Tomatoes:Guidelines

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GUIDELINES: TOMATO PRODUCTION



STATISTICS

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OUTLINE OF MANAGEMENT ACTIVITIES

Cultural Practices

_____ Test soil for nutrient status and pH every year. _____ Maintain records of test results and fertilizer applications. _____ Test soil organic matter at least once every three years. _____ Apply fertilizer and lime according to test results, crop requirements and expected uptake, accounting for additional nitrogen from organic matter, compost, manure, and cover crops. _____ Apply nitrogen fertilizer by split application (One application made just before planting and one or more applications are made as a sidedress or through trickle irrigation). _____ Apply some fertilizer in a broad band in the bed at planting and cover with plastic to increase nitrogen availability to the plant and reduce risk of leaching. _____ Perform a pre-sidedress nitrate test to determine amount of nitrate-N available. Additional nitrogen should be applied as sidedress according to test results. _____ Turn under crop residue after harvest (plow or disk deeply). _____ Use a winter cover crop to preceded the tomato crop. _____ A cover crop of legume or legume/grass mix is prefered. _____ The nitrogen contribution of the cover crop needs to be calculated. _____ Adjust fertilizer application to calculations. _____ Preference is for plants grown in stake and weave or "basket weave" culture. _____ Grow early and late cultivars in separate or isolated fields. _____ Use at least some plants with resistance to soil-borne diseases. _____ Use at least some plants with resistance to foliar diseases. _____ Use high tunnels for early season crop.



Pesticide Management

_____ Use approved and registered pesticides according to label. _____ Maintain application records including date, location, applicator, target pest, pesticide name, EPA registration number, formulation, rate and number of acres treated. _____ Calibrate all sprayers at the start of the season. _____ Minimize pesticide drift. _____ Develop and implement a resistance management plan. _____ Select pesticides which will preserve natural enemies of pests. _____ Use separate sprayers for herbicides and insecticides. _____ Check sprayer(s) calibration at least once during the season. _____ Recalibrate each sprayer as needed. _____ Maintain records of planting dates for treated fields. _____ Keep records of stage of crop of treated field. _____ Use water-sensitive spray cards to test coverage of leaf surfaces. _____ Use a boom sprayer for fungicide and insecticide applications to reduce spread of bacterial diseases. _____ Use a drop nozzle system for fungicide applications on staked or trellis tomatoes.



Insect Pest Management

_____ Scout "SUSPECT INSECTS" .. Fruit and Foliage Pests .. Beet Armyworm .. Lygus Bugs .. Potato Tuberworm .. Stink Bugs .. Tomato Fruitworm .. Tomato Pinworm .. Yellowstriped Armyworm .. Foliage Pests .. Beet Leafhopper .. Green Peach Aphid and Other Early Season Aphids .. Hornworms .. Leafminers .. Loopers .. Potato Aphid .. Tomato Russet Mite .. Whiteflies .. Seed and Seedling Pests .. Cutworms .. Flea Beetles .. Wireworms

_____ Monitor aphids (green peach aphid, potato aphid, melon aphid) weekly by direct observation of two leaves per plant on 25 to 50 plants per field. _____ Use insecticides for aphid control only if aphid densities exceed action thresholds recommended by Cooperative Extension. _____ Monitor Colorado Potato Beetle densities weekly from transplant to fruit set, counting numbers of larvae and adults on 25 -50 plants per field. _____ Record defoliation estimates and percentage of clipped stems weekly. _____ Use Colorado Potato Beetle controls according to Cooperative Extension recommended action thresholds. _____ Monitor Colorado Potato Beetles weekly from fruit set to harvest by rating infestations as absent, light, medium or heavy. _____ Record percentage of fruit injury and percentage of defoliation. _____ Apply Colorado Potato Beetle controls after fruit set only if fruit injury or defoliation exceed Cooperative Extension recommended action thresholds. _____ Monitor hornworms, spider mites and other occasional pests during weekly scouting. _____ Controls are applied only if defoliation or infestation exceeds 20% of plants or if injury is significant. _____ Monitor Tomato Fruitworm populations by egg sampling or pheromone traps and/or fruit and foliage damage. _____ Bacillus thuriengensis may be a useful control for hornworm.



