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Plant Disease Clinic -- Highlights
This article was published originally on 7/14/1993Leaf Spot - turf
Leaf spot has been a common problem on turf this spring and summer. Leaf lesions are initially reddish-brown to dark brown. As they enlarge they take on an oblong shape and develop a lighter center with a dark border. Heavily infected blades may turn yellow, wither, and die. The pathogen may also move to the crown and cause plant death. This is referred to as melting out. At the melting out stage, the lawn appears to thin out; this damage is sometimes mistaken for drought injury (not in 1993!). There are a number of cultural management practices that aid in controlling this disease:
Wet spring and early summer conditions have favored the development of fungal blights of tomato. Two common foliage diseases of tomato are early blight, caused by Alternaria solani, and Septoria blight, caused by Septoria lycopersici.
Lower leaves are usually attacked first. Early blight causes brown spots (up to more than 1/2" in diameter) that contain concentric rings of darker brown. Septoria causes smaller brown spots that eventually turn light tan or gray in the center with a dark border. Both diseases cause foliage to eventually turn brown and die.
Cultural practices can help reduce disease outbreaks. Just after transplanting, apply a 2-4" layer of mulch (leaves, grass clippings, straw, etc.). This acts as a barrier against the introduction of fungal spores from the soil. Space plants adequately to allow good air circulation. Since these fungi can overwinter on infected leaves, it is also important to remove plant debris at the end of the season. Rotate away from tomatoes and potatoes for several years.
Fungicide sprays, such as Daconil 2787, may be needed. Sprays should be applied every 7 to 10 days from fruit set through harvest.
Year of Publication:
IC-465(18) -- July 14, 1993