PEACH SCAB AND ITS CONTEOL. 23 



from the mouth of the flask to the surface of the fruit. In many cases fruits can be 

 found so situated that the neck of the flask may be firmly attached to the twig and 

 swaying rendered impossible. 



METHOD OF INOCTJLATION. 



The metliod employed in the fruit-moculation experiments of 1913, 

 in all essentials applicable to all the fruit-inoculation work, is briefly 

 described as follows : 



All inoculation work of the season of 1913 was conducted in the orchard of Mr. I. C. 

 Wade, Cornelia, Ga. The trees used were 8-year-old Elbertas, located on a sandy 

 clay soil, with good air and surface drainage and a western exposure. On account of 

 the freeze of March 29 the crop was very short. This part of the orchard was, conse- 

 quently, unsprayed. 



The experimental fruits were carefully selected and bagged on May 8, about three 

 weeks after the falling of the calyces. The bags were of heavy manila paper, but they 

 were replaced after a few days by the glassine bags, which had been delayed in ship- 

 ment. The bagging was planned for an earlier date, but was delayed, pending the 

 arrival of the glassine bags, as long as outdoor conditions seemed to render protection 

 from natural infection unnecessary. The three weeks preceding May 8 were unu- 

 sually favorable in this respect, comprising a period of unbroken drought except for a 

 very slight shower on April 26 and another on April 27, both of which were followed by 

 brisk winds which rapidly dried the trees. Furthermore, microscopic examinations 

 of scab lesions on twigs from the field showed practically no production of conidia dur- 

 ing this period. Thus any considerable natural infection of the experimental fruits 

 prior to bagging was not considered feasible. The correctness of this assumption was 

 clearly demonstrated in the com'se of the experiments, as will be set forth later. 



The inoculations were made on noted oval areas about 3 cm. horizontally by 2 cm. 

 vertically on the exposed and on the protected equatorial surfaces of the fruits. The 

 spores were applied in suspension in sterile water or in nutrient solutions by means 

 of sterile De Vilbiss atomizers. The sm-faces inoculated, being highly resistant to 

 wetting, were gently tapped with a finger, in order to facilitate the penetration of the 

 spore-bearing liquid through the thatch of hairs to the epidermal cells. The hands 

 were washed and rinsed in sterile distilled water prior to the application of each spo- 

 riferous suspension, and due precautions were, of course, observed throughout the 

 operations to prevent mixing the sources of inoculation. As soon as each inoculation 

 was made, a moisture apparatus of the type previously described was attached in such 

 fashion as to maintain a moist zone approximately 2 cm. wide about the equatorial 

 region of the peach. The bag was then replaced. 



All apparatus used was thoroughly clean, and all glassware and metal ware was 

 sterilized. " 



The watering apparatus, which functioned for about four days after filling, waa 

 refilled at noted intervals, which varied with the different series. 



Throughout the season the inoculations were noted at intervals of about one week. 



In certain cases bags were torn. The facts were noted and new bags were put on. 

 There was no evidence of the entrance of infection in any such case. In the light of 

 life-history studies outlined later, this is not smprising, since the rents always occurred 

 in such position that an unbroken thatch covered the fruit and prevented access 

 of water-borne spores. 



All inoculations were made in triplicate unless otherwise noted, and germination 

 tests were made with drops of each sporiferous suspension used. 



REPORT or A TYPICAL EXPERIMENT. 



As illustrative of the fruit-inoculation experiments, one typical 

 series planned for securing final evidence regarding the pathogenicity 



