Vegetable Gardening (23 page)

One of the best things you can do to conserve moisture is to mulch around your tomato plants. Plastic mulch conserves some moisture but is best used in conjunction with soaker hoses or the ditch watering method (see Chapter 15 for details). The best water-conservation mulch is a 4- to 6-inch layer of hay or straw. The mulch is thick enough to prevent weeds from germinating and stop soils from drying out.

Hay and straw mulches keep soil cool, but tomatoes love heat. So, if you're in an area that has cool summers, wait until the soil has warmed and the plants are thriving before mulching with these materials.

Mulching and watering evenly also prevents many fruit problems, such as blossom-end rot and fruit cracking. See the section "Weather-related problems," later in this chapter, for details on these conditions.

Eliminating pests and other problems

Tomatoes grow so vigorously that they often outgrow any problems and still give you a harvest. But to get the most out of your plants, look out for the troubles in the following sections, which are caused by insects, diseases, or weather. (For a general description of and a plan of action against common insects and diseases, see Chapter 17.)

Spray with pesticides only as a last resort; many plants can withstand a small infestation of bugs or a few diseased leaves.

Insects to watch for

Here are a few insects that are a particular problem with tomatoes:

Tomato hornworm:
These huge, green caterpillars, which sometimes grow to 4 inches long, look like the monster that ate Tokyo (see Figure 4-5). They eat leaves and fruits of tomatoes, and I swear that if you're quiet enough, you can hear them chewing. A few hungry hornworms can devastate a tomato plant quickly.

The simplest control is to handpick the caterpillars off the plants and wrestle them into a can of soapy water to drown. Early morning is the best time to remove these pests from plants — like many people, they're still sluggish at this time of day.

Tomato fruitworm:
This green, 1-inch-long caterpillar with white or yellow stripes feeds on foliage and fruits. They can be handpicked from plants as with the hornworm; however, for a severe infestation, you also can spray plants with Bt.

Stink bug:
A problem mostly in warmer areas, these 1/2-inch-long gray or green shield-shaped insects primarily feed on fruits, causing hard, white or yellow spots on the tomato skin. To control stink bugs, keep your garden weed-free — the pests hide in weeds around the garden — and spray plants with pyrethrin.

Chapter 17 discusses pests and ways to rid your garden of them, such as using Bt and pyrethrin, in more detail. Flip there to read more.

Got a disease?

Leaf diseases, such as the ones in the following list, can devastate tomatoes:

Blights and leaf spots:
The devastation starts with the lower leaves getting brown spots, turning yellow, and eventually dying. The symptoms of leaf spot look similar to the symptoms of late and early blight. The disease slowly spreads up the plant, eventually defoliating the whole plant. These fungal diseases are particularly active during warm, wet weather. To control blight and leaf spots:

• Clean up and destroy all diseased foliage in the fall.

• Rotate crops, as described in Chapter 16.

• Mulch the plants with plastic, hay, or straw after planting to prevent water from splashing the spores from the ground onto the leaves.

• Before the condition gets severe, spray with an organic fungicide, such as copper or
Bacillus subtilis.

Verticillium and fusarium wilt:
These soil-borne fungal diseases cause yellowing, wilting, and early death of tomato plants. Once infected, the plants will likely die and should be removed. The best prevention is to rotate your plantings and plant wilt-resistant plants (indicated by the letters V and F after the variety name).