Contents

Common questions and answers about tobacco mosaic virus

Tobacco mosaic virus (TMV) is highly transmittable through routine greenhouse operations. If you have found TMV on plants in your greenhouse this season, Michigan State University Extension recommends their immediate disposal. We have compiled common questions from growers and their answers.

What is TMV?

TMV is a single-stranded RNA virus that commonly infects Solanaceous plants, which is a plant family that includes many species such as petunias, tomatoes and tobacco.

What are the hosts of TMV?

Pathologists estimate that there could be up to 350 plant species susceptible to TMV. According to Spence et al. in the European Journal of Plant Pathology, some of the more susceptible species that show symptoms are petunia, bacopa, verbena, scaevola, diascia, calibrachoa and lobelia. Some species can be a host for the virus, but not show symptoms.

How stable is TMV?

TMV is an incredibly stable virus. In fact, it is so stable that it can remain in tobacco plants after the extensive processing necessary to make tobacco products.

Why do symptoms differ between infected plants?

Symptoms differ between infected plants depending on the stage of disease severity, the genetic line of the virus and the host plant.

Can tobacco products carry TMV?

Yes, tobacco products can carry the virus and using them without washing your hands afterwards can potentially spread TMV. For that reason, do not use tobacco in the greenhouse or without washing your hands prior to handling plant material.

Can TMV stay viable in plant debris or dead plant material?

Yes, TMV can stay active in dead plant material for long periods of time. It can even stay viable without the presence of a host on surfaces such as greenhouse benches, floors and worker’s clothes.

How effective is spraying plants with milk to prevent the virus from spreading?

Spraying plants with 20 percent nonfat dry milk has been shown to be somewhat effective in preventing the spread of the virus from TMV-infected tobacco plants to uninfected tobacco plants. We recommend spraying plants prior to transplanting to reduce the risk of spreading TMV as part of a methodical management strategy.

How “full-proof” is spraying plugs or liners with milk?

While spraying milk on plugs or liners may have some effectiveness in reducing the spread of TMV, spraying milk should not be the primary management tool for TMV in your greenhouse. In order for milk to inactivate TMV, it must be liquid. Remember to continue scouting, testing, disinfecting and implementing the best sanitation possible in your facility.

How does the milk work to inactivate the virus?

Milk coats the virus and inactivates it.

Is it possible to receive a positive and a negative TMV test result from two different samples on the same plant?

TMV may not be spread equally throughout the plant tissue. Therefore, it is possible to test one leaf on a plant and get a positive TMV result, while another leaf may yield a negative TMV result.

If one plant is infected in a combo pot, will the others become infected?

Yes, it is possible for one plant to spread TMV to a neighboring plant just by growing together as their leaves come in contact with one another.

Is TMV spread by insects?

No, TMV is not spread by the most common greenhouse insects that often vector other viruses, like thrips and aphids. In addition, beneficial insects have not been linked to spreading TMV. However, there are a couple minor exceptions that may only be applicable to certain production facilities. First, pollinators such as bumble bees used in the pollination of some greenhouse crops, like cucumbers and tomatoes, can spread TMV. Also, larger chewing insects – not common in greenhouse production – such as grasshoppers can spread TMV.

Can simply brushing an infected plant and then a non-infected plant spread TMV?

Yes, the slightest brush of clothing infected with TMV was sufficient to spread the virus to uninfected plants, according to a study by Losenge et al.

How can I wash my clothing between work days to ensure that the cloth is not harboring TMV?

Washing clothes with standard amounts of laundry detergent or in milk was effective to inactivate TMV on clothing to prevent spread, according to Losenge et al.

Is there a preferred hand sanitizer on transplant lines?

To our knowledge, there has not been widely published evidence that there is a preferred type of hand sanitizer for TMV. According to the Centers of Disease Control and Prevention, alcohol-based hand sanitizers are effective against human viruses with a membrane, such as Rhinovirus, also known as the common cold. Since TMV does not have a membrane, there is minimal evidence that alcohol-based hand sanitizers will inactive it. We recommend washing your hands with soap and water as frequently as possible.

On a transplanting line, we recommend that the plants be sprayed with a milk solution before going through the machine or transferred by hand. The milk solution on the plants should still be wet as they are transplanted. Employees on a transplanting line should wear gloves and periodically dip their hands in milk solutions for the most effective control.

If a grower needs to trim a basket, how do you recommend sterilizing the scissors?

We recommend dipping your scissors in a container of liquid (20 percent dry powdered milk, 80 percent water) milk to inactivate TMV and prevent spread of the virus. Milk has been established to be a good disinfectant on cutting tools. Consider plug and liner dips into plant growth regulators for aggressive species in combination pots for next season.

How often should you remix a 1:10 bleach solution for disinfecting the greenhouse floors and benches?

We recommend that a grower remix a bleach solution every four hours.

How important are the at-home TMV tests in the overall management strategy for TMV?

We recommend using the at-home TMV strips as a tool in a methodical approach to test and rogue all plants that test positive, whether they have symptoms or not. We also recommend sending in samples of plants to a diagnostic lab, such as MSU Diagnostic Services, to have documentation of your results should you need it in the future.

What should I do with my weed mats if I have had the virus in my greenhouse?

We recommend you dispose and replace the weed mat if you have had TMV in your greenhouse this season.

What if I have potentially-infected petunias in baskets above tomato transplants?

Tomato plants can also be a host of TMV, so we recommend moving the tomatoes into a less risky area or switching the location of your baskets, if possible.

A grower performed a TMV test and it did not come back positive in 30 minutes, but came back positive only after 24 hours. Which result is accurate?

Always follow the manufacturer’s instructions for virus testing kits. The positive result after 24 hours is likely a false positive.

Tobacco mosaic virus
(tobacco mosaic)

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Zhang ZK, Li YG, Fang Q, Mei WQ, Li YH, 1992. Using technique of electron microscopy detecting the pathogens of Yunnan tobacco virus diseases. Journal of South China Agricultural University, SUPPL:27-29; 5 ref.

Zhu PF, Yang YZ, Lu ZQ, Xu L, 1992. Effect of cultivation measures on the relationship between the green peach aphid and tobacco virus disease. Plant Protection, 18(4): 20.

Zindovic J, Dukic N, Bulajic A, Latinovic J, Ðekic I, Duduk B, Krstic B, 2007. Presence and distribution of tobacco viruses in Montenegro. (Prisustvo i rasprostranjenost virusa duvana u Crnoj Gori.) Pesticidi i Fitomedicina, 22(1):39-44.

New Users

Introduction

Tobacco mosaic virus (TMV) results in losses in North Carolina of about 1 to 2 percent of the crop by reducing the yield and quality of flue-cured tobacco. The ideal way to control mosaic is by the use of resistant varieties; several new hybrids, which have acceptable yield and quality, are now available. Strict sanitation procedures are necessary to prevent the virus from becoming established in the crop and to prevent spread of the virus if efforts to keep it out of the crop are unsuccessful. Crop rotation helps to keep losses minimal in fields where mosaic has occurred.

Symptoms

Mosaic is so common that most tobacco growers know the symptoms of the disease in the field. The most characteristic symptom is a “mottled” appearance of the leaf (alternate areas of light and dark green tissue) (Figure 1). The tissue may be rough (Figure 2), and will burn on hot, sunny days (Figure 3). Several other viruses cause symptoms on flue-cured tobacco that look like mosaic. Symptoms on seedlings are much milder and easily overlooked. Stunting and mild mottling may be observed (Figure 4). The first step in controlling mosaic, therefore, is to be sure that the virus causing the mosaic symptoms is TMV. Growers who have a mosaic problem should get assistance from their County Extension Center if there is any doubt as to the identity of the causal virus.

Pathogen biology and epidemiology

Properties of the Virus: Tobacco mosaic virus, like other viruses, is a very small chemical particle that can multiply only in a living host and only can be seen with an electron microscope. It differs from other viruses that infect tobacco in two ways that are important in its control. First, TMV is very resistant to destruction. It will survive for at least 50 years in dead, dried tissue while other viruses become inactive when their host plant dies. Second, TMV is primarily transmitted mechanically while insects primarily transmit the other viruses.

Transmission: Tobacco mosaic virus is transmitted mechanically by any means that results in the virus coming in contact with injured cells of a host plant. The primary mechanism for this is contaminated worker’s hands or equipment that comes into contact with a healthy plant. Contaminated hands can be freed of the virus by washing with a detergent. The virus can be inactivated on equipment by scrubbing it with a brush using detergent or by steaming. Although the virus is transmitted primarily on worker’s hands and equipment, anything that mechanically moves the virus from a source to a healthy plant can transmit it. Chewing insects, such as flea beetles and grasshoppers, are capable of transmitting the virus, but such transmission is very rare in nature. Seed may be infested with the virus and transmit the virus.

Source of the Virus: Tobacco mosaic virus overwinters in a number of ways, and these must be understood for successful control through sanitation practices. Infection of tobacco from overwintering sources of the virus is known as “primary infection.”

A. Tobacco Products – All forms of tobacco may carry TMV so it is advisable that these products not be used by workers, especially around greenhouses and during transplanting. Spraying plants with milk prior to pulling and transplanting will reduce the number of plants that become infected. It should always be used during transplanting in situations where tobacco use by workers cannot be prevented. Transplants should be sprayed until runoff with one pound of dried milk in a gallon of water immediately prior to pulling.

B. Tobacco Trash – Tobacco mosaic virus will survive for years in dried tobacco tissue, so anything that may be contaminated with pieces of leaf, stem, or root tissue should be cleaned prior to use in the crop. This includes float trays that may have infected roots in the walls of the tray.

C. Soil-Borne Virus – tobacco mosaic virus overwinters in infected stalk and root. Experimental data in North Carolina indicates that infection occurs at transplanting when a plant is pushed against a piece of virus-infected tissue. The number of transplants that become infected in this way will depend on quantity of overwintering tissue surviving. The virus will overwinter in dead as well as living plant tissue, but dead tissue contains less active virus than living tissue. Numerous studies during the past 40 years in North Carolina has shown that from 0.1 to 5.5% of the plants planted to a field that contained mosaic the previous year will become infected with TMV.

D. Other Crops – Tomato, pepper, and eggplant are hosts of the TMV and in addition to not being used in rotation should not be handled prior to working in tobacco. Fruit from these crops also contain active virus and should not be handled while working in tobacco. There is, for example, enough active TMV in one infected tomato to infect every tobacco plant grown in North Carolina.

E. Weeds – A number of weeds are known to be hosts of TMV, but horsenettle is the only one found thus far to be infected in North Carolina. This weed is common where flue-cured tobacco is grown and frequently is found infected with TMV. The virus can be transmitted from infected horsenettle to tobacco mechanically, and this weed is suspected to be the source of TMV found in many tobacco fields. The only way horsenettle can be eliminated as a source of TMV is to eradicate it. Growers should consult with their County Extension Center for eradication procedures.

Secondary Spread: Most of the mosaic plants in heavily diseased fields were infected by virus that was spread from a few tobacco plants infected from overwintering sources of the virus. Secondary spread can be reduced by removing primarily infected plants from the field or by cultivating in a manner to prevent spread of the virus. In seedling production, clipping is a very effective means of spreading TMV. Seedlings should be scouted closely for TMV at each clipping.

There are a number of factors that must be considered when deciding if roguing in the field is feasible, so the final decision must be based on each situation. As a general guideline, however, the two most important factors are the time that primary infection occurred and the number of infected plants.

Although primary infection can occur anytime during the growing season, the most critical time is during transplanting. Plants infected at this time from any of the overwintering sources will show mosaic symptoms in 2 to 4 weeks. Generally, if fewer than 100 plants per acre are showing symptoms at this time it is feasible to remove them. Roguing should, of course, be done prior to cultivation. Plants used to replant rogued plants frequently become infected from virus in the roots left in the soil when plants are removed so replanting is not recommended. If too many plants are infected to make roguing feasible, secondary spread can be reduced by carrying out cultivation operations so that equipment does not touch the plants. Where this is possible, cultivation should be done when the plants are dry and preferably partially wilted because less virus transmission occurs under these conditions.

It is seldom feasible or of value to rogue plants after layby because most secondary spread occurs during or before this operation. Losses can be reduced by keeping a good supply of water to the crop because mosaic burn, the most damaging form of the disease, usually occurs only when infected plants come under water stress. Irrigation of a field containing a significant amount of mosaic may be worthwhile under conditions of moisture stress that would not be of value to rogue after layby if fewer than 10-20 plants are showing symptoms by the time the crop is knee-high. This will reduce losses on the current year’s crop somewhat, and perhaps more importantly, prevent extensive spread to the remainder of the crop and thus overwintering of virus in stalks and roots.

The problem of TMV carry-over in stalks and roots can be reduced by crop rotation or by using a mosaic resistant variety.

Crop Rotation: Crop rotation for mosaic control consists of planting a crop that is not susceptible to mosaic in alternate years. Crops planted in North Carolina that are susceptible to TMV are tobacco, tomato, pepper, and eggplant. Tobacco varieties carrying mosaic resistance are essentially non-hosts of the virus and can be used as a rotation crop. Growers who do not want to plant their entire crop to mosaic resistant varieties might at least consider planting them in fields where a mosaic problem occurred the previous year.

Growers who find rotation unfeasible and who do not want to plant any of their crop to a mosaic resistant variety can reduce virus carry-over by doing a thorough job of stalk and root destruction. This will significantly reduce, and may in some situations eliminate, infection during transplanting from infested old crop debris. Plants that do become infected should be removed prior to the first cultivation to prevent spread of the virus.

