Troubles with Tomatoes

August 16th, 2007

Having trouble growing a decent tomato lately?

You’re not alone.

This most popular of all vegetable-garden crops seems to be getting more and more troublesome – no thanks to a laundry list of woes ranging from leaf diseases to groundhogs to too-hot weather.

Take Doris and Richie Ranaglia of Derry Twp., who have been growing tomatoes since 1964.

These would-be tomato plants are dead from disease by September.

They’ve been having increasing trouble, but nothing like last year when just about all of their fruits suddenly rotted on the vine – most likely a result of a fungal disease such as early blight or anthracnose.

“Those that were picked ripe lasted only a day or two before getting soft spots and spoiling,” says Doris. “Those that were picked a day or so before they were ripe did the same thing.”

This year the Ranaglias resorted to spraying their plants every 14 days with an aspirin-water solution, which is supposed to heighten plant immune systems. (See below for more details.)

So far, so good, she says, although the yield still isn’t as impressive as in the good old days.

“We didn’t used to have problems,” Doris adds. “It’s started mostly in the past six or seven years.”

Joe Martin also grew nice tomatoes for 10 years, but the going has been much tougher since moving to East Pennsboro Twp. six years ago.

He says his tomatoes “have been plagued by wilt, leaf spot, blossom-end rot and pests,” not to mention plants that were chewed to the ground by deer the first year at his new house.

“The past three years, they’ve been attacked by an insect I can’t identify,” Martin says. “It looks like an armored vehicle that gets on the ripening fruit and eats into it.”

The culprit is most likely stink bugs or tarnished plant bugs – just two of the insects that enjoy ripe tomatoes as much as humans do.

This year Martin is fighting back by switching to new tomato varieties, spraying an organic fungicide, increasing the space between plants, watering more often and mulching with red plastic (a product that’s been found to inhibit disease and increase tomato yield).

Things are going much better, but tomato-growing has become almost a full-time job.

Then there’s Ray Matty of Mechanicsburg, who’s been growing tomatoes for 40 years but only recently started getting another soil-borne fungal problem called Septoria leaf spot. This one causes leaf spotting, wilting and then leaf-dropping, which exposes fruit to scalding from the sun and ultimately to an early fruit shutdown.

Matty knows he ought to rotate his crops and not plant tomatoes in the same spot more than once every three years. “But I only have a very small garden that I only grow tomatoes in,” he says.

So he’s reluctantly begun spraying Ortho disease control every 10 days and has been fertilizing with Miracle-Gro every two weeks.

That’s helped, but he adds, “I never dreamed I would need to go to this extent in order to have healthy tomatoes.”

What gives here?

A few possibilities…

One issue is that home gardens are shrinking, which makes it easier for diseases to be transmitted and harder to stop soil-borne infections that could be short-circuited by rotating with non-susceptible crops.

Another is that many gardeners have returned to using at least some old-fashioned or “heirloom” tomato varieties. While these may taste better, their yield is usually less and they’re generally not as disease-resistant as newer hybrids.

Also a possibility is hotter and more erratic weather.

“Heat can be a problem with setting fruit,” says Annette MaCoy, consumer horticulture educator at Cumberland County Extension. “If temperatures are too hot, especially overnight, the flowers will abort. And you can’t do anything about that.”

Wild swings between drought and soaking rains don’t help either. Drought wilts. Sogginess rots. And alternating between the two causes blossom-end rot, an annoying nutrition-related problem that causes the fruits to rot from the bottom up.

“That’s the most common problem,” says MaCoy. “We see that every year. We tell people to be sure they have the ground mulched and that the plants are getting an inch of water every week. Without regular moisture, the roots are unable to get the needed calcium up into the fruits.”

Tim Elkner, a horticulturist at Lancaster County Extension, said a lot of failures occur because people think tomatoes are more trouble-resistant than they really are.

He says tomatoes may be one of the EASIER edible crops to grow, but they’re nonetheless not EASY.