Disease Pest Management

_____ Select tomato seed tested and found to be disease-free. _____ Select tomato seed treated with sodium hypochlorite _____ Select seed treated with hot water. _____ Use transplants that are grown in-state _____ If transplants are grown on-farm, the growing medium does not include field soil. _____ Use tomato plants not grown in the same greenhouse with ornamental plants. _____ Sanitation practices in the greenhouse include cleaning of benches, trays, hoses, etc. and avoiding contamination of the transplant media and hoses. _____ Humidity in the greenhouse is reduced through proper timing of watering, ventilation and air circulation. _____ Streptomycin or copper-based material is used ONLY if farm has a problem or a history of bacterial canker or other bacterial disease of tomato. _____ Fungicide/bactericide mixtures are used ONLY if field has a history of bacterial canker or other bacterial diseases of tomato. _____ Bactericides are applied only if symptoms of bacterial diseases are present on the farm more than four weeks after transplanting. _____ Use initial fungicides for control of early blight and Septoria leaf spot. These are triggered by date (first week of July) or disease forecasting (TOMCAST software, or accumulation of 35 Disease Severity Values (DSV) since planting). _____ Monitor fields weekly for disease. _____ Record scouting results, including disease symptoms, percent infested plants and percent of foliage with symptoms. _____ Scheduling of fungicides for control of Alternaria early blight and Septoria is based upon weather conditions (i.e. long leaf wetness periods and warm temperatures) or presence of disease symptoms. _____ Chemical controls for disease other than Alternaria early blight, Septoria leaf spot and bacterial canker are applied only after accurate diagnosis and when chemicals are effective against the disease. _____ Apply fungicides and bactericides only when the application will be followed by a drying period of at least two hours. _____ Take precautions to avoid spreading pathogens during pruning and tying of plants. Work the crop only when plants are dry. _____ If late blight is identified, protectant fungicides are used to prevent the spread of the disease.



Weed Pest Management

_____ Scout "SUSPECT WEEDS" .. barnyardgrass (Echinochloa crus-galli) .. bermudagrass (Cynodon dactylon) .. bindweed, field (Convolvulus arvensis) .. broomrape (Orobanche ramosa) .. canarygrasses (Phalaris spp.) .. chickweed, common (Stellaria media) .. crabgrass, large (Digitaria sanguinalis) .. datura, sacred (Datura wrightii) .. dodders (Cuscuta spp.) .. fleabane, hairy (Conyza bonariensis) .. goosefoot, nettleleaf (Chenopodium murale) .. groundcherries (Physalis spp.) .. groundsel, common (Senecio vulgaris) .. horseweed (Conyza canadensis) .. jimsonweed (Datura stramonium) .. johnsongrass (Sorghum halepense) .. knotweed, common (Polygonum arenastrum) .. lambsquarters, common (Chenopodium album) .. lettuce, prickly (Lactuca serriola) .. lovegrasses (Eragrostis spp.) .. mallow, little; cheeseweed (Malva parviflora) .. mustards (Brassica spp.) .. nettle, burning (Urtica urens) .. nightshade, black (Solanum nigrum) .. nightshade, hairy (Solanum sarrachoides) .. nutsedge, purple (Cyperus rotundus) .. nutsedge, yellow (Cyperus esculentus) .. oat, wild (Avena fatua) .. pigweeds (Amaranthus spp.) .. purslane, common (Portulaca oleracea) .. rocket, London (Sisymbrium irio) .. shepherd's-purse (Capsella bursa-pastoris) .. sowthistles (Sonchus spp.) .. sweetclovers (Melilotus spp.) .. thistle, Russian (Salsola tragus) .. tobacco, Indian (Nicotiana quadrivalvis) .. tomatillo (Physalis philadephica) .. velvetleaf (Abutilon theophrasti)

_____ Use last years scouting records to begin this year's scouting. _____ Scout field(s) for weeds in prior year mid-to-late season. _____ Record all weeds by identity and field locations. _____ Use banding of herbicides & cultivation to reduce herbicide use rates or control weeds through cultivation (no herbicide use). _____ Don't use herbicides of the same class on the same field in succeeding years. (Use crop rotation and corresponding herbicide selection). _____ Prevent weeds in field alleys and roadways from going to seed. _____ Use an experimental plot to test a different weed management technique and record the results.



Weather and Crop Monitoring

_____ Monitor weather and crop parameters _____ Keep daily records.

Date: - Min/max temperatures: - Rainfall: - Hours of leaf wetness: - Stage of tree development (by cultivar, weekly):



DEVELOPMENT

The main development stages that tomatoes pass through include seedling establishment, vegetative growth, flowering, and fruiting stages.


Seedling Growth

Root growth is extremely important for seedling establishment. A deep root system with a strong taproot and a few secondary roots is the ideal root system and can usually be obtained in well-drained soils. A well-developed root system makes water management more productive and benefits the plant. The above ground portion of the plant is extremely sensitive in early stages. The plant is relatively small compared to the root system, but it is important that it does not become damaged as this will inhibit the energy levels and slow the growth. Weeds should not shade the seedlings and insects must be controlled so not to destroy any top growth. Tomatoes have a difficult time recovering from such losses in early stages.


