220 



SCIENCE 



[N. S. Vol. XXVI. No. 659 



was noted on the seventeenth of June. At 

 this time the scale leaves at the points of 

 origin of the apples were slightly lifted. On 

 June 26, the young apples had increased in 

 size so that they could be easily dete^^ted with 

 the hand lens or even with the naked eye. 

 All apple trees and other possible hosts were 

 carefully examined and the rust spots showed 

 at that date nothing but the spermogonia. 

 They did not even show the characteristic 

 hypertrophy of the under surface which pre- 

 cedes the formation of the cluster-cups, and 

 the stage of development at present indicates 

 that no mature secidiospores will be formed 

 until near the middle of July. This apparent 

 retardation of the development over that of 

 last year is to be explained by the general 

 backwardness of vegetation due to the cold 

 spring. 



In addition to these observations I should 

 mention that some small cedars were enclosed 

 in glass houses during the spring of 1906. 

 These houses were ventilated by means of 

 windows provided with cotton screens to pre- 

 vent infection from the outside. The first 

 part of July they were examined and a few 

 cedar apples were found, the small number 

 being due presumably to the fact that condi- 

 tions in the houses were very unfavorable for 

 growth. 



Considering these observations here re- 

 corded, two explanations suggest themselves: 



1. The fung-us is either perennial in the 

 cedar, or 



2. The secidiospores of one season produce 

 the cedar apples which appear in June of the 

 next year and reach maturity in the autumn. 



We have some evidence of a perennial char- 

 acter, especially in trees that are badly in- 

 fected. '• In such eases it is quite easy to find 

 new apples growing out from the side of old 

 ones, or even from the middle of old ones. It 

 is, however, quite possible that such cases 

 represent new infections rather than the per- 

 sistence of an old mycelium. The second ex- 

 planation however seems more probable to the 

 writer. If this is true the cedar is probably 

 infected in the summer and autumn, but no 

 evidence of the resulting cedar apples can be 



noted until the nest season when growth has 

 been resumed. It would then require two 

 full years for a cedar apple to develop. It 

 remains for further observations to com- 

 pletely substantiate this view. 



F. D. Heald 

 Ageicultural Experiment Station, 

 Lincoln, Nebraska 



a blight disease of young conifers' 

 During the past spring there occurred in 

 the large conifer nursery at Halsey, Nebraska, 

 a very serious outbreak of " blight " of the 

 needles of two-year-old seedlings of Pinus 

 ponderosa and P. divaricata. The damage 

 was very considerable, there being several hun- 

 dred thousand of the trees affected. What is 

 of more moment than the actual damage sus- 

 tained, however, is the threatened danger to 

 the many nurseries of the country which are 

 engaged wholly or in part in the growing of 

 young conifers for reforesting purposes. The 

 present outbreak shows that the fungus 

 causing it is capable of very serious and ex- 

 tensive attacks wherever it may happen to be 

 present. The disease is characterized by a 

 gradual dying back of the needles from the tip 

 to the base. The fungus very evidently then 

 proceeds into the stem of the affected tree and 

 finally kills the entire plant. In the speci- 

 mens of diseased trees examined by the writer 

 no fungous fruiting bodies could at first be 

 detected; upon remaining in a moist chamber 

 for a few days abundant black pustules broke 

 out upon all of the dead tissues of the attacked 

 needles. These were found to be exuding 

 masses of- spores of a species of Pestalozzia. 

 The pustules occurred universally upon all 

 dead parts and no other organism thus accom- 

 panied the disease; it seemed apparent at 

 once that the Pestalozzia was closely connected 

 with the trouble. Pure cultures of the fungus 

 were made and then used in making inocula- 

 tions upon healthy seedlings of Pinus ponder- 

 osa in the greenhouse, which were about one 

 month old. The inoculations succeeded, 

 causing the typical disease in plants which 



' Published with permission of the Secretary of 

 Agriculture. 



