366 



SCIENCE 



[N. S. Vol. XLIII. No. 1106 



andinus Lagh. causing the formation of large 

 galls. These usually occur just above the ground, 

 but it is often the case that they may also occur 

 higher up on the stem, as much as two feet above 

 the galls, which are located near the roots. Both 

 kinds of galls have essentially the same histolog- 

 ica,l structure. In the deeper portions of the galls, 

 near the pith where infection evidently starts, pe- 

 culiar tissue-strands are formed which are similar 

 in some respects to the tumor strands which have 

 been found in the stems of certain plants infected 

 with the crown-gall organism, Psendomonas tume- 

 faoiens. The strands consist of whorl-like ar- 

 rangements of thin-walled cambiform cells which 

 usually enclose groups of sporanges of the fungus. 

 Short tra,cheids sometimes accompany the strands. 

 The strands may occur singly or in groups, and 

 usually run in a vertical direction. They have been 

 found both in the galls located near the ground 

 an^ in those higher up on the stem, but there is 

 no indication of them in the normal part of the 

 stem between two such galls. They are purely 

 local and have no relation one gall with another. 

 The fact that abnormalities in the tissues of the 

 host plant are to be found in or nearly to the pith 

 in the infected parts, indicates that the stems be- 

 come infected while they are still quite young, 

 probably before secondary thickening starts. This 

 offers a possible explanation as to how the upper 

 galls on the stems come about. In the young 

 seedling plant there are a number of short inter- 

 nodes formed near the ground which lengthen out 

 by subsequent growth. If the lower internodes 

 should become infected at this time the infected 

 parts would probably be carried up later by the 

 lengthening of the stem. 



Anthracnose (Colletotrichum lagenarium (Pass.) 

 E. and S.) a Serious Disease of Cucurbits 

 (preliminary report) : J. J. Tatjbenhads. 

 Watermelons, cantaloups and cucumbers are im- 

 portant crops in" the trucking districts of Dela- 

 ware. Of late growers are experiencing great 

 difficulty in raising these cucurbits, especially 

 watermelons. Conditions are similar in neighbor- 

 ing states of New Jersey, Maryland and Virginia. 

 Investigations on cucurbit diseases undertaken at 

 Delaware have shown that the difficulties men- 

 tioned are occasioned by several diseases. One of 

 the chief causes of failure of watermelons in Dela- 

 ware and vicinity is the anthracnose disease. The 

 latter causes a deep spotting on the rind of the 

 fruit impairing its shipping quality. The disease, 

 too, is the cause of a serious leaf spot, and a blight 



and canker of the vines. The attacks are severest 

 on the watermelon crop in its second successive 

 year. For this reason growers are forced to prac- 

 tise a rotation of six years or longer. Colleto- 

 trichum lagenarium also causes a serious leaf and 

 fruit disease of cucumbers and citrons, the latter 

 of which are usually considered the most immune 

 of all cucurbit plants. It also attacks the fruits 

 of cantaloups and the ornamental gourd. Pump- 

 kins and squashes seem to be free from the at- 

 tacks of the fungus. Cultures of Colletotrichum 

 lagenarium from all the cucurbitaceous hosts men- 

 tioned are very easy to obtain. Cross inoculations 

 with pure cultures have shown that the anthrac- 

 nose from watermelons, cantaloups, cucumbers, cit- 

 rons and ornamental gourd are all one and the 

 same ; the disease may be readily transferred from 

 one to the other. Investigations are now under 

 way to determine the life history of Colletotrichum 

 lagenarium, its relationship to the various hosts 

 and to other species of CoUetotrichums, especially 

 C. lindemuthianum, and methods of control. Be- 

 sides anthracnose there are two other apparently 

 new diseases of the watermelon which are being 

 investigated. 



Fungi producing the Eeart-rot of the Apple: B. 



O. Dodge. 



Polyporus admirabilis Peek was found on many 

 living apple trees at Litchfield, Conn., during the 

 month of August. The fruit bodies were growing 

 singly or in clusters. Individual sporophores vary 

 in size from ten to forty centimeters in diameter. 

 The heart-wood is first attacked and the fungus 

 gradually encroaches on the sap-wood until the 

 limbs and trunk are weakened to such an extent 

 that they are broken down during wind-storms. 

 Apple trees of the east are more commonly at- 

 tacked by another type of polypore. These are 

 the white bracket forms frequently found on the 

 inside of hollow trees near knotholes. When grow- 

 ing on the outside of a tree the mycelium pene- 

 trates the sap-wood up and down for some dis- 

 tance so that the base of the trunk may bear a 

 large number of imbricated sporophores. This 

 type of fungus belongs to the Spongipellis group. 

 Polyporus galactinus, or Polyporus spumeus var. 

 malicola is the species found in the old apple 

 orchards of the New England states. The form 

 attacking the apple tree in Virginia, identified as 

 Polyporus fissilis, is very near to P. galactinus, 

 but it has larger pores and thicker flesh. 



H. H. Babtlett, 



Secretary 



