This time of year, my inbox is full of pleas for help from gardeners having trouble with their tomatoes. I wish that I could give each and every one of you a personal response, but the volume of mail makes it impossible. The quickest way to get an answer is to posting your questions on our discussion board.
Blossom End Rot
Blossom end rot appears as a large, dark brown, soft spot at the bottom of the tomato just as it is beginning to ripen. You can't save a tomato once it is affected, and picking off all of the bad fruit will allow the plant to devote it's energy to developing healthy tomatoes. The ruined fruit can be tossed on the compost pile.
Blossom end rot is caused by a calcium deficiency, which is usually the result of an uneven water supply. Tomato plants need a steady supply of water to absorb the necessary calcium from the soil.
Tips:
- Water deeply and thoroughly to encourage your plants to send out deep roots that aren't as sensitive to brief dry spells as shallow roots.
- Mulch around your plants to help the soil retain moisture.
- Agricultural lime contains calcium, and in severe cases, working a little lime into the soil may help. A very acid pH will also prevent the plant from absorbing calcium, and lime will help to correct a pH problem.
Tomato Hornworms
These distinctive creatures are masters of camouflage. The four-inch larvae are stem green with seven or eight diagonal white stripes down their sides. Each stripe is shadowed by a row of black dots, and punctuated with a huge false eyespot and black tail. They feed in the daytime, nibbling at fruit and consuming tremendous quantities of leaves. Little souvenirs similar in appearance to rabbit pellets are sometimes left behind. Target plants include tomatoes, peppers, potatoes, eggplant and dill.
Adult hornworms are huge grayish brown moths with wingspans of up to five inches. They are also known as hawk or hummingbird moths, and they are sometimes mistaken for hummingbirds as they hover in front of flowers feeding on the nectar at dusk. Wings are ornamented with a wavy line pattern and the body is marked with orange spots.
Pupae hibernate underground in hard, two-inch cases shaped like spindles. Fall tilling helps to destroy the pupae.
Controls
Deterrent plants include borage, opal basil and marigolds. Dill makes an excellent trap crop. The huge worms are easy to spot on dill plants, and can then be handpicked. Handpicking is the preferred method of control. Although they are huge, they usually aren't numerous. A blast of cold water from the hose will cause them to thrash about and make handpicking easier.
If you can't bear to handpick the worms (even with gloves on) spray susceptible plants with Bt.
Trichogramma are paracitic insects that feed off the eggs laid by tomato hornworms. They are harmless to humans and pets.
Other Insects
Aphids
These tiny, soft-bodied bugs are less than 1/10 inch across. The color varies.
Deterrents:
- Plant alliums such as garlic and chives, as well as anise, coriander, nasturtiums, and petunias as companion plants.
- Use yellow sticky traps or yellow dishes containing soapy water to trap aphids.
- Spray plants with or mint tea.
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Lacewings will eat up to 100 aphids per day, and ladybugs also eat large quantities of aphids.
Flea Beetles
These tiny jumping insects are less than 1/10 inch long. The color varies.
Deterrents:
- Keep the garden clean and free of debris.
- Wormwood Spray and Red Pepper Spray are effective remedies.
At GardenGuides we have recipes for wormwood and red pepper sprays.
Colorado Potato Beetles
These predators will strip the plant of foliage. Adults are 1/3 inch long with a hard round outer shell. They are creamy yellow in color with ten black stripes. Larvae are reddish with two rows of black dots, and a black head and legs.
Deterrents:
- Rotate crops in the Solanaceae family, which includes potatoes, tomatoes, eggplant, and peppers.
- Interplant with horseradish, dead nettle, catnip, coriander, nasturtiums, and tansy.
- Spray with cedar or basil tea or a solution of 2 tbs. Epsom salts in a gallon of water.
Stinkbugs
These hard backed gray bugs exude a stinking fluid when touched. Younger bugs are brown.
Deterrent:
- They drop off plants when disturbed. Try knocking them into a can with a stick.
- Lizards will eliminate them.
Curly-Top Virus and Leafhoppers
These two problems go hand-in-hand since the virus is spread by leafhoppers. Curly top virus causes the plant to stop growing and producing fruit, and the fruit already on the vines will not ripen. The leaves curl upward and turn yellow, and the plant will eventually die. Here are some tips on discouraging leafhoppers:
- Provide your tomatoes with a little afternoon shade. Use a shade cloth if necessary.
- Keep the garden free of weeds.
- Plant tomatoes later than usual to avoid the majority of leafhoppers.
The Attack Squad
These hordes of hungry insects will prey on many destructive garden bugs. This pest control program provides you with 3 bi-weekly shipments of 8,000 Trichogramma pretiosum and 1,000 Chrysoperla carnea (green lacewings).
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Blossom Drop
This condition is usually caused by low night temperatures. Try to wait until you are reasonably sure that the night temperatures are going to stay above 55 degrees before setting out your tomato plants. If cool temperatures cause you to loose your first blooms, the plants will eventually flower again, but your harvest will be delayed.
There are varieties that can withstand cool nights, but they usually produce smaller, less flavorful fruit. If you want to get a head start, try planting some of these cold resistant varieties as an early crop, followed by a main crop of your favorite varieties.
Other possible causes for blossom drop are magnesium deficiency and fungal infection. Epsom salt is a good source of magnesium. Dilute a tablespoon of Epsom salt in a gallon of water, and spray the plants as needed. If you suspect a fungus may be the cause of the problem, spray with a fungicide.
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