Resistant Varieties: Mosaic resistant varieties have historically been lower in yield and quality than non-resistant varieties. Some of the new releases compare favorably with non-resistant varieties, however. Even when resistant varieties may not perform as well as resistant varieties on a given farm, there are two situations where they would be of benefit. The first is on problem mosaic farms where losses to mosaic exceed the differential income potential between a mosaic resistant and a susceptible variety. The other situation is where monoculture is practiced and a mosaic resistant variety can be grown on a problem field to break the cycle of virus carry-over. Varieties with TMV resistance are available in the Tobacco Production Guide:

Other Links

North Carolina Ag Chem Manual:

Creation date: 2001

Revision date: April 2010

Key words: tobacco, mosaic, rotation, resistance, variety

Glossary terms: mottling, transmission, infection, spread

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for Mosaic Virus

Affecting a wide variety of horticultural and vegetable crops — roses, beans, tobacco, tomatoes, potatoes, cucumbers and peppers — mosaic is a viral diseases found throughout the United States.

Plant viruses can be difficult to detect as symptoms look similar to many nutrient deficiencies and vary depending on the age of the plant when infection occurs. Look for:

  • Yellow, white or green stripes/ streaks/ spots on foliage
  • Wrinkled, curled or small leaves
  • Pronounced yellowing only of veins
  • Stunted growth and reduced yields
  • Infected fruit appears mottled and develops raised “warty” areas

Mosaic virus overwinters on perennial weeds and is spread by insects that feed on them. Aphids, leafhoppers, whiteflies and cucumber beetles are common garden pests that can transmit this disease. Soil, seed, starter pots and containers can be infected and pass the virus to the plant. Cuttings or divisions from infected plants will also carry the virus.

Treatment

There are no cures for viral diseases such as mosaic once a plant is infected. As a result, every effort should be made to prevent the disease from entering your garden.

  1. Fungicides will NOT treat this viral disease.
  2. Plant resistant varieties when available or purchase transplants from a reputable source.
  3. Do NOT save seed from infected crops.
  4. Spot treat with least-toxic, natural pest control products, such as Safer Soap, Bon-Neem and diatomaceous earth, to reduce the number of disease carrying insects.
  5. Harvest-Guard® row cover will help keep insect pests off vulnerable crops/ transplants and should be installed until bloom.
  6. Remove all perennial weeds, using least-toxic herbicides, within 100 yards of your garden plot.
  7. The virus can be spread through human activity, tools and equipment. Frequently wash your hands and disinfect garden tools, stakes, ties, pots, greenhouse benches, etc. (one part bleach to 4 parts water) to reduce the risk of contamination.
  8. Avoid working in the garden during damp conditions (viruses are easily spread when plants are wet).
  9. Avoid using tobacco around susceptible plants. Cigarettes and other tobacco products may be infected and can spread the virus.
  10. Remove and destroy all infected plants (see Fall Garden Cleanup). Do NOT compost.

Tomato Mosaic Virus Symptoms: Managing Tomato Mosaic Virus

Tomato mosaic virus is one of the oldest described plant viruses. It is extremely easily spread and can be devastating to crops. What is tomato mosaic virus and what causes tomato mosaic virus? Keep reading to learn more about tomato mosaic virus symptoms and tomato mosaic virus treatment.

What is Tomato Mosaic Virus?

Tomato mosaic virus is a serious and extremely contagious disease. It is also hard to identify, with symptoms varying wildly depending upon the variety and age of the infected plant, the strain of the virus, and environmental conditions. To make matters worse, it is very hard to distinguish from the closely related tobacco mosaic virus.

Tomato mosaic virus symptoms can be found at any stage of growth and all parts of the plant may be infected. They are often seen as a general mottling or mosaic appearance on foliage. When the plant is severely affected, leaves may look akin to ferns with raised dark green regions. Leaves may also become stunted.

Infected plants may have a severe reduction in fruit set and those that do set may be dotted with yellow blotches and necrotic spots while the interior of the fruit is brown. Stems, petioles, leaves and fruit may all show signs of infection.

Tomato Mosaic vs. Tobacco Mosaic Virus

Tomato mosaic virus

and tobacco mosaic virus are very closely related and very hard to distinguish from each other. They do differ genetically, but to the casual observer they are easiest to tell apart by their hosts of choice. Mosaic virus infects a large number of plants in addition to tomatoes. A few of the more common ones include:

  • Tobacco
  • Beans
  • Squash
  • Roses
  • Potatoes
  • Peppers

Tomato mosaic is also known to infect apples, pears, and cherries.

Tobacco mosaic will also infect tomato plants, but it has a much wider range, including lettuce, cucumbers, beets, and, of course, tobacco.

Mosaic virus symptoms mimic those caused by other plant diseases as well as herbicide or air pollution damage and mineral deficiencies. While this viral disease rarely kills the plant, it lowers the quantity and quality of the fruit. So what causes tomato mosaic virus and are there any methods for treating tomato mosaic virus?

Tomato Mosaic Virus Control

This viral disease is able to overwinter on perennial weeds and is then spread by several insects including aphids, leafhoppers, whiteflies and cucumber beetles. Both cuttings and divisions from infected plants will be infected. The disease is spread into the plant via small wounds caused by mechanical injury, insect chewing, and grafting. Leftover plant debris is the most common contagion.

Tomato mosaic virus of tomatoes can exist in the soil or plant debris for up to two years, and can be spread just by touch – a gardener who touches or even brushes up against an infected plant can carry the infection for the rest of the day. You should wash your hands with soap and disinfect tools after handling tomato plants to keep the disease from spreading.

Treating mosaic virus is difficult and there are no chemical controls like there are for fungal diseases, although some varieties of tomato are resistant to the disease, and seeds can be bought that are certified disease free. Sanitation is the most important application to practice when controlling tobacco mosaic virus. Tools should be boiled for 5 minutes and then washed with a strong detergent. Bleaching doesn’t work for viral decontamination. Destroy any seedlings that appear stunted or distorted and then decontaminate tools and hands.

Keep the area around the tomatoes weeded and free of plant detritus to minimize areas the disease can harbor. Control insects as well to lessen the chances of contamination. If you spot the disease in your garden, you should immediately dig up and burn infected plants. Don’t plant tomatoes, cucumbers or other plants that are susceptible to mosaic virus in that same area again.

Integrated Pest Management

Fact Sheets > Vegetables > Crop Specific Articles > Tomatoes

Mosaic Diseases of Tomatoes

Common Mosaic and Cucumber Mosaic

Pathogens. Tobacco mosaic virus (TMV) and the closely related tomato mosaic virus (ToMV) cause common mosaic; cucumber mosaic virus (CMV) causes cucumber mosaic. Both diseases cause stunting of the plants and a lowering of yield. For both diseases, symptoms can vary widely, depending on the age of the plant, the variety of tomato, the strain of the virus causing the disease, and the environmental conditions.

