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Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Early blight Causal agent: Alternariasolani (fungus) Signs: light to dark brown conidia are borne on olive brown conidiophores Symptoms: Leaf spots often with darker rings within the spots. Total image number: 8
It one of the most common diseases of tomato.
The fungus can infect many parts of the plants must most commonly leaves and stems.
The fungus is shown in comparison to a leaf hair and some type of insect in the 2nd row, 4th image.
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Septoria leaf spot Causal agent: Septoria lycopersici (fungus) Signs: Raised spore-producing bodies ("pycnidia") when mature can be seen within the spots. Symptoms: Dark leaf spots often smaller than with early blight. Total image number: 7
Another common disease in which the fungus can infect many parts of the plants must most commonly leaves and
stems. The fungus produces its spores in a sack ("pycnidium") and they protrude from this sack in a gelatinous ooze
which can be seen in images in the 1st row, 4th image and 2nd row, 1st image.
Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: canker Causal agent: Rhizopus (fungus) Signs: Mycelium with sporangia of the fungus in webs within the pith Symptoms: Portions of the stem are tan colored where the pith and stem tissues have been infected. Total image number: 15
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Leaf mold Causal agent: Fulvia fulva (fungus) Signs: mold growth usually on lower surface of leaf. Symptoms: Spot are usually yellow to brown on upper leaf surface with moldy growth on the lower leaf surface. Total image number: 9
This disease is more common in greenhouses but can occur in the field under prolonged humid, wet conditions.
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Stem rot, Timber rot Causal agent: Sclerotinia sclerotiorum (fungus) Signs: black survival structures called "sclerotia" (see in culture plates). Symptoms: a dry stem rot usually with disintegrated pith tissue.
On the stems, notice at the margin between healthy and diseased tissue you will see a copper/brown area on the stem.
Within this area you can see a pattern of alternating lighter and darker copper/brown lines
Total image number: 5
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Bacterial canker Causal agent: Clavibacter michiganensis subsp. michiganensis (bacterium) Signs: Symptoms: Stunted plants, yellowed leaves, pith browning and decay. The leaves also tested positive for Cmm in a separate sample than the pith tissue, each by ELISA. Total image number: 4
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Tomato spotted wilt (TSWV) Causal agent: Tomato Spotted Wilt Virus (virus) Signs: Symptoms: Plants may be stunted and younger tissue will usually show leaf/petiole symptoms.
TSWV leaf symptoms could be similar to the later stages of 'glyphosate' injury to leaves. Total image number: 14
Row 1: Leaves with broader, dead areas
Row 2: Leaves with discrete spots
Row 3: Stem with darkened, wavy depressions
Rows 4 and 5: Fruit infection
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: herbicide injury Causal agent: 'glyphosate' ("RoundUp") Signs: none Symptoms: Plant foliage, especially new growth, will yellow first and then turn brown and die. Total image number: 8
1st and 2nd row images are of initial leaf symptoms.
Last row (4 images) are leaf symptoms in later stages of development.
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: herbicide injury Causal agent: growth regulator (e.g. 2,4-D) Signs: none Symptoms: leaves narrow with wavy margins and elongated tips. Total image number: 4
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: catfacing Causal agent: cold or growth regulator (e.g. 2,4-D) Signs: none Symptoms: This is an extreme case of "Catfacing". Catfacing symptoms are associated with adverse growing
conditions during blossoming; the adverse conditions result in poor pollination, which leads to irregularly shaped fruit.
Catface symptoms are most often seen in large-fruited fresh market varieties (although other varieties can also be
affected) and are associated with disturbances in flower production such as low temperature injury 3 weeks before
flowers are mature, especially in early plantings, but also with injury from growth regulators such as 2,4-d. Pruning
and high nitrogen can also aggravate the problem. Total image number: 3
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: herbicide injury Causal agent: triazine herbicide (e.g. metribuzin) Signs: none Symptoms: Yellowing of major veins starting at the base. Older leaves show injury before younger ones. Total image number: 4
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: cold injury, likely Causal agent: cold injury, likely Signs: none Symptoms: The dead areas mostly between the veins of the older leaves and at the tips of the
very youngest leaves are due to an abiotic cause, not a pathogenic disease. The pattern of the injury on old and new
leaves indicates the injury occurred at one point in time. The cause could be cold injury or some type of air pollutant
from a heater that is not functioning properly. Total image number: 8
1st row of 4 images is from a greenhouse sample.
2nd row of 4 images is from a plastic high tunnel structure where there was no artificial heating involved.
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: oedema or edema Causal agent: physiological accumulation of water in cells Signs: none Symptoms: leaves where cells along the major veins are swollen with water.
Sample is from a plastic high tunnel structure. Total image number: 9
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Fruit rot Causal agent: Botrytis cinerea (fungus) Signs: mold often called "gray mold" may be see in infected area.
Conidiophore and conidia micrographs also shown. Symptoms: Decay of fruit often with mold present. Total image number: 5
Can occur in prolonged wet/cloudy weather.
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Fruit rot Causal agent: Pythium sp. (fungus) Signs: Oospores and intercalary sporangia shown. Single oogonium and antheridium shown in seprate image. Symptoms: A very soft, watery decay of the fruit. Total image number: 4
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Buckeye rot Causal agent: Phytophthora spp. (fungus) Signs: Symptoms: Fruit decay often with darkened rings around the margin. Total image number: 4
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Blossom end rot Causal agent: Calcium deficiency. Blossom-end rot is induced when demand for calcium exceeds supply. This may result from low calcium levels or high amounts of competitive cations (e.g. ammonium, potassium, magnesium) in the soil, drought stress, or excessive soil moisture fluctuations which reduce uptake and movement of calcium into the plant, or rapid, vegetative growth due to excessive nitrogen fertilization. Signs: none Symptoms: Dry, sunken decay developed on the blossom end (opposite the stem) of fruit, especially the first fruit of the season. Total image number: 2
Plant: Tomato (Lycopersicon esculentum) (Solanaceae) Back to List Disease/Disorder: Anthracnose Causal agent: Colletotrichum spp. (fungus) Signs: Rings of spore-producing bodies (acervuli) often exuding tan-colored spores in masses.
Mature spore-producing bodies often have large, sterile, dark hairs (setae). Symptoms: Fruit decay seen as a sunken area with rings of spore-producing bodies. Total image number: 11