Chapter 27   Tomatoes - Field

Link to IPM Elements for Fresh-market tomatoes and Greenhouse tomatoes.

Link to New York Tomato Crop Profile

Link to Resource Guide for Organic Insect and Disease Management

Recommended Varieties

Most commercial tomato hybrids are determinate, having a restricted branching and fruiting pattern and branches terminating in a flower cluster. These varieties are preferred for commercial production because the harvest period is more concentrated and the plants are more compact and bushlike, making optimal spacing more predictable and facilitating cultivation. Many home garden varieties, some commercial staking varieties, and some cherry tomato varieties are indeterminate, continuing to produce new branches and flowers throughout the growing season.

Planting Methods

Because tomatoes are sensitive to frost, transplants are seldom put in the field before May 10 in upstate New York. The latest plantings for fall harvest are at the end of June. Transplants are grown in greenhouses at 70° to 75°F day and 60° to 65°F night temperatures. Bottom heat (75°F) improves emergence. For early market, a two to three inch cell for each plant in the flat is recommended. Plants are usually six to seven weeks old and just showing buds when taken to the field.

Before transplanting to the field, tomato seedlings should be hardened by withholding water and nitrogen, not by exposure to cold temperatures. Transplants exposed to cold (60° to 65°F day and 50° to 60°F night) for one week or longer are more prone to catfacing, a serious physiological disorder that can reduce marketable yield substantially.

See Cornell Report: Brushing for height control in transplants

Staking and pruning can hasten early fruit production by a week or more, protect fruit quality, and facilitate harvest. The cost-effectiveness of this system depends, in part, on the prices paid for early and high quality fruit. Wooden stakes, four to five feet long and one inch square, are generally used; they are driven one foot into the ground between every other plant in the row. Weather-resistant twine is tied to an end stake, passed along one side of the plants, and looped around each stake until the end of the row. The process is repeated on the other side of the plants. A short length of metal conduit or PVC pipe is often used as an extension of the stringer’s arm, with the twine fed through the tube. The first stringing is at an eight to ten inch height when the plants are 12 to 16 inches tall. The next stringing is six to eight inches higher and applied before the plants start to fall over. It may be necessary to string three or four times.

Pruning will result in a lower total yield, but the fruits produced will tend to be larger, and the first set may mature a few days early. Pruning involves removing all suckers (when they are two to four inches long) up to the one immediately below the first flower cluster. More severe pruning is not recommended because it will cause leaf curl and plant stunting. Some growers prune only one or two suckers or none at all, particularly if the variety does not have a vigorous growth habit. Plants should be pruned before the first stringing and not when they are wet because this could spread disease.

See Cornell Report: Brushing for height control in transplants

2000 Cornell Report: Paper Mulch: Can it Replace Plastic? : Upstate (Photos, Text)

2001 Can paper mulch replace black plastic? (.pdf files: text | tables) photos

2002 Alternative Mulch Product (text and photos | table)

2003 Cornell Report: Alternative Mulch Products (text, table1, table2, photos)

2004 Cornell Report: Alternative Mulch Products (text | table1 | table 2 |Tips for Success with Biodegradable Mulches | photos )

2005 Cornell Report: Alternative Mulch Products text | table1 | photos | Tips for Success with Biodegradable Mulches

Commercial Biodegradable Mulch Sources

2002 Cornell Report:: Growing Heirloom Tomatoes (text | photos| table)

Crop rotation and disease management article

Fertility

Maintain a pH of 6.0 to 6.5. Zinc may be needed if the organic matter is low and the pH is greater than 7. If these conditions exist, apply zinc sulfate in the transplant water. For transplants, add 1/2 pound zinc sulfate in 100 gallons of transplant water for a 0.2 percent solution. See Table 27.2 and Table 27.3 for the recommended rates of nitrogen, phosphorus, and potassium.

Cornell cover crop decision tool

See Cornell article on nutrient deficiency symptoms

Go to Cornell Nutrient Analysis Lab website to find out how to get soil samples tested.