Even then, he says, they’re only easier “if you pay attention to them. People try to treat tomatoes like cactus and walk away from them. Tomatoes need water, they need nutrition and maybe some pesticides, primarily to control disease problems.”

Elkner says Septoria leaf spot is the main disease problem he sees, and that’s usually controlled by regular applications of the fungicide chlorothalonil (Daconil).

He also sees a lot of blossom-end rot, which he attributes mainly to “poor watering habits.”

Lack of time also prevents many home gardeners from fertilizing as often as they should, Elkner adds, and that lowers yield and results in less robust plants.

Those are just the common things.

A groundhog was sampling this nearly-ripe tomato.

You also might run into: late blight (the devastating fungus that caused the Great Irish Potato Blight); cutworms that can chew down young transplants; hornworms that can nearly defoliate whole plants; two deadly wilt diseases that particularly threaten heirloom varieties; cracked fruit from excess rains; “mysterious” deaths from being planted too closely to walnut trees; growth-stunting root-knot nematodes; birds that peck holes in the ripening fruits; groundhogs that take huge bites out of every red fruit the day before you pick them, and assorted nutrient deficiencies.

Oh, yeah. Deer.

Makes you wonder how any of us ever did get any of those luscious, juicy red gems.

And very appreciative of the people who run farmer’s markets.

Ten things that can go wrong with your tomato crop and what to do about it:

* Leaves spotting, yellowing and dying. Don’t plant in the same spot every year or rotate with potatoes (same family). Mulch the ground. Remove diseased leaves from the garden. Spray a fungicide labeled for use on tomatoes every 7 to 10 days. Copper and neem oil are organic options.

* Fruits rotting from the bottom up. Keep the soil consistently damp throughout the season. Work eggshells or a light sprinkling of lime or gypsum into the soil each season.

* Whole plants wilt and die. Choose disease-resistant varieties. Look for the letters “V” and “F” after the variety name, which stands for resistance to Verticillium and Fusarium wilt diseases.

* Sickly look or browning leaves. Disinfect cages and stakes with a 10 percent bleach solution before reusing each year. Apply fresh mulch each season. Try using newly available plant proteins and biofungicides that supposedly activate tomatoes’ own defenses. Two examples are Messenger and Serenade. One ordinary aspirin dissolved in 1 gallon of water and applied every two weeks also is reputed to do the same thing.

* Small fruits, poor yield, weak growth and/or poor leaf color. Work an inch or two of compost into the soil before planting each spring. Fertilize every few weeks during the growing season with a granular or organic fertilizer formulated for tomatoes. A soil test wouldn’t be a bad idea if you haven’t done that lately.

* Fruits have green shoulders. Check soil acidity (pH). Do a soil test to be sure nutrient levels are adequate. Try a different variety next year. Excess heat also could be the culprit.

* Curled or twisted leaves. Could be herbicide damage. Cumberland County Extension saw a lot of this in May, around the time many lawns were being treated for broadleaf weeds. Curled-up leaves could be a heat response or aphids. Curled-down leaves could mean lack of water or reaction to a walnut tree planted nearby.

* Plants chewed down or fruits eaten by deer. Fence the entire area with a 10-high fence. Spray plants with a deer repellent (many are available in garden centers). Use scare tactics such as hanging pie tins from string around the perimeter of the garden.

* Big, fat green worms chewing the leaves. Pick off and smash these hornworms or spray plants with the caterpillar-targeted bacterium Bt (Bacillus thuringiensis). If you see what appear to be little rice grains on the hornworm’s back, no need to do anything. These are eggs of a parasitic wasp that will kill the hornworm shortly.

* Fruits eaten by groundhogs. Trap the groundhogs by using a cage trap baited with cantaloupe rinds. (Lead the rinds into the trap.) Fence the garden. Bury the bottom a foot deep or a foot out and leave the top unsecured to discourage climbing. Or give up and go to the farmer’s market.