COMrARATIVE GROWTH OF BRANCHES AND LEAF BUDS. 98 



or uii av(M-!ii,a' of over ;>:'. iiiohos for tho V\ shoots. That this astonish- 

 ing- pushing of now basal buds was not duo to injury of tho top ])v the 

 spray was shown ])y tho inuuonso amount of dark groen foliage tho 

 sprayed half of the tree produced and from tho amount and perfec- 

 tion of the fruit it bore. It was evidently an aided or stinuilatod basal 

 growth. In ta))le 1) is shown the comparative health or disease of 

 the spring wood measured. Where shoots had suttered from disease 

 to such an extent that they wore enlarged, crooked, or otherwise dis- 

 torted or injured ])y the disease, they were classed as diseased; when 

 not so injured, they were classed as healthy. In respect to this classi- 

 fication the table gives the following facts: On the unsprayed trees the 

 new shoots measured on growth of 18!>4 or older amounted to 10,599 

 inches, of which 6.703 inches was of healthy wood and 3,896 inches 

 of diseased wood, or, in other words, 63 per cent of the wood was 

 healthy and 37 per cent diseased. On tlie spiayed trees the total 

 length of new shoots measured on 1S'.I4 growth or older was 17,045 

 inches; of this, 16,988 inches was of healthy wood and only 47 inches 

 of diseased wood, or Wi per cent was lu'althy and ^ per cent diseased.^ 

 ^lany peach orchards are cultivated under conditions of moisture and 

 nourishment that enable the trees to grow throughout the entire sum- 

 mer. In such situations trees badly diseased in the spring are apt to 

 so far recover before frost that there is little apparent difierence between 

 them and the trees saved from curl by the use of sprays. That this 

 recovery is not entire, however, is shown by actual comparisons. In the 

 Riviera orchard. Live Oak, Cal. , were obtained the following records, in 

 February, 1894, f ron 10 sprayed and 10 unsprayed Crawf ords Late peach 

 trees. The trees are fully described under the following heading of this 



' These comparative records of the length of healthy and di.sea.sed branches upon 

 sprayed and unsprayed trees fully serve the i)urpose of comparison for which they 

 are here intended. There is another pha.«e of the matter, however, which .should 

 not be overlooked or misunderstood at this time. A branch classed as diseased does 

 not mean that it was disea.sed or swollen throughout its entire length, but that 

 external signs of a diseased or injured condition were noted at some point in its 

 course. If it be supposed that one-third of the injuries noted were dead ends or 

 other imperfections not due to the infecting of the branch by the fungus, but indi- 

 rect injuries arising from the loss of foliage, there remain two-thirds of the injuries 

 which may be properly assumed to be due to the infection of branches by means of 

 mycelium coming from diseased leaves. There would then appear to be 25 per cent 

 of the cases which might be classed as diseased from mycelium infection. As already 

 indicated, however, this does not mean that these branches are infected throughout 

 their entire length, but show one or more points of infection at the buds. It is 

 thought by the writer that not more than 1 bud in 10 is actually infected in these 

 diseavsed branches. If this estimate is approximately correct, the number of infected 

 buds on the unsprayed trees would be represented by one-tenth of 25 per cent, or 2.5 

 per cent of the buds on the tree. In brief, it is believed that it is rare for more than 

 3 per cent of the buds of a badly diseased tree to become infected by the mycelium 

 from diseased leaves — in other words, that rarely more than this percentage of buds 

 of one year carry a perennial mycelium to the next spring. 