Growth

Between the seedling stage and flowering stage is where the most vegetative growth occurs. Most of the plants' energy is being devoted to new shoots and leaves increasing the overall size of the plant. As the shoots and leaves increase in number and size, a cluster of fruit will form which receives its energy from the leaves. When this occurs, the vegetative growth stops and all of its energy goes into producing the fruit. It is extremely important at this time that the plant is under no stresses whether they be water or pest related. If the plant experiences delayed growth due to stresses, both the size of the plant and yield are ultimately affected.


Fruiting

Pole and cherry tomatoes produce clusters of fruit along each stem and fruit can be produced over a long period of time. The harvest time for these plants is long because fruit is continually being produced on the long vines. Bush tomatoes are smaller and more compact than pole varieties. Both grow to a certain size, produce flowers and set fruit during a relatively short period. These varieties are essential for high yields with mechanical harvest. Because the length of time spent on the vine before harvest varies significantly between the varieties, each is exposed to a different range of pests and must be dealt with accordingly.


GROWTH REQUIREMENTS=

Nutrient Requirements

The following graph indicates how much of primary nutrients are removed from the soil in thirty tons of tomatoes.

N (Lbs) P<->2</->O<->5</-> (Lbs) K<->2</->O (Lbs)

Fruit 170 55 360 Vines 80 25 120 Total 250 80 480

Proper nutrient levels are essential for optimal production of tomatoes and some research suggests the need for a starter fertilizer under the tomato seeds. Most nutrients that are taken up in the plant are available in the upper two feet of soil. When plants are nutrient deficient, they are less likely to tolerate stresses placed on the plant. Although tomato plants require all major and minor nutrients to be available for optimal growth, usually only nitrogen and phosphorus need to be applied. A soil test will determine if the soil is highly deficient in any of the other nutrients.


Water

One of the best factors in determining a good tomato production is to have a well-developed water management program. The roots should always be moist throughout the season, but not saturated. Roots that do become dry during the growing season result in blossom drop, small fruit, and fewer flowers set. Water supply should be cut off a few days prior to harvest but the roots should still maintain a good moisture level so that the fruit does not suffer during this time. The following is a simple chart showing the relationship between yields of tomatoes that experienced different levels of moisture applications.

MOISTURE STRESS EFFECT ON VARIETY YIELDS

Variety No Moisture Moisture Stress Yield Stress During Fruit Reduction Development (tons/acre) (tons/acre) (tons/acre)

VF-145-7879 41.0 27.4 13.6 VF-145-513 42.8 26.7 16.1 VF-65 41.6 13.5 28.1 Napoli 36.9 14.0 22.9

When developing a water management program, it is important to remember that much of the water, as much as 90% will pass through the roots, stems, and leaves and evaporate into the air. Therefore, by taking this into consideration, fewer plants will suffer from lack of water and the roots will always be able to remain moist.


Temperature

It is important to remember that tomatoes thrive in warm weather and should not be exposed to cool temperatures. Most tomatoes are a result of direct seeding which should not occur until the soil temperature reaches 57° F for three consecutive days. The seeds should be planted 3/4 to 1 inch deep in the soil. The following is a chart indicating the effect soil temperature can have on emerging seedlings.

EFFECT OF SOIL TEMPERATURE ON EMERGENCE OF TOMATO SEEDLINGS

Average Soil Days to Temperature,°F Emerge At two-inch Depth

55 25 *57 16 59 15 61 14 73 9 78 8 80 6

  • Proper time to begin first plantings.

Tomatoes have an extensive root system, which may be 4-5 feet deep. This root system is extremely important in supplying the proper nutrients to the plant. During the early stages of growth, there is little nutrient uptake when compared to the latter part of the growing period. Most tomatoes need about 125 days to reach proper maturity before they can be harvested. The optimal temperature for tomatoes to be grown under is between 79° to 90°F (26° and 32°C); however, growth can still occur when temperatures fall or rise above this range. Nighttime temperatures are also important for good fruit set to occur. These temperatures should fall in the range of 55° to 75°F (13° to 24°C). It should be noted that temperature is one of the most important factors that affects tomatoes growth and development.


