Tomato Fusarium Crown Rot

Fusarium crown rot strikes at the root and wreaks havoc on the entire root system. It is extremely widespread in places with sandy, acidic soil. Southern Florida, for example, is much more likely to experience it than Colorado. Causes and Symptoms Caused by the fungus fusarium pseduograminearum, tomato fusarium crown rot is so prevalent because the fungus is easily picked up by weak or young plants. It can also be carried over to new soil from infected plants, thereby leaving both soil and plants extremely susceptible to plague. There is…

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Rhizoctonia on Tomato Plants

Rhizoctonia rot Rhizoctonia solani is common in most soils and is able to cause some form of disease in almost all cultivated plants. Different ‘strains’ of R. solani, called anastomosis groups, have been recognized. The anastomosis groups differ in their host range and pathogenicity.The most common diseases are damping-off of seedlings, root and stem rots, stem cankers and fruit rot. The diseases often have common names that describe symptoms on the particular host, for example base rot of lettuce, black scurf of potato tubers, crater rot of beetroot, and wire…

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Septoria Leaf Spot of Tomato

Septoria leaf spot, which is caused by Septoria lycopersici, results in spotting and wilting of tomato foliage. This fungal disease causes circular spots with dark brown margins and tan to gray centers dotted with black pycnidia. A narrow yellow halo is often associated with leaf lesions. If the leaf lesions are numerous, some infected leaves turn slightly yellow and then brown, and they wither. Fruit infection is rare. Septoria leaf spot overwinters on infected tomato debris or debris of solanaceous weed hosts, such as horsenettle. The fungus can also survive on…

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Alternaria Cankers

Tomato alternaria canker is a bacterial fungus that can cause significant damage the stems, leaves and fruit of the tomato plant. Once a plant is infected, it is difficult to eliminate, but there are ways to minimize the damage. Causes and Symptoms Alternaria needs moisture to survive, and thrives in areas with humid climates, or where there has been significant rainfall. It lives in the seeds and seedlings, and is also spread by spores, as they become airborne and land on plants. Alternaria canker flourishes in dead plants that have…

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Early Blight of Tomato

Introduction Early blight of tomato, caused by the fungus Alternaria solani, is perhaps the most common foliar disease of tomatoes in the Northeast and is also common on potatoes. This disease causes direct losses by the infection of fruits and indirect losses by reducing plant vigor. Fruit from defoliated plants are also subject to sunscald. Environmental Conditions Alternaria spores germinate within 2 hours over a wide range of temperatures but at 80 to 85ºF may only take 1/2 hour. Another 3 to 12 hours are required for the fungus to…

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Gray Leaf Spot on Tomato Leaves

If your tomato plants have unusual brown or gray spots on the underside of leaves, then you may have a gray leaf spot problem. The spots begin as small black or brown specks on both young and mature tomato leaves, resulting in unhealthy and diseased looking plants. Causes and Symptoms The cause of gray leaf spot disorder usually begins on tomato seeds in the form of a fungus. The spores of the fungus travel to other plants by rain or wind. Once they find a wet leaf, the spores grow…

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