Tomato, Greenhouse and High Tunnel

Tomato, Greenhouse and High Tunnel Evonne Gong
Greenhouse & High Tunnel Tomato Disease Control
Greenhouse & High Tunnel Tomato Insect Control
Greenhouse & High Tunnel Tomato Physiological Disorders

Introduction

Tomato is the most widely grown high tunnel and greenhouse vegetable crop because of strong consumer demand for its high-value fruits, and because of its ability to utilize the vertical growing space and to maintain production over a relatively long harvest period. In New England, tomato yield and quality are usually greatly improved when growing in protected culture compared to the field. Greenhouse tomatoes are grown in a wide range of structures from simple hoop-houses and high tunnels to more expensive greenhouses with permanent foundations and sophisticated environmental controls. Regardless, the horticultural principles are the same.

Types and Varieties

Some growers plant field tomato varieties in tunnels, but most use varieties bred specifically for greenhouse production. In general, these varieties are indeterminate, bred for sustained production over many months when pruned to a single stem, and have some tolerance to common greenhouse diseases. Recently, a number of “hybrid heirlooms” have been introduced. These have appearance and flavor similar to heirlooms, but also have more resistance to leaf spot and vascular pathogens and are not subject to as much variability in fruit size and shape. Many growers use grafted plants to produce a more vigorous plant and help control soil borne disease.

High Tunnel and Greenhouse Tomato Varieties

 

Type Variety Disease Resistance
Hybrid Heirlooms Ginfiz F, Lm, ToMV, V
Marbonne F, ToMV
Margold LM, ToMV, V
Marnero F, ToMV, V
Marnouar F, LM, ToMV, V
Beefsteak Arbason F, TMV, V
Beorange F, LM, ToMV, V
Bigdena F, ToMV, V, TMV
Caiman F, ToMV, V, TSWV
Geronimo LM, F, V, TMV, PM
Rebelski F, LM, PM, TMV, V
Trust F, LM, ToMV, V
Grafting Rootstock DRO 141TX LM, ToMV, F, V
Estamino LM, ToMV, F, V, TSWV
Maxifort ToMV, F, V
Resistance to: F=Fusarium, LM=leaf mold, PM=powdery mildew, TMV=tobacco mosaic virus, ToMV=tomato mosaic virus, TSWV=tomato spotted wilt virus, V=Verticillium wilt

 

 

 

Fertility and Growing Media

 

To obtain sufficient quantity and quality of yield to justify the expense of greenhouse tomato production, careful attention must be paid to the growing medium. There are different approaches to production: soil vs. soilless culture and in-ground vs. container culture. With any system, the physical environment of the medium must promote good root growth. Nutrient supply must be optimized and maintained to encourage healthy plants and good fruit production.

 

The benefit of crop rotation holds true with in-ground systems, but not with soilless or hydroponic systems where the media is entirely replaced each growing season. In the latter, all containers should be sterilized before the next crop. Many growers do not rotate in-ground tomato crops from year to year because the greenhouse is designed specifically for that crop; in this case, sanitation is especially important. Remove all plant residues, twine, clips, mulch, etc. and maintain the house free of all vegetation, including weeds, for several weeks or months in-between tomato crops. The use of disease resistant varieties and rootstocks is also desirable.

 

In-Ground Culture

 

A greenhouse may be placed over high-quality field soil, but be sure to avoid the soil compaction that can occur during the construction of the greenhouse. Even if the topsoil is worked up after heavy traffic, plants may suffer once roots reach the compacted subsoil. On compacted soils or poor fertility sites, it may be advisable to make raised beds. 

 

Field soil in a greenhouse is usually initially amended with a large volume of organic matter such as well-made compost before growing greenhouse tomatoes. If uncomposted manure is used it should be applied at least 4 months prior to harvest to avoid contamination from human pathogens such as E. coli. Use of chicken manure in a greenhouse can generate excess ammonia that will damage plants. 

 

Annual soil testing is critical to optimizing soil fertility for good productivity. Greenhouse soils amended with compost or manure will likely require additional fertilization or liming for good plant and root growth. Often, additional N and K are needed annually but P levels may be excessive, especially after many years of compost application. Beds should be deeply tilled each year since nutrient salts tend to accumulate in the top 1-2" of soil. The soil should be tested for soluble salts (electrical conductivity) because rain does not leach salts from the greenhouse. If salt levels are excessive, the soil should be intensively irrigated, or the plastic covering should be removed over winter, to leach salts down into the soil profile. If leaching is necessary, it should be done well before planting. This allows time to retest the soil and apply appropriate nutrients since leaching often reduces nutrient levels. Avoid fertilizers with a high salt index (like potassium chloride) and those high in ammonium forms of N. Peat moss can be used to maintain organic matter and dilute high salt levels without adding additional nutrients or salts. High salt levels can also be diluted by mixing in low fertility field soil.

 

If a tunnel/greenhouse soil has been heavily amended with compost or manure, the use of the saturated media extract (SME) potting soil test as well as a regular field soil test (modified Morgan’s extract) is recommended, in order to measure water-soluble as well as reserve nutrient levels. The SME also tests for available nitrogen (as nitrate and ammonium) as well as salt levels. The combination of these 2 tests is offered as the “long-term high tunnel test” by the University of Maine Agricultural Testing Lab.

 

Fertilization should be based on soil test results and yield goals. Yields may vary from about 1-5 lbs/sq ft., depending on the duration of the crop, cultivar, and crop management.

 

N application rate based on yield goal

 

Yield Goal Yield Goal
(lb/A)		 Yield
(lb/ft2)		 Yield
(lb/stem, at 4 ft2/stem)  		 Approx. Plant Height
(ft)		  N need
(lb/acre 
@ 90% recovery)		 Total N Need
(lb/1,000 ft2)
Low 40,000 1 4 8 100 2.3
Medium 80,000 2 8 12 200 4.6
Good 120,000 3 12 16 300 6.9
High 160,000 4 16 20 400 9.2

 

 

 

P205 application rate based on modified Morgan’s soil test result and yield goal

 

Yield Goal Low
(<40 lb/A =
<20 ppm)		 Medium
(40-80 lb/A =
20-40 ppm)		 High/optimum
(80-160 lb/A =
40-80 ppm)		 Excessive
(>160 lb/A =
>80 ppm)
lb/acre lb/1000 ft2 lb/acre lb/1000 ft2 lb/acre lb/1000 ft2 lb/acre lb/1000 ft2
Low Yield Goal 180 4.1 120 2.8 60 1.4 0 0
Medium Yield Goal 240 5.5 160 3.7 80 1.8 0 0
Good Yield Goal 300 6.9 200 4.6 100 2.3 0 0
High Yield Goal 360 8.3 140 5.5 120 2.8 0 0

 

 

 

K20 application rate based on modified Morgan’s soil test result and yield goals

 

Yield Goal Low
(<400 lb/A =
<200 ppm K)		 Medium
(400-800 lb/A =
200-400 ppm K)		 High/optimum
(800-1200 lb/A =
400-600 ppm K)		 Excessive
(>1200 lb/A =
>600 ppm K)
lb/acre lb/1000 ft2 lb/acre lb/1000 ft2 lb/acre lb/1000 ft2 lb/acre lb/1000 ft2
Low Yield Goal 300 6.9 200 4.6 100 2.2 0 0
Medium Yield Goal 450 10.3 300 6.9 150 3.4 0 0
Good Yield Goal 600 13.8 400 9.2 200 4.6 0 0
High Yield Goal 750 17.2 600 13.8 300 6.9 0 0

 

 

 

Container Culture

 

This system typically employs ‘grow bags’ that contain artificial soil mix and allow for adequate drainage. Such mixes are similar to potting soils, comprised of peat, vermiculite and/or perlite, lime, fertilizers, and wetting agents. There are many brands and formulations available. Be sure to select one that has a proven track record. These mixtures need to be supplied with additional nutrients after plants are well established to sustain crop growth. Soluble fertilizers can be injected into the irrigation water and adjusted to meet the needs of the plants. N-P-K should be supplied in a ratio of 1:1:1.25 until the fourth flower cluster, then the ratio is adjusted to 1.25:1:3 to increase the proportion of N and K. The level of N in solution is usually maintained at around 100 ppm during early growth stages, and gradually increased to 200 ppm by the time the plants are about 3' high. A popular program is to use calcium nitrate plus a 7-11-27 or similar liquid fertilizer. These 2 materials are mixed with water to make separate stock solutions. These should be injected separately, but at the same time with 2 injectors. Follow directions on the 7-11-27 fertilizer label.

