Author Topic: Tomato Disease Visual Guide  (Read 2875 times)

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Tomato Disease Visual Guide
« on: Jul 29, 2007, 07:01:02 AM »
Well Pholks its that time of year, Here is just a few of the worst tomato problems, and I will add more.
For natural and organic solutions, see my previous post "Homemade Helpers"  in the gardening board
Grey Leaf Spot

Small brownish-black specks first appear on undersides of leaves. These later develop into larger necrotic areas, and the tissue often falls out, leaving a shot hole type appearance. Spots may be surrounded by a yellow halo. Yellowing, leaf drop, and defoliation may occur in severe cases.
The fungus can survive from year to year on Solanaceous weeds, so weed control is important. Leaf moisture from rains or dew increases disease severity. Fungicides may be used as recommended. Many commercial varieties are resistant.

Leaf Mold

Symptoms appear as light green patches on upper surfaces of older leaves. Underneath the leaves in these areas, a purplish or olive-green patch of mold growth is visible. Infected leaves turn yellow and drop off the plant.
Fungus is spread is by wind currents. High humidity and warm temperatures encourage mold growth. The problem is especially severe in greenhouses, where adequate ventilation and air movement reduce disease severity by lowering moisture at the leaf surface. Fungicides are effective controls.

Powdery Mildew

Powdery mildew is first noticed on older leaves as a yellow spotted appearance, that upon closer inspection has a whitish-gray powder on the surface. The leaves will eventually die, but usually remain attached to the stem. The disease is worse under warm, dry conditions.
Sulfur dusts or wettable sulfur sprays are effective preventative controls. The established disease will require one of the labelled mildew fungicides.

Early Blight

Leaf symptoms of early blight are large irregular patches of black, necrotic tissue surrounded by larger yellow areas. The leaf spots have a characteristic concentric banding appearance (oyster-shell or bull's eye).
Minimize wetting of the leaves by using drip or furrow irrigation. Infection occurs rapidly during periods of warm, wet weather. Fungicide sprays control the disease effectively.

Late Blight

Lesions on leaves appear as large watersoaked areas, that eventually turn brown and papery. Lesions may be surrounded by a white ring of mold if leaf wetness is high. Green to black irregular lesions are also present on the stems.
The fungus develops during periods of cool wet weather. Fungicide sprays as a preventative measure during these periods may be needed if the crop is being grown near large areas of tomato relatives (Solanaceous weeds, potatoes).

Septoria Virus

Circular water-soaked lesions occur first on older leaves. These spots eventually turn brown with gray centers and die, and if infection is severe enough, the entire leaf will die.
The fungus can survive in the debris from previous crops and/or weeds. Clean cultivation is important. The disease can be controlled by labelled fungicides.

Bacterial Speck

Bacterial speck is widely distributed. Symptoms may appear on any plant part. Leaves of infected plants are covered by small, dark brown, irregular patches of necrotic tissue that are surrounded by yellow halos. Disease severity is increased by leaf wetness, from sprinkler irrigation, rain, or heavy dews.
Minimize wetting of the leaves by using drip or furrow irrigation. Copper sprays provide effective control.

Bacterial Spot

Dark brown water soaked spots appear on the leaves; later these spots become blackish, and eventually the affected tissue drops out leaving a hole in the leaf. Black, raised specks that later become scab-like spots appear at the same time on fruit.
Crop rotations and careful transplant selection are important. Copper sprays provide some control. Good sanitation practices including prompt plow-down of stubble and weed control help prevent the disease.

Alternaria Canker

Symptoms of Alternaria canker appear on stems, leaves and fruit. Large areas of the leaf lamina between veins is killed, leading to leaf curling and eventual death of the entire leaf.
Fungus overwinters in crop residue and is easily spead by wind. Wounding of young plants (by mechanical damage or pruning) provides an entry site for infection. Furrow or drip irrigation is preferred over sprinkler irrigation.

Offline Patty S

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Re: Tomato Diasease Visual Guide
« Reply #1 on: Jul 29, 2007, 10:31:59 AM »
:Wow: What a terrific contribution this is, Phil! :clap: I found it very helpful & informative, although I haven't had problem-one with my tomatoes this year (or anything else in the garden, for that matter), other than a short lived bout with Whitefly, & they weren't around long enough to do any permanent damage.
Now that I've said that out loud,!

This type of info (& also that in your Homemade Helpers post) definitely makes them archivable keepers! Thank you! :kissies: