I have noticed minuscule ... - Ask Extension
I have noticed minuscule black flies on my tomato plants. The flies, around 1/16" long, have tiny black bodies with clear, slender wings. After the f...
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I have noticed minuscule ... #156414
Asked October 09, 2013, 5:08 PM EDT
I have noticed minuscule black flies on my tomato plants. The flies, around 1/16" long, have tiny black bodies with clear, slender wings. After the flies show up, the plants start getting little white spots on their leaves. Eventually, (though this might be caused by a tomato virus, unrelated to the flies), the leaves develop brown spots, and the leaf yellows and dies. Some of the "yellow pear" cherry tomatoes (the fruits themselves) are also getting little brown spots. Do you have ideas on what the black flies are, what to do about them, and ways to prevent the damage next year? (I know it is too late this year.) Are the other two issues (brown-spotted/yellow/dying leaves and the little brown spots on my cherry tomato fruits) part of the insect issue, or a tomato disease? (Attached photos show brown spots on leaves. The flies were too small for me to photograph.) Thanks!
Ramsey County Minnesota
Expert Response
As your question illustrates, tomatoes are susceptible to many pests and diseases.
Although we can't be sure without seeing the flies or sharp photos, we guess that what you have described might be winged aphids. Do they look like this? http://www.augsburg.edu/wp-content/uploads/2013/02/Aphid-Winged-OnGrass-close.jpg
If so, go to this website to learn more about aphids and how to control them.
http://www1.extension.umn.edu/garden/insects/find/aphids-in-home-gardens/
Although aphids often transmit viruses, the leaves in the photos show evidence of fungal disease--most likely alternaria, commonly known as early blight. This disease and another called septoria leaf spot are almost ubiquitous where tomatoes are grown and they sometimes cause complete defoliation before the end of the growing season. Go to the following website to learn more about tomato leaf spot diseases and how to deal with them.
http://blog.lib.umn.edu/efans/ygnews/2012/07/tomato-leaf-spot-season-begins.html
Some of the diseases that affect tomato leaves also affect the fruit. We can't be sure what's causing the spots on the cherry tomatoes without seeing them or sharp photos. However, the following website discusses and illustrates bacterial speck and bacterial spot, two diseases that cause spots on tomato fruits.
http://vegetablemdonline.ppath.cornell.edu/factsheets/Tomato_Bacterial.htm
Following is an excellent diagnostic tool for identifying tomato diseases including those what cause spots on fruit. Unfortunately the site isn't working properly for us now. If it fails to work for you too, try visiting it later to see if the problem has been corrected.
http://www1.extension.umn.edu/garden/diagnose/plant/vegetable/tomato/fruitspots.html
Although we can't be sure without seeing the flies or sharp photos, we guess that what you have described might be winged aphids. Do they look like this? http://www.augsburg.edu/wp-content/uploads/2013/02/Aphid-Winged-OnGrass-close.jpg
If so, go to this website to learn more about aphids and how to control them.
http://www1.extension.umn.edu/garden/insects/find/aphids-in-home-gardens/
Although aphids often transmit viruses, the leaves in the photos show evidence of fungal disease--most likely alternaria, commonly known as early blight. This disease and another called septoria leaf spot are almost ubiquitous where tomatoes are grown and they sometimes cause complete defoliation before the end of the growing season. Go to the following website to learn more about tomato leaf spot diseases and how to deal with them.
http://blog.lib.umn.edu/efans/ygnews/2012/07/tomato-leaf-spot-season-begins.html
Some of the diseases that affect tomato leaves also affect the fruit. We can't be sure what's causing the spots on the cherry tomatoes without seeing them or sharp photos. However, the following website discusses and illustrates bacterial speck and bacterial spot, two diseases that cause spots on tomato fruits.
http://vegetablemdonline.ppath.cornell.edu/factsheets/Tomato_Bacterial.htm
Following is an excellent diagnostic tool for identifying tomato diseases including those what cause spots on fruit. Unfortunately the site isn't working properly for us now. If it fails to work for you too, try visiting it later to see if the problem has been corrected.
http://www1.extension.umn.edu/garden/diagnose/plant/vegetable/tomato/fruitspots.html