 

Leaf Analysis. With both in-ground and container culture, leaf tissue (foliar) analysis is valuable for determining the nutritional status of tomato plants and the adequacy of a greenhouse fertility program. For accurate results, submit 15-20 recently matured whole leaves: these should be the 3rd or 4th leaf from the growing point, the first one to be at a 90º angle to the stem. Test early in the growing season so fertility adjustments can be made in a timely fashion. 

 

Irrigation

 

A steady, sufficient supply of water is essential to good tomato production. Irregular or insufficient watering can result in blossom-end rot and fruit cracking. Some form of drip irrigation is recommended. Sufficient lines should be in place to completely wet the area that roots are expected to explore. In many tunnels this requires 3 or 4 drip lines per bed. An insufficient number of drip lines will leave areas of soil dry, therefore limiting root growth and nutrient uptake. 

 

In-ground growing systems can utilize sensors at several locations and depths to monitor soil moisture, although many growers simply feel the soil or growing medium by hand to assess its water content. Once tomato plants are well-grown, they utilize large quantities of water. Irrigation may then be needed more than once a day to maintain a consistent moisture supply. In order to minimize the development of foliar diseases, it is critical to avoid wetting the leaves of the plants when watering. Otherwise, an important benefit of greenhouse production will be lost. 

 

Transplants

 

Healthy transplants are key to a healthy crop. If starting your own plants, provide optimal conditions (light, heat, nutrients, water) to produce strong, stocky plants. Scout seedlings often for pests, and use sticky cards, indicator plants and other tools to monitor for infestations. If purchasing plants, inspect them carefully to be sure that they are not infected with disease, such as powdery mildew, or harbor insect pests, such as thrips. Close examination with a hand lens is essential. A period of quarantine and observation in a single area is advisable before setting plants out into tunnel(s). 

 

Transplants with large root systems tend to take off faster, yield earlier, and cope with environmental stresses better than those with smaller roots. Thus, small pots, at least 2.5" in diameter, are preferable to cell trays for the last weeks of transplant production. The optimum germination temperature for tomato seed is 75°F, and the optimum temperature range for growth of the transplant is 60-70°F. Seeds should be sown approximately 5-7 weeks before transplanting. 

 

Excessive watering, nitrogen, temperature or low light will cause excessive “leggy” growth. A good tomato transplant should be stocky. Tomato transplants can be conditioned or “hardened off” starting about 10 days before transplanting by taking plants from the starter greenhouse and exposing them to outside temperatures (over 50°F) and wind for a few hours each day. Tomatoes can be transplanted into tunnel or greenhouse soil once soil temperatures reach 60°F at a 2" depth. For early production, row covers, raised beds, plastic mulch, and (back-up) heat should be considered to promote growth and/or reduce risk of chilling injury.

 

Each leader on tomato plants should occupy about 3.5-6 sq ft of area. Using a high planting density can lead to increased yields, but will also reduce air movement, which can promote foliar disease, especially in susceptible cultivars and in tunnels with inadequate ventilation. 

 

Grafting

 

Grafting is a way to manage root diseases and increase plant vigor. In particular, tomatoes grown in-ground, may benefit from grafting because growing tomatoes in soil rather than in artificial media often leads to problems with root disease. Any tomato variety can be used as the scion (top) but far fewer varieties are available for rootstocks, and these vary in the degree of vigor they confer on the plant.

 

Two common grafting techniques are top grafting and side grafting. With top grafting, the scion is completely cut off from its roots and placed on top of the rootstock stem. Side grafting involves making a partial cut into the stem of the scion plant and then inserting the cut-off stem of the rootstock into that cut. The seedling is then allowed to retain both sets of roots until the graft with the new rootstock heals, after which the original root is cut from the plant. Top grafting relies on a tiny plastic tube or sleeve to hold the scion and rootstock together until the graft heals. Top grafting is quicker and less complicated to do than side grafting because it requires only a single complete cut through both the root and the shoot portions of the graft. 

 

Side grafting takes longer but is preferred by some growers because it is more forgiving. If greenhouse conditions for graft healing are less than ideal, the grafted seedling still has its original set of roots to help during the transition. Side grafting can also be done with seedlings that have become larger than is ideal for top grafting. A small clip, much like an office binder clip, is used to hold side grafted plants together until they heal.

 

Some growers produce sequential plantings of seedlings over several days to assure that they have the right selection of plant sizes to choose from for grafting. The scion and rootstock stem diameters must be similar, and grafting is most effective on very small plants. The ideal size is when the stems are about 2 mm in diameter for top grafting and 2-3 mm for side grafting. After grafting, keep the plants in a shaded area at 80-85°F and 95% relative humidity while the grafts heal. They should be misted enough to maintain relative humidity, but not so much that the leaves are wet all the time. Healing takes about 4-5 days for top grafts and 6-7 days for side grafts. Placing high plastic domes over trays of top-grafted plants appears to enhance success. For a couple of days before setting the grafted plants out, gradually increase their exposure to direct light by pulling them out from under cover for a few hours early or late in the day. If using plastic domes, prop them open during this time to increase air flow.

 

Because grafted plants are more vigorous, they will produce a lot of vegetative growth at the expense of reproductive growth—too much foliage and not enough fruit. Vigor can be reduced by allowing the first sucker on the scion to grow into a second fruiting leader. Leaf removal also reduces vigor. Only 10-12 fully expanded leaves are needed to capture sunlight to feed a grafted tomato plant in the Northeast. Take care to leave sufficient leaf cover over the fruit clusters to avoid sun scald. 

 

Mulching

 

For early tomato production, black, clear, or IRT (infrared transmitting) mulch can be applied to increase soil temperatures and reduce weed emergence and soil evaporation. For maximum transfer of heat, black plastic mulch should have good contact with the surface of the bed. Embossed plastic mulch will fit tightly over the bed. Clear plastic will increase soil temperatures significantly more than black plastic, but weeds will emerge under the clear film. White plastic (white-on-black or white) will significantly lower soil temperatures and can be used for late summer or fall high tunnel tomato production. Woven landscape fabric has little impact on soil temperature and can be reused for many years, but should be sanitized between uses. Organic mulches such as straw, hay, or compost create a favorable environment for many beneficial insects while increasing organic matter. Since most organic mulches do not have a warming effect on the soil, it is best to apply them after the soil has already warmed up in the spring.

