DISEASES OF PLANTS. 55 



management in handling tlae plants may have something to do with their 

 susceptibility. The Fusarium trouble at present is believed to be incidental, 

 attacking the weakened stems at the surface of the ground. Experiments 

 are under way for methods of control of this disease. 



A spinach disease new to Massachusetts, H. M. Jennison (Massachusetts 

 Sta. Rot. J910, pt. i, pp. l-'i6-L'i8, pi. 1). — A description is given of a disease 

 of spinach which has appeared in Massachusetts, a more extended account by 

 Reed of the disease as it occurs in Virginia having been given elsewhere 

 (E. S. R., 25, p. 846). 



The trouble is due to the fungus Heterosporiuin variabile, and at Amherst 

 it was found infecting winter spinach, growing on two widely separated lots. 

 A careful examination failed to reveal any indications of the disease on young 

 plants, and this seems to indicate that the fungus is not a true parasite but 

 is able to infect old plants or those which have been injured in various ways. 



No extended investigations have been made, but tlie author believes that the 

 use of seed from healthy and vigorovis plants, prevention of injury, and the 

 application of better methods of cultivation would tend to the control of this 

 disease. 



Some diseases of apples and pears in 1910, F. C. Stewart (West. N. Y. 

 Hort. Soc. Proc, 56 {191 1), pp. 61-65). — The author discusses oedema of pear 

 trees in nursery storehouses, failure of pear grafts, powdery mildew of the 

 apple, trunk injury from veneer tree protectors, pruning apple trees affected 

 with canker, russeting, spray injuiy, and keeping quality of apples. The first 

 4 topics have been previously noted from another source (E. S. R., 24, p. 549). 



The author does not believe that apple trees should be unduly pruned to 

 rid them of apple cankers, as thei*e will always remain a sufBcient number of 

 spores clinging to the limbs and larger branches, and overlooked small cankers, 

 to thoroughly reinfect the trees. He believes that keeping the trees in a 

 vigorous condition by good cultivation and regular thorough spraying is the 

 best method of control. 



Bitter pit in apples, Jean White {Reprint from Proc. Roy. Soc. Victoria, 

 11. ser., 24 (1911), No. 1, pp. 19, pis. 9). — The author gives the results of her 

 investigations and experiments on the cause of bitter pit of apples, and 

 reaches the conclusion that the disease is the direct result of spraying the 

 fruits with poisonous liquids. 



In an orchard under observation one part was sprayed with lead arsenate 

 just after the petals had fallen, while another portion was left unsprayed. 

 A.pples from the sprayed plat showