8 BULLETIN 360, U. S. DEPARTMENT OF AGRICULTURE. 
TaBLE III.—Jnoculation of Razoumofskya campylopoda on Pinus ponderosa, 
made in November, 1911. 
[x=Inoculation effective; 0=inoculation not effective. ] 
Seeds | Results in November, 1914, on branch— 
: sown on 
Age of part of branch tested. | paren 
ternode. | No. 1.-| No. 2. | No. 3. | No. 4. | No. 5. 
SERROWHS RONAN saebe capkboseoaseelSoocceuccécescse 10 Xx x x 0 0 
WNVG2i ro ac eset sce Saonseoncaeseecsoseodeonsescagcconce= 10 0 0 x x 0 
DO WiCAIS nies eee occ cowie Bes ene ce siete eee 10 0 0 0) 0 ox: 
OVCATS 4720 ae oie fate S len eee es eee 10 0 0 0 0 0 
LNA NES SO = 8 no See 25 Pe AES Hoel oa Rah in as 5 10 0 0 0 0 0 
Sy ViGATS MRE Ss ve ee eh 2 Se ere ies Se ere 10 0 0) 0 0 0 
GV COLTS ee eta te eee 2 SR a Arete ee Ca 10 0 0 0 0 0 
d FORTS ee rs ee ee es Se eo ar ee ee 10 0 0 0 0 0 
O  ViCA TS ie Fa oes meer hee a pe ene ge eta ine Jue ag a 10 0 0 0 0 0 
QO! Vears oo ase oe ey ee ae ee ela ee 10 0 0 0 0 0 
ORCAS eee ee ee ee 10 0 0 0 0 0 
A study of Table III shows that the branches were infected in 
three out of the five test cases on the youngest and last internode on 
which the seeds were placed. Infection occurred on two of the five 
tested branches on that part 1 year old at the time of sowing, one 
infection only being on the 2-year-old portion. Infection did not 
take place on the older parts of the branches. A tree never be- 
comes too old for infection to occur on its youngest branches. Sup- 
pressed trees may escape, owing to the fact that slowness of growth 
and more rapid formation of thick bark lessens the chance of infec- 
tion; also shortness of twig growth gives less opportunity. The 
demand for a fair amount of light is also a factor in such a case, 
not, however, for the stages of germination and penetration of the 
primary root, but for the subsequent development of the aerial parts. 
Mature trees becoming infected on tender branches may not suffer 
any appreciable injury, but in time the decline of the tree is surely 
hastened, since the gradually increasing hypertrophy of the branches, 
the breakages, and the thinning out of the foliage of the tree as a 
whole cause it to be greatly weakened. Almost always the result of 
a heavy infection on the trunk and branches of some conifers is the 
death of the upper portion of the crown,’ causing staghead (fig. 6), 
1 The dying back of the crown of trees, commonly known as spiketop, or staghead, is 
attributed to various causes; as many, in fact, as the varied conditions under which trees 
grow. One of the most common theories is that on opening up a stand the admission of 
light to the trunk and lower crown deflects the transpiration current to the older brane’ 
orders or, as with some species, promotes the formation of a secondary crown on the 
main trunk. This stimulated foliar activity below reduces the water supply at the top 
of the crown; consequently the topmost branches die back. This is exactly what happens 
in the case of mistletoes. The extra crown development below, by brooming, starves out 
the crown above, resulting in its death. Mitinch (Silva, December, 1911, pp. 415-416) 
claims to have found a parasitic Ascomycete which causes staghead in the oak of Europe 
by attacking the bark and outer wood of the main shoots. The writer has found a 
wood-destroying fungus which attacks the upper crown branches of the chestnut in 
southern Indiana and causes their death. The ‘“ pencil rot,’ which seems to be fre- 
quently the cause of staghead in the western red cedar, is another example of fungi at- 
tacking the crown of trees. Lightning is.a common cause of staghead; also injury by 
insects. 
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