General information on tomato growing
Tomatoes are Americans
favorite fruit. Tomatoes are a fruit
even though most of us prefer to use them as a vegetable. If you are a gardener chances are
you are growing tomatoes. There is nothing
like the taste of a vine ripened tomato - those hard supermarket things sold as
tomatoes are no match. And tomatoes are
an easy start for beginning vegetable gardeners. They can even be grown in containers and
hanging baskets.
Tomatoes are native to South
America. When they were brought back to
Europe by early explorers they were first grown as ornamental plants and were
considered to be poisonous. And all parts of the plant except the fruit are
poisonous. It took many years before
they became part of local cuisine but now most countries of the world have
popular dishes that feature tomatoes.
Tomatoes are actually tender
perennials and in tropical zones or a sunny greenhouse they can grow for
several years. Most gardeners
however, treat them as annuals; planting them after the last frost in the area
and letting the first hard frost kill them.
Tomato flowers are yellow
shooting star like blooms born in clusters. Tomatoes can be pollinated by
insects or by vibration of the plants which knocks pollen off to land on nearby
flowers. Tomato fruit starts off green and although red tomatoes are the most
familiar and the most popular, ripe tomato fruit can be any color but
blue.
The stems of tomato plants
have the ability to produce roots from tiny bump like nodes anywhere the stems
touch the soil. Tomato plants can be
anywhere from 2 feet high to over 6 feet high.
The leaves of tomatoes are somewhat variable. There are two main types- normal and potato
leafed varieties. A few unusual leaf
forms do exist. Indeterminate tomato
plants keep growing and producing fruit until killed by frost but determinate
plants, reach a set size then ripen all of their fruit in a short time.
Tomato connoisseurs will tell
you that each variety of tomato has a slightly different taste. What all varieties have in common is that
the best tomato flavor develops when fruit is allowed to ripen on the
vine. However, tomatoes are different
from many other vegetables and fruit in that they will continue to ripen after
picking, if the fruit is mature size and just starting to change color when
picked.
Growing Tomatoes
Most gardeners buy
transplants to plant in the garden after the soil is warm and there is no
danger of frost. Choose tomato plants
with dark green leaves that are sturdy looking.
Plants in cell packs should not have blooms or fruit, these plants are
stressed. If the plant is in a large
container it is fine if it has blooms and fruit.
If you want some of the
hundreds of unusual and heirloom varieties of tomatoes then you will probably
start with seeds. Plant the seeds indoors about 6 weeks before you expect your
last frost. Plant the seeds in sterile
seed starting mix and keep them warm- above 70 degrees for best
germination. Tomato seedlings need the
brightest light possible, a sunny greenhouse or windowsill or grow lights. After all danger of frost has passed, choose
a shady day to transplant into the garden or shade the plants with something
for a few days and keep well watered. If
tomato plants you bought or grew are tall and lanky, you can bury the stem of
the tomato up to the second set of leaves and the stem will develop roots.
Tomatoes like rich, loose
soil and must have full sun for best fruit development. The location where you plant tomatoes should
be changed every year to avoid the build up of soil born disease. Tomatoes should never be planted where the
roots of a Black Walnut tree may invade their root space, as this will kill
them. They are also heavy feeders, and
using a fertilizer formulated for tomatoes is recommended.
Tomatoes have less disease
problems and take less space if they are caged or staked. Use sturdy cages or use stakes and tie the
plants to them. Put the stakes or cages
in when you plant the tomatoes to avoid injuring the plant later. Prune off any branches or leaves that touch
the ground. If you do allow the plants
to sprawl on the ground, mulch under the plants with plastic or straw and leave
at least 3 foot of space between plants and 4 foot between rows.
Always water tomatoes at the
base of the plant and try to avoid getting foliage wet. This helps prevent fungal diseases. Water tomatoes early enough in the day so
that foliage dries before dark. Water
deeply once a week rather than frequently, but if plants wilt and the soil
feels dry they should be watered regardless of how long it’s been. Don’t over water- tomatoes do not like soggy
soil.
In early September gardeners should pinch off any new growing tips and flowers that develop on
their indeterminate tomato plants. This
will concentrate the plants energy into growing and ripening the fruit already
on the plant before the first frost.
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| Tomato flower. |
Tomato problems
Tomatoes need to be kept
evenly moist to help prevent blossom end rot.
This is a large black scabby area on the bottom of the tomato which if
the disease is severe, may spread further into the fruit and cause a black,
mushy rotted area. A lack of calcium in
the soil can also cause blossom end rot.
Using a fertilizer for tomatoes will generally supply the calcium
needs.
Fungal diseases are the
biggest problem tomato grower’s face.
