will begin to ripen. At
this time a cellophane-like wrapper around the outer surface of the tomato
becomes thicker and more rigid to protect the tomato during and after harvest.
If the water supply is restored after ripening begins, the plant will resume
translocation of nutrients and moisture into the fruit. This will cause the
fruit to enlarge; which in turn splits the wrapper around the fruit and results
in cracking. The single best control for cracking is a constant and regular
water supply. Apply a layer of organic mulch to the base of the plant. This
serves as a buffer and prevents soil moisture fluctuation. Water plants
thoroughly every week. This is especially important when the fruits are
maturing. Some varieties are resistant to cracking, but their skin is
tougher.

12. Q. What could cause the leaves of my tomatoes to turn brown along the edges?

A. Leaf-burn or scorch generally indicates root injury, quite often
caused by heavy amounts of fertilizer applied too near the roots. This injury
often results in browning and die back of the ends and margins of the leaves.
Other possible causes are root injury caused by nematodes, insects or physical
injury by cultivation. Also overwatering or underwatering along with diseases
might cause leaf-tip burn.

13. Q. About the time my tomatoes ripen and turn red, I lose at least half my crop to bird damage. What can prevent this?

A. Bird damage is common in all areas. One control method which works
quite well is to take old nylon stockings and cut them into pieces 10 to 12
inches long. Tie a knot in one end of the stocking and slip the open end over
the entire cluster of tomatoes. Secure the end above the tomato cluster with a
rubber band or twist-tie. Birds will not be able to peck through the nylon.
Slip the stocking off the cluster and harvest the ripe fruit and replace it to
protect later-ripening fruit. Also, birds damage fully mature fruit more
readily than breaker or pink fruit. Harvest in breaker or green-wrap stage.
Gardeners have tried many ways to reduce bird damage. Scarecrows, aluminum
strips, tin foil plates and noisemakers will work until the local birds become
accustomed to seeing or hearing them. Fabric covering materials such as
Grow-Web and Reemay can also be used as a barrier mechanism.

14. Q. What causes the black spots on the bottom of my tomatoes?

A. Blossom end rot, caused by improper (fluctuating from too dry to too
moist) moisture. Maintain uniform soil moisture as the fruit nears maturity.
Remove affected fruit.

15. Q. What causes tomato leaves to curl?

A. The exact cause of tomato leaf roll is not fully known. Tomato leaf
roll appears about the time of fruit setting. The leaflets of the older leaves
on the lower half of the tomato plant roll upward. This gives the leaflets a
cupped appearance with sometimes even the margins touching or overlapping. The
overall growth of the plant does not seem to be greatly affected and yields are
normal. This condition appears to be most common on staked and pruned plants.
It occurs when excessive rainfall or overwatering keeps the soil too wet for
too long. It is also related to intensive sunlight which causes carbohydrates
to accumulate in the leaves. Some varieties of tomatoes are
characteristically curled.

16. Q. What causes some of my early tomato fruit from the spring garden to be oddly shaped and of poor quality?

A. This condition is usually caused by low temperatures during bloom and
pollination. Fruit that set when temperatures are 55 degrees F. or below
often are odd-shaped and of poor quality. The blooms these tomatoes develop
from often are abnormal because of temperature conditions and grow into
abnormal, odd-shape fruit.

17. Q. Do products which are supposed to aid in setting tomatoes really work and if they do, how should they be used?

A. These hormonal products are designed to substitute for natural
pollination. These products work better when tomatoes are failing to set
because of too cool temperatures. Tomatoes which set after use of these
products will be puffy and have less seed.

18. Q. What is the plant advertised as a tree tomato?

A. The tree tomato is a member of the Nightshade family. The regular
tomato belongs to the same plant family but is a different species. The tree
tomato has the scientific name Cyphomandra betacea. Like the true
tomato, it is a native of Peru. It is grown in market gardens there and in
several subtropical countries including Brazil and New Zealand. The tree
tomato is woody, grows from 8 to 10 feet tall, bears fruit 2 years after
seeding and may continue to bear for 5 to 6 years. They are not winter hardy
except in southern areas and would need to be taken inside over winter. Fruits
of the tree tomato are oval, about 2 inches long and change from greenish
purple to reddish purple when fully ripe. The fruits are low in acid and the
flavor is moderately agreeable. Some varieties of the tree tomato produce
bright, red fruits. The fruits can be used in stew or preserves after the
tough skin and hard seeds are removed.

19. Q. Should you allow tomatoes to become fully ripe and red on the vine before harvesting?

A. Generally, yields will be increased by harvesting the fruit at first
blush or pink instead of leaving them on the plant to ripen fully. A tomato
picked at first sign of color and ripened at room temperature will be just as
tasty as one left to fully mature on the vine. Picking tomatoes before they
turn red reduces damage from birds.

20. Q. If tomatoes are picked green or before they are fully mature, how should they be handled to insure proper ripening and full flavor?

A. Never refrigerate tomatoes picked immature. Place them in a single
layer at room temperature and allowed them to develop full color. When they
are fully ripe, place them in the refrigerator several hours before eating.
Those handled in this manner will be of high quality and full flavor.

