j ( ; IOWA AGRICULTURAL COLLEGE. [iu 



in the Bast. Recently I also noticed it in Northern Texas. In Missouri it 

 is common in the streets of cities, along railroads, and even growing in 

 woods. a 



The field Sow-Thistle (Sonchus ^rvensis, L.), which in one of our adjoin- 

 ing States, Wisconsin, has been recognized in the weed law, Is found in con- 

 siderable quantity along one of the great trunk linesentering Chicago. This 

 is a pest somewhat t<> be dreaded it' it should appear in Iowa, as it is a peren- 

 nial and is much harder to stamp out than the common Sow-Thistle (Sonchus 

 olearaceus, L.) In Chicago and near St. Louis I have seen one of the Pig- 

 weeds (Atriplex i><(inht, L. var. hastata) in large numbers. Mr. Hitchcock 

 has recently reported it from Iowa City. 



A great many more troublesome weeds could be added to this list, especially 

 such as are found in the streets, and along public highways-, but those may 

 be considered at some other time. It would be a great aid to the Botanical 

 Department if the farmers of the State would send in weeds of various kinds,, 

 giving their common names, and stating how troublesome they are. 



PLANT DISEASES. 



During the past summer some of the cherry and pear trees in the orchard 

 were seriously affected with fungous parasites. These diseases were espe- 

 cially troublesome in the new orchard set out by Captain Speer, of the experi- 

 ment station, and some of the seedlings in the nursery of the horticultural 

 department. 



These diseases were chosen as thesis work hy some of the special students 

 in the laboratory, and as some of the facts may be of interest I give abstracts 

 of their papers below.* The first paper was prepared by J. A. Kelsey. 



LEAF BLIGHT AND CRACKING OF THE TEAK. (EntomOSponium mdCUlatum, L.) 



That pear trees were attacked by some destructive agent other than the 

 common fire-blight has been a well known fact to botanists of Europe and 

 America for almost a century. The loss from this disease must amount to a 

 great many thousand dollars annually. Every year large numbers of seed- 

 lings are completely destroyed by this fungus, while older trees are fre- 

 quently defoliated by the 4th of July. This not only prevents the develop- 

 ment of the fruit during the same year, hut often destroys the prospect of a 

 crop the succeeding year, since it not unfrequently happens that a second 

 sel of Leaves and blossoms is put forth the same autumn. The value of the 

 fruit is greatly deteriorated if not completely destroyed by the unsightly 

 appearance or cracking which the malady produces. The bark is also 



attacked. SO that all parts of the tree except the roots are subject to more or 

 Less injury. The disease makes itself manifest in early spring. Many of the 

 leaves instead of retaining a uniformly green appearance are dotted with 

 small carmine-red spots, first appearing on the upper and Later on the Lower 

 surf ace of the leaf . The carmine-red color soon changes to a dull brown. 



During the early Stages the fungus remains hidden beneath the cuticle of the 

 leaf, but later it is ruptured and exposes to the surface a countless number 



•in these abstracts it is not Intended to give referenoea to the valuable papers 

 w blob have been published on the subjects t reated, but rat her t<> some facts about a 

 r. w oommoii and troublesome diseases. 



