1
point
Tomato disease

Tomato    Paraguay

What is this disease? These tomato plants, I would like to know what is the problem please. Thank you


Posted by: Guido Lopez (2 points) Guido Lopez
Posted: March 2, 2016


Tony commented,
These symptoms may be due to tomato russet mite (Aculops lycopersici). If this is the problem damage will begin with yellowing of lower leaves and progressively move up the plant to the tip, weakening the plant as it progresses and causing malformation/stunting of leaves and fruit Another characteristic symptom is a reddish bronze colour on stems due to the presence of the mites Another typical feature is a rapid acceleration of damage during warm/hot dry weather The mites drain plant nutrients and inject toxins causing the weakening and plant death if untreated Miticides can be used to control, the softest option being liquid sulphur. Good coverage with a pressure spray unit is necessary and retreatment will probably be needed. They are persistent pests and I do not know of any natural enemies.
almost 4 years ago.

ALICE KAZUKO INOUE NAGATA commented,
Sorry to this late response. I work in Brazil, and these problems seem to be similar to ours. The first picture shows a tomato plant with typical symptoms of spotted wilt (peste negra). I agree with Ravi, and add some other recommendations: when removing the diseased plants, place them in a plastic bag as soon as you cut from the base; use resistant materials; eliminate all plants after harvesting; control thrips; plant tomatoes far from peppers and egg plants. The second picture shows a leaf with typical interveinal chlorosis symptom. It seems to be a plant infected with a crinivirus (amarilleo del tomate). This is an emergent virus in these regions. It is transmitted by whiteflies (silver leaf and greenhouse whitefly). The symptoms are clearer (chlorosis, leaves become brittle and curly) in old leaves. Losses are high if infection is at early time points. No resistant cultivars are available. Control is difficult: try to manage the whiteflies, eliminate plant debris soon after harvesting; do not leave old plants unprotected. In the fruits, not sure, maybe thrips damage when the fruit was young. Diagnosis based on symptoms is always very difficult.
almost 4 years ago.



Answers

1
point
From the leaf pictures you included it looks to me like this tomato is infected with early blight (Alternaria solani). However the brown streaks on the fruit is most likely from damage/irregular growth rather than the disease. To manage this you should remove infected leaves and treat with copper spray or a biofungicide but the best control of early blight is prevention. The fungus prefers humid conditions so if there is a large rainfall coming I suggest you spray beforehand.


Posted by: Kelsee Baranowski (3 points) Kelsee Baranowski
Posted: March 2, 2016


Guido Lopez commented,
Thank you Kelsee , very kind for your answer.
almost 4 years ago.



1
point
I think the disease is tomato spotted wilt caused by virus ( image 1). It is mainly transmitted by thrips (insect). Do agree with Kelsee that some infection of alternaria can be seen (in second image). And on fruit yes it is physical damage.

Symptoms of tomato spotted wilt virus
1. Appearance of bronze or dark spots on upper side of young leaves
2. Some time tip dieback may occur
3. Unripened fruits may show slightly raised areas with faint, concentric zones. (this symptom is not clear from your image, please upload one more close up photo)

Management
1. Remove the infected plant and burn them
2. Keep the field free from weeds
3. If thrips infestation is severe spray suitable insecticide


Posted by: Dr. Ravishankar Narayana (11 points) Dr. Ravishankar Narayana
Posted: March 2, 2016




0
points
These symptoms may be due to tomato russet mite (Aculops lycopersici).
If this is the problem damage will begin with yellowing of lower leaves and progressively move up the plant to the tip, weakening the plant as it progresses and causing malformation/stunting of leaves and fruit.
Another characteristic symptom is a reddish bronze colour on stems due to the presence of the mites.
Another typical feature is a rapid acceleration of damage during warm/hot dry weather.
The mites drain plant nutrients and inject toxins causing the weakening and plant death if untreated.
Miticides can be used to control, the softest option being liquid sulphur. Good coverage with a pressure spray unit is necessary and retreatment will probably be needed. They are persistent pests and I do not know of any natural enemies.


Posted by: Tony (1 point) Tony
Posted: March 12, 2016


Tony commented,
So we have several potential diagnosis all very well explained with recommendations. There are several ways to firm up the conclusion and be better prepared for a future recurrence: 1. Direct diagnosis of pathogens - there are affordable test kits for some viruses including Tomato Spotted Wilt (TSWV) and Tomato-Tobacco Mosaic (TMV) and possibility others in your country - availability of test kits will vary. Samples can also be sent to diagnostic services for microbial and viral testing 2. High thrips and whitefly levels can be a strong indicator of a virus problem, although not all thrips species are vectors of TSWV. Sometimes thrips infect plants and move on before detection. Not sure if I mentioned that we have fund that wester flower thrips pupae can survive in the ground for months and re-emerge and infect new plants with TSWV. It is important to keep thrips numbers low, especially toward the end of a season. In Australia and in Europe at least there are effective biological control agents that can achieve this. Commercial greenhouse growers will fumigate their soil when they believe that there is a high residual thrips level at the end of the crop. There are also effective natural enemies for whitely 3. A positive response to the correct chemical treatment and prevention measures is also a strong indicator. Viruses cannot be cured, only restrained in their spread. Alternaria can be treated as described. 4. One more option for the home gardeners and commercial farmer is to plant habitat vegetation for natural enemies. This can be very effective. The plants used depends on what you wish to encourage, but small parasitic wasps were found to be very diverse on some plants researched in South Australia ie selected chenopode species, including species that attack western flower thrips and possibly other species of thrips. 5. Similarly some plants (including weeds, ornamentals and other vegetables) can harbour viruses like TSWV which are then transferred by insect vectors. Host species for many diseases are listed on the internet.
almost 4 years ago.



0
points
Sorry to this late response. I work in Brazil, and these problems seem to be similar to ours. The first picture shows a tomato plant with typical symptoms of spotted wilt (peste negra). I agree with Ravi, and add some other recommendations: when removing the diseased plants, place them in a plastic bag as soon as you cut from the base; use resistant materials; eliminate all plants after harvesting; control thrips; plant tomatoes far from peppers and egg plants. The second picture shows a leaf with typical interveinal chlorosis symptom. It seems to be a plant infected with a crinivirus (amarilleo del tomate). This is an emergent virus in these regions. It is transmitted by whiteflies (silver leaf and greenhouse whitefly). The symptoms are clearer (chlorosis, leaves become brittle and curly) in old leaves. Losses are high if infection is at early time points. No resistant cultivars are available. Control is difficult: try to manage the whiteflies, eliminate plant debris soon after harvesting; do not leave old plants unprotected. In the fruits, not sure, maybe thrips damage when the fruit was young. Diagnosis based on symptoms is always very difficult.


Posted by: ALICE KAZUKO INOUE NAGATA (1 point) ALICE KAZUKO INOUE NAGATA
Posted: May 14, 2016




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