They cause spots on the leaves, which then turn yellow and fall
off. They can also infect the fruit. The plants may quickly die or remain sickly
and unproductive. Things you can do to
prevent disease are; avoid getting
foliage wet when watering, space plants so that there is good airflow around
them and plant disease resistant varieties.
Keep plants off the ground and mulch the soil around them
Early Blight and Septoria
leaf spot are common fungal diseases. These two diseases seldom kill plants
outright, leaves die at the bottom but the plant continues to put out new
leaves. However this makes the plants
weak and keeps them from producing the best fruit. In the
last few years Late Blight has become a problem for Michigan tomato
growers. It causes blackened vines,
leaves and fruit and quickly kills plants.
There is no cure for fungal
disease, only prevention. Use a garden
fungicide safe for vegetables according to label directions. While many organic products will provide some
protection for early blight, septoria and some other tomato diseases, no
current organic product works well for late blight. Michigan gardeners are strongly encouraged
to protect their tomatoes from late blight.
A product containing chlorothalonil is probably the best option for
homeowners. For more about late blight
read this article.
Tomatoes seldom have insect
problems other than the tomato hornworm.
The hornworm is the larvae stage of a pretty moth called the sphinx
moth. The hornworm is a green fat worm
spotted with white that sports a big spine on its rear end which in Michigan
can be red or black. Tomato hornworms
can be hard to see, they are well camouflaged.
They eat leaves and fruit and can be quite destructive. Picking them off a few plants is probably the
best homeowner strategy. If you have
many plants or can’t stand fat caterpillars use a garden insecticide safe for
tomatoes.
Some varieties
There are hundreds of tomato
varieties on the market. Why not
experiment a bit each year and find ones you like? Keep in mind that heirloom varieties may not
be very disease resistant and most were developed to perform well in specific
areas of the country. There are modern
hybrids that combine disease resistance with old-fashioned flavor. The more letters after a variety name such as
VFNTASt, the more disease resistance it has.
Pay attention to catalog descriptions such as days to maturity, and
whether the plant has special resistance to cold soil or where it was
developed, to choose varieties right for you. Color and size are personal
preferences; lighter colors are generally lower in acid.
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Tomato terminology
Tomatoes are the number one vegetable that people grow, but
if you are looking for seeds to buy to start your own plants, or even picking
up plants at a local garden center you may get confused with the various
descriptive terms used on tomatoes. To
make your selection easier here is some tomato terminology and what it means.
Determinate and
indeterminate – An indeterminate tomato keeps growing and setting fruit
until frost kills it. A determinate
tomato tends to set and ripen its fruit all at one time. Most garden varieties of tomatoes are
indeterminate but if you can tomatoes you may want to choose a determinate
variety so you have a concentrated harvest.
Determinate tomatoes are shorter and bushier and can be better for
container growing too.
Potato leaf tomato-
many species of tomato went into producing today’s varieties of tomatoes. Some of those had a leaf shaped more like a
potato leaf and some of the new varieties of tomato retain that shape. It does not affect the plants growth
qualities or taste of the fruit.
Paste tomatoes
have thicker “meat” portions of the fruit and tend to be less juicy. They are usually cooking tomatoes, used for
sauces and paste. Many are oblong or
teardrop shaped. They are good for
eating too. Oxheart tomatoes are larger
meaty tomatoes, usually of European origin.
Cherry, grape, and
currant tomatoes are all types of small tomatoes that grow in
clusters. Currant tomatoes are the
smallest, very tiny 1 bite tomatoes.
Cherry and grape tomatoes are essentially the same.
Salad tomatoes
usually refer to smaller smooth round tomatoes.
Beefsteak can be a variety name or refer to tomatoes which are very
large often with an oblong, flattened shape.
Tomatoes come in a variety of shapes, depending on
variety. Some are smooth and round;
others have ridges or what appear to be segments joined together. There are also hollow tomatoes, which look
like a pepper inside. There are pear
shaped tomatoes and very flattened oval shaped tomatoes.
Tomatoes also come in many colors, even though red remains
the favorite. Colors can be white,
yellow, pink, orange, green, purple, brown, and striped. Tomatoes also vary in taste, a tomato ripened
in the sun always tastes better than one ripened in the store but the taste of
tomatoes can range from sweet, non-acidic to very acidic and “robust”. Taste is subjective and growing conditions
can affect how a tomato tastes also.
Heirloom tomatoes don’t always taste better than modern hybrids; try
many varieties of tomatoes to see what you like.
What do the letters
in the name mean?