 

Pruning

 

Greenhouse tomatoes are normally pruned to a single stem and the plant is supported by nylon twine tied loosely at the base of each plant row and secured to a wire at least 8' above the bed. The twine is clipped to or spiraled around the stem as it grows. All suckers are removed, ideally when they are 2-3" long. Cut or snap off suckers cleanly; do not leave stubs on the stem that may promote disease. The plant may be topped when it reaches the supporting wire or, to extend the production season, the plant can be looped over the top wire and allowed to grow 3-4' down the other side before topping. This, however, may lead to a dense canopy with poor air circulation, setting up conditions for disease. Another way to prolong the season is to lower the plants 2-3' and lay the stems on the ground, with the use of specialized rollers or other plant lowering systems. Remove the lower foliage after harvest of the lower clusters to improve air circulation and allow for lowering the plants; the lower leaves contribute little to the plant at this stage. NOTE: Frequent handling of plants is a primary means of spreading tobacco Mosaic Virus (TMV) and tomato canker. Wash hands frequently and don't handle tobacco products.

 

Pollination

 

Tomato plants do not need a specific day length in order to flower. The flowers are self- pollinated but require vibration by shaking, wind, or insects to assure good pollination. The optimum temperatures for pollination are 68-75°F (night) and 60-90°F (day). Air temperature below 55°F or over 95°F can cause flowers to drop from the plant. High humidity can also adversely affect pollination. Daily shaking of flowers, especially during damp and cloudy weather when pollen does not release well, can be achieved with a hand-held mechanical vibrator with a probe that just touches the flower cluster. Some growers shake the plant support wires daily, but this may not be adequate for lower clusters. A backpack blower will also provide good pollination and reduce labor costs. Electric units are preferable to internal combustion engines which release ethylene and carbon monoxide; both can damage tomatoes and the latter is harmful to humans. Commercially available hives of bumble bees are widely used to assure effective pollination of greenhouse tomatoes. A well-ventilated high tunnel in a steadily breezy location is usually adequate, once outside temperatures are warm enough to open the tunnel during the day. 

 

Temperature

 

High-quality thermostats should be used to manage greenhouse temperatures. Daytime temperature of 75-80°F is ideal; use ventilation and/or shading to keep temperatures below 85°F. Maintain night temperatures of 62-65°F after sunny days and 60-62°F after cloudy days. Rough fruit develops with temperatures lower than 60°F during flower initiation, which begins several weeks before flowers appear. For passively ventilated gothic-style high tunnels, consider installing a ridge vent or gable vents in the top of end walls to promote ventilation and cooling. Roll-up sides alone are often inadequate for good ventilation, especially in locations with little wind and once the tomato canopy is dense. If mechanically ventilating, fans and louvers should be properly sized to move air through and out of the greenhouse or tunnel even when the tomato canopy is fully mature. Root-zone heating can be beneficial to early season production, as it is difficult to warm the soil from above, whether the air is heated passively or with a heating system. 

 

Humidity

 

Effective ventilation is also needed to manage humidity. Keeping relative humidity below 90% will help avoid foliar diseases and optimize pollination. Excess humidity also restricts transpiration and water flow through the plant which restricts calcium uptake and can lead to blossom end rot and/or fruit cracking. Edema is caused by excessive water uptake when soils are warm and moist but humidity is high, so leaf stomates are closed and leaf cells ‘burst’. Cool air can exacerbate this condition.

 

On cool nights, a combination of ventilation and heating is needed to reduce humidity. Ventilation exchanges moist air with drier air from outdoors while heating brings outdoor air up to optimum growing temperature and increases the capacity of the air to hold moisture, avoiding condensation. In greenhouses with vents, turn on the heat and crack the vents open so warmed humid air can escape and be replaced with drier outside air. In houses with fans, they should be operated for a few minutes to cool the house down from day to evening temperatures. The venting and heating cycle should be done several times after the sun goes down and at sunrise. For some greenhouses it may take a few minutes per air exchange; with passive ventilation, it may take 30 minutes. Heating and venting is effective even if it's cool and raining outside. The relative humidity of air at 50°F/100% RH can be cut in half (50%) when it is heated to 70°F.

 

Horizontal air flow (HAF) fans keep the air moving in the greenhouse, helping to mix it, thus minimizing temperature and CO2 differentials. This can reduce condensation in colder areas. Air that is moving along the surface of leaves is less likely to cool below the dew point so does not condense on plant surfaces. In a 30’ x 100’ greenhouse, 4 fans each with at least 1600 cfm output are needed to keep the air mass moving. Fans should be mounted above the canopy, about ¼ of the width of the greenhouse from the sidewall. On each side, the first fan should be located 10-15’ from the endwall to catch air coming around the corner, the next fan should be located 30-50’ away, but no closer than 50’ from the endwall, to keep the air moving.

 

For more information on environmental controls, see High Tunnels.

 

Managing Plant Growth

 

Greenhouse tomatoes tend to cycle between being overly vegetative (too much plant growth and too few fruit) early in the season and being overly generative (too little plant growth and excessive fruit load) later in the season. The greenhouse environment can be manipulated to try to balance plant growth. A well-balanced plant has a stem about 3/8" (1 cm) thick at a point 6" below the growing point. It has dark green leaves, and large, closely spaced, readily-setting flower clusters.

 

Low light and low transpiration tend to promote vegetative growth. In an overly vegetative plant, stems are thicker and fruit set is low. Flowers appear far down from the top of the plants, open slowly and incompletely and are pale yellow. The uppermost leaves are flat, soft, long, light-colored, and may have a somewhat mottled appearance. The cluster stem is thin and long. Fruit will be slow to develop, few in number, and may be misshapen.

 

To steer the plant to a more generative growth pattern the difference between day and night temperatures can be increased by up to 9ºF and temperatures reduced more quickly in the early evening when going from day to night set-points. Greenhouse temperatures should be raised, the relative humidity should be lowered, and ventilation should be increased. Increasing transpiration reduces turgor pressure and inclines the plant to generative, rather than vegetative growth. CO2 enrichment also encourages generative growth.

 

In an overly generative plant, stems are thinner (indicating lack of carbohydrates), growth is slow, and trusses are short and horizontal. Dark yellow flowers appear immediately below the top of the plant and open quickly. Although fruit are large, well-shaped, and develop rapidly in an overly generative plant, over the long term, yields will be reduced because growth is reduced at the top. Leaves at the very top of a too generative plant develop slowly resulting in short, dark, strong leaves, which may be curled under.

 

To correct an overly generative plant, day temperatures are lowered to re-direct assimilate from the already-set fruit to the top of the plant and the developing trusses, but do not lower night temperatures as this will slow down fruit ripening, prolonging the problem of too much assimilate going to the older fruit. Reducing transpiration by raising relative humidity or reducing ventilation also stimulates vegetative growth.

 

Ethylene Injury

 

Combustion gases, which contain ethylene, can enter the greenhouse via faulty heat equipment. Even at very low levels, ethylene can make tomato leaves bend downward or become twisted and contorted (epinasty), and if exposure is ongoing, stems may thicken, branching may increase, and flower buds may abort or develop into malformed fruit. To prevent ethylene injury, hire professionals to perform proper heating system maintenance before the start of the heating season. High ammonium can stimulate plants to produce ethylene. Avoid fertilizers high in ammonium and be sure composts are finished. Composts should always be tested before using in the greenhouse. If growing in containers, be sure they have adequate bottom drainage. Saturated, highly organic media in the bottom of containers can spontaneously generate ethylene in rare cases.

 

Harvest and Storage

 

Greenhouse tomatoes destined for wholesale markets are usually picked at the turning stage or later and packed by uniform ripeness and size in single or double layer cartons. Fruits are sensitive to compression injury so pack and display accordingly. For best flavor greenhouse fruits should be fully ripe when harvested, if your markets may allow, but cracking is a risk if fruit are left on the plant too long. Ripe fruit can be held for a couple of days at 45-50°F but flavor and aroma may be reduced compared to storage at room temperature.