CULTURAL PRACTICES=

Field Selection

Field selection is an important factor when determining the success of a crop of tomatoes. Several things should be taken into consideration which include, choosing a field with deep, uniform soil which allows water and herbicides to penetrate a well developed root system. Also, submitting the soil to a local laboratory for analysis will determine if there are any left over herbicides residues remaining in the soil from previous crops which may hinder tomato development. This test will also be able to make recommendations to prevent mineral imbalances in the soil. Finally, avoid fields that are infested with difficult to control weeds and pests. Many times herbicides that are applied to control difficult weeds cause more damage to the tomato plants rather than taking care of the weed problem, which ultimately destroys the final yield.


Land Preparation

Well prepared fields will increase the overall productivity of the field. Many suggested ideas include having good drainage in the field, having the land properly graded, furrowing out listed beds in the fall to avoid later compaction of the soil, and making the bed tops flat and uniform. These items will help ensure that the field is evenly watered and herbicides are evenly distributed. Better weed control, less chance of root disease, and easier irrigating and cultivating will make other production operations more efficient.


Planting Methods

Direct Seeding

Direct seeding should take place when the soil is warm and moist. Ideally, the soil should be at least 57°F (14°C) or more for three consecutive days. The seeds can be planted 2 to 5 cm (3/4 to 2 inches) deep, depending on soil texture, moisture, and other conditions. They can also be planted in either single or double rows, depending on the soil and moisture type available. Usually high seedling rates help to ensure that many plants will survive and seedlings won't die due to outside factors such as cutworms or other seedling pests.


Clump Planting

One method of planting is clump planting which has three to five plants that are within a space of 7 to 8 cm (3 inches) and clumps are spaced 22 to 30 cm (9 to 12 inches) apart. The advantage of this method is that the plants act as a large single plant and can better fight against diseases or pests which may attack. Planting can be done with a precision planter or a continuous line and thinned to clumps later. Obviously precision planting is easier and more efficient but these fields must have a good weed control system because early hoeing in these fields will offset the savings provided by this method.


Plug Planting

Plug planting uses special equipment which sets a "plug" of planting mix and tomato seeds into the soil in regular intervals. The advantage of this method is that the seeding mix contains chlorpropham (Furloe), a preplant herbicide that is not safe for tomatoes. The reason that the seedlings can survive with this herbicide in the planting mix is the vermiculite in the mix acts as a shield and protects the seedlings. This herbicide prevents nightshades that are a problem in tomato fields. Using plugs is also advantageous in that the soil can be kept moist without being exposed to rain before planting.


Transplanting

The advantage of transplanting is that the tomato plants can be established and can have a head start on weeds that are a problem during the emergence period. However, these plants also have a weaker root system than direct seeded plants and may be sensitive to the "new" soil conditions.


SEED VARIETIES

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FERTILIZING

It is essential that the soil is properly fertilized and that all minerals are available to the plant to produce maximum yields. Most soils will only need nitrogen and phosphorus added in significant amounts but a professional soil test should be taken to adjust the fertilizer program as needed. Testing can determine most mineral imbalances, excess salinity, and unfavorable acidity. Testing is extremely important in fields where tomatoes were not previously planted or the crop history is unknown. As the plants mature it is possible to determine if growth is inhibited by nutrient deficiencies. Tomatoes that are not properly fertilized do not produce maximum yields and compete poorly with weeds or other pests.


Preplant Fertilizer

The only nutrient that should not be applied as a preplant fertilizer is potassium in soil with less than approximately 80 parts per million (ppm). These soils need 100-200 pounds of potassium applied per acre and this much will burn seedlings. Therefore, the potassium should be incorporated before planting begins.


Starter Fertilizer

Starter fertilizers are important in the seedling stage for the plants to compete well with weeds and seedling pests. The placement of fertilizer is important so that as the root system develops it has direct access to the nutrients available. It should be in a band 5-10 cm (2-4 inches) directly below the seed row. The two most important elements in starter fertilizer are nitrogen and phosphorus.


Sidedressings

Sidedressing fertilizers usually only include nitrogen, but may be complete fertilizers. Tomato plants are efficient nitrogen users and the amount of nitrogen applied needs to be adjusted according to soil type, frequency of irrigation, and crop history. Bush tomatoes, including both processing and fresh market varieties, need a single sidedressing of 36 to 45 kg (80 to 100 pounds) of nitrogen per acre, applied at thinning. Pole tomatoes need more total nitrogen per season than bush varieties because they continue growing and producing fruit over a longer period. Excess nitrogen is usually not a problem since the extra growth it produces can be pruned off and does not interfere with harvest.


IRRIGATION

Proper water management is extremely important for high productivity. When plants do not receive enough water and become stressed the overall growth of the plant is reduced and fruit production occurs prematurely. If the plants are exposed to excess water, the root system becomes oxygen deficient and creates fungal infections. Soil tubes and augers are available to check the soil moisture to prevent these problems from occurring. A rigid watering schedule should never be implemented; water the plants according to their need. Also, when preparing the field, prepare the land to prevent ponding so not to keep water standing in the field for a long amount of time.