TMV is a worldwide pathogen and one of the first plant viruses that scientists described. It has been important in Europe since the mid-1800s. In the United States, it was first reported in Connecticut on tobacco in 1899 and on tomato in 1909. It has a very wide range of hosts, including tomato and the related plants of eggplant, nightshade weeds, pepper, potato, and tobacco. TMV is seen on apple, beet, sugar beet, buckwheat, currant, grape, pear, spinach, and turnip, as well. In addition, ornamentals, foxglove, phlox, snapdragon, zinnia, and weeds of the amaranth and goosefoot families are affected.

CMV is another widespread virus. It was first reported in the 1900’s in several places in North America. It is now considered to be worldwide. It has a very wide host range, which includes tomato, carrot, celery, cucurbits, legumes, lettuce, spinach, pepper, dahlia, delphinium, columbine, geranium, petunia, phlox, zinnia, viola, and many weeds, such as chickweed, pokeweed, and milkweed.

Symptoms. Common mosaic (TMV/ToMV) often causes leaves to be stunted or elongated, in a condition called “fernleaf.” This name is due to the strong resemblance of these leaves to leaves of many kinds of ferns. The youngest leaves may be curled. Leaves may be mottled yellow and dark green. This is the symptom which gives the disease the name “mosaic.” The dark green areas may be raised. Mottling usually occurs most severely on plants grown under low light and low temperature, conditions which may exist in a greenhouse during the winter. Leaf stunting and distortion are usually worse under these conditions, as well.

Stem streaking occasionally occurs with dark streaks that are either sparse and short or prevalent and long. Such stems are easily broken and have brown areas inside. Fruit is rarely affected. It may be mottled or a brownish bronze color inside, which can be seen through the thin skin of the fruit. Fruit may show uneven ripening or yellow rings, as well.

Severe strains of TMV/ToMV cause the lower leaves to turn downward at the petiole, become rough and crinkled or corrugated, and possibly cause the leaflets to curl downward at the edges. Younger leaves may have extensive yellow to white areas with dark green blisters.

When some tomato varieties are infected with TMV/ToMV and kept at high temperature conditions (80o to 85o F) for a prolonged time, they develop dead areas on leaves, stems and roots.

Cucumber mosaic virus (CMV) causes plants to become yellow, bushy and very stunted. Leaves may be extremely distorted and malformed. Leaflets are often very narrow – this is called “shoestring”. Often the leaves on one portion of the plant (e.g., the top or the bottom) show severe symptoms, while those higher or lower in the plant are less affected. Other leaf symptoms include a yellow and green mottling similar to tobacco mosaic symptoms. Severely affected plants produce few fruit.

Identification of the Diseases. It is difficult to diagnose which virus is present without the assistance of an experienced diagnostician. The fernleaf and the shoestring symptoms are very similar, and the mosaic symptoms are indistinguishable. Control and prevention measures are very different for the two diseases, so accurate diagnosis is important.

Prevention. TMV is spread readily by touch. The virus can survive on clothing in bits of plant debris for about two years, and can easily enter a new plant from a brief contact with a worker’s contaminated hands or clothing. Tobacco products can carry the virus, and it can survive on the hands for hours after touching the tobacco product. Ensure that workers do not carry or use tobacco products near the plants, and wash well (with soap to kill the virus) after using tobacco products. Ensure that workers wear clothing not contaminated with tomato, tobacco or other host-plant material. Exclude non-essential people from greenhouses and growing areas.

Choose resistant varieties. Use disease-free seed and transplants, preferably certified ones. Avoid the use of freshly harvested seed (2 years old is best if non-certified seed is used). Seed treatment with heat (2 to 4 days at 158o F using dry seed) or trisodium phosphate (10% solution for 15 minutes) has been shown to kill the virus on the outside of the seed and, often, most of the virus inside the seed as well. Care must be taken to not kill the seeds, though. Use a two-year rotation away from susceptible species. In greenhouses, it is best to use fresh soil, as steaming soil is not 100% effective in killing the virus. If soil is to be steamed, remove all parts of the plant from the soil, including roots. Carefully clean all plant growing equipment and all greenhouse structures that come into contact with plants.

When working with plants, especially when picking out seedlings or transplanting, spray larger plants with a skim milk solution or a solution made of reconstituted powdered or condensed milk. Frequently dip hands, but not seedlings, into the milk. Wash hands frequently with soap while working with plants, using special care to clean out under nails. Rinse well after washing. Tools should be washed thoroughly, soaked for 30 minutes in 3% trisodium phosphate and not rinsed.

Another method for control of this disease is to artificially inoculate plants with a weak strain of the virus. This will not cause symptoms on the plants but protect them against disease-causing strains of the virus. This is used commonly in Europe, but strains of the virus are not yet available in the United States due to concerns about the possibility of the weak virus strains causing disease on the plants.

Cucumber mosaic is spread in a nonpersistant manner by aphids. It is not spread by seed. Control weeds, many of which are host species. Surrounding tomato fields with a taller, non-susceptible plant, such as corn, may help shield the plants from aphids blowing in from other areas. See current recommendations for control of aphids, although it is generally considered that insecticides will not control this disease. The aphids pick the virus up from the plants in about a minute and are able to spread it immediately. Insecticides take longer than this to kill the aphids. Mineral oil sprays can be used to prevent the virus from being transmitted.

At this time there are no tomato varieties resistant to CMV.

References.

By: Pamela S. Mercure, IPM Program Assistant, University of Connecticut, 1998

Reviewed by: T. Jude Boucher, IPM, University of Connecticut. 2012

The information in this document is for educational purposes only. The recommendations contained are based on the best available knowledge at the time of publication. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension System does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. The University of Connecticut, Cooperative Extension System, College of Agriculture and Natural Resources is an equal opportunity program provider and employer.

20 Common Tomato Plant Problems and How to Fix Them

If you’re one of the three million people who planted a home garden this year, you’re most likely growing tomatoes. Nine out of 10 gardeners grow tomatoes, and that number would be 10 out of 10 if the holdouts would taste a fresh garden tomato and compare it to a grocery store purchase. Nothing beats the taste of a fresh home-grown tomato!

Many gardeners who grow tomatoes, however, are frustrated with the progress of their plants. The plant may not set fruit. Or your tomatoes may ripen, but have ugly, spongy black spots at the bottom. Worse still, your plants may look great in the evening when you say goodnight to them, but in the morning, they’re skeletons waving empty branches in the breeze.

Welcome to the world of tomato problems. This list of 20 common tomato problems and their solutions will help you identify an issue — whether it’s just starting or already full-blown — and show you how to correct it, so you can save your tomato plants and harvest yummy tomatoes this year.

Identify Tomato Plant Problems and Diseases

Before diving into the list, it’s important for you to correctly identify the problem or tomato plant disease. When trying to identify tomato plant diseases, use these steps:

  1. Identify the affected part of the plant — Is it the tomato itself, the leaves, stems, flowers or roots?
  2. Note differences — When you compare your tomato plant to a healthy plant, how does yours differ? For example, a healthy tomato plant has softly fuzzed, medium-green leaves. If the leaves of your plant have brown or black patches, holes, chewed edges or fuzzy mold growing on them, make a note of that before perusing the list of problems.
  3. Look for insects — What insects do you see on your plants? If you need help identifying them, take a photo and contact your local Cooperative Extension agent to identify the insects.

Armed with this information, you can easily scan this list and narrow down the possible tomato plant disease or pest problem and how to fix it.

20 Common Tomato Problems

The list is divided into two sections: 16 diseases caused by poor cultivation habits, bacteria or fungi, and 5 insect-specific tomato problems. We have also included some tips for growing delicious, healthy tomato plants so you can keep those problems away next year.

16 Tomato Plant Diseases

Tomato diseases, garden fungi and certain environmental conditions can quickly cripple your plants. Oftentimes, you can rescue the tomato plant with a little TLC, but some circumstances may require you to destroy the plant and plant another crop in its place.

Be sure to browse the extended information below on tomato plant problems, but, overall, here are the most common disease and fungus triggers in tomato plants:

  • Not enough fertilizer. (Solution: Test your soil and apply fertilizer as appropriate for the growth stage.)
  • Over-pruning. (Solution: Always use a tomato cage and leave enough foliage to shield the fruit.)
  • Not enough calcium. (Solution: Test your soil, apply lime and gypsum as needed.)
  • Planting before temperatures raise to ideal levels. (Solution: Wait for the right planting time for your Hardiness Zone.)
  • Too much water or too little water. (Solution: Water them evenly through the growing season.)
  • Watering overhead, which promotes fungal growths. (Solution: Water at the base of the plant. and apply fungicide.)
  • Lack of air flow around plants. (Solution: When planting, space tomato plants at appropriate distance from one another and prune leaves (but not too much, see above) as they grow. Apply fungicide if powdery mildew appears.)

1. Blossom End Rot

  • What it looks like: The tomato plants appear healthy, but as the tomatoes ripen, an ugly black patch appears on the bottoms. The black spots on tomatoes look leathery. When you try to cut off the patch to eat the tomato, the fruit inside looks mealy.
  • What causes it: Your plants aren’t getting enough calcium. There’s either not enough calcium in the soil, or the pH is too low for the plant to absorb the calcium available. Tomatoes need a soil pH around 6.5 in order to grow properly. This soil pH level also makes it possible for them to absorb calcium. Uneven watering habits also contribute to this problem. Hot, dry spells tend to exacerbate blossom end rot.
  • What to do about it: Before planting tomatoes in the spring, have your local garden center or Cooperative Extension conduct a soil test. Tell them you’ve had problems with blossom end rot in the past, and they will give you recommendations on the amendments to add to your soil. Lime and gypsum may be added for calcium, but they must be added in the proper amounts depending on your soil’s condition. That’s why a soil test is necessary. Adding crushed eggshells to your compost pile can also boost calcium naturally when you add compost to the soil. A foliar spray containing calcium chloride can prevent blossom end rot from developing on tomatoes mid-season. Apply it early in the morning or late in the day — if sprayed onto leaves midday, it can burn them. Water plants regularly at the same time daily to ensure even application of water.

2. Blossom Drop

  • What it looks like: Flowers appear on your tomato plants, but they fall off without tomatoes developing.
  • What causes it: Temperature fluctuations cause blossom drop. Tomatoes need night temperatures between 55 to 75 degrees F in order to retain their flowers. If the temperatures fall outside this range, blossom drop occurs. Other reasons for blossom drop on tomatoes are insect damage, lack of water, too much or too little nitrogen, and lack of pollination.
  • What to do about it: While you can’t change the weather, you can make sure the rest of the plant is strong by using fertilizer for tomatoes, drawing pollinators by planting milkweed and cosmos, and using neem oil insecticides.

3. Fruit Cracks

  • What they look like: Cracks appear on ripe tomatoes, usually in concentric circles. Sometimes insects use the cracks as an opportunity to eat the fruit, or birds attack cracked fruit.
  • What causes them: Hot, rainy weather causes fruit crack. After a long dry spell, tomatoes are thirsty. Plants may take up water rapidly after the first heavy rainfall, which swells the fruit and causes it to crack.
  • What to do about them: Although you can’t control the rain, you can water tomatoes evenly during the growing season. This prevents them from being so thirsty that they take up too much rainwater during a heavy downpour.

4. Sunscald

  • What it looks like: The plants look healthy, and the fruit develops normally. As tomatoes ripen, yellow patches form on the red skin. Yellow patches turn white and paper-thin, creating an unpleasant appearance and poor taste.
  • What causes it: As the name implies, the sun’s rays have actually scalded the tomato.
  • What to do about it: Tomato cages, or a wire support system that surrounds the plants, give the best branch support while shading the developing tomatoes naturally. Sunscald usually occurs on staked plants that have been too-vigorously pruned, exposing many of the tomatoes to the sun’s rays. Leaving some foliage and branches provides shade during the hottest part of the day.

5. Poor Fruit Set

  • What it looks like: You have some flowers but not many tomatoes. The tomatoes you do have on the plant are small or tasteless.
  • What causes it: Too much nitrogen in the soil encourages plenty of green leaves but not many flowers. If there aren’t enough flowers, there won’t be enough tomatoes. Another cause may be planting tomatoes too closely together. Tomatoes are self-pollinating, meaning that each flower contains both the male (stamens) and female (pistils) parts. Wind typically pollinates tomatoes, but if plants are too close together, the wind can’t reach the flowers.
  • What to do about it: Have your soil tested. If you’re planting tomatoes in the spring, leave at least two feet or more between plants so that good air circulation can help pollinate them. If your plants are already in the garden, you can simply shake the flowering branches to simulate wind and get the pollen from the stamens to the pistils.

6. Catfacing

  • What it looks like: Catfacing makes tomatoes appear deformed. The blossom end is rippled, bumpy and lumpy.
  • What causes it: Plants pollinated during cool evenings, when the temperatures hover around 50 to 55 degrees F, are subject to catfacing. Blossoms fall off when temperatures drop too low. However, if the flower is pollinating before the petals begin to drop off, some stick to the developing tomato. This creates the lumps and bumps typical of catfacing.
  • What to do about it: If possible, plant tomatoes a little later in the season. Make sure the weather has truly warmed up enough to support proper tomato development. Devices such as a “Wall of Water” — a circle of water-filled plastic tubes — raise temperatures near the tomato and help keep them high enough on cold nights to prevent cold-related problems. Using black-plastic spread on the soil can also help. As the plastic heats during the day, it releases the heat back towards the plants at night. Black plastic can be used as a temporary measure until the temperatures warm up enough that it’s no longer needed.

