or benomyl (Tersari 1991) may be warranted. Two or more applications, spaced 7 to 14 



days apart, are recommended. A more effective, long-term solution to the problem is 



to seed shady areas with a shade -tolerant grass, such as a fine-leaf fescue or rough 



bluegrass (Poa trivialis) . If the shade is extremely dense, consider a shade -tolerant 

 ground cover or use redwood bark chips and stones to cover the area. 



Helminthosporium leaf spot has now advanced to melting-out . The crowns of lawn grasses 

 turn dark-brown to black and rot. Lawns infected with this disease have been get- 

 ting thin for the past several weeks and areas have turned brown. The remainder of 

 the lawn usually has a reddish-brown cast. Fungicide sprays are of little value in 

 controlling the disease now, but you should consider overseeding late this summer 

 with a resistant Kentucky bluegrass variety. 



Sclerotinia dollar spot and rust can also be found on lawns now. On Kentucky bluegrass, 

 fine-leaf fescues, and bermudagrass , dollar spot appears as bleached- tan spots 4 to 

 6 inches in diameter. Individual grass blades are girdled by yellow to light-tan le- 

 sions with reddish-brown borders. 



CORN DISEASES 



Anthracnose . Corn growers, home gardeners and commercial producers alike, should be 

 on the lookout for a seedling leaf blight. This disease, which attacks both 

 sweet corn and field or dent corn, is known as anthracnose. Sweet corn appears to be 

 considerably more susceptible than dent corn. Anthracnose is caused by the fungus 

 Colletotriahum graminiaolum , which requires high humidity, heavy dews, or rainy weath- 

 er to infect and spread. The pathogen overwinters as spores or mycelia in crop resi- 

 dues . New spores are produced in the spring and summer during wet periods and are car- 

 ried from the debris by wind and splashing rains. 



Small (1/16 to 1/8 inch), round to slightly oblong spots appear on the leaves. The 

 spots at first appear water-soaked, but then turn yellow. The spots may grow as large 

 as 1/2 inch in diameter and become tan in the center with a narrow, yellowish halo or 

 reddish-brown border. Later, leaf tissues turn yellow in streaks that extend from the 

 lesions and the lesions may grow together. Severely infected leaves turn yellow, then 

 brown, and finally die. The same fungus may cause root and stalk rots later in the sea- 

 son. 



The fruiting bodies of the fungus that causes anthracnose appear as translucent, spore - 

 bearing structures and large, black, sterile setae that look like pin cushions under 

 the microscope. The setae are the identifying sign of the disease. 



Control measures include crop rotation, sanitation, and balanced fertility. To date, 

 no chemical has been cleared by the federal Environmental Protection Agency (EPA) for 

 use on sweet corn, popcorn, or dent corn to control anthracnose and the university of 

 Illinois, at this time, is recommending no chemical to control anthracnose. 



However, greenhouse experiments have shown that the zinc- ion plus maneb complex (Di- 

 thane M-45, Manzate 200) --which is registered by the EPA--will control the disease. 

 Zinc- ion plus maneb can be applied within seven days of harvest on sweet corn and 

 popcorn and within 40 days of harvest on dent corn to control Helminthosporium leaf 

 blights (northern and southern), at the rate of 1-1/2 pounds of fungicide per acre in 

 sufficient water to wet the foliage. Adding a suitable spreader -sticker (surfactant) 

 will improve the efficiency of the fungicide. 



Stewart's Disease . Populations of flea beetles- -the insect that transmits the bacteri- 

 um Xanthomonas stewartii , which causes Stewart's disease of corn- -are high in some 