Furrow Irrigation

Furrow irrigation is one of the most practical ways of watering the tomato plants, however, it is less effective in poorly drained soils, in fields with severe low spots, or fields that are established on a steep slope. Where furrow irrigation is used for germination, it is usually best to plant in split beds, then switch to permanent furrows when seedlings are established. The furrows need to be in good condition throughout the season to avoid excess moisture on beds and the development of soil-borne diseases. Fruit should not contact wet soil to avoid molds and rots.


Sprinkler Irrigation

Sprinkler irrigation is a good way to keep the soil surface moist without using too much water, but when the plants reach significant size, it is best to switch over to furrow irrigation. Sprinklers can spread diseases and after fruit has set, the free standing water on the fruit will encourage molds or blights. The amount of water distributed by the sprinklers needs to be closely monitored so that surface puddling or runoff occurs. It is easier to get uniform application of water at an acceptable rate by using moderate-sized sprinklers, close spacings, small nozzles, and adequate, uniform water pressure.


Drip Irrigation

Drip irrigation is a smart way to irrigate but it is usually economically impractical. It is used on pole tomatoes and where local soil and slope conditions make other types of irrigation difficult. As with other forms of irrigation, it may encourage disease or weed growth if the soil surface is too damp or if a broken line causes flooding. Fertilizers and some pesticides can also be applied using this method.


Scheduling Irrigations

To ensure that the soil is not receiving too much or not enough water can be determined by setting a watering schedule. This schedule needs to be specific for each field. It is important to first determine the water holding capacity of the soil and how much water is available to the crop when the soil is at field capacity. Soil tubes and augers can be extremely helpful by examining the soil profile before planting occurs. After the schedule is determined, tomatoes generally need to be irrigated when about 50% of the available water in the rooting depth is used. Using flow meters or other measuring devices can help estimate how much water was used and where it was applied. Adjustments can be made according to this data.


Soil Moisture

The soil moisture should be monitored at least once a week by randomly testing the moisture content throughout the field. Tomatoes receive most of their water from the top two feet of soil below the surface. When the second foot of soil in this zone reaches 50% moisture, then it is time to water again, and this area should be the focus of monitoring the moisture level. However, it is also important to check for moisture deeper than these levels to account for fluctuating water table or areas of soil compaction. Tensiometers, gypsum blocks, and other special equipment may be useful for monitoring soil moisture in some situations, but always check instrument readings against direct observation of soil moisture before applying water.


Water Budgets

Much of the water used in irrigation is lost either by evaporation or by transpiration, or evapotranspiration. If it is possible to determine when the soil is at field capacity and how much water is applied, it is possible to determine the amount of water lost due to evapotranspiration. When it becomes time to irrigate again, the amount of water applied can be adjusted so that less water is lost from evapotranspiration keeping the overall water bill down.


Irrigation Requirements Through the Growing Season

To ensure that the soil is properly prepared before planting, the soil must be brought to field capacity if there has not been enough rain to already bring the soil to field capacity. It will be difficult to maintain the soil moisture later in the season without flooding the plants if the deep soil moisture dries too quickly. Underwatering will cause the plants to become stressed and be smaller, producing small yields. Over irrigating will damage the root system causing early collapse of the plant. A certain amount of water stress is desirable during the preharvest period (up to a month before) in processing tomatoes because it prevents late growth, speeds ripening, increases the percent of soluble solids in fruit and makes harvesting easier. However, do not allow the plants to dry completely, irrigation will be needed closer to harvest for the root system that is closest to the surface.


SANITATION

Preventing pests or disease from the beginning can significantly reduce problems later on in the season. Following good sanitation habits is a must to avoid introducing other infestations to the field. The following is a list of precautions to avoid potential problems: use clean seed, use clean transplants from fumigated soil, only use sterilized compost, do not irrigate with tail water (waste water) that carries other infestations, if using canal water install a screen to filter out unwanted seeds or weed parts, always clean equipment between fields, disc all crops and destroy growing culls, destroy all residue left in the field from a previous crop, spot treat all problem weeds as soon as they are spotted and before they set seed, and destroy weeds along the borders of the fields which will set seed and spread to the crop.


MISC. PHOTOS

Tomato + hot cap (H. F. Schwartz; Colorado State University)

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Tomato production - hot caps (H. F. Schwartz; Colorado State University)

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Tomato production - hot caps (H. F. Schwartz; Colorado State University)

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