7. Leaf Roll

  • What it looks like: Mature tomato plants suddenly curl their leaves, especially older leaves near the bottom. Leaves roll up from the outside towards the center. Sometimes up to 75% of the plant is affected.
  • What causes it: High temperatures, wet soil and too much pruning often result in leaf roll.
  • What to do about it: Although it looks ugly, leaf roll won’t affect tomato development, so you will still get edible tomatoes from your plants. Avoid over-pruning and make sure the soil drains excess water away.

8. Puffiness

  • What it looks like: The tomato plants look fine, they bloom according to schedule, and ripe red tomatoes are ready for harvest. When the tomato is sliced, the interior has large, open spaces and not much fruit inside. Tomatoes may feel light when harvested. The exterior of the tomato may have an angular, square-sided look.
  • What causes it: Under-fertilization, poor soil nutrition or inadequate pollination.
  • What to do about it: Make sure you are feeding your tomato plants throughout the season. A balanced fertilizer such as a 10-10-10 should be fed biweekly or monthly. Tomatoes are heavy feeders and need fertilizer throughout the growing season. For gardeners, frequent top-dressings with homemade compost and compost teas are a must.

9. Bacterial Canker

  • What it looks like: Often confused with cloudy spot disease, bacterial cankers start as yellow dots on ripening red tomatoes. If you look carefully at the spots — using a magnifying glass if you have one — you’ll see a dark, birds-eye-type rim around each of the yellowed spots. This is what distinguishes bacterial canker from cloudy spot disease.
  • What causes it: A bacteria called Clavibacter michiganensis. The bacteria occurs naturally but can be brought into the garden on infected plants or tools. Once it gets into the soil, rainwater splashes it up onto the plants. If there’s an open sore, such as insect damage or a leaf missing from pruning, it can enter the plant and infest it.
  • What to do about it: Remove the infected plants immediately and do not plant tomatoes again in that soil for at least three years. Rotate your crops regularly to prevent these and other diseases from taking hold in the soil. Don’t compost the dead plants — instead, put them in the trash to avoid spreading the bacteria.

10. Anthracnose

  • What it looks like: As tomatoes ripen, a dark, bull’s-eye circle appears on the blossom end or bottom of the tomato. The spot is sunken and mushy to the touch. When you slice into the tomato, there’s a black mushy spot underneath that looks like rot.
  • What causes it: A fungus called Colletotrichum phomoides. The fungus loves hot, moist weather and is often spread by overhead irrigation, sprinklers striking infected soil and splashing the fungus up onto the plants, and infected plants.
  • What to do about it: Switch your watering methods so water drips on the roots, not the leaves of the plants. Harvest tomatoes when ripe, since overly ripe tomatoes tend to contract the fungus more than tomatoes in the early stages of ripening.

11. Early Blight

  • What it looks like: You’ll find brown spots on tomato leaves, starting with the older ones. Each spot starts to develop rings, like a target. Leaves turn yellow around the brown spots, then the entire leaf turns brown and falls off. Eventually the plant may have few, if any, leaves.
  • What causes it: A fungus called Alternaria solani. This fungus can live in the soil over the winter, so if your plants have had problems before like this, and you’ve planted tomatoes in the exact same spot, chances are good the same thing will happen to your plants this year.
  • What to do about it: Crop rotation prevents new plants from contracting the disease. Avoid planting tomatoes, eggplants or peppers in the same spot each year as these can all be infected with early blight. A garden fungicide can treat infected plants.

12. Septoria Leaf Spot

  • What it looks like: After the plants begin to develop tomatoes, the lower leaves break out in yellow spots. Within the yellow spots, dark gray centers with dark borders appear. Black dots appear in the center of the spots. Foliage dies and falls off.
  • What causes it: A fungus called Septoria lycopersici thatinfects foliage.
  • What to do about it: Avoid watering tomatoes from the top, as the spray can force the spores developing on the leaves back into the soil and continue the disease cycle. Certis Double Nickel 55™ Fungicide & Bactericide was developed for use against Septoria Leaf Spot on tomatoes.

13. Fusarium Wilt

  • What it looks like: Your tomato plants look fine, when suddenly, they start to wilt. At first, only one side may be affected, but then the whole plant is wilting. You water them, and the problem gets worse. Within a day or two, the plant is dead!
  • What causes it: A nasty fungus called Fusarium oxysporum f.sp. lycopersici that attacks the vascular system of the plant, roughly equivalent to a human’s veins. The fungus destroys the xylem tubes, which transport water and nutrients up from the roots and into the leaves.
  • What to do about it: In the case of fusarium wilt, the best defense is a good offense. Rotate your crops so tomatoes aren’t planted in the same section of the garden each year. Purchase wilt-resistant varieties if you’ve lost tomatoes to wilting diseases in the past, since the fungus can overwinter in garden and lawn soils.

14. Verticillium Wilt

  • What it looks like: Yellow blotches appear on the lower leaves. As the blotches spread, the veins in the leaves turn brown. After the leaves turn brown, they fall off. The disease progresses up the stem until the plant is stunted.
  • What causes it: A fungus that lives in the soil, Verticilliurn albo-atrum, attacks the roots and travels up the xylem tubes with water. It then prevents the normal flow of water and nutrients to the leaves.
  • What to do about it: Once plants are infected, there isn’t much you can do to treat Verticillium wilt. Rotate your crops, because the fungus can live for long periods in the soil and even live among weeds such as ragweed. Choosing wilt-resistant varieties to plant is the best way to prevent Verticillium wilt.

15. Viral Diseases

  • What they looks like: Viral diseases mainly attack the tomatoes themselves. You might find black spots on tomatoes, or weird stripes on them. Don’t confuse signs of disease for just how some heirloom tomatoes look with natural stripes.
  • What causes them: Many of these viruses spread when plants are stressed by heat, drought or poor soil.
  • What to do about them: If you’ve read through all of these tomato problems and think your tomatoes may be suffering from a viral disease, spray your tomato plants with neem oil. Good soil management and using organic fertilizer for tomatoes helps keep your plants healthy, which can help them naturally resist viruses better.

16. Powdery Mildew on Tomatoes

  • What it looks like: Powdery mildew is easy to find on tomato plants as it looks like someone brushed the leaves with a white powder. You might find white spots on tomato leaves or even the stem. If you let the fungi thrive it will turn your tomato leaves yellow and then brown.
  • What causes it: Powdery mildew on tomatoes is more common in greenhouses than an outdoor garden because of the lack of air flow and high humidity.
  • What to do about it: The best way to prevent powdery mildew on tomato plants is to use a preventative spray formulated with sulfur. For more information, read this post on prevention and treatment of powdery mildew on plants.

5 Insects That Can Destroy Your Tomatoes

In addition to diseases, insects can damage tomato plants, too. Not all bugs are bad — some insects are extremely helpful, and some will even attack the “bad” bugs plaguing your tomato plants.

