Jan. 21 191 8 Irrigation Experiments on Apple-Spot Diseases 131 



pies became very badly shriveled and wrinkled (PI. 5, C), and Jonathan 

 and Delicious apples showed slightly less serious effects; but with the 

 return of irrigation water all of these regained their turgor without spot- 

 ting. The Winesap and Stayman Winesap apples did not become as 

 badly shriveled as the White Pearmain, but they developed typical 

 drouthspots before they became shriveled. It was also observed that 

 the oozing of the fruit sap, as well as the spotting of the fruit, preceded 

 the renewal of irrigation. The apples subjected to the early drouth were 

 also involved in the later ones, and the result was a series of spots on the 

 same apples that could be distinguished as to time of formation by the 

 color of the skin and the depth of the pitting. 



On September 3 samples of fruit were obtained from the Jonathan 

 trees that had suffered most severely from drouth, and on October 13 

 similar samples were secured from the Winesap, Stayman Winesap, and 

 White Pearmain trees. All of the apples were placed in cellar storage 

 until January 13 and were then cut open and examined. The Jonathan 

 and White Pearmain apples had developed no spots, but their flavor was 

 decidedly poor. With the Winesap and Stayman Winesap apples the 

 spots had not enlarged, and there was but little brown tissue beneath 

 the skin (PI. 3, F). The flavor of the affected tissue was bitter and 

 acrid, but that of the rest of the apple was normal. 



The above trees that had suffered from drouth appeared to recover 

 largely before the close of the season and their leaves came out normally 

 the following spring; but a number of them died a few months later, and 

 the remainder showed a lack of vigor throughout the summer. Their 

 foliage was thin and they appeared to suffer from drouth even with a 

 slight decrease in the percentage of soil moisture. The usual number of 

 irrigations were made, and there were no real drouth periods; yet more 

 than half of the apples on some of the Winesap and Stayman Winesap 

 trees developed typical drouthspots. The weak condition of these trees 

 and the death of others earlier in the summer probably resulted from the 

 destruction of some of the smaller roots during the drouth of the preced- 

 ing season. 



CORK 



The disease or group of diseases called "cork" may be similar to 

 drouthspot in cause, but is distinctly different in many of its gross char- 

 acteristics. Instead of being subepidermal, the spots are located in the 

 pulp of the apple, often quite deeply seated and often closely associated 

 with the larger vascular bundles (PI. 5, B). The patches of dead, brown 

 tissue are usually much larger than in the case of bitter-pit and much 

 deeper than in drouthspot. They resemble the internal browning of the 

 former disease, but are firmer in texture, more corky, and less spongy. 

 Affected apples are often slightly less firm than others, and usually have 

 a cheesy consistency when cut. When the spotting occurs near the core 