Cornell Soil Health website and manual

SARE Publication: "Building Soils for Better Crops"

SARE publication: "Managing Cover Crops Profitably"

Table 27.2 Recommended nutrients based on soil tests for transplants in bare ground.
N pounds/acre	P2O5 pounds/acre				K2O pounds/acre			Comments
	Soil Phosphorus Level				Soil Potassium Level
	low	med.	high		low	med.	high
100	150	100	50		180	120	60	Total recommended.
50	150	100	50		180	120	60	Broadcast and disk-in.1
50	0	0	0		0	0	0	Apply when first clusters set fruit.2
1: If equipment is available, apply half of the phosphorus and potassium in bands 4" deep and 4" from the row at planting. 2: Nitrogen can be applied as a split application. Apply half at fruit set and the rest when fruit are 1" in diameter.

Table 27.3 Recommended nutrients based on soil tests for transplants in plastic mulch. (If plastic mulch is used without fertigation, broadcast and incorporate all fertilizer before laying plastic mulch).
N pounds/acre	P2O5 pounds/acre				K2O pounds/acre			Comments
	Soil Phosphorus Level				Soil Potassium Level
	low	med.	high		low	med.	high
100	150	100	60		180	120	60	Total recommended.
40	90	40	0		120	60	0	Broadcast and disk-in.1
20	20	20	20		20	20	20	Apply 1 week after transplanting.
20	20	20	20		20	20	20	Apply when first fruit are 1" in diameter.
20	20	20	20		20	20	20	Apply when first fruit turn color.
1: If equipment is available, apply half of the phosphorus and potassium in bands 4" deep and 4" from the row at planting.

Table 27.4 Nonpathogenic disorders.
See Cornell Tomato Diagnostic Key
Disorder	Recommendation
Blossom end rot (BER)	Characterized by a large, leathery brown or black spot on the bottom of the fruit caused by a calcium deficiency. Test the soil to make sure calcium levels are adequate, and maintain uniform moisture. Varieties vary in susceptibility. See photo gallery of blossom end rot of tomato Tomato disorder fact sheet Ohio BER fact sheet
Catface	Severe scarring on the blossom end of the fruit, usually most severe on the earliest fruit of large, fruited varieties. Temperatures during fruit set of 60ƒ to 65ƒF during the day and 50ƒ to 55ƒF at night aggravate the problem. Do not harden transplants by lowering the temperature.
Fruit cracking	Due to rapid uptake of water by the fruit, as a result of heavy rain or watering. Choose crack resistant varieties, and maintain uniform soil moisture by mulching and steady watering.
Yellow or green shoulders	Tops of fruit never ripen completely. This is a genetic problem that can be eliminated by growing plants with the uniform ripening gene. See Section 27.1 Recommended Varieties.
Blossom drop	Due to daytime temperatures in excess of 90ƒF and nightime temperatures over 80ƒF. Varieties vary in susceptibility.
Sunscald	Symptoms appear as a yellow to white water-soaked area on the side of the fruit exposed to the sun. Ensure plants are adequately fertilized, so healthy foliage shades fruit. Do not prune plants after fruit has formed.
Internal browning/ blotchy ripening/graywall	Fruit ripens slowly and unevenly. Exact cause is unknown but may be related to tomato mosaic virus (TMV); cloudy, moist, cool weather; soil compaction; or low potassium levels.

Harvesting

Fresh-market tomatoes, especially those that will be shipped, may be dumped from field or transport containers into large tanks of water to prevent bruising immediately after harvest. Water temperature in dump tanks should be slightly higher (5° to 10°F) than fruit temperature to prevent the movement of bacteria into the stem end of the fruit. Fruit are usually washed with a water spray immediately after the dumping operation regardless of whether a wet or dry dumping method is used. Only chlorinated water should be used. See Section 10.1 in the Postharvest Handling chapter.

Tomatoes should be stored between 55° and 70°F and 90 to 95 percent relative humidity. Chilling injury can develop if temperatures are below 50°F for more than 24 hours. Tomatoes ripen more quickly as temperatures increase; although they ripen faster at 75°F than at 70°F, they will have a better color to firmness ratio at 70°F. Temperatures above 80°F will inhibit red color development. Tomatoes harvested at mature green can be held for up to two weeks at 55°F. Ripening of mature green fruit can be initiated by a 24 to 48 hour exposure to 100 to 150 parts per million of ethylene at 70°F and 85 to 90 percent relative humidity.