Be sure to browse the extended information on tomato plant pests below, but, overall, here are your best options for fighting insect infestations on tomato plants:

  • Caterpillar Killer with B.t. (Solution: Fight hornworms and other plant-eating caterpillars with this OMRI Listed® biological control that targets destructive larvae.)
  • Insect Killing Spray for Tomatoes. (Solution: An insect-killing formula for use on tomatoes that’s compliant for use with organic gardening and fights tomato hornworm, Colorado potato beetles, whiteflies and other caterpillars.)
  • Insecticidal Soap. (Solution: An OMRI Listed® insecticide soap that can be used up to the day of harvest on aphids, mealybugs, spider mites and other pests.)
  • Insecticidal Soap with Pyrethrin. (Solution: By mixing the features of insecticidal soap and pyrethrin, you can maintain your organic garden and fight spider mites, hornworms and destructive beetles.)
  • Neem Oil. (Solution: Neem oil kills insects in every life stage — from eggs to adults.)
  • Insect Traps. (Solution: Lure pest insects away from your plants and trap them before they can do more damage.)

The following tend to be the most common causes of various tomato pest problems.

1. Cutworms

  • What they are: Cutworms feed at night on seedlings. They “cut” or eat through the stem at soil level or an inch or less above the soil. Cutworms aren’t exactly worms — they are the larvae of certain moths. They only emerge at night and can be difficult to spot. Cutworms kill tomato plants by snipping them right in half.
  • What to do about them: Prevent cutworm damage by making a paper collar that fits around your seedlings. Just take newspaper or cardboard and fold it into an inch-wide strip. Use tape to make a collar around the plant, leaving about two to three inches around the stem. Remove the collar once the plant has several sets of leaves. You can also cut the bottom off of a paper cup and slide the open-bottom cup over the seedling to prevent cutworm damage.

2. Hornworms

  • What they are: Tomato or tobacco hornworms can decimate mature tomato plants in one night. These crafty insects are large green worms about two to three inches long with tiny horns on their head and ridged bodies. Hornworms are perfectly camouflaged so they look exactly like a tomato stem or branch, making them difficult to spot. They emerge at night, eat all the leaves off the plant and move on to the next section or plant.
  • What to do about them: Nature provides the best control for tomato hornworm in the form of a parasitic wasp that lays her eggs on the body of the hornworm. As the wasp’s larvae hatch, they eat into the living worm and eventually kill it. Natural methods to control tomato hornworms include planting marigolds around tomatoes. The strong marigold scent repels them naturally. Safer® Brand Caterpillar Killer II With B.T. uses a naturally occurring fungus to quell hornworms without harming earthworms. You can also use an insect-killing spray.

3. Colorado Potato Beetle

  • What they are: Colorado potato beetles are native to the United States. They love plants in the nightshade family, especially potatoes. If they can’t find potatoes, however, they will gravitate towards tomatoes, eggplant and other nightshade family vegetables. The beetles are about the size of dimes, with yellow-and-black striped wings. The adults use their mouthparts to chew holes in the leaves of tomato plants. Females lay clusters of bright gold or yellow eggs underneath the leaves. When the larvae hatch, they spread out among the tomato leaves, easily eating their way through the entire plant. Larvae are red to dark pink with black spots and frequently hide under the leaves during the day.
  • What to do about them: Use a pesticide with pyrethrins to spray on your tomato plants. This method works best in early spring before the larvae mature.

4. Stink Bugs

  • What they are: The brown marmorated stink bug isn’t only an annoyance inside the home. These insects also use their needle-like mouthparts to suck the juice right out of your tomatoes. They can be spotted with the naked eye on your tomatoes, or you can see their damage in the yellow, uneven spots that appear on the ripening tomatoes. When you slice into a yellow-spotted tomato, white sections appear under the yellow spots, which distinguish stink bug damage from fungal or viral problems.
  • What to do about them: Safer® Brand makes stink bug traps that harmlessly attract the insects to the trap and away from your tomatoes.

5. Spider Mites

  • What they are: Spider mites are difficult to see because they’re so tiny, but you can clearly see the damage they leave behind. Mites scuttle along the stems and leaves, piercing the leaves to feed on the juices. Eventually, tomato leaves look stippled and bronzed, with damage to the plant’s leaf structure.
  • What to do about them: The best method for treating spider mites on tomato plants is to use a neem oil spray. Another option is insecticidal soap, which also offers a treatment for spider mites.

Not Just Bugs: Bird Problems

One final tomato problem is often mistaken for insect damage: birds. Some birds, especially crows, love to eat ripening fruit, and tomatoes are technically a fruit. Crows peck with their large, sharp beaks at the ripening tomatoes, ripping open gashes and eating partial segments from various fruits. Other birds and even squirrels may also be at work if you find tomatoes that look like they have bites taken out of them.

The best control for bird problems is a net. A large fruit tree net, available at your local home or garden store, can be draped over the plants. The net is an effective deterrent to birds and usually a good deterrent for squirrels, too.

Although this list of tomato problems is extensive, don’t let it deter you from growing great tomatoes. The good news is that most of these diseases and problems still leave you with some edible tomatoes. And once you take precautions to avoid these diseases and pests in your future gardens, your tomatoes will continue to be fruitful and successful.

Tell Us About Your Tomato Problems

Join the Safer® Brand Community on Facebook, where we want to see the pictures of your tomato and garden problems. When you upload a photo or ask us a gardening question, we’ll get on the case and offer suggestions for your next steps.

Also, be sure to subscribe to the Safer® Brand E-Newsletter — signing up gives you links to helpful articles like this one.

Tomato: Diseases and Symptoms

Damping Off

Damage symptoms

  • Damping off of tomato occurs in two stages, i.e. the pre-emergence and the post-emergence phase.
  • In the pre-emergence the phase the seedlings are killed just before they reach the soil surface.
  • The young radical and the plumule are killed and there is complete rotting of the seedlings.
  • The post-emergence phase is characterized by the infection of the young, juvenile tissues of the collar at the ground level.
  • The infected tissues become soft and water soaked. The seedlings topple over or collapse.

Favourable conditions

  • High humidity, high soil moisture, cloudiness and low temperatures below 24° C for few days are ideal for infection and development of disease.
  • Crowded seedlings, dampness due to high rainfall, poor drainage and excess of soil solutes hamper plant growth and increase the pathogenic damping-off.

Survival and spread

  • Primary: Soil, Seed, Water
  • Secondary: Conidia through rain splash or wind.

Septoria leaf spot

Damage symptoms

  • Less vigorous plant are usually affected
  • Small, round to irregular spots with a grey center and dark margin on leaves
  • Spots usually start on lower leaves and gradually advance upwards
  • Spots coalesce and leaves are blighted
  • Complete defoliation of affected leaves
  • Stems and flowers are sometimes attacked
  • Fruits are rarely attacked

Survival and spread

  • Primary: Mycelium or conidia in pycnidia in infected plant debris or on solanaceous weeds
  • Secondary: Conidia through rain splash or wind and also by slimy conidia sticking on to hands and clothing of tomato pickers

Favourable conditions

  • Poor vigour of plants due to nutrient inadequacy or in late season
  • High humidity or persistent dew at 25 °C
  • Moist weather with intermittent shower.

