Q: I water my vegetable garden five or 10 minutes with the hose every day, and yet every thing seems to be drying up. Is it because something is wrong with my soil?
A: Light sprinkling is of little value and can do more damage than good because it merely wets the crust or top quarter inch of soil. This encourages plant roots, including lawn grasses, to grow in the direction of the water sources, making them shallow-rooted. Hot drying winds quickly evaporate the light sprinklings, and there is not moisutre for the roots.
Water thoroughly or not at all. During dry periods apply water to thoroughly wet the soil to a depth of six inches. Do this once a week, skipping only those weeks when you get adequate rainfall.
Overwatering can be damaging to plant root systems. Continuous soggy soils deprive root systems of the air necessary for healthy growth and lead to root decay.
Q: In a small garden plot, tomatoes cannot be grown a second season in the same spot. Is there some nutrient we could add to take care of the problem?
A: The problem is not loss of nutrients but disease, including fusarium and verticillium wilts, which are caused by fungi in the soil and kill the plants just as the first fruit is about to ripen.
Planting resistant varieties can take care of the problem.
Anthracnose or ripe rot is another of the serious diseases. Infection takes place when the fruit are green, but the symptoms do not appear until the fruit ripen. Typical symptoms are circular, sunken spots in the skin.
Planting tomatoes in a different place each year is no guarantee of protection, but it may help. But be sure to plant disease resistant varieties.
Q: Where does the tomato hornworm come from and what are those white things on his back? I bought some Sevin, but don't know when to spray.
A: The tomato hornworm spends the winter in the soil as hard-shelled pupa and emerges in late spring as a moth (called hummingbird moth) which deposits greenish-yellow eggs on the underside of foliage.
The white things on its back are the cocoons of a parasitic braconid wasp, which injects eggs into the body of the hornworm. They hatch, feed inside the hornworm body, then eat their way outside to spin cocoons.
Your best method of control with a small number of tomato plants is to pick the hornworms off and destroy them. But don't bother those with cocoons. The wasps are beneficial.