S36 IOWA DEPARTMENT OF AGRICULTURE 



FUNGUS DISEASES IN IOWA FOR THE YEAR 1013 



BY L. H. PAMMKL AND CHABLOTTE M. KING. 



For nearly a quarter of a century observations have been made here 

 at Ames, on fungus diseases of plants. The notes thus gathered have 

 been published at various times in reports of the State Horticultural 

 Society, proceedings of the Society for the Promotion of Agricultural 

 Science, the Iowa Academy of Science, etc. In volume 16 of the Iowa 

 Academy* the data for a number of years was brought together. In 

 the report of the Iowa State Horticultural Society** for 1912 weather 

 maps were published to show the influence of temperature and moisture 

 on the development of fungus diseases. It has been shown by Melhus*** 

 that temperature has a marked influence on the germination of spores 

 in white rusts. The effect of cloudy weather and precipitation during 

 the month of April this year had a marked influence on the spread 

 and infection of lettuce mildew (Brernia). The dry weather during 

 the past season especially at the time when oats and wheat were head- 

 ing out, checked the spread of grain rusit. On the other hand, smut 

 of oats will germinate under conditions favorable for the germination 

 of oats. The record of oats smut in this state during the present season 

 shows that the loss was not far from $6,000,000. This is a disease which 

 can largely be prevented. 



The growing season of 1913 started in with splendid prospects for a 

 large crop of grain and fruit. The soil was in excellent condition, there 

 was enough moisture to insure a good hay and grass crop. However, 

 cold and wet weather when small grain was sown made the stand of 

 oats very unequal. This was shown in the yield of oats in some fields 

 where it was sown early, the yield was good but where the oats was 

 sown during the cold, wet weather the straw was short with a low yield. 



Mr. Chappel of the Iowa Weather and Crop Service reported on April 

 20th that- "Nearly a full week of bright sunshine with practically no 

 rain has started growth of all vegetation, put the ground in fairly good 

 condition, and enabled farmers to do a great amount of field work." 

 The bulk of the oats, was in by the end of the week ending May 4th. 

 This indicated that it was too cool for normal growth of the vegetation. 

 There was a heavy frost on April 28tli. The week ending May 11th showed 

 cold and wet weather in many parts of tlio state. The week ending 

 .lune 22d showed excessively high temperature and bright sunshine with 

 showers in many parts of the state on Friday of that week. Tne crop 

 indications on .Tune 29th were: High temperatures, bright sunshine, the 

 straw and heads of oats were short. 



••Proc. la. Acad, of Sci. 16:41. Oontr. Bot. Dept., I. S. O. No. 41. 

 ••Kept. la. State Hort. See. 47:180. 

 »»*iPhytopathology, 2:197'. 