See UC Davis post harvest guide for tomato

See North Carolina post harvest guide for tomato

See Cornell Report: Food Safety Begins on the Farm

See Cornell "Smart Marketing" series.

See USDA grade standards for fresh tomatoes, greenhouse tomatoes, green tomatoes, processing tomatoes, and italian canning tomatoes

See USDA Marketing site

See current wholesale prices from US markets

See "Fresh Now from New York Farms"

SARE Publication: "Marketing Strategies for Farmers and Ranchers"

SARE Publication: "Direct Marketing Resource Guide"

Disease Management

| Bacterial canker | Bacterial speck | Bacterial spot | Bacterial soft rot | Damping-off | Early blight | Anthracnose | Septoria leaf spot | Fusarium & Verticillium wilts | Buckeye fruit rot and Phytophthora root rot |Botrytis gray mold, gray leaf mold, white mold or timber rot | Late blight | Viruses: Cucumber Mosaic Virus, Double Virus Streak, Tobacco Mosaic Virus, Tomato Spotted Wilt Virus |

SARE Publication: "A Whole-Farm Approach to Managing Pests"

See Cornell Tomato Diagnostic Key

See Cornell fact sheet on bacterial diseases of tomato

See photo gallery of bacterial diseases of tomato

Organic management of bacterial diseases on solanaceous crops

Time for concern: Canker - plant emergence through harvest; Speck - planting until first formed fruits are one third their final size; Spot - early flowering and fruit setting period.
Key characteristics: Canker - early symptoms of the disease include wilting, curling of leaflets, and browning of leaves, often only on one side of the plant. Leaf lesions up to 1/4 inch in diameter appear on the upper leaf surface and/or slightly raised spots 1/16 inch in diameter appear. Marginal burning of the leaves is common, giving the leaves a scorched appearance. White spots 1/8 inch in diameter develop on exposed fruit surfaces. The spots have a dark brown center surrounded by a distinct, white halo. Speck - leaf symptoms consist of black lesions, 1/8 to 1/4 inch, with a discrete yellow halo. The lesions of spot are similar but tend to have a greasy appearance, whereas those of speck do not. Lesions are slightly raised and 1/16 inch in diameter. Spot - leaves show small, irregular, dark lesions which can coalesce and cause the leaves to yellow. Infection causes early blossom drop. On green fruit, small, water-soaked spots are first noticed. These spots become raised, with irregular, brown, sunken centers, 1/8 to 1/4 inch in diameter. See References 1 and 2.

See Cornell Tomato Diagnostic Key

See Cornell fact sheet on bacterial diseases of tomato

See photo gallery of bacterial diseases of tomato

Time for concern: Harvest and postharvest
Key characteristics: Small, sunken, light to dark colored, water-soaked areas appear on fruit, usually near injuries or natural openings. See Reference 1.

See Cornell Tomato Diagnostic Key

Photo of seedling damping off

UCONN fact sheet on damping off

Time for concern: Transplant production
Key characteristics: Pythium causes a dark colored, water-soaked lesion on the root extending to the stem above the soil line. This causes the seedling to fall over. Rhizoctonia causes brown, reddish brown, or black lesions near the soil line. The stem becomes soft, and the plant falls over and dies. See Reference 1.

Check NYS PIMS (Product, Ingredient, and Manufacturer System) to see if the label is current for New York. SPECIAL NEW YORK RESTRICTIONS MAY APPLY. (http://magritte.psur.cornell.edu/pims/)

See Cornell Tomato Diagnostic Key

Organic management of EB on solanaceous crops

Time for concern: All stages of plant development
Key characteristics: Lesions first appear in the field as small, brownish black target spots on older foliage. Lesions next appear on younger leaves. The earlier the maturity of a variety, the more susceptible it is to early blight.

See a report of 2001 efficacy trials for OMRI approved (organically approved) materials for tomato early blight

See Cornell Tomato Diagnostic Key

See Cornell fact sheet on tomato antracnose

See photo gallery of anthracnose of tomato

Organic management of anthracnose on solanaceous crops

Time for concern: Ripe fruit
Key characteristics: Symptoms appear on ripe fruit as small, sunken, water-soaked, circular spots. The lesions increase in size, and the central portion darkens. The darkened area contains many small, fungal structures from which masses of salmon-colored spores are released in moist weather. See Reference 4.