Tomato Pests and Diseases, Symptoms, Control

Tomato Pests and Diseases:

The following information is about Tomato Pests and Diseases that affect the Tomato crop yield.

Tomatoes are one of the most cultivated crops, Tomato crops can be easily grown under proper conditions and regular maintenance. Tomato crops can host of production problems and pathogens when conditions and maintenance are not ideal.

This article gives you the information that helps you to grow better tomatoes. Basically, your geographic location, environmental conditions, and cultural methods will affect disease and pest pressures.

Foliar Diseases in Tomato crop:

The Main factors that spread the foliar diseases are High humidity, elevated temperatures, and lack of adequate air circulation. The main prevention step is to provide with adequate air flow: do not crowd plants; constant pruning; good ventilation.

Common foliar diseases in Tomato crop

• Bacterial speck: Bacterial speck is a foliar disease that mainly affects the fruit, whether green or ripe. The affected leaves have minuscule dark spots; on green fruit, dark spots; and on ripe fruit, sunken dark spots. This disease can reduce the yields of plants and make fruits unpalatable/unmarketable. To prevent this disease, select varieties that are disease resistant to bacterial speck race 0, race 1.
• Gray leaf spot: Gray Leaf Spot on tomato leaf is the sign of gray leaf spot disease, the development of small, dark-colored lesions on the leaves. These diseases will reduce productivity and eventual leaf drop. There are very limited high-quality commercial tomato varieties with grey leaf spot resistance as there are with other resistances.
• Early blight: It is also called Alternaria leaf blight, early blight is a widespread disease, older and leaves are the initial site of infection. The lesions turn small, dark, irregularly shaped spots that increase gradually to concentric rings. This disease can cause leaf death and reduced yields. This infection often begins in the lower portion of the plant, it can extend into the upper leaves, and stems and fruits can be infected at any stage. Select tomato varieties which are resistant to early blight, and even in these varieties, resistance does not confer complete immunity from the disease, but the resistant plants are able to delay and minimize disease symptoms and sustain production.
• Late blight: Late blight is a nickel-sized, wet or greasy-looking, grayish-black or brown spots on leaves, and white, fuzzy fungal growth on the underside of leaves. The fruit is also infected, resulting in dark-colored lesions that are hard and sunken. Late blight spreads rapidly and can be very destructive. The different races and disease-resistance genes can prevent disease.
• Leaf mold: It is the most common tomato crop disease. Mainly affects due to high humidity and low air circulation. The upper- and undersides of the affected leaves with yellow will turn, irregularly-shaped spots on the upper-side and fuzzy olive-green, gray, or tannish-brown splotches on the underside. Leaf mold resistant varieties of tomatoes are common in varieties bred for greenhouse production. 
• Powdery mildew: The reason for powdery mildew on tomato crop is due to warm, dry climates. The signs of infection are circular collections of powdery-white pustules that sometimes coalesce on the upper side of the leaves. The leaves infected with powdery mildew eventually die as the infection spreads. There are very fewer varieties of commercial crops with PM resistance, and so far, the level of resistance is intermediate at best.

• 

Read: Tomato Farming Project Report.

Soilborne Disease of Tomato Crop

Soil-borne diseases in regions where tomatoes are grown as repeated crops. Crop rotation with non-solanaceous crops and grafting to disease-resistant rootstocks will reduce the occurrence and impact of soilborne diseases.

• Bacterial wilt: The leaf wilt is mainly causing at high temperatures, but can be recovered during cool, nighttime temperatures. When the disease advances, extreme wilting and desiccation leads to plant death. This can be prevented by selecting bacterial wilt resistance varieties or using grafted plants with disease-resistant rootstocks.
• Corky root rot: Mainly attacks the cool-temperature plantings, larger roots will take a corky texture, while smaller roots may rot and decay. The plants infected with corky root rot are often smaller and less vigorous. Growing the plants grafted to resistant rootstock is the best method to control corky root rot.
• Fusarium crown and root rot: The Fusarium crown and root will affect the roots of young plants by entering through wounds and natural openings. The plant show signs by leaf yellowing and loses lower leaves. As the disease progresses, it leads to root rot, leaf wilting, and eventual plant death. Many FOR-resistant varieties are available, and most rootstocks are highly resistant to this disease.
• Fusarium wilt: Fusarium wilt interrupts the flow of nutrients and water in a plant’s vascular system, which leads to yellowing and eventual leaf drop. Modern hybrid tomatoes and tomato rootstocks are resistant to Fusarium wilt.
• Verticillium wilt: This fungalenters through small abrasions or lesions that can occur on the root surface. It interrupts the flow of nutrients and water within a plant’s vascular system, that leads to wilting and yellowing of the lower leaves. The leaves may show V-shaped lesion that can enlarge and eventually cause leaf death. Modern hybrid tomatoes and tomato rootstocks are resistant to Verticillium Wilt.