The letters behind the variety name of some tomatoes
indicates they have resistance (not immunity) to certain diseases. Not all tomatoes will have these
letters. V=verticillium wilt, F =
fusarium wilt- there can be 3 F’s indicating the 3 strains of fusarium wilt
that infect tomatoes, N=nematodes, T = tobacco mosaic virus, A = alternaria
stem canker, St= stemphylium gray leaf spot, TSWV=tomato spotted wilt
virus. There are a few tomatoes that are
resistant to late or early blight. If so
that information is generally provided in the description. If you have lots of disease problems look for
the varieties with the most letters after their name.
Indigo series tomatoes are a strain of tomatoes developed to
have more anthocyanin, the blue pigment that is supposed to be so healthy for
us. Indigo tomatoes are a deep purple
almost black with red highlights. There
are several varieties and sizes. These
are a bit different from older varieties of “black” or chocolate tomatoes. They were developed with conventional
breeding and are not GMO.
Grafted tomatoes are becoming popular. These combine a disease resistant, hardy root
stock (bottom portion) with a fruiting or top portion that may lack those
traits. Many times a heritage tomato is
the top part. One note on grafted
tomatoes, don’t buy a tomato grafted on a potato unless you just want a
novelty. Despite the promises of both a
tomato and potato crop, in reality neither crop grows well like this.
When choosing your tomato varieties you may want to look
into what part of the country the variety is said to do best in. Some perform better in the north; others have
a very long maturation rate and do better in the south. Check the tag or
description for days to maturity. In
tomatoes that starts when you transplant them into the garden. You should see
such information offered in the catalog or tag description. Early varieties
ripen in 55-70 days, medium varieties 70-90 days and late varieties more than
90 days. Many modern hybrids are bred to
do well all over the country, whereas many heirlooms tend to do better in
specific areas where they originated.
You can ask other gardeners in your area what tomatoes grow
well for them. Grow several varieties
and keep records on whether you liked the taste of each and how each produced
for you. Each year try something new,
but make sure to plant some of your tried and true favorites. Tomatoes that do well in Michigan include
Early Girl, Better Boy, Kellogg’s Breakfast, Goliath, Big Beef, Bonnie Best,
Rutgers and Delicious.
Don’t let terminology confuse you and stop you from growing
tomatoes. No matter what you choose your home grown
tomatoes will taste better than store purchased ones and you’ll have fun
growing them.
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Planting your tomatoes
No tomato tastes better than a tomato ripened on the
vine. You can have your own vine ripened
tomatoes beginning this summer. Tomatoes
are the number one garden vegetable that people plant and they are fairly easy to grow, even for
beginners. You can even plant tomatoes
in large pots if you don’t have a garden space, as long as you have a place
that gets at least 6 hours of sun a day.
While you can grow tomatoes indoors under lights this article is going
to give instructions and tips for planting tomatoes outside.
Most people start with tomato plants, which are available in
almost every garden shop in the nation.
You can start tomatoes from seed, but you’ll need to start about 6-8
weeks before the date you want to plant them outside. If you are new to gardening it’s probably
better to begin your tomato growing experience with a young plant, called a
transplant. Do consider growing several
kinds of tomatoes, because each variety has a distinctive taste and different
varieties begin ripening sooner than others.
There are traditional red tomatoes but there are also yellow, orange,
pink, white, green, purple and striped tomatoes.
How many tomato
plants should you buy?
That depends on the space you have to grow them, you’ll need
about 3 square feet per plant. If space
isn’t a problem consider whether you want fresh tomatoes for eating or if you
want tomatoes for canning. A family of
four will probably get all the fresh tomatoes they want from 3-4 plants. If you want to can or freeze tomatoes, or
make sauces and salsa you’ll want at least a dozen plants.
If you can, choose some early and some later ripening varieties
of tomatoes so that you will have a constant supply. Read the plant label to see how many days the
tomato variety takes to maturity, which means the number of days from when you
set the plants into the ground, or a large container, to when the tomatoes
produce ripe fruit. Early tomatoes have
fruit that is generally smaller than later ripening varieties but the flavor is
usually great.
Choosing healthy
plants
Tomato plants are available in a variety of sizes and
prices. Cell packs contain 4-6 small
tomato plants, usually all of one variety.
They are generally the least expensive way to buy tomatoes. Healthy tomato plants in cell packs will
quickly catch up to larger potted plants in growth. The disadvantage of cell
packs is the plants are generally all the same variety and if you want several
varieties, you’ll have a lot of plants.
When you are choosing healthy tomato plants in cell packs look for
stocky, dark green plants without flowers or fruits. Lanky, yellowish plants with flowers or fruit
are stressed and won’t do well in the garden.
Don’t choose them.
Tomatoes that are potted individually in larger pots can be
taller and even support flowers and fruit, depending on the size of the pot,
without being stressed. The larger the
pot, the more advanced the plant can be, a plant with small green tomatoes
should be in a pot at least 6 inches across.
