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Tomatoes suffer from many fungal, bacterial,
and viral diseases. This tutorial will discuss only a few of
the most significant diseases. |
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1A |
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1B |
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Late blight
(Phytophthora infestans) [shown photo1A] causes large
lesions on the leaves, stems and fruit. It is most common during
cool, wet weather. Most other pathogens are more damaging during
warm, wet conditions. These include early blight (Alternaria
solani) [photo 1B] and gray leaf spot (Stemphylium
solani). Fungicidal sprays and resistant varieties are used
to control these fungal diseases. [photos
of these fungal diseases] |
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2 |
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Bacterial spot
(Xanthomonas campestris pv. vesicatoria) [photo
2] creates lesions on leaves and fruit, especially during the
rainy season. Copper compounds, pathogen-free seed, and furrow
irrigation are used to control this bacterium. |
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3 |
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Several soil-borne pathogens cause rapid wilting
symptoms. These include bacterial wilt (Ralstonia solanacearum)
[photo 3], fusarium wilt (Fusarium oxysporum f.s.
lycopersici), and southern blight (Sclerotium
rolfsii). These diseases are best managed by rotating with
non-Solanaceous crops and using raised beds to improve drainage.
Resistant varieties are available for fusarium wilt, and tolerant
varieties are available for bacterial wilt. [photos
of these wilt diseases] |
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4A |
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4B |
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Virus symptoms typically involve yellow mottling
or distortion of foliage and/or streaking on fruits. Tomato
Yellow Leaf Curl Virus (TYLCV) [photo 4A], Tomato Mosaic
Virus (TMV), and Tomato Spotted Wilt Virus (TSWV)
[photo 4B] are most common. These diseases are prevented by killing
insect vectors and sowing resistant/tolerant varieties. [photos
of these viral diseases] |
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