TOMATOES ARE probably the most popular of all vegetables in today's gardening surge. They provide tasty eating, large amounts of vitamin C and many minerals necessary for proper nutrition. But despite their popularity and versatility, there are some problems that plague the tomato grower.

A good job of preventative action can avoid most of them and result in a rewarding crop. Once the disorders strike, there are few cures.

They are naturally deep rooted. On many soils their roots go down six foot or more. The depth of rooting depends on the variety, the soil, the soil's moisture content, and other factors.

When you water tomatoes, the best practice is to moisten the soil slightly deeper than the root system. Several physiological diseases of tomatoes are caused by either lack of moisture or fluctuations of the moisture supply in the soil. Many times during droughts tomato plants survive, but their fruit is of little value. During dry weather they should be watered every week or 10 days.

If they have not been fertilized since being planted, give each plant a heaping tablespoonful of 5-10-5 fertilizer (or its equivalent) when they get green tomatoes on them the size of large marbles, and repeat a month later.

Scatter the fertilizer on the ground around the plant eight to 10 inches from the stem and work it into the soil. Then water the soil thoroughly to wash the fertilizer down into the rot zone. The fertilizer will stimulate new growth that will produce more tomatoes for a longer season and also increase the size of mature fruit.

Tomatoes are attacked by a number of insects. Chemical-control measures usually should not be used because they attack fruits near harvest. Wash them off with the garden hose.

Blossom drop occurs frequently early in the season, particularly with tomatoes in shady areas. Nothing can be done after this occurs, except wait for later flowers to produce fruit. Rarely does a plant continue to drop its flowers.

To get the best flavor and color, harvest tomatoes after they are fully ripe. Tomatoes picked green may be ripened at temperatures between 55 and 72 degrees. Light will increase color some but is not essential to ripening. In direct sunlight, the added heat often deteriorates their quality.

Mulches help prevent weeds, reduce water loss from the soil, and stablilize soil temperature. Newspapers, straw or compost can be used as a mulch.