These plants are more expensive but it’s often fun to get at least one
tomato plant that already has flowers or fruit so that you get early ripe
fruit. Choosing individual tomato plants
in pots allows the person who doesn’t have a lot of garden space to have
several varieties of tomatoes.
Potted tomato plants that are flowering or that have fruit
take a little extra care when they are planted.
Look for potted plants that are compact and dark green. A few yellow leaves on the bottom of the
plant are normal, but avoid plants that have a lot of yellowed leaves or spotted
and curled leaves. Look for plants
without signs of insect damage or insects on the leaves.
When to plant
Tomatoes are tropical plants and need warm soil and frost
free conditions to grow. The best time
to plant tomatoes is when the lilac plants in your area are in full bloom or
the leaves on the oak trees are the size of your thumb. Even then keep an eye on the weather and be
prepared to cover the plants if the weather forecast calls for a frost or
freeze.
Don’t be in a rush to get your tomatoes into the
ground. If the weather and soil are cool
the plants will just sit there, barely surviving. Tomatoes planted after the weather is warm
and settled will take off quickly and be strong and productive. They often catch up to and surpass plants
that sat through cold periods or suffered frost damage.
Choosing a good
location for planting
Tomatoes need at least 6 hours of sunlight to produce good
fruit. They thrive in a variety of
soils but loose, fertile soil where tomatoes haven’t been planted in at least a
year is best. If your soil is very sandy
or is heavy clay, you can work in a generous amount of compost before
planting. You can also add some
fertilizer formulated for tomatoes before planting and work it into the soil.
Make sure that tomato plants are at least 50 feet from a
black walnut tree, even if the tree doesn’t shade them. Tomatoes are very sensitive to a chemical
that black walnut trees produce in their roots.
About the time they start producing fruit they will suddenly wilt and
die if their roots are close to black walnut roots. If you can’t get the tomatoes far enough from
black walnut trees plant them in containers.
The actual planting
Dig a hole several inches deeper than the root ball of the
tomato plant. Unlike most plants
tomatoes have the ability to grow roots from little “bumps” along their stems
and planting them slightly deeper than they were in the nursery helps them form
a good, extensive root system. Remove
any leaves below the soil line before you fill in the hole around the plant. If you have tall, lanky tomatoes, maybe
bargain ones left at the end of the season, you can remove all but one or two
sets of leaves and bury the stem deeply.
Space your tomato plants at least 3 feet apart. That looks like a lot when they are small but
when they are large the plants need good air flow around them to help prevent
disease. Don’t plant tomatoes against a
building or solid fence. The reflected
heat and poor airflow will cause many problems.
Place your tomato cages, stakes or other supports when you
plant the tomato. All tomatoes should be
kept off the ground to avoid problems with fungal disease. If you are going to use plastic mulch that
should be placed on the ground before you dig the holes. You will cut holes in it where the tomatoes
are placed. If you are going to use a
mulch such as straw or shredded bark wait a week or so after planting to put it
down and make sure the soil is moist first.
Mulch is good to suppress weeds but don’t make it more than 3” deep as
it will prevent water from reaching the plant roots.
Make sure to water the tomato generously after you plant
it. The best day to plant tomatoes is a
cloudy one. If the weather is hot, sunny
and windy cover the plant with something such as a sheet of newspaper or some
light fabric to lightly shade it. This
keeps it from wilting as it grows new roots.
Remove the shade after 2-3 days.
Caring for the tomato
plant
Tomatoes produce the best quality fruit if they are watered
regularly. How often that is will depend
on the weather and your soil. Don’t
allow them to wilt, but don’t keep the soil soggy wet. If tomatoes are in containers they must have
good drainage. Generally a deep watering
once a week will be fine, but when the weather is very hot and dry or your soil
sandy you may need to water more often.
Try to keep the water off the leaves when you water, direct water to the
base of the plants. If you do water from
overhead do it several hours before sundown so the plants are dry before dark. This helps prevent fungal disease.
Too much fertilizer will produce tall plants with lots of
leaves but little fruit. Use a slow
release granular fertilizer when you plant the tomatoes or use several
applications of water soluble fertilizer during the growing season, following
the label directions carefully. A
fertilizer made for tomatoes is best, but a fertilizer labeled for vegetables
will work.
Keep the tomato plant off the ground by regularly tying it
to a stake or other support or use heavy duty tomato cages. Remove any yellowed or spotted leaves
regularly and dispose of them away from the plants. Tomato fungal diseases are the bane of all
tomato growers and by summers end almost all tomato plants will be suffering
from some degree of fungal disease if they are not being sprayed regularly with
a fungicide. You must prevent fungal
disease, you cannot cure it. Some fungal
diseases cause minor loss of fruit and plant quality, and decreased yield, others,
such as late blight, can kill the plant.
