MYCOLOGICAL SECTION. 129 



a more radical metliod has been found serviceable, which, is to cut 

 off the whole top to within a foot or two of the ground. It can be 

 practiced to advantage upon trees that are as much as ten years old, 

 or even older. 



GRASS FUNGI. 



The grasses are especially subject to the attacks of fungi, every 

 part — the stem, leaves, flowers, and grain — being exj^osed to their rav- 

 ages. They are the prey to members of nearly every order of the 

 class of fungi, but those of the Ustilaginece — the " sm.ut "-producing 

 Species — are the most destructive of all. Ergot, produced in the flow- 

 ers of many grasses valued for hay or forage, is caused by a pyreno- 

 mycetous fungus {Claviceps purpurea). This is the most notable 

 among the grass fungi on account of its effect upon stock that may 

 feed upon hay affected with it. 



All these fungi that do more or less injury to our grass crop are 

 of interest to the farmer and stock raiser, and as material can be 

 collected and observations made they will be severally treated. 



Last year Prof. William Trelease, of the Shaw School of Bot- 

 any, furnished for this division a report on the "smut of timothy," 

 which was published in the annual for 1885. This year, at my re- 

 quest, he has very kindly contributed an original paper on the leaf- 

 spot disease of orchard grass. 



A SPOT DISEASE OF ORCHARD GRASS. 



Scolecotrichum graminis Fckl. 



(Plate VIII.) 



By William Trelease. 



The drought at Madison, Wis., and through the West generally, 

 was extreme in the summer of 1886. For months there was not a 

 shower sufficiently heavy to wet the ground. Pastures parched up so 

 as to appear completely dead. Lawns were kept green only by daily 

 sprinkling, and even then there was no use for the lawn-mower. In 

 the latter part of August an abundance of rain fell, enough, indeed, 

 to bring the average for the summer up to the normal amount. Stim- 

 ulated by this, and the prevalent warmth, grasses of all descriptions 

 made a rapid growth, even the browned turf starting into vigorous 

 vegetation. 



Soon after this change, when the basal leaves of orchard grass 

 {Dactylis glomerata) had reached their full length, my attention was 

 attracted by a very abundant discoloration of this species, sometimes 

 confined to the extremity of the leaves, sometimes extending nearly! 

 to their base. So far as my observations went nearly every stool of^ 

 orchard grass was affected. j 



The characteristic appearance of the diseased leaves is shown in Fig. 

 1. Plate VIII. Elongated dark-brown or purjilish-brown spots, visi- 

 ble on both surfaces of the leaf, api)eared in greater or less profusion. • 

 Frequently, and as a rule when old, these spots were gray or whitish 

 at the center, where they were marked by very minute black dots, 

 barely visible to the naked eye, that occurred, in more or less regular 

 rows, parallel to the nerves of the leaf. The tips of leaves that had 

 been diseased for some time were dead and brown, but paler than the 

 9 AG— '86 