 

Tomato, Greenhouse and High Tunnel Disease Control

Tomato, Greenhouse and High Tunnel Disease Control ashahane
Greenhouse & High Tunnel - General
Greenhouse & High Tunnel Tomato Insect Control
Greenhouse & High Tunnel Tomato Physiological Disorders

NOTES: For the disease control products listed below, a product trade name and formulation are provided for each active ingredient (common name) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same active ingredient. Please see Table 26 and Fungicides and Bactericides Alphabetically Listed by Trade Name for more information on products with the same active ingredients.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

PESTICIDE USE IN GREENHOUSES AND HIGH TUNNELS:

Pesticides can be used on high tunnel and greenhouse crops if: 1) the crop and pest/disease is on the label, AND the products specifically says it can be used in the greenhouse OR 2) the crop and pest/disease is on the label, AND the product is ‘silent’ about use in the greenhouse. Products that specifically prohibit greenhouse use cannot be used in greenhouses or high tunnels regardless of the crops or pests/diseases listed on the label.

Management practices that will reduce disease in greenhouses and high tunnels are the use of resistant varieties, sanitation, fungicides and cultural practices that keep the humidity below 90%.

See also: Table 20: Fungicides and Bactericides Labeled for Vegetable Transplants

Bacterial Canker (Clavibacter michiganensis pv. michiganensis)

Initial symptoms are often a wilting and/or scorching of half of a leaf or one side of a plant. Necrotic leaf lesions up to 1/4" in diameter may appear on the upper leaf surface of mature leaves. Slightly raised white spots called “birds-eye spots” about 1/16" in diameter can appear on the fruit, usually when the green fruit in ½-2" in diameter. When these symptoms occur, remove the entire plant, including roots, from the greenhouse. Wash hands with soap and water before handling healthy plants. There are few effective bactericides to control this disease. If extensive bacterial canker occurs in the greenhouse, steaming of the soil is advised. Pruning, harvesting, and handling, especially when plants are wet, spreads the bacterium down the row. For more information see bacterial canker in the Tomato (Outdoor) section.

  • Bacillus subtilis strain QST 713 (Serenade ASOOG): 2.0 to 4.0 qt/A; PHI 0d, REI 4h, Group BM02. See label for tank mix rates and restrictions for greenhouse use.

Gray Mold/Botrytis Blight (Botrytis cinerea)

White ring spots or “ghost spots” may appear on green fruit due to early infection that was halted by the fruit. Management of the environment is very important in controlling this disease. Keep humidity below 80% by heating and ventilating, especially at night. Avoid wetting the foliage during times when drying is slow. Practice strict sanitation, removing senescent tissues and infected crop debris. Pruning of lower leaves to clean-cut stubs aids in disease prevention by improving air circulation through the crop. Fungicide rotations and combinations are important because strains resistant to benlates, dichloran, captan, and iprodione have been reported.

  • Bacillus subtilis strain QST 713 (CeaseOG): 3.0 to 6.0 qt/100 gal/A; PHI 0d, 4 hr, Group BM02.
  • copper sulfate basic (Cuprofix Ultra 40 DisperssOG): 0.75 to 3 lb/A fresh market, 0.75 to 1.33 lb/A processing; REI 48h, Group M01.
  • cyprodinil plus fludioxonil (Switch 62.5 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12.
  • fenhexamid (Decree 50 WDG aka Elevate 50 WDG): 1.0 to 1.5 lb/A; PHI 0d, REI 12h, Group 17. Treated greenhouse tomatoes cannot be used for processing. See label for additional restrictions.
  • fludioxonil (Emblem aka Spirato GHN): 5.5 to 7.0 oz/A; PHI 0d, REI 12h, Group 12. Alternate with a different mode of action (FRAC group) after 2 applications.
  • fluopyram plus pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 9. See label for specific instructions for greenhouse use.
  • penthiopyrad (Fontelis): 26.0 to 24.0 fl oz/A; PHI 0d, REI 12, Group 7.
  • polyoxin D (Affirm WDG): 6.2 oz/A; PHI 0d, REI 4h, Group 19.
  • potassium bicarbonate (MilStopOG aka PB 133OG): 1.25 to 5.0 lb/100 gal water; PHI 0d, REI 1h, Group NC. Use solution within 12 hours of preparation. See label for small volume application rates.
  • pyrimethanil (Scala SC): 7.0 fl oz/A; PHI 1d, REI 12h, Group 9. Use only in a tank mix with another effective fungicide recommended for Botrytis. Apply only in well-ventilated plastic tunnel houses or glass houses. Ventilate for at least 2 hours after application.

Late Blight (Phytophthora infestans)

Protectant fungicides are a key tool for management; however, many strains of P. infestans have become resistant to mefenoxam. When resistant strains are present, early blight fungicides will give as much protection against late blight as mefenoxam combinations. Avoid the use of overhead irrigation. Promptly incorporate old tomato crops after harvest in high tunnels; in the greenhouse remove all debris and clean greenhouse thoroughly after harvest. Eliminate cull piles and volunteer plants of both tomato and potato. Some resistant cultivars are available.

  • Bacillus subtilis Strain QST 713 (CeaseOG): 3.0 to 6.0 qt/A; PHI 0d, REI 4h, Group BM02.
  • copper hydroxide (Kocide 3000): 0.5 to 1.5 Tbsp/1000 sq ft (1 lb/A); PHI 0d, REI 24h, Group M01. Do not apply in a spray solution having a pH less than 6.5.
  • copper soap (Camelot OOG): 0.5 to 2.0 gal/30 to 100 gal water; PHI 1d, REI 4h, Group M01.
  • cyazofamid (Ranman 400SC): 2.1 to 2.75 fl oz/A; PHI 0d, REI 12, Group 21. See label for surfactant recommendations. For use in transplant production only. Alternate applications with fungicides from a different FRAC Group.
  • hydrogen dioxide plus peroxyacetic acid (Oxidate 2.0): See label for specific dilution rates; PHI 0d, REI 0h, Group NC.
  • mancozeb (Dithane M45): 1.5 to 2.0 lb/A; PHI 5d, REI 24h, Group M03.
  • mancozeb plus zoxamide (Gavel 75DF): 1.5 to 2.0 lb/A; PHI 5d, REI 48, Groups M03 & 22.
  • mandipropamid (Micora): 5.5 to 8.0 fl oz/A; PHI 1d, REI 4h, Group 40. For use in greenhouses with permanent flooring only, on tomato transplants for re-sale to customers only. Do not make more than 2 consecutive applications. See label for surfactant recommendation. Not for use in Maine.
  • mandipropamid plus difenoconazole (Revus Top): 5.5 to 7.0 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40.
  • oxathiapipprolin plus mandipropamid (Orondis Ultra): 5.5 to 8.0 fl oz/A; PHI 1d, REI 4h, Groups 49 & 40. See label for application methods and restrictions.
  • phosphorous acid (K-Phite 7LP): 3 to 5 qt/20 gal water/A; PHI 0d, REI 4h, Group P07.

Leaf Mold (Passalora fulva)

This disease occurs in both soil or hydroponic production and is most important in poorly ventilated plastic greenhouses. The pathogen produces large numbers of conidia on infected tissue; the disease can spread rapidly throughout a greenhouse by air currents, water, insects, and workers. Start with certified disease-free seed. Use resistant cultivars. Improve air circulation by adequate row/plant spacings and removal of lower leaves. Avoid the formation of water droplets on leaves by watering in the morning. Reduce relative humidity by a combination of heating and venting, especially at night. Avoid excessive nitrogen fertilization. Remove diseased leaves and destroy. At the end of crop cycle, remove and destroy all plant residue.

  • copper hydroxide (Kocide 3000): 0.5 to 1.5 Tbsp/1000 sq ft (1 lb/A); PHI 0d, REI 24h, Group M01. Do not apply in a spray solution having a pH less than 6.5 or tank mix with Aliette.
  • famoxadone plus cymoxanil (Tanos): 8.0 oz/A; PHI 3d, REI 12h, Groups 11 & 27.
  • mancozeb (Dithane M45): 1.5 to 2.0 lb/A; PHI 5d, REI 24h, Group M03.
  • mancozeb plus zoxamide (Gavel 75DF): 1.5 to 2.0 lb/A; PHI 5d, REI 48h, Groups M03 & 22.
  • mandipropamid plus difenoconazole (Revus Top): 5.5 to 7.0 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40.
  • polyoxin D (OSO 5%OG): 6.5 to 13.0 fl oz/A; PHI 0d, REI 4h, Group 19.

Pith Necrosis (Pseudomanas corrugata)

This disease typically occurs in early planted tomatoes growing when night temperatures are cool, humidity levels are high, and when plants are growing vigorously because of excessive levels of nitrogen. The disease is associated with prolonged periods of cloudy, cool weather. Symptoms consist of yellowing and wilting of young leaves. Serious infections result in yellowing or wilting of upper portions of plants with brown to black lesions on infected stems and petioles. When stems are cut longitudinally, the center of the stem (pith) may be extensively discolored, hollow, and/or degraded. Stems may be swollen, numerous adventitious roots can form, and infected stems may shrink, crack, and collapse. Preventive measures to minimize the occurrence of this disease in high tunnels include adequate ventilation to avoid high humidity levels, avoiding excessive nitrogen levels to prevent vigorous plant growth, incorporation of crop debris to speed decomposition of residue and associated bacteria, and crop rotation. 

Powdery Mildew (Oidium neolycopersici)

Powdery mildew of tomato is an important disease of greenhouse crops. This pathogen is favored by low light and cool temperatures. In contrast to other fungal plant pathogens, it does not require free water to germinate and cause disease. Resistant varieties are available.

  • Bacillus pumilus strain QST2808 (Sonata ASOOG): 2.0 to 4.0 qt/100 gal of spray; PHI 0d, REI 3h, Group BM02. For disease suppression only in greenhouse use.
  • Bacillus subtilis strain QST 713 (CeaseOG): 3.0 to 6.0 qt/A; PHI 0d, REI 4h, Group BM02.
  • cyprodinil plus fludioxonil (Switch 6.25 WG): 11.0 to 14.0 oz/A; PHI 0d, REI 12h, Groups 9 & 12. Do not apply to small tomatoes such as cherry or grape in the greenhouse.
  • fludioxonil (Emblem aka Spirato GHN): 5.5 to 7.0 oz/A. PHI 0d, REI 12h, Group 12. Do not make more than 2 applications before rotating to a fungicide from a different FRAC group.
  • fluopyram plus pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 0d, REI 12h, Groups 7 & 9. See label for specific instructions for greenhouse use.
  • paraffinic oil (JMS Stylet-Oil): 3.0 to 6.0 qt/100 gal water; PHI 0d, REI 4h, Group NC. Spray for thorough coverage of upper leaf surface.
  • penthiopyrad (Fontelis): 16.0 to 24.0 fl oz/A; PHI 0d, REI 12, Group 7.
  • phosphorous acid (K-Phite 7LP): 1 to 4 qt/20 gal water/A; PHI 0d, REI 4h, Group P07.
  • polyoxin D (Affirm WDG): 6.2 fl oz/A; PHI 0d, REI 4h, Group 19. See label for restrictions.
  • potassium bicarbonate (MilStopOG aka PB 133): 1.25 to 5.0 lb/100 gal water; PHI 0d, REI 1h, Group NC. Use solution within 12 hours of preparation. See label for specific rates and restrictions.
  • potassium salts of fatty acids (M-PedeOG): 1.5 to 2% v/v solution alone, or 1 to 2% v/v solution tank-mixed; PHI 0d, REI 12h, Group NC. See label for precautions.
  • mandipropamid plus difenoconazole (Revus Top): 5.5 to 7.0 fl oz/A; PHI 1d, REI 12, Groups 3 & 40.
  • sulphur (Microthiol DisperssOG): 5.0 to 20 lb/A; PHI 0d, REI 24h, Group M02. Do not use within 2 weeks of an oil spray treatment. Crops grown in greenhouses may be much more sensitive to sulfur injury. Do not use if temperature will exceed 90ºF within 3 days following spraying.
  • triflumizole (Trionic 4 SC): 2.0 to 4.0 fl oz/100 gal.; PHI 1d, REI 12h, Group 3. Apply only as foliar spray. See label for surfactant recommendation.

Soilborne Diseases

Several fungi including Rhizoctonia, Colletotrichum, Verticillium, Sclerotinia, and Fusarium, the oomycetes Pythium and Phytophthora, the bacterium that causes tomato canker, and root knot nematodes may become established in greenhouse soils or survive in tomato roots left from a previous crop.

White rot (Sclerotinia sclerotiorum) on stems occurs erratically during moist, cool periods in the spring. Distribution of diseased plants in a greenhouse is random but is often associated with low spots. Plants of all ages are susceptible. The pathogen produces hardened black fungal survival structures called sclerotia that can survive several years in the soil. Cut the plant off at the base and remove from the greenhouse.

Depending on which soilborne pathogen is present, rotation or the use of resistant varieties in addition to the use of grafted plants with vigorous rootstocks may be viable alternatives. Otherwise, steam or chemical treatment of the soil is necessary. It should be considered, however, that treatment of soil may not entirely eliminate the pathogens and, in the case of Pythium, Rhizoctonia, and Fusarium, the pathogens may rapidly recolonize the soil. There is no effective chemical treatment for the wilt and decline diseases caused by Verticillium and Fusarium. The most effective management techniques are resistant cultivars and sanitation, including soil pasteurization. NOTE: the current Bayer label for Coniothyrium minitans (Contans) does not include tomato. The label does include most other vegetable crops, which are also hosts for the disease, and so the product can be applied prior to planting a labeled crop to act on sclerotia in the field and manage the disease in a subsequent tomato crop.

  • Bacillus subtilis strain QST 713 (Serenade ASOOG): 0.1 to 3.0 fl oz/100 lb seed; PHI 0d, REI 4h, Group BM02. See label for tank mix rates and restrictions for greenhouse use.
  • cyazofamid (Ranman 400 SC): 3.0 fl oz/100 gal water; PHI 0d, REI 12h, Group 21. Pythium only. Soil drench. Tomato transplants only.
  • Gliocladium catenulatum, aka Clonostachys rosea, strain J1446 (P-VentOG): See label for rates; PHI 0d, REI 4h, Group BM02.
  • phosphorous acid (K-Phite 7LP): See label for rates and application methods; PHI 0d, REI 4h, Group P07. May be applied as a ground application, through chemigation, as a root dip or transplant drench, or to soil.
  • propamocarb HCl (Previcur Flex): See label for rates; PHI 2d, REI 12h, Group 28. Prevent intense sunlight after application by applying Previcur Flex in the evening. May be applied to rock wool cubes, seed beds at seeding or after emergence, through drip, or as a soil drench. Pythium and Phytophthora only.
  • Streptomyces sp. strain K61 (MycoStopOG): See label for specific uses and rates; PHI 0d, REI 4h, Group BM02.
  • Streptomyces lydicus WYEC 108 (Actinovate AGOG): 3.0 to 12.0 oz/A soil drench; PHI 0d, REI 4h, Group BM02.
  • Trichoderma asperellum (ICC 012) and T. gamsii (ICC 080) (Bio-Tam 2.0OG aka Bioten WP): See label for use and rates; REI 4h, Group BM02.