Whether to use a fungicide on your tomato plants is a
personal decision. Fungicides are
pretty safe if you choose one labeled for tomatoes and follow the directions on
it carefully. You must apply it
consistently. Healthy plants will
produce nutritionally better fruit than ones struggling with disease, and
careful washing will remove pesticide residue, but you must decide if that
route is for you. There are so called
organic fungicides but they are either as toxic as non-organic ones or just not
very effective.
Other than tomato hornworms, a big fat green worm that
strips tomato leaves and also munches fruit, tomatoes have few insect
problems. Hornworms are best controlled
by hand picking and squashing.
If you like eating tomatoes you’ll enjoy them even more if
you grow them yourself. Pick one warm
from the sun, bite into it and let the juice run down your chin. Think bacon and tomato sandwiches with really
luscious, flavorful tomatoes. Picture
jars of cheerful red canned tomatoes lining your cupboard selves. Get out there and plant some tomatoes.
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Tomato anthracnose – fruit rot
A common tomato problem is really prevalent this season.
Many people call it fruit rot but the culprit is Tomato anthracnose (Colletotrichum coccodes). Tomato anthracnose is one of those nasty
fungal diseases that are so hard to control.
This disease also affects the leaves, stems and roots of tomato plants
but it’s the infection of the fruit that is most problematic. The
disease frequently begins in late summer, and early fall with temperatures over
80 degrees and rainy weather being prime anthracnose weather.
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| Tomato anthracnose damage. |
Tomato’s that are ripe or nearly ripe develop what is called
“watersoaked” spots, sunken, shiny areas with a number of small black spots in
the center that eventually create a large black spot and the fruit rots around
and under the lesion. The black spots produce salmon colored spores which can
infect other fruits around them. When
you cut a tomato with anthracnose you often see a black area on the meat inside
below the outer spot. The rotted spots
may also grow a secondary fungus; gray, fuzzy mold if left long enough. .
Tomatoes can have one spot or several.
Green fruits often have the fungal spores on them but the
disease isn’t obvious until tomatoes begin to ripen. If your green tomatoes have large rotted
areas and your tomatoes plants look blackened and wilted you may have the more
serious problem of late blight. Late
blight will quickly kill all the tomato plants in your garden.
Tomato anthracnose also makes the lower leaves on the plants
get yellow spots with a tan center, and they eventually wilt and turn
gray-brown. The stems may also develop
spots. These foliar symptoms are very
similar to other fungal disease of tomatoes and tomato plants can have more
than one fungal disease going at the same time.
In fact diseases like early blight weaken the plant and make anthracnose
more common.
Tomatoes vary in how susceptible they are to “fruit
rot”. At any time you may have some
tomatoes with the spots and some without, even on the same plant. Your plants won’t die from the disease,
although the disease often combines with other tomato fungal diseases to limit
production and make the plants look horrible.
Plants without many leaves don’t have the sugars and other nutrients
that make fruit tasty and you may notice the tomato’s flavor isn’t as good.
You can cut off small rotted areas and eat the fruit without
problems but if you like to can tomatoes you may have a problem. Tomatoes with anthracnose often cause
bacterial problems in canned products resulting in spoilage. Don’t
use any fruit with rotted spots for canning. It’s not wise to use them in frozen products
such as tomato sauces either. Ripe
tomatoes without rotted spots, even if you know anthracnose is around, are safe
to use.
Prevention and
control of anthracnose
Anthracnose can be prevented with fungicide sprays started
as soon as there is fruit on the vine. Homeowners can use sprays with
chlorothalonil (Daconil) or fungicide sprays with copper. Check the label to see if the product says it
controls anthracnose and follow label instructions for use. If you have had problems with anthracnose in
previous garden seasons a preventative spray program is a wise move.
Like other fungal diseases mulching and keeping plants off
the ground by staking or tying them helps.
Good airflow is important so don’t crowd plants. Some weeds harbor the
disease so keep your garden weeded. Water at the base of the plant and try to
keep plant foliage from getting wet.
Tomatoes
require well drained soil and wet soil often results in bigger problems with
fungal disease.
If you get anthracnose in the garden it’s very important to
remove all tomato plant debris and rotted fruits to a separate, remote compost
pile or to plastic trash bags and the landfill.
The fungus spores overwinter in tomato debris. And rotate your crops! This disease can also live in the soil
through the winter and infect your plants next year.
Don’t allow your fruits to get over ripe on the vine. Pick them while red and still firm if you
suspect you have anthracnose in the garden.