21. Q. What is a husk tomato?

A. Husk tomato is also called Ground Cherry, Poha Berry or Strawberry
Tomato. It is grown the same way as regular tomatoes and produces a fruit the
size of a cherry tomato. The fruits are produced inside a paper-like husk
which, when ripe, turns brown and the fruit drops from the plant. If left in
the husk, the fruit will keep for several weeks. Like tomatoes, they are
sensitive to cold weather and should be set out from plants after all danger of
frost in the spring. Space the plants 1 feet apart in rows at least 3 feet
apart. When ripe the small fruit can be used in pies, jams or may be dried in
sugar and used like raisins.

22. Q. I have the best tomato crop I have ever had, but the large tomatoes are falling off the vines. Even the ones that stay on the vine are jarred off easily. What is the problem?

A. Cool fall temperatures cause the abscission zone, the area where the
tomato is attached to the plant to weaken, and the heavy fruit subsequently
falls. Gather fallen tomatoes as soon as possible, wipe them clean and store
them in a warm place to ripen. These aborted tomatoes will rot if left on
the ground.

23. Q. I have large translucent areas on my tomato fruit. What’s going on?

A. This is an environmental problem. The translucent areas are sun
scalds. Heat from direct intense sunlight destroys the color pigments of the
tomato. This damage does not make the tomato inedible.

24. Q. Can I propagate tomatoes for the fall garden from spring- planted vines?

A. If quality transplants of Extension recommended varieties cannot be
found, use suckers or layering (cover with soil until roots appear) of existing
vine. Do this several weeks before the recommend transplanting date for fall
tomatoes, and use early-maturing tomato varieties.

25. Q. Can spring-planted tomatoes be cut back in late summer or early fall resulting in renewed growth and increased production until the first killing frost?

A. This can be done in some areas, especially in the southern parts.
However, the plants must be healthy and free of insect problems. Trying to
carry an unhealthy plant through the summer into the fall usually means
disaster. If the plants are to be cut back, avoid removing too much of the
foliage since hot weather can burn the plants to death. After pruning, apply
additional fertilizer and water to renew growth and increase tomato production
well into the fall.

26. Q. How do you tell when a green tomato harvested early to prevent freeze damage will ever turn red and ripen?

A. This can simply be done with a sharp kitchen knife. Harvest a tomato
typical of the majority of green tomatoes on your plants. Look at size but pay
particular attention to fruit color. Slice through the center of the tomato.
Closely examine the seed within the fruit. If the seeds are covered with a
clear gel which cause them to move away from the knife, then that fruit will
eventually turn red and ripen. If the seeds are cut by the knife then those
fruit will never properly ripen. Compare the color and size of the tested
fruit when harvesting tomatoes on your plants. Most similar fruit will
eventually ripen and turn red.

27. Q. Is a tomato a fruit or a vegetable.

A. The tomato is legally-declared a vegetable by the Supreme Court of the
United States. A vegetable is a herbaceous (non-woody) plant or plant part
which can be eaten without processing and is usually consumed with the main
meal.

28. Q. The foliage on my tomatoes is infected by irregularly- shaped spots which cause it to turn yellow and drop off. This occurs in all seasons and is on the top as well as the bottom leaves.

A. Several types of leaf spots will attack tomatoes. Septoria leaf spot
is seen quite often. It can be controlled with a combination chlorothalonil
and benomyl (Benlate) spray program. Begin the spray program early in the life
of the plant. Apply chlorothalonil every 7 to 10 days adding benomyl every
second spray (14 to 20 days)if humidity is high or rain and dew cause wet
foliage.

29. Q. The leaves on my tomato plants are distorted. Why?

A. This is a mosaic virus. If the virus is severe, remove the plants to
prevent spread to other plants. Many viruses are insect transmitted and are
difficult to control even with insecticides.

30. Q. My tomato plants are stunted and have a pale yellow foliage. The root system has knots or swellings on the roots.

A. These are root knot nematodes. Varieties such as Celebrity, Better
Boy and Small Fry resist this problem. If other varieties are to be grown
nematode populations must be reduced. Root knot is a species of nematode
which causes galls or swellings on plant roots. It restricts the uptake of
nutrients from the root system to the foliage, resulting in a yellow and
stunted plant. Root knot lives in the soil and can survive on a number of weed
and vegetable crops. It is best controlled by planting a solid stand (close
enough for root systems to overlap) of marigolds three months before the first killing frost of fall and/or planting cereal rye (Elbon) for a winter cover
crop. Cereal rye should be shred and tilled into the soil 30 days before
planting a spring crop. Nematode resistance is indicated by the letter N
after the tomato name. Example: Celebrity VFN.

31. Q. My tomatoes were healthy during the spring and early summer, yet after a recent rain, they wilted and died very rapidly. I found a white fungal growth at the base of the plant.

A. This is southern blight. It is a soilborne fungus and lives on organic
material in the soil. Terrachlor used as a preplant treatment will reduce this
problem. Also, the deep burial of undecomposed organic material in the soil
will reduce the problem. Control foliage diseases on tomato plants because the
fallen leaves around the base of the plant will feed the fungus, and it will
build up in this area and cause damage later. Crop rotation will also reduce
southern blight.