Gray Leaf Spot (Stemphylium lycopersici, S. solani, and S. botryosum)

See the Disease Control section in Tomato, Outdoor for more information about this disease. 

  • azoxystrobin plus difenoconazole (Quadris Top): 8.0 fl oz/A; PHI 0d, REI 12h, Groups 11 & 3. See label for restrictions.
  • copper hydroxide (Nu-Cop 50WPOG): 1.0 lb/A; PHI 1d, REI 48h, Group M01. See label for warnings and restrictions.
  • difenoconazole plus fluopyram (Luna Flex): 10.0 to 13.6 fl oz/A; PHI 0d, REI 12h, Groups 3 & 7. See label for warnings and restrictions.
  • fluopyram plus pyrimethanil (Luna Tranquility): 11.2 fl oz/A; PHI 1d, REI 12h, Groups 7 & 19. See label for application restrictions.
  • mancozeb (Dithane F-45 Rainshield): 1.2 to 2.4 qt/A; PHI 5d, REI 24h, Group M03. Start applications when seedlings emerge or transplants are set. See label for additional restrictions.
  • mancozeb plus copper (ManKocide): 1.75 to 3.0 lb/A; PHI 5d, REI 24 or 48h, Groups M03 & M01. See label for application warnings and restrictions.
  • mancozeb plus zoxamide (Gavel 75DF): 1.5 to 2.0 lb/A; PHI 5d, REI 48h, Groups M03 & 22. See label for restrictions.
  • mandipropamid plus difenoconazole (Revus Top): 5.5 to 7.0 fl oz/A; PHI 1d, REI 12h, Groups 3 & 40. Begin applications prior to disease development. Do not make more than 2 sequential applications before alternating to a fungicide from a different FRAC Group. See label for additional restrictions.
  • tetraconazole (Mettle 125ME): 6.0 to 8.0 fl oz/A; PHI 0d, REI 12h, Group 3. See label for restrictions.

Viruses

See Tomato (Outdoor) for a discussion on viruses.

Disease Control

Tomato, Greenhouse and High Tunnel Insect Control

Tomato, Greenhouse and High Tunnel Insect Control ashahane
Greenhouse & High Tunnel - General
Greenhouse & High Tunnel Tomato Disease Control
Greenhouse & High Tunnel Tomato Physiological Disorders

NOTES: For the insecticides listed below, one product trade name and formulation is provided for each active ingredient (AI) as an example of rates, preharvest interval (PHI), restricted entry interval (REI), and special instructions. In many cases, there are other products available with the same AI. Please see Table 27 and Insecticides Alphabetically Listed by Trade Name for more information on these insecticides.

The designation (Bee: L, M, or H) indicates a bee toxicity rating of low, moderate, or high. See the Protecting Honeybees and Native Pollinators section for more details.

The symbol * indicates a product is a restricted use pesticide. See Pesticide Safety and Regulations for more details.

The symbol OG indicates a product is listed by the Organic Materials Review Institute (OMRI) as approved for use in organic production. See Organic Certification section for more details.

For best results with aerosols, apply when air temperature in the greenhouse is 70-80°F. Keep vents closed and fans off during treatment. Ventilate greenhouse before entering. DO NOT perform this operation alone.

PESTICIDE USE IN GREENHOUSES AND HIGH TUNNELS:

Pesticides can be used on high tunnel and greenhouse crops if: 1) the crop and pest/disease is on the label, AND the products specifically says it can be used in the greenhouse; OR 2) the crop and pest/disease is on the label, AND the product is ‘silent’ about use in the greenhouse in the greenhouse. Products that specifically prohibit greenhouse use cannot be used in greenhouses or high tunnels regardless of the crops or pests/diseases listed on the label.

Aphids, Two-spotted Spider Mite, Thrips, Fungus Gnats

Scouting and preventative, timely releases of biological controls can be effective in managing aphids, thrips, spider mites and fungus gnats in greenhouse tomato. See potato aphid in the Potato insect control, green peach aphid in the Pepper insect control, and spider mites in Tomato, Outdoor. Refer also to the Transplant Insect and Mite Management section for more information about greenhouse pests, including Table 19 for biological control guidelines and Table 21 about insecticides labeled for vegetable transplants in the greenhouse. Note that some of the products listed in these tables are only labeled for transplants that will be planted on-farm, not plants to be sold.

Please refer to the following guides for more information on the biology and monitoring of these pests in greenhouse crops and how to integrate cultural practices, biological control and pesticides: The New England Greenhouse Floriculture Guide and the Penn State manual Greenhouse IPM with an Emphasis on Biocontrols. 

  • abamectin (Agri-Mek SC): 1.75 to 3.5 oz/A; PHI 7d, REI 12h, Bee: H, Group 6. Two-spotted spider mite and thrips only. Must be mixed with a non-ionic activator type wetting, spreading, and/or penetrating spray adjuvant. Do not use binder or sticker type adjuvant.
  • acequinocyl (Kanemite 15SC): 31 oz/A; PHI 1d, REI 12h, Bee: L, Group 20B. Two-spotted spider mite only. Do not use less than 100 gal water/A. Use of an adjuvant or surfactant is prohibited.
  • azadirachtin (Azatin OOG): 4 to 16 oz/A foliar or drench, 4 to 16 oz/100 gal in greenhouses; PHI 0d, REI 4h, Bee:L, Group UN. When using lower rates, combine with adjuvant for improved spray coverage and translaminar uptake.
  • Bacillus thuringiensis subsp. israelensis (Gnatrol WDGOG): 3.2 to 6.4 oz/100 gal light infestations, 13 to 26 oz/100 gal heavy infestations; REI 4h, Bee: L, Group 11. Use higher rate for heavy infestation. Apply as soil drench to flats to control larvae. Fungus gnat larvae only.
  • Beauveria bassiana (Mycotrol ESOOG): 0.5 to 1 lb/100 gal aphids, 1 to 2 lb/100 gal thrips; PHI 0d, REI 4h, Bee: L, Group UN. Aphids and thrips only. Treat when populations are low and thoroughly cover foliage. Takes 7-10 days after the first spray to see control. Repeat applications may be needed.
  • bifenazate (Floramite SC): 4 to 8 oz/100 gal water (apply 1 to 4 qt mix/100 sq ft or 100 to 400 gal/A); PHI 3d, REI 12h, Bee: L, Group 20D. Mites only. Apply when mites first appear.
  • Burkholderia spp. strain A396 (Venerate XCOG): 2 to 4 qt/A aphids and mites, 1 to 4 qt/A thrips; PHI 0d, REI 4h, Bee: M. Group UN. Suppression only. Not for fungus gnats. 
  • chlorfenaspyr (Pylon Miticide-Insecticide): 6.5 to 13 oz/A mites, 9.8 to 13 oz/A thrips; PHI 0d, REI 12h, Bee: M, Group 13. Mites and thrips only.
  • Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 2 to 3 lb/A; PHI 0d, REI 4h, Bee: M. Group UN. Not for fungus gnats. 
  • cyantraniliprole (Exirel): 13.5 to 20.5 oz/A; PHI 1d, REI 12h, Bee: H, Group 28. Suppression of thrips only.
  • dinotefuran (Venom): 1 to 4 oz/A foliar, 5 to 7.5 oz/A soil; PHI 1d foliar, 21d soil, REI 12h, Bee: H, Group 4A. Soil application may be as a band during bedding, in-furrow at seeding, as a transplant or post-seeding drench, as a sidedress, or through drip. Do not apply to varieties with fruit that is less than 2" such as cherry or grape tomatoes. Do not apply to vegetables grown for seed.
  • imidacloprid (Admire Pro): 0.6 oz/1,000 plants; PHI 0d, REI 12h, Bee: H, Group 4. Aphids only. Use on mature plants only. Apply in a minimum of 16 gal water. Do not apply to plants grown in non-soil media.
  • insecticidal soap (M-PedeOG): 1.25 to 2.5 oz/gal water; PHI 0d, REI 12h, Bee: L. Spray to wet all infested plant surfaces. Not for fungus gnats. Repeat application every 2 to 3 days until pest is under control. For enhanced and residual control, apply with companion labeled aphicide.
  • Metarhizium anisopliae Strain F52 (Met 52 EC): 40 to 80 oz/100 gal drench, 8 to 64 oz/A foliar; PHI 0d, REI 4h, Bee: L, Group UN. Thrips and mites only.
  • petroleum oil (Suffoil XOG): 1 to 2 gal/100 gal water; PHI 0d, REI 4h, Bee: L. Not for fungus gnats.
  • pyrethrin (PyGanic EC5.0OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.
  • pyriproxyfen (Distance IGR): 2 oz/100 gal as a surface drench to top 1" of soil media, 3 to 6 oz/100 gal as a heavy coarse spray to soil surface for fungus gnats and shore flies; 6 oz/100 gal for suppression of aphids and western flower thrips; PHI 1d, REI 12h, Bee: L, Group 7D. Do not apply to tomato varieties less than 1" in diameter, such as cherry or grape tomatoes.