Discard tomatoes with the rotted spots away from your garden, not in the
compost pile either. If you pick
tomatoes and notice small rotted spots cut out the spot and use them at once or
toss them as they will quickly rot.
When storing tomatoes for fresh eating for a few days, try
to put them in a single layer, not touching each other until used. If one has anthracnose that you didn’t spot
it is less likely to spread to the other fruit if they don’t touch. And tomatoes should not be stored in the
refrigerator! It ruins the flavor and
they will actually spoil faster.
Tomatoes are not the only plants that get anthracnose. Peppers, eggplant, potatoes, cucumbers,
strawberries, some squash and pumpkins also get anthracnose. Some of these strains of anthracnose can
“crossover” especially in closely related species like tomatoes and peppers.
Even if some of your tomato fruit gets
anthracnose late in the season you may still get enough good fruit for eating
and cooking. Next year you may want to
begin preventative sprays early in the season.
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Tomato hornworms
Those big green “worms” you find eating your tomatoes in
your Michigan
garden came from a rather pretty moth that you probably didn’t mind in your
garden. The fat green caterpillars are
known as tomato or tobacco hornworms. These
little buggers can go from eggs to tiny caterpillars to huge fat caterpillars 4
inches long and as big around as your thumb in a matter of 3 weeks. To grow that fast they eat a lot of your
tomato plant, preferring leaves and green fruit.
Tomato hornworms have a large curved spine or hook on the
upper side of the rear end that can be either red or black, depending on the
species. The caterpillars start out a
lighter, yellow green color but soon their green bodies are the same shade as
tomato leaves. Tomato hornworms are
hairless and the body is marked with a series of white v shaped markings and
tiny black lines that look like stitches.
Along the bottom edge of the caterpillar are round spots outlined in
gold that almost look like grommet holes.
To confuse predators there are two round markings on the hook or rear
end that look like eyes.
The tomato hornworm
life cycle
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| Tomato hornworm. |
Like many moths hawk moths are generally active at dusk. In
some areas of Michigan
both species of moths and caterpillars of both hook colors are present. The adult moths do not eat tomatoes, they sip
nectar. They lay single pale green eggs
on the undersides of leaves of tomato, pepper, eggplant and potato plants and
weeds in the same family such as nightshade and horsenettle. While the caterpillars occasionally eat these
other plants they prefer tomatoes.
In Michigan
tomato hornworms are usually noticed about the first week of August and they
generally feed for a few weeks before falling to the ground. The caterpillars
burrow into the ground and turn into pupa.
The pupas are brown, hard, shiny, worm-like things with a curved
“handle” on the front end, generally found buried in a few inches of soil.
In Michigan
there is generally only one generation a year, in the south there may be two
generations. The tomato or tobacco hornworm over winters as a pupa in Michigan . Moths may come from warmer areas in the
spring to lay eggs also. While tomatoes
are their favorite garden plant hornworms will sometimes eat peppers, eggplant
and potatoes. And of course they also
eat on tobacco plants in the south.
Finding hornworms
The first sign you might notice of the tomato hornworms
presence is green or blackish green pellet-like excrement under and on plants. There will be lots of bare stems and partly
eaten green tomatoes, particularly at the top of the plant. Hornworms rarely
eat ripe tomatoes. In the last week or so of the caterpillar stage their
appetite is enormous and the damage becomes very noticeable. The caterpillars may have been on the plants
for weeks. Caterpillars do move from
plant to plant if the plants are close.
It takes a sharp eye to spot the culprit as tomato hornworms
are perfectly camouflaged as they lie on tomato stems. Smaller hornworms may hide on the undersides
of leaves. Stay still and quiet and you can sometimes trace them by their
munching sounds. Usually they are found near the top of plants.
Tomato hornworms will not kill a tomato plant although the
damage can look bad for a while. They do
destroy a lot of young fruit if left unchecked. There are usually only a few tomato
hornworms per plant. To find the
hornworms scout each plant carefully and look right above any piles of
greenish-black caterpillar poop. They
are more easily found in the early morning or evening when they are most active
Control of tomato
hornworms
Tomato hornworms have few natural predators although
chickens sometimes eat them. They are
filled with tomato foliage, which is poisonous, although a chicken eating one
or two doesn’t seem to have any problems.
Here are some ways to control hornworms.
- Handpick them and squish them. If you are squeamish about handling tomato hornworms you may be able to pay a kid to look for them. They do not bite or “sting” humans and the hook is harmless.
- Use insecticidal soaps formulated for garden plants.
- Use a Bt product. These only kill caterpillars.
- Use a garden insecticide safe for food plants. Insecticides with carbaryl, spinosod, permethrin, or bifenthrin will work. Read and follow label directions carefully.
