Heavily in the red

For the last few years we’ve had less than great tomato harvests in our backyard. But this year is different. By July, one vine was already taller than me and about as big around as a young sequoia. Every few days I have to cut back the vining stems that threaten to overrun the garden or come though the bedroom window and strangle us in our sleep. I exaggerate only a little.

Countless tomatoes hide inside, and a dozen or so ripen each day. I planted it in a homemade, columnar cage of welded wire that measures 6 feet tall by 3 feet across, but that sturdy support disappeared weeks ago under the dark green foliage.

That’s the way it’s supposed to be this time of year. There should be enough juicy, vine-ripened fruit for pasta, salads and salsa, and eating right off the vine. If not, something is wrong. Plants may be getting too much water or fertilizer, or not enough sun. It might be too cool and breezy where you’re trying to grow tomatoes, or too hot. Or perhaps tomatoes have been grown in the same spot for too long.

Though we planted several kinds, ‘Abraham Lincoln Hybrid VFNASt’ is the most productive, an old heirloom strain from 1923 that’s recently been cross-bred to improve vigor and disease resistance (that’s what all those initials after the name represent). It’s an “indeterminate” type that just gets bigger and bigger until frost or the gardener cut it to the ground. It already looks like a haystack, only green, of course.

But I suspect the biggest reason our vines are doing exceptionally well is because we found a new spot in the garden to grow tomatoes. My wife and I garden near the coast where these heat-loving plants shiver in the chilly coastal breeze. But a tree fell over last winter and left us with a sunny new spot where tomatoes had not been grown before. Several of the most common tomato diseases can live for several seasons in the soil, so it’s important to find new places for tomatoes every few years. Our new spot is out of the wind and against a south-facing wall so it’s toasty warm and gets a full day of blazing sun.

We’ve also been very careful not to over-water this year. Near the coast we can get away with watering every few weeks. When we do water, it’s a good, deep soaking. We haven’t fertilized at all, because the soil is naturally rich from years of adding compost. We’re keeping an eye out for tomato worms, as is the mockingbird, who’s quite good at seeing the green worms amid all the green foliage.

Listed below are some of the common summer problems and the most likely causes, plus a few fixes suggested by the University of California Extension. Note that none is quick — spraying or fertilizing seldom does the trick. It often helps to try a completely different variety, one known for disease resistance.

In the list of maladies that follows, note how often this kind of cultural sea change is recommended. If this isn’t a stellar year, don’t abandon hope. Next year can be.

Plants grow slowly, then suddenly wilt and die in hot weather.

Diagnosis:

Phytophthora root rot (above), often caused by a soil that’s too wet. Next season, improve drainage and plant in a different spot. (Phytophthora can linger in the soil for several seasons.)

Blossom failure

Problem:

Plants make blossoms but they drop off.

Diagnosis:

Blossom drop. It can be caused by many things, such as days that are too hot (over 90 degrees) or nights that are too cool (below 58 degrees), too much shade, smog, excess nitrogen, heavy fruit set. Plants in full sun usually recover when conditions change, but try modifying watering and fertilizing.

No fruit

Problem:

Leaves are lush but there is little fruit.

Diagnosis: Too much nitrogen, a basic fertilizer element. Fertilize at planting time but not later in the season.

Leaves yellow, wilt and die, progressively from the bottom to the top of the plant. When stems are cut or split lengthwise, there are brown streaks inside, or the stem is brownish instead of ivory.

Diagnosis:

Verticillium or fusarium wilts. Plant will die and fruits usually don’t ripen. Next time, plant resistant varieties (look for a name followed by initials VF). Plant in different part of garden. Send infected plants to the dump.

Rolling leaves

Problem:

Leaves roll upward, are firm and leathery but not yellow.

Diagnosis:

Weather and culture — does not affect growth or fruit production. Try pruning less and avoiding overly wet soils. Do not cultivate deeply near plants.

Mottled leaves

Problem:

Leaves crinkled, mottled yellow and green, smaller than usual.

Diagnosis:

Mosaic viruses, transmitted from other plants by insects, or from tobacco. Never handle tobacco or smoke near plants. No cure. Remove infested plants and send to dump.

Darkened fruit

Problem:

Fruits are brownish black on blossom end. Spots become sunken and leathery.

Diagnosis:

Blossom-end rot, caused by the relationship of calcium to soil moisture during hot weather; is more common on sandy soils and on certain varieties. Next time, try different varieties.

Holes in fruit

Problem:

Fruit has holes in it.

Diagnosis:

Moth larva. If the hole is in the stem, it’s probably tomato fruitworm. If there are large gouges, it’s probably hornworm (egg is shown above). Hand pick or spray with nonpoisonous BT.

Scarred fruit

Problem:

Fruit has cracks or is scarred.

Diagnosis:

Catfacing — misshaped areas or cavities lined with scar tissue. It is caused by incomplete pollination. Next time, encourage bees and plant different varieties; don’t water from above. Sudden rapid growth when it’s hot or a heavy irrigation can cause fruit to split.

Ragged edges

Problem:

Leaves cupped, distorted, curled, curved downward, often ragged at edges.

Diagnosis:

Herbicide damage. Keep herbicides well away from plants.

Mites

Problem:

Leaves look greasy, becoming bronzed and stippled; turn brown and paper-like but do not wilt.

Diagnosis:

Mites, which look like slowly moving dust on undersides of leaves. Wash down plants, especially undersides of leaves, or use sulfur (follow label directions).

Sun damage

Problem:

White or yellow patches on green fruit become grayish, flattened, paper-like areas.

Diagnosis:

Sunscald, caused by hot weather and loss of leaves. Where fruits are exposed to sun, lightly shade clusters with thin fabric or shade cloth on hot days.

Sources: Yvonne Savio, University of California Cooperative Extension, Common Ground Garden Program; “Pests of the Garden and Small Farm” (University of California). Photographs copyright UC Regents, courtesy of ANR publications.