Seedborne Diseases in Tomato Crop

Seedborne diseases in tomatoes are controlled by seed treatment practices. Growers can control these diseases by purchasing seeds from a reputable dealer.

• Bacterial canker: This is a common and destructive disease, mainly for greenhouse cultivators. The seedling infected will develop white leaf spots and show wilting, often leading to plant death. And the mature plants show symptoms on the leaves, fruit, and stems. This disease can be managed with preventive seed treatment practices.
• Bacterial spot: Signs of bacterial leaf spot are small, irregular brown spots on the upper side of the leaves. As it progresses, the leaves turn yellow and shed, exposing the fruits to the possibility of sunscald. Sunscald can cause large lesions may also develop on the fruit. This disease can be managed with preventive seed treatment practices.

Read: Frequently Asked Questions About Plant Diseases.

Stem Diseases in Tomato Crop

Alternaria stem canker: This disease affects not only the stems but also the leaves and fruits. The dark-brown to black cankers form on tomato plant stems, this cause most damage to the plant. As the cankers grow, they encircle the stem, causing the plant to die.

To reduce the spread of disease use drip irrigation rather than overhead watering. Treatment the affected plants with fungicides, which may not reduce the disease, but can help to slow the spreading.

Damping off: This is a most common seedling disease affects the young seedlings at the base of the stem, near the soil line. The affected stems appear weak, withered, or pinched. Low irrigation, cool conditions become more prevalent for this disease. Preventive control measures for damping off are using sterilized or composted soil mixes, avoiding overwatering, ensuring good air flow, and spraying trays with a light copper solution after sowing.

Pests in Tomato Crop:

Hornworms:

These are green caterpillars that feed on the leaves and matured hornworms feed on fruit. This can show great impact in reducing productivity and yield. There are two types hornworms that attack tomatoes, tobacco hornworm and the tomato hornworm. These two hornworms are very similar in appearance. These can be controlled by handpicking the caterpillars off the leaves and destroying them or using some organic insecticide.

Whiteflies:

These pests feed on the fruit and leaves of tomatoes and carry diseases. They lay eggs on the underside of the leaves. The whiteflies can cause irregular ripening disorder in tomatoes.

Preventive measures are, encouraging of natural enemies, proper sanitation, and crop rotations with nonhost species, together with insecticides, such as horticultural oils, insecticidal soaps will show to have some limited effect. Using silver- or aluminum-colored mulch can help to control whiteflies.

Thrips:

The thrips can cause tomato spotted wilt virus. The thrips can be prevented by rotating crops and planting tomatoes away from where other host plants.

Aphids

Aphids can be controlled by some natural parasitic and predatory enemies, and, as with whiteflies, repelled by the placement of reflective mulches early in the season.

Tomato/potato psyllid:

This pest feeds on the underside of leaves and injects some toxins to the leaves that induce chlorosis and stunting of the plant’s growth tips, a condition known as psyllid yellows. These pests can lead to severe wilting and stem death.

Nematode Pests in Tomato Crop: 

Root-knot nematode:

This mainly infects the roots of the plants. The affected roots are less effective at taking up nutrients and water. Which makes plants stunted, less vigorous, and produce lower yields. All the modern hybrid tomato varieties are resistant to root-knot nematode.

Pest and Diseases Prevention Basics

When growing tomato crops, following are the preventive measures:

• Make a deep study about pest and disease pressures are common in your area and select resistant varieties.
• Select varieties that are suitable or specific growing environment (field, greenhouse, high tunnel, hydroponic system).
• Use best cultural practices: practice crop rotation; good hygiene, remove the crop debris in every season; and proper care, neither overwatering nor underwatering, to create an environment favorable to plant growth, rather than conditions that set the stage for problems. 

Read: Growing Mushrooms.

Bottom Line: If you are a tomato farmer and growing tomatoes commercially, you must take care of tomato pests and diseases for healthy plant growth, quality fruits, and higher yields.