- Till the soil in the fall to bring pupa to the surface to freeze and rotate the area where you grow tomatoes each year.
- Some people have good luck keeping the hornworms off their tomato plants by planting marigolds, basil, dill, or lavender near them.
If you notice a rather sluggish tomato hornworm with small
white projections all over it leave it alone.
The Braconid wasp lays its eggs on living hornworms; they feed on
hornworms, weakening them and then turn into the little cocoons which are on
the caterpillar. Each cocoon will turn
into a wasp which lays eggs on more caterpillars, keeping their numbers in
check.
Tomato hornworms are excellent fish bait. If you are a fisherperson you may want to
check the tomato plants before you head to your favorite fishing hole.
While tomato hornworms are startling and scary to some
people they are easier to deal with than some other tomato problems. Do not rip out your plants. Gardeners will find that they can harvest
plenty of tomatoes with just picking the caterpillars from the plants at the
first sign of damage.
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Blossom end rot of tomatoes
In July home gardens begin producing those luscious ripe
tomatoes everyone craves. But tomatoes
can be tricky little devils when it comes to getting them to produce perfect
fruit. One of the problems home
gardeners may face is blossom end rot.
This is a gray- black, leathery looking sunken area at the bottom of the
tomato. It can be cut off and the tomato
is safe to eat but not it’s not safe to can.
But many people feel the rotted area affects fruit taste as well as
spoiling the looks of the fruit.
Tomato end rot is caused by a number of factors but they all
boil down to not getting enough water to tomato fruits. This can be because of genetics; some
varieties have less efficient root systems, it can be because the roots were
restricted by a small container or root damage occurred. Usually though, the cause of tomato end rot
is simply not enough water.
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| Blossom end rot. Photo from Flixr. |
In July and August tomato plants are growing quickly while
trying to also support lots of fruit. In
hot, dry weather the plant loses water rapidly from its leaves in
transpiration/ evaporation and in an effort to cool the plant and maintain
turgor the tomato plant pulls water from developing fruit to send to the leaves
and stems. It can always make more fruit
when conditions improve. This results in
the sunken, cell damaged area at the bottom of tomato fruits.
Calcium deficiency is often cited as a reason for blossom
end rot but most soils are not deficient in calcium, plants just need lots of
water to access the mineral. It doesn’t
hurt to use a liquid fertilizer for tomatoes which contains extra calcium if
you follow label directions. But your
plants still may need additional water.
To prevent tomato end rot make sure your tomato plants have
plenty of water. They need an inch or
more a week, on a regular schedule, perhaps divided into 2 or 3 waterings. Plants should never be allowed to wilt, but
damage to fruit can show up even before the plant wilts. Put up a rain gauge and when there hasn’t
been an inch of rain in seven days use supplemental watering. Water plants
deeply, the first two inches of soil should be moist. A large tomato plant with fruit can usually
absorb 2 gallons of water if it has been dry.
If your plants wilt – water right away.
Water tomato plants at their base and well before dark to
help prevent fungal disease. If the leaves stay wet overnight the plants are
more likely to support the growth of fungal spores. Tomato plants in containers
may need watering once a day – even twice a day. And the containers should be large enough to
support a good root system. Anything
that restricts the roots of tomatoes, such as hard packed clay soil, can also
cause blossom end rot.
Surprisingly if a tomato is over watered, particularly in a
pot with poor drainage, the roots of the plant may rot and once again the plant
stems and foliage will be left without sufficient water. This can cause the same symptoms as too dry
conditions, including blossom end rot, because the roots are unable to furnish
the plant with enough moisture. Check
the soil in pots before water is added.
In short blossom end rot is caused by a tomato
plant allocating precious water to stems and foliage by taking it from the
tomato fruit. This causes cell damage on
the bottom of the fruit, which then rots.
Keeping tomato plants watered deeply and consistently will prevent
blossom end rot from occurring
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Help my tomato plants are dying
If your tomato plants are dying or losing a lot of leaves
you may have one of the tomato fungal diseases.
Two common fungal diseases are Septoria Leaf
Spot and Early Blight. Also there is the
not as common and much more deadly, Late Blight. Late Blight likes cool, wet weather. Late Blight also affects potato plants.
Disease identification
Tomatoes are prone to a number of fungal diseases. Identification
of the exact fungal disease tomatoes have isn’t always easy, but for the most
part, prevention and control is pretty much the same for all forms of fungal
disease. If your green tomato fruits are
developing large areas of blackened, rotting tissue, and the stems of your
tomato plants have large, dark brown or black areas, if the leaves turn grey
black, roll and dry up and the disease is progressing very fast throughout the
whole plant you are probably seeing Late Blight. Late Blight also causes a white, fuzzy,
mold-like growth on some of the dark spots in wet weather.
