White County
 Gardening
Podcast
July 6, 2010
Managing Tomato Diseases (Series 3 of 3)
(2:25 minutes)
Audio/Video Script
Sherri Sanders
County Extension Agent - Agriculture
Hello this is Sherri Sanders County Extension Agent-Agriculture in
White County with the final segment of a three part series on tomatoes
Fungal Diseases are favored by warm, wet conditions and poorly drained soil.
The fungi are common in many soils.
Early Blight is a very common disease of Arkansas tomatoes and is favored by
warm, rainy weather. The fungus survives on seed, infected by plant debris,
volunteer tomatoes, or certain other plants like potatoes, eggplants, horse
nettles or black nightshade. Poor fertilization favors the diseases as well.
Spots form on leaves, stems, and fruit. Leaf spots start as small, dark brown
areas sometimes with a yellow border. They grow rapidly under favorable
conditions, forming lighter brown bands with a dark center. Stem spots have even
more noticeable rings than leaf spots and may cause plant death if the stem is
girdled. Fruit spots start at or near the stem attachment and also develop a
dark, ringed appearance. Spots are leathery-feeling and may be covered by a
blackish dust, consisting of numerous, microscopic spores of the fungus.
Infected fruit often drops off soon after infection.
For management grow resistant varieties. Avoid diseased transplants, if
possible. Eliminate weeds and volunteer tomatoes and rotate to other areas every
two years. Use proper fertilization and fungicides.
Southern Blight is a common problem in Arkansas on soils that have grown
tomatoes for several years. The fungus survives as hard, brown "sclerotia" that
look like tiny BBs in the soil or on infected tomato debris. It is spread by
anything that moves soil or debris in the field. Sclerotia can survive for
several years without a host.
If young plants are infected, they may fall over at the soil line.
Rotate with corn or wheat for 1-2 years. Avoid beans or eggplants in the
rotation. Deep plow the soil to bury infected plants. Use only disease free
transplants and soil. Plastic mulch may help somewhat. Fertilize with calcium
nitrate to minimize disease and use fungicides.
For additional information on horticulture related topics, contact your
county office of the University of Arkansas Cooperative Extension Service. This
has been Sherri Sanders in Searcy
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