Caterpillars: Hornworms, Fruitworms, Loopers, and Armyworms

Hornworms are large green caterpillars with white stripes along the sides that may grow up to 4" long. Look for the large pellet-like fecal droppings on the plastic under the plants, defoliation of leaves with only bare stems remaining, or surface feeding scars on green fruit.

Caterpillar infestations usually begin in July and may extend through September. Spot–treat areas of the greenhouse. Use selective insecticides to preserve natural enemies and avoid secondary pest outbreaks (i.e. aphids). See cabbage looper in the Cabbage insect control, and tomato fruitworm and tomato hornworm in Tomato (Outdoor) insect control for more information on these pests. Several species of armyworm feed on tomato fruits. See pepper section for more on armyworm.

  • azadirachtin (Azatin OOG): 4 to 16 oz/A foliar or drench, 4 to 16 oz/100 gal in greenhouses; PHI 0d, REI 4h, Bee: L, Group UN. When using lower rates, combine with adjuvant for improved spray coverage and translaminar uptake. For young larvae.
  • Bacillus thuringiensis subsp. aizawai (XenTariOG): 0.5 to 1.5 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested. Apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt kurstaki products (Dipel).
  • Bacillus thuringiensis subsp. kurstaki (Dipel DFOG): 0.5 to 2 lb/A; PHI 0d, REI 4h, Bee: L, Group 11. Must be ingested. Apply in evening or early morning, before larvae are actively feeding. Adherence and weather-fastness will improve with use of an approved spreader-sticker. Use high rate at cool temperatures. For resistance management, may be rotated with Bt aizawai products (XenTari).
  • Burkholderia spp. strain A396 (Venerate XCOG): 1 to 4 qt/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • chlorfenaspyr (Pylon Miticide-Insecticide): 6.5 to 13 oz/A; PHI 0d, REI 12h, Bee: M, Group 13.
  • Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 1 to 3 lb/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • novaluron (Rimon 0.83EC): 9 to 12 oz/A; PHI 1d, REI 12h, Bee: L, Group 16B. Most effective on 1st and 2nd instars.
  • pyrethrin (PyGanic EC5.0OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.

Slugs

  • iron phosphate (Sluggo: Snail and Slug BaitOG): 20 to 44 lb/A, 0.5 to 1 lb/1,000 sq ft., or 0.5 tsp/9" pot; PHI 0d, REI 0h, Bee: L, Group 9B. Apply to moist soil in evening. Scatter on soil around plants, or in and around pots.
  • metaldehyde (Deadline Bullets): 25 lbs/A; PHI 0d, REI 12h, Bee: L. Soil surface treatment broadcast pre-planting, or band treatment between rows after formation of edible parts. Apply to moist soil in the evening. Do not apply directly to or contaminate edible portions of plants.

Spotted Wing Drosophila (Drosophila suzukii)

Spotted wing drosophila (SWD) is an invasive pest that first arrived and spread throughout New England in 2011. It is primarily a pest of fruit crops, where the ability to oviposit in sound fruit (especially blueberry, raspberry, cherry, and peach) makes it a more serious pest than native fruit flies. SWD is deterred from laying eggs in sound tomato fruit by the strength of the tomato skin. However, where there are cracks and other openings, eggs are laid and larvae build up in fruit, liquefying the fruit contents and leaving nothing but an empty skin. Thus the management of cracked fruit is key to preventing buildup of SWD populations in tomato and possible contamination of cracked tomato fruit and containers postharvest. Infestation can occur in the field or in high tunnels and greenhouse tomatoes. Buildup in tomato can increase the risk to more susceptible crops on the farm.

Cultural practices are likely to be more effective than insecticides in reducing these risks. Avoid planting varieties that are prone to cracking. When possible, maintain steady soil moisture to avoid a surge in uptake of water by tomato plants, which increases cracking. Remove culls from the greenhouse. Minimize cracked fruit by harvesting before fruit is completely ripe—especially with cherry tomatoes which are prone to cracking. The same postharvest practices that you already use to minimize native fruit flies will also help with SWD. Keep packing areas clean and remove culls daily. Keep cherry tomatoes in shallow containers for easier sorting. Compost and cover culled, injured, or cracked fruit. Store fruit at the coolest temperatures suitable for tomato to delay egg hatch, if eggs are present.

Follow Extension monitoring alerts to know when SWD is starting to build up in your area. Currently, there are no thresholds for use of insecticides to control SWD in tomato. Few insecticides are registered specifically for control of SWD on tomato. Consult Extension SWD materials for updates on efficacy of products labeled for tomato.

  • malathion (Malathion 57 EC): 2.5 pt/A; PHI 1d, REI 12h, Bee: H, Group 1B.

Variegated Cutworm (Peridroma saucia)

Variegated cutworms will feed on leaves, but will also chew shallow or deep holes in the fruit during mid- to late summer. Caterpillars are brownish-grey, with diamond-shaped marks along the back and light lines along the sides. They are up to 2" long. Scout fruit for damage during harvest. Spray tomatoes if 1% of the plants are infested with variegated cutworms. For best results, make application after dark when cutworms are actively feeding. Thorough coverage of the foliage is needed for good control. Neem (azadirachtin) interrupts larval development and acts as a feeding deterrent. See Tomato (Outdoor) section for more information on variegated cutworm.

  • azadirachtin (Azatin OOG): 4 to 16 oz/A foliar or drench, 4 to 16 oz/100 gal in greenhouses; PHI 0d, REI 4h, Bee: L, Group UN. When using lower rates, combine with adjuvant for improved spray coverage and translaminar uptake. For larvae only.
  • Burkholderia spp. strain A396 (Venerate XCOG): 1 to 4 qt/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 1 to 3 lb/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • spinosad (SeduceOG): 20 to 44 lb/A or 0.5 to1 lb/1000 sq ft.; PHI 1d, REI 4h, Bee: M, Group 5. Spread bait on soil around plants.

Whiteflies, Greenhouse (Trialeurodes vaporariorum) and Sweet Potato (Bemisia tabaci)

The primary whitefly species in greenhouses are the greenhouse whitefly (Trialeurodes vaporariorum) and sweet potato whitefly B-biotype or silverleaf whitefly (Bemisia tabaci or B. argentifolii). Greenhouse whitefly is more common on greenhouse tomatoes, but both species occur in greenhouses, and correct identification of which species is present is important in order to select effective biological controls. The host range of greenhouse whitefly includes many ornamentals and vegetables; among greenhouse-grown vegetables the most common hosts are tomato, eggplant, and cucumber. In the field, bean, cucumber, cantaloupe, lettuce, squash, tomato and eggplant are good hosts, with cabbage, sweet potato, pepper, and potato less suitable. Sweet potato whitefly also has a wide host range, with cucurbit crops, sweet potato, and fruiting crops favored.

Greenhouse whitefly adults are most active at temperatures around 75ºF. Adults are winged, white, and 1/16" (2.0 mm) long. Greenhouse whitefly adults hold their wings flat, parallel to the top of the body. Females lay more than 20 eggs in a small circle. Newly laid eggs are white and eventually turn gray. Young nymphs (crawlers) are white, have legs and antennae, and move short distances before locating suitable places to initiate feeding. More mature nymphs (3rd and 4th instars) are typically found on the lower leaves. Pupae do not feed, and have distinct, visible red eyes. Greenhouse whitefly pupae may possess long waxy filaments encircling the outer edge, and are elevated in profile with vertical sides, resembling “cakes” on leaf surfaces.

Sweet potato whitefly B-biotype adults prefer warmer temperatures than greenhouse whiteflies, >80ºF. The adults are yellow and smaller than greenhouse whitefly. Their wings are tilted, and held roof-like over their bodies. Adult females live up to 6 weeks, and produce up to 200 eggs, which are randomly laid in small clusters on new plant growth. Newly laid eggs are white and then turn amber-brown. Young nymphs have legs and antennae and move short distances before locating suitable places to initiate feeding. More mature nymphs (3rd and 4th instars) are typically found on the lower leaves. Sweet potato whitefly B-biotype nymphs are yellow, oval, and dome-shaped, and do not possess long waxy filaments.

Large populations of whiteflies cause leaves to turn yellow, appear dry, or fall off plants. Honeydew excreted by whiteflies encourages growth of black sooty mold, and also attracts ants that interfere with natural enemies of other pests.

Avoid overfertilizing crops, as this increases their attractiveness to adult whiteflies. Whiteflies may be introduced into greenhouses on infested cuttings or plants arriving from outside sources. Carryover or stock plants may also be a source of whiteflies. Using appropriate sanitation practices like weed removal helps alleviate whitefly problems in subsequent cropping cycles. Manage whiteflies during transplant production to avoid introducing whiteflies to production greenhouses or to the field; for more information on controls on transplants see whiteflies in the Insect and Mite Management section of Vegetable Transplants.

Scout weekly by checking the undersides of 1-2 leaves on 10-20 plants throughout the greenhouse. Use yellow sticky cards to capture whitefly adults. Hang traps near the tops of the plants, 1-4 cards every 1,000 sq ft of greenhouse. Check and replace weekly, recording the number of adults per card. Use this information to decide if natural enemy releases or insecticides are needed.

As with all biological controls, it is important to begin releases early, before the pest builds up, and continue releases as the crop grows. The parasitic wasps Encarsia formosa and Eretmocerus eremicus can be used to control greenhouse whiteflies on greenhouse tomato and other crops, and to control sweet potato whitefly, respectively. Please consult the following guides for more information on the biology and monitoring of whiteflies in greenhouse crops and how to integrate cultural practices, biological control and pesticides: The New England Floriculture Guide and the Penn State manual Greenhouse IPM with and Emphasis on Biocontrols. 

  • buprofezin (Talus 70DF): 6 to 9 oz/100 gal; PHI 1d, REI 12h, Bee: L, Group 16. Apply when population level reaches economic threshold. Good coverage is essential. Applications must be made with high volume, low volume, or ultra-low volume ground equipment only.
  • Burkholderia spp. strain A396 (Venerate XCOG): 2 to 4 qt/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • Chromobacterium subtsugae strain PRAA4-1 (GrandevoOG): 2 to 3 lb/A; PHI 0d, REI 4h, Bee: M. Group UN.
  • cyantraniliprole (Exirel): 13.5 to 20.5 oz/A; PHI 1d, REI 12h, Bee: H, Group 28. For best performance, use an effective adjuvant. 
  • dinotefuran (Venom): 1 to 4 oz/A foliar, 5 to 7.5 oz/A soil; PHI 1d foliar, 21d soil, REI 12h, Bee: H, Group 4A. Do not apply to varieties with fruit that is less than 2", such as cherry or grape tomatoes. Do not apply to vegetables grown for seed. 
  • imidacloprid (Admire Pro): 0.6 oz/1,000 plants; PHI 0d, REI 12h, Bee: H, Group 4. Use on mature plants only. Apply in a minimum of 16 gal water. Do not apply to plants grown in non-soil media.
  • insecticidal soap (M-PedeOG): 1.25 to 2.5 oz/gal water; PHI 0d, REI 12h, Bee: L. Spray to wet all infested plant surfaces. Repeat application every 2-3 days until pest is under control.
  • Metarhizium anisopliae Strain F52 (Met 52 EC): 40 to 80 oz/100 gal drench, 8 to 64 oz/A foliar; PHI 0d, REI 4h, Bee: L, Group UN.
  • petroleum oil (Suffoil XOG): 1 to 2 gal/100 gal water; PHI 0d, REI 4h, Bee: L.
  • pyrethrin (PyGanic EC5.0OG): 4.5 to 17 oz/A; 0.25 to 0.50 oz/gal, 3 gal/1000 sq ft in greenhouse for backpack sprayers; PHI 0d, REI 12h, Bee: M, Group 3A.
  • pyriproxyfen (Distance IGR): 6 oz/100 gal; PHI 1d, REI 12h, Bee: L, Group 7D. Foliar spray. Do not apply to tomato varieties less than 1" in diameter, such as cherry or grape tomatoes.
Insect Control

Tomato, Greenhouse and High Tunnel Physiological Disorders

Tomato, Greenhouse and High Tunnel Physiological Disorders ashahane

Greenhouse & High Tunnel - General
Greenhouse & High Tunnel Tomato Disease Control
Greenhouse & High Tunnel Tomato Insect Control

Blotchy Ripening

See Blotchy Ripening section of Tomato (Outdoor).

Blossom End Rot

See Blossom End Rot section of Tomato (Outdoor).

Fruit Cracking

Fruit cracking in tomatoes can be a serious market problem, reducing profits. This can range from splitting to skin russeting. The causes of fruit cracking are varied and are subject to debate by researchers. Several factors have an effect on fruit cracking. Water uptake, humidity, temperature, and soluble solids (sugars) as well as calcium nutrition and standing water on the fruit are thought to have roles in fruit cracking, along with genetics. Cultural practices that can have an effect on fruit cracking include water management and light levels. The rate of fruit development can be affected by management practices. Irregular water uptake going from very dry to very wet plays a major role in fruit cracking. High temperatures also play a role. Irrigation can be used to modify both. Growers can increase the frequency of irrigation to prevent moisture extremes from developing under both field and greenhouse conditions. Overhead irrigation can also be timed to cool the crop in extreme conditions. High humidity and calcium nutrition are also associated with fruit cracking. Management practices must allow good transpiration rates as well as adequate calcium levels in the soil or fertilizer solution. Likelihood of cracking increases if tomatoes are allowed to fully ripen on the plant. Increased light and fruit growth can occur when new plastic is put on or with topping to increase fruit size. Watering schedules may need to be modified to reduce cracking under those conditions.

Physiological Disorders