As summer heats up, vegetable gardeners wait anxiously for the first tomatoes to ripen, sun-warmed and sweet. But it's not always an easy wait.
Many things can go wrong with a tomato crop. Some you can guard against or fix and some you
can't. But remember a few key points:
No tomato crop will ever be perfect. A
certain amount of imperfection and loss is normal, though some years are tougher on tomatoes
than others. There's little point in chasing perfection with noxious chemicals.
Many problems can be prevented. If
tomatoes are properly chosen, planted and cared for, they are less susceptible to pests and
many other problems. Let your troubles teach you how to prepare for next year.
Alertness saves tomatoes. Many
problems can be corrected if you catch them early, so visit your tomato patch every day or two
and check around for anything unusual.
Weather happens. Expect that some years it will be too hot, too dry, too stormy or too
something else, and your harvest will suffer. But the good years will make up for it.
Imperfect tomatoes may still be good eating. The flavor of a cracked or misshapen tomato still
will beat one from the supermarket. Just cut out any unsightly parts, or use it for
For detailed diagnosis, see this University
of Texas Extension Web page or consult your local university extension office.
But here are some of the common
problems that can beset tomatoes on their way to the dinner table:
Got lots of leaves, but no fruit? The
plant is likely getting too much nitrogen, which triggers it to grow foliage, and not enough
phosphorus, which favors flowering and fruiting. Choose a fertilizer that has a balanced ratio
of the three major elements, such as 10-10-10, or where the middle number (phosphorus) is
larger than the first number (nitrogen), such as 2-3-1. Tomatoes are heavy feeders and usually
do need fertilizer unless your soil is very rich. But follow the directions carefully to avoid
overdoing it. Slow-release fertilizers, including organic formulas such as Burpee's
Organic Tomato Fertilizer with Aragonite have a greater margin of error than fast-release
Do the blossoms fall off before fruit
forms? Blossom drop is usually caused by too-cool weather; tomatoes are native to
subtropical Central America, where they evolved to need warmth to form their fruit. The problem
will clear up as the weather warms. Cool weather can also cause curled, leathery leaves, which
also is harmless. These are among many reasons not to rush tomatoes into the garden in
Is the tomato puckered or distorted?
Does it have a big scar at the blossom end? That scar is called a "catface." Tomatoes often get
catfaced or misshapen if the nights are too cool while the fruits are forming -- another good
reason not to plant too early. Look for varieties that have been bred to be resistant to
catfacing. Misshapen fruits are edible. Bear in mind, too, that many older varieties prized for
their flavor, such as 'Brandywine,' are normally not perfectly red and round.
Are the tomatoes cracked? This
indicates that when the fruit was forming, it didn't get an even supply of moisture from the
plant's roots. A sudden rush of water up through the stem can pop the skin of a ripening fruit
like an overfilled water balloon. Take care with your watering; instead of a quick sprinkle
every day, water deeply once or twice a week (depending on rainfall) so the moisture soaks deep
into soil where the roots can take it up as needed. Soaker hoses can help here. Stick your
finger into the soil every day to check that it is evenly moist (not wet) a couple of inches
below the surface. And always mulch tomatoes to keep moisture from evaporating, even in
containers. So-called "self-watering" or "sub-irrigated" containers can help even out the water
supply for plants in pots. Some tomato varieties resist cracking (at the expense of a tougher
skin). Cracked tomatoes are edible.
Do the tomatoes have a soft or rotten spot on the
bottom? Blossom end rot is a sign of a calcium deficiency. Most often, this is
caused by uneven watering; swinging between wet and dry soil interferes with the plant's
ability to use calcium. A soil test before planting will tell you if there is a calcium
deficiency in your soil. Fertilizers made for tomatoes usually include calcium. You can eat
tomatoes with a small amount of blossom-end rot if you cut the rotted part off.
Are the leaves wilting or yellow?
Although healthy soil normally contains many microorganisms, some fungi and bacteria cause
diseases in tomatoes. The most common are verticillium wilt and fusarium wilt. You can spot
them if you cut through a major stem and find the inside is discolored. Diseased plants can't
be saved, so concentrate on preventing a recurrence. First, get diseased plants entirely out of
your garden; put them in the landscape waste, not the compost pile. Always rotate your crops:
To interrupt the life cycle of soil-borne diseases, don't plant tomatoes or related plants such
as peppers in the same place in the garden more than once in three years. Don't re-use potting
mix that held a diseased plant. Too-wet soil can encourage fungus diseases, so once again, work
at maintaining steady moisture in the soil. Fungicides are at best partially effective in
preventing infection, and only if they are applied regularly all season, starting at planting.
They won't stop an infection once it has started. Look for tomato varieties that have been bred
to resist disease; catalog descriptions and seed packets often will have a code such as "VF" to
indicate that they are disease-resistant. Heirloom varieties may be more susceptible to disease
-- that's one of the reasons hybrid varieties were developed -- so if you choose them, be aware
of the increased risk.
Do leaves have spots? Tiny spots may
be due to spider mites, which tend to gather on the undersides of leaves, as do tiny pale
aphids. A good spray from the hose (including both sides of the leaves) often will take care of
such an infestation. If that doesn't work, try an insecticidal soap (avoid home-grown soap
solutions, which can strip the protective coating from leaves). Sometimes brown spots indicate
a minor fungus infection. To deter fungus problems, avoid overwatering and stake plants so they
get good air circulation.
Do the stems have spots? Brown patches
on the stems, especially at the joints, can be the earliest symptom of a nasty fungus disease
called late blight whose
spores spread to tomatoes from potatoes, often after periods of wet weather. It has been a big
problem in the Northeast in recent years. If you suspect late blight, act quickly to dispose of
the infected plant before the disease spreads.
Do the tomatoes have pale spots? This
may be due to sunscald, if you pruned so severely that the tomatoes don't have enough leaves to
give them a bit of shade. Be careful not to over-prune when you are staking and tending your
vines. Little round pale spots are often caused by stinkbugs, which suck the sap from the
fruit. You can eat the unspotted part of the tomato.
Are the edges of the leaves nibbled?
Look around for tomato hornworms, the two-inch-long green caterpillars of a large moth. Pluck
them off and drown them in soapy water. But if a caterpillar has white knobby growths on it,
leave it be. You are getting help from a parasitic wasp that has laid its eggs in the
caterpillar's flesh. As the eggs hatch, baby wasps will eat the worm. Yum!
Are chunks bitten out of the tomatoes?
Often the culprit is squirrels. The only real way to protect a tomato crop is with a physical
barrier, such as by surrounding it (including the top) with chicken wire. Since there are so
many squirrels in the world, you may have to resign yourself to planting enough so that you can
afford to let the squirrels have some. To be safe from disease, don't eat the unbitten part of
a squirrel-sampled tomato.