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| Late blight |
Other fungal diseases rarely affect green fruit and the
plant continues to put out new green growth near the top. In other fungal diseases the leaves may have
brown spots surrounded by yellow areas that gradually turn the whole leaf
yellow or brown and then it falls off.
The process begins on the bottom of the plant and works its way up. In very favorable conditions, however,
Septoria Leaf Spot or Early Blight can
also kill plants in a few days.
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| Septoria leaf spot |
Your local county
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| Early blight |
How tomato fungal diseases are spread
Some years the weather keeps fungal disease to a minimum,
but in other years it’s a contributing factor in widespread disease. To get a disease you have to have three
things, a suitable host, the infecting agent, in this case fungal spores, and
suitable conditions. Wet, stormy weather, whether cool or warm,
seem to be favorable conditions for most fungal diseases. Fungal spores can be present on plants you
buy from a nursery, they can be transferred to plants from clothing and shoes
or they can blow in on the wind. Fungal
spores may lay dormant until conditions are right, but when conditions do get favorable
they can sometimes develop and spread so quickly that large tomato plants can
be lost in just a few days.
Prevention and control or tomato fungal disease
If you have tomato plants in your garden this year and
haven’t yet had disease problems, you may want to act preventativly. Prevention is always better than trying to
“cure” infected plants, whether you are using conventional or organic
products. In fact there is no cure once
fungal disease sets in, only control of some of the worst symptoms if you begin
soon enough. In years with heavy
disease pressure, such as this one, organic products, good soil and planting
resistant varieties of tomatoes may not be enough to keep fungal disease away.
Examine your tomato plants every day. Symptoms can appear overnight. Get all plants off the ground if you can or
mulch under them. Don’t work in your
garden when the foliage is wet as this may transfer fungal spores. It’s up to you if you want to apply organic
or more conventional fungicides to try and prevent infection but this year
fungicides are highly recommended. If
you don’t spray preventively begin spraying the minute you notice symptoms.
Probably the easiest to find and safest conventional
fungicide homeowners can use on tomatoes is chlorothalonil, most often sold as
Daconil 2787. Use a daconil product
formulated for vegetables, Ortho Garden Disease Control® is a good
example. Look on fungicide labels for
that information; it should list tomatoes as a crop that it can be used
on.
Organic fungicides for the prevention and control of fungal
disease include neem oil, Serenade® and Oxidate®. Compost tea is often recommended by organic
aficionados, but research doesn’t support its effectiveness. Fungicides containing copper may have some
effect but these products have a higher risk rating than conventional
fungicides.
Follow the label directions exactly on all fungicides. Apply the product so that it thoroughly wets
the leaves, stems and fruit and apply it as often as the label allows. For example if the label says every 7-10
days, apply every 7 days. The products
listed above are examples of fungicides and others are available.
Tomato plants that appear heavily damaged should be pulled
up and placed in plastic trash bags.
This is especially true of plants with symptoms of Late Blight, which
seldom recover even with treatment. If
plants are just becoming affected remove all spotted, yellowed or black leaves and
damaged fruit and place them in plastic bags.
Try to get all fallen leaves or fruit near the plant picked up
also. Do not compost this infected plant
material or leave it lying by the garden.
Seal your plastic bags and dispose of them in the trash or leave them in
the sun to thoroughly cook in the heat.
Infected plant material can also be buried several feet in the ground,
away from the garden area.
If you grow potatoes in the garden and think you have late
blight pull any affected potato plants too and make sure you get every piece of
potato tuber. Late blight can
over-winter in buried potato pieces.
Nightshade, a weed related to tomatoes, also gets Late Blight and if any
is near the garden it should be pulled and disposed of as above. (For a picture and description of nightshade
go here). Potato tubers are safe to eat
if plants are infected with Late Blight if they appear undamaged.
Tomato fruit that doesn’t have diseased areas can be
eaten. Green fruit that doesn’t appear
affected from plants you are discarding can be ripened on the windowsill, but
be aware that some fruits may develop fungal disease as they ripen. If you treat plants with any kind of
fungicide wash the fruit well before eating and follow the label directions for
the correct time to harvest after applying a product. If you manage to save some plants but they
were heavily defoliated, the fruit may not taste as well as fruit from normal
plants. Tomato plants need lots of
leaves producing lots of food for them to develop normal tasting fruit.
Clean up your vegetable garden thoroughly each fall. Don’t leave stems and roots in place over
winter and remove all fallen fruit. Next
year do not plant tomatoes, peppers, eggplant or potatoes in a spot where one
of these crops was grown this year.
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