Bacterial stem and fruit canker

Damage symptoms

  • Disease appears as spots on leaves, stems and fruits and as wilting of leaves and shoots
  • White blister like spots in the margins of leaves
  • Spots become brown with age and coalesce, but leaves do not fall off
  • Leaflets on one side of rachis show withering initially
  • Light coloured streaks on stems and petioles at the joints
  • Cracks develop in streaks and form cankers
  • Slimy bacterial ooze through the cracks in humid weather
  • Small, shallow, water soaked, spots with white halo develop on fruits
  • The centers of spots become slightly raised, tan coloured and rough
  • Vascular discolouration is seen in split open stems

Survival and spread

  • Primary: Bacterial cells survive on infected plant debris and seed (both internally and externally) and also on solanaceous weeds such as Solanum nigrum
  • Secondary: Bacterial cells transmitted through rain splash

Favourable conditions

  • Soil temperature of around 28 °C
  • High humidity or persistent dew
  • Moist weather with intermittent showers.

Early blight

Damage symptoms

  • This is a common disease of tomato occurring on the foliage at any stage of the growth.
  • The fungus attacks the foliage causing characteristic leaf spots and blight. Early blight is first observed on the plants as small, black lesions mostly on the older foliage.
  • Spots enlarge, and by the time they are one-fourth inch in diameter or larger, concentric rings in a bull’s eye pattern can be seen in the center of the diseased area.
  • Tissue surrounding the spots may turn yellow. If high temperature and humidity occur at this time, much of the foliage is killed.
  • Lesions on the stems are similar to those on leaves, sometimes girdling the plant if they occur near the soil line.
  • Transplants showing infection by the late blight fungus often die when set in the field. The fungus also infects the fruit, generally through the calyx or stem attachment.
  • Lesions attain considerable size, usually involving nearly the entire fruit; concentric rings are also present on the fruit.

Survival and spread

  • Primary: The fungus spends the winter in infected plant debris in or on the soil where it can survive at least one and perhaps several years. It can also be seed borne.
  • Secondary: The spores are transported by water, wind, insects, other animals including man, and machinery. Once the initial infections have occurred, they become the most important source of new spore production and are responsible for rapid disease spread.

Favourable conditions

  • Warm, rainy and wet weather

Bacterial leaf spot

Damage symptoms

  • Moist weather and splattering rains are conducive to disease development. Most outbreaks of the disease can be traced back to heavy rainstorms that occur in the area.
  • Infected leaves show small, brown, water soaked, circular spots surrounded with yellowish halo.
  • On older plants the leaflet infection is mostly on older leaves and may cause serious defoliation.
  • The most striking symptoms are on the green fruit. Small, water-soaked spots first appear which later become raised and enlarge until they are one-eighth to one-fourth inch in diameter.
  • Centers of these lesions become irregular, light brown and slightly sunken with a rough, scabby surface.
  • Ripe fruits are not susceptible to the disease. Surface of the seed becomes contaminated with the bacteria, remaining on the seed surface for some time.
  • The organism survives in alternate hosts, on volunteer tomato plants and on infected plant debris.

Survival and spread

  • Primary: Bacterial cells survive on infected plant debris and seed (both internally and externally) and also on solanaceous weeds such as Solanum nigrum
  • Secondary: Bacterial cells transmitted through rain splash

Favourable conditions

  • Moist weather and splattering rains
  • High humidity or persistent dew.

Bacterial wilt

Damage symptoms

  • Characteristic symptoms of bacterial wilt are the rapid and complete wilting of normal grown up plants.
  • Lower leaves may drop before wilting. Pathogen is mostly confined to vascular region; in advantage cases, it may invade the cortex and pith and cause yellow brown discolouration of tissues.
  • Infected plant parts when cut and immersed in clear water, a white streak of bacterial ooze are seen coming out from cut ends.

Survival and spread

  • The spreads through wounds, soil and implements.

Favourable conditions

  • Relatively high soil moisture and to be checked.

Leaf curl

Damage symptoms

  • Leaf curl disease is characterized by severe stunting of the plants with downward rolling and crinkling of the leaves. The newly emerging leaves exhibit slight yellow coloration and later they also show curling symptoms.
  • Older leaves become leathery and brittle. The nodes and internodes are significantly reduced in size.
  • The infected plants look pale and produce more lateral branches giving a bushy appearance. The infected plants remain stunted.

Favourable conditions

  • Whitefly is the vector for transmitting of leaf curl virus.

Mosaic

Damage symptoms

  • The disease is characterized by light and dark green mottling on the leaves often accompanied by wilting of young leaves in sunny days when plants first become infected.
  • The leaflets of affected leaves are usually distorted, puckered and smaller than normal. Sometimes the leaflets become indented resulting in “fern leaf” symptoms.
  • The affected plant appears stunted, pale green and spindly.

Survival and spread

  • The virus is spread by contact with clothes, hand of working labour, touching of infected plants with healthy ones, plant debris and implements.

Tomato spotted wilt disease

Damage symptoms

  • Symptoms vary among hosts and in a single host species
  • Stunting is a common symptom of TSWV infection
  • Chlorotic or necrotic rings form on the leaves of many infected hosts
  • Thickening of veins and bronzing of young leaves
  • Growing tips may die-back and terminal branches may be streaked
  • Affected plants may have a one sided growth habit or may be entirely stunted and have drooping leaves, suggesting a wilt
  • Pale red or yellow areas with concentric circular marking in the normal red skin of ripe tomato are formed
  • Discoloration of seed.

Survival and spread

  • Primary: Virus particles in infected plants of many hosts like Acanthospermum hispidum, Aster sp., Boerhaavia diffusa, Chrysanthemum sp., Cleome gynandra, cowpea, Dahlia variabilis, egg plant, French bean, Gerbera sp., groundnut, Lagasca mollis, lettuce, marigold, pea, chilli, pineapple, potato, Trianthema portulacastrum, water melon and Zinnia elegans
  • Secondary: Virus particles transmitted by thrips, Frankliniella schultzii, Scirtothrips dorsalis.

Fusarium wilt

Damage symptoms

  • The first symptom of the disease is clearing of the veinlets and chlorosis of the leaves.
  • The younger leaves may die in succession and the entire may wilt and die in a course of few days. Soon the petiole and the leaves droop and wilt.
  • In young plants, symptom consists of clearing of veinlet and dropping of petioles. In field, yellowing of the lower leaves first and affected leaflets wilt and die.
  • The symptoms continue in subsequent leaves. At later stage, browning of vascular system occurs. Plants become stunted and die.

Survival and spread

  • Soil and implements

Favourable conditions

  • Relatively high soil moisture and soil temperature

IPM for Tomato

To know the IPM practices for Tomato, .

Source: NIPHM, and Directorate of Plant Protection, Quarantine & Storage

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