Commercial Tomato IPM

Author: Donna M. Tuckey

Publication Number 444-121w; Posted June 2001

Insects

• Many natural aphid predators will help control populations and should be considered prior to treating.
• Apply insecticide if one or more aphids is/are observed on 25% or more of the fully expanded leaves.
• Supplemental aphid sprays are rarely warranted given that they are often controlled with the broad-spectrum treatments used for other insect pests.

Lepidopteran Pests: (Fall Armyworm and Tomato Fruitworm)

• Use blacklight and pheromone traps to monitor moth flight. Treatment is recommended if moth catches in local blacklight traps average 20 or more per night and most corn in the area is mature.
• Following the initial threshold spray, apply insecticide every 5-7 days until worm pressure is reduced.
• Later plantings are at higher risk of worm infestation.

Stink Bugs:

• Monitoring for stink bugs should occur on a weekly basis. They are usually found on field edges although they may be difficult to find given that they quickly drop from the plant if disturbed.
• Stink bugs tend to move into tomatoes from the weeds bordering the fields.
• Chemical treatment should be applied if fruit damage is seen in 2 or 3 areas of a field.

Thrips:

• Scout tomatoes beginning at plant emergence and continue for approximately 6 weeks after planting. Apply an insecticide if thrips are found. A preventative treatment may be applied at planting to help prevent thrips infestation in fields or areas with a history of their presence.

Spider mites, beet armyworms, cabbage loopers, tomato pinworms, vegetable leafminers and fruit flies may cause problems under unusual conditions, often due to seasonal variations.

European corn borers, flea beetles, tomato hornworms, tobacco hornworms, true armyworms, and whiteflies are also pests of tomatoes in Virginia, but are easily controlled given currently labeled insecticides.

Consult the Commercial Vegetable Production Guide (456-420) for insecticide recommendations.

Diseases

• No economic thresholds have been established, but treatment is recommended if initial symptoms of these diseases have been observed. Apply a fungicide every 7 days if the threat of disease is present.
• The use of certified plants is critical, especially in areas where bacterial disease is not yet established.
• A crop rotation of 2-3 years between tomato plantings may help manage the causal agents of bacterial canker, speck and spot, but not bacterial wilt.

Late Blight:

• Blight forecasting systems can be very effective in identifying proper timing of fungicide sprays.
• If cool, wet conditions prevail, a preventative fungicide application is recommended every 7 days.
• Resistance management should be practiced when selecting a fungicide.

Leaf Spots: (Early Blight, Septoria Leaf Spot, Gray Leaf Spot)

• No economic thresholds have been established. Preventative fungicide applications are the best means of leaf spot control, especially in areas where this disease has been a problem.
• Good sanitation practices and crop rotation can help prevent leaf spot establishment.

Wilts: (Fusarium Wilt and Verticillium Wilt)

• No effective chemical or biological controls are currently available.
• Cultural practices such as good sanitation and the use of resistant tomato cultivars should be used if the disease has previously been a problem. Crop rotations are not usually very effective given the persistence of the fungi in the soil.

Gray mold, powdery mildew, Southern blight, timber rot (Sclerotinia) and post-harvest rots often show up under unusual conditions such as weather or result from poor cultural practices. Fruit rots (Pythium and Phytophthora) may also occur from time to time.

Consult the Commercial Vegetable Production Guide (456-420) for fungicide recommendations.

Weeds

• Scout each field and keep records of the weed species present, their location and population density.
• Design a control program based on weed records for the specific problems in each field.
• Many types of weeds compete with tomato plants for light, water and nutrients, however yellow nutsedge, in particular, is becoming increasingly difficult for producers to control.
• Herbicides are valuable tools for weed management, but cultural practices such as the use of black plastic mulch over plant beds have become increasingly important as methyl bromide and other fumigants are being phased out. Herbicides may be applied to row middles or over the top.
• Select the herbicide that best fits your specific weed infestation. Preplant-incorporated, preemergence, and postemergence treatments are available. Emergency and Special Local-Needs Labels may be requested; contact local Extension Offices or Extension Specialists.

Nematodes

• The root knot nematode is the most common species affecting tomatoes.
• In Virginia, both diagnostic and predictive nematode assay programs are available. Diagnostic assays help determine the cause of problems during the growing season. Diagnostic samples should be sent to the Disease Clinic at Virginia Tech for analysis and are processed free of charge. Predictive nematode assays are done on samples collected after harvest. These are also sent to Virginia Tech, but must be collected in the fall no later than November 20. Predictive samples are processed at a cost of $11 (vermiform) and $19 (cyst) per sample. Contact the local Extension office for details on nematode assays.
• Crop rotation with non-host crops is recommended in the event of nematode activity.

Consult the Commercial Vegetable Production Guide (456-420) for nematicide recommendations.

References

For further information, contact your local Extension agent.

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