the use of (1) resistant varieties, (2) certified seed, (3) a hot -water or anaerobic- 

 soak seed treatment, or (4) a Vitavax seed treatment, (See Report on Plant Diseases 

 No. 101, ''Barley Smuts" and Report on Plant Diseases No. 112, ''Loose Smut of Wheat," 

 for further details. These reports are available from the Department of Plant Path- 

 ology, 218 Mumford Hall, Urbana, Illinois 61801. 



A NOTE ABOUT THE USE OF VITAVAX 



Vitavax is cleared by the Environmental Protection Agency for use as a seed treatment 

 on registered and foundation wheat or barley, Uniroyal also has a label for the ex- 

 perimental use of this product, and up to 1,500 pounds of Vitavax can be applied this 

 year in Illinois. Since Vitavax is only effective against Basidiomycetous fungi (smuts), 

 it will probably be manufactured (formulated) to include some other protectant fungi- 

 cide, such as maneb , captan, or thiram to make it broad- spectrum in effectiveness. 



POWDERY MILDEW OF WHEAT 



Powdery mildew is now serious in some Illinois wheat fields, especially where the 

 stand is thick and nitrogen was applied in more than adequate amounts. Wide dif- 

 ferences in resistance and susceptibility are evident in variety- trial plots. Here 

 are some notes taken recently that you might find interesting. 



Because the powdery mildew fungus (Erysiphe graminis) is highly specialized into 

 numerous subspecies, physiologic races, or strains, the same variety of wheat may- 

 well react differently to mildew from one location to another. However, the hard 

 and soft wheats listed below gave very much the same reading in all replicate plots 

 at both agronomy test locations . 



Reaction of Winter Wheat Varieties to Infection by Powdery Mildew at Brownstown and 

 Urbana, Illinois [Data Recorded by Drs . CM. Brown and H. Jedlinski , May 22-23, 1972] 



Hard Wheats = == ~ Soft Wheats ~~ 



Variety Percent of infection^/ Variety Percent of infection!!/ 



Centurk 69 Arthur 



Gage 39 Arthur 71 



Ottawa 85 Benhur 62 



Parker 85 Blueboy 51 



Pawnee 91 Blueboy II 61 



Scout 66 56 Knox 62 78 



Triumph 64 57 Monon 87 



Timwin 52 



a/ Average percentage of the area of leaf surface covered by the growth of powdery 

 mildew fungus in three replicates at each location. 



CHLORO IPC 



Word came from the EPA on May 24 that they have received appeals from PPG Industries 

 and Uniroyal about some of their products containing Chloro IPC. It is our under- 

 standing that the filing of these appeals will permit the continued use of those prod- 

 ucts this season. 



OATS AFFECTED BY ATRAZINE RESIDUE 



There are a few reports of spring -seeded oats dying where atrazine was used on corn 

 in 1971. Remember that oats should not be seeded the year after atrazine has been 

 used alone or in combination with another herbicide. 



