IOMarlh, 1916.] 



The Wdlnut. 



15; 



dying and drying up after their work is done. Various attempts have 

 been made to obtain the blight organism from these darkened catkins, 

 but without success. 



Blossom End Infection.— While the nuts may be infected at any point 

 in the surface, by far the most common, as well as most, virulent form of 

 infection is at the blossom end, near what is technicallv called the stigma. 

 This is the weakest part of the nut, and is especially sensitive to the 

 blight. The bacteriosis is very bad on the small nuts, and when once 

 it has started at this point it rapidly continues its growth within the 

 tissue, until the small nut is sufficiently weakened to fall. 'Not all the 

 infected nuts fall when they are small, but some remain on even until 

 harvest time. In the nuts the disease gradually grows within the tissue 

 until the kernel is reached, which at length becomes blackened anrl then 

 destroyed. The disease may start at any place on the nut, and gradually 



Fig. 33. 



-Developing walnuts attacked by bacteriosis- 

 distrlct, 1913. 



-Bright 



extend through other tissues into the kernel, but by far the most of the 

 infections that injure the kernels are fi'om the blossom end. (Plate 33.) 

 Lateral Nut Infection. — The disease on the nuts starts at one or 

 more points on the surface as a small, circular, raised, discoloured area 

 that at first has a water-soaked appearance, and may not be larger than 

 the point or head of a pin when first visible. The diseased area in its 

 earliest stages is slightly raised above the surrounding healtliy tissue, 

 but as the disease progresses the spot becomes more or less sunken below 

 tlir normal tissue. The spot gradually enlarges in size, and becomes 

 black iu ap])earaiice. Surrounding tlie l)lM<'kcned area is a paler zone, 

 having tlu; same water-soaked ajjpcarancc already referred to. This 

 band of tissue lies between the healthv ti-;-^nc and the blackencil aren, and 

 represent the cells of tlie tissue that ai-(> being acted U]ion by tlie 

 ferments secreted by the organism, whidi break down tlic tissue and 



