fields and those planted with hybrids that are highly susceptible to northern corn 



leaf blight. 



Com in the early tassel stage with ten or more southern or northern leaf blight 

 lesions on the upper leaves will benefit the most from fungicide sprays. Com 

 that is already in the early dough stage is likely to produce satisfactorily, even 

 if sprays are not applied. 



Fungicide and application suggestions . The fungicides suggested for control of 

 scathe m corn leaf blight will also give protection against northern leaf blight, 

 vellow leaf blight, eyespot, and rust. For at least ten years, Dithane M-45 and 

 Manzate ZOO have been used successfully to protect vegetables, fruits, turf grasses , 

 ornamental plants, and fields crops against many disease -causing fungi. These 

 maneb and zinc- ion products have also provided good control of both the northern 

 and southern corn leaf blight (race Oj on sweet corn in Florida since 1965. 



Both materials are registered by federal agencies for use without feeding restric- 

 tions on all types of corn grown for grain, fodder, or silage. They may be applied 

 up to seven days before harvest. 



Cit-cop 4H--a new, finely divided, liquid copper fungicide that is also cleared for 

 use on corn- -showed promising results in several 1970-71 field trials. However, it 

 has not been tested as extensively as the naneb and zinc-ion products. 



Follow label directions and precautions closely when using any fungicide . 



,r .\ormal" Illinois weather conditions during the corn growing season favor development 

 and spread of southern com leaf blight. Fortunately, such conditions --warm, humid, 

 cloudy weather with one or two rains a week- -do not usually appear until about the 

 time com readies the tassel ing stage. So the general recommendation is to start 

 spraying against blight at the early tassel stage. However, if lesions appear on 

 the upper leaves and increase rapidly in size and number and if weather conditions 

 seem to favor further blight development, spraying can be started earlier. 



Two to four applications should be enough to protect the crop from earlv tassel to 

 the early dent stage. Seed-production fields may need one to two extra spray appli- 

 cations for added protection. Blight damage is usually slight if the infection ap- 

 pears after the crop has reached the dent stage. Sprays applied at this time tend 

 to u c of little value, but they may improve the grain quality and may prevent further 

 development of ear rot caused by the southern corn leaf blight. 



.Apply sprays every seven to ten days. If the rains are frequent or the threat of 

 blight is severe, do not wait more than seven days between applications. If hot, 

 dry weather is expected, the spray interval can be lengthened to ten days. 



Thorough coverage of leaves and leaf sheaths on the top half of the com plant is 

 essential. Hie food produced in the upper five or six leaves produces the bulk of 

 the grain. Properly equipped aircraft or ground sprayers can be adjusted to apply 

 spray deposits on the leaves, leaf sheaths, and ear husks. These are the areas 

 where most infections occur. 



The ideal time to spray is just before a rain. But try to allow enough time for the 

 spray film to dry. The fungicide diffuses into the water film left by rain or dew 

 and spreads to other plant parts. So, fine spray droplets- -less than ZOO microns 

 in diameter- -are not necessary . 