32. Q. My tomato plants wilted rapidly. When I cut the stem open, I found a brown ring around the inside.

A. This is Fusarium wilt. It is a soilborne fungus that attacks tomatoes
and other crops. It is controlled only through the use of resistant varieties.
Most commercial tomato varieties are resistant. Before you plant a variety,
make sure it is resistant to Fusarium wilt. This resistance is denoted by the
letter F after the name. Example: Celebrity VFN.

33. Q. What do the letters “VFN” associated with particular tomato varieties indicate?

A. VFN indicates the tomato variety is resistant to three types of
diseases; Verticilum wilt, Fusarium wilt and nematodes. Many of the new hybrid
varieties are VFN types. Disease resistant varieties preferred in areas of
Texas where these problems are severe and cause great losses to home
gardeners.

34. Q. The lower foliage on my tomatoes is beginning to turn yellow and drop. The leaves have circular, dark brown to black spots.

A. This is Alternaria leaf spot or early blight. It is a common problem
on tomatoes and causes defoliation, usually during periods of high rainfall.
Plant tomatoes on a raised bed to improve water drainage. They can be spaced
enough so air can move, dry the foliage and prevent diseases. Follow a spray
program using daconil beginning when the fruit is set and continuing at 1- to
2-week intervals during the growing season until harvest.

Insects

35. Q. My tomato fruit have small yellow specks on the surface. When the fruit are peeled, those yellow specks form a tough spot that must be cut off before eating the tomatoes. What’s wrong?

A. Your problem is not of a varietal origin. The yellow speckling is
caused by sucking insects such as stinkbugs or leaf- footed bugs. Early
control of sucking insects that feed on the fruit is helpful in alleviating the
problem.

36. Q. We planted tomatoes in our small garden. They are loaded and are the best tomatoes we have ever had; however, there are some small holes near the stem end of the tomato. When we cut the tomato open, there is a small worm inside. What is it and what can we do?

A. You have been invaded by the tomato pinworm. They usually do not
damage all fruit and can be controlled only by a preventive insecticide spray
every 7 to 10 days. When the damage is evident, it is too late to do anything
about it.

37. Q. What causes my tomato leaves to turn yellowish and fall off?

A. Many conditions may cause these symptoms including spider mites,
diseases and nutrient deficiencies. Examine the underside of the leaves for
small red to greenish mites. If mites are found, treat with Kelthane,
malathion or sulfur dust. Make two to three applications at 5-day intervals
for best results.

38. Q. On some of my ripe tomatoes I have discovered
small holes with numerous ants in them. I was unaware that ants could do this
to tomatoes. How can I control them?

A. Ants aren’t really your problem. They are just attracted to the
moisture in the holes which were caused by other insects. A likely culprit is
the tomato fruitworm, also known as the corn earworm. Bt (Bacillus
thuringensis) is a nontoxic biological control which you can apply to the
plants.

39. Q. My tomatoes wilted and died soon after they bloomed. Last fall I had the soil tested and followed the recommendations. I didn’t notice any insects on the tomatoes, and none of the other plants growing in that area were
affected. The plants were in full sun, though one limb from a black walnut
tree which is about 20 feet from the garden reaches over that corner at about
30 feet above the ground. Could the slight shade from this branch cause such a
severe problem?

A. The branch is not the cause of your problem, but the tree it is
attached to probably is. Roots of black walnut and butternut trees release a
substance called juglone which kills roots of sensitive plants. Tomatoes
happen to be among the most sensitive, and should not be planted within at
least 50 feet of these trees. Juglone is emitted from living and dead roots
and can persist in the soil for over a year, so avoid areas where juglone
producing trees have grown for two to three years after removing the trees.

40. Q. What is disease resistance?

A. Disease resistance is the ability of a plant to withstand attack from disease causing organisms such as bacteria, fungi, or viruses. The extent of resistance can vary from being strongly resistant to infection to being only somewhat more tolerant of the disease than standard varieties. Resistance is not immunity. Improper culture of a resistant variety may negate that resistance.

A. Plant breeders have a tough job to breed disease resistance into crops because there are so many diseases and often several strains of a given disease. What is often done is to select the disease that causes the most problems and work on breeding resistance to that disease. Seed catalogs and packets indicate what, if any, disease resistance a variety has in descriptive text or with initials following the variety name.

Disease resistance in tomatoes indicated by initials include:

V – Verticillium wilt

F – Fusarium wilt (F1, race 1; F2, race 2)

N – nematode

T – tobacco mosaic virus

A – Alternaria alternata (crown wilt disease)

L – Septoria leafspot

Source Texas AgriLife Extension Service, Texas A&M System

Tomato Growers supply company has a website that I often use as a reference when looking for seedlings and seed at my local nursery.
Along with a good quality picture they also give a short description of it’s mature appearance, days to maturity and a bit of other useful information on each variety offered.
They have more than 500 varieties of tomatoes and peppers, including huge selections of both hybrid tomato seeds and heirloom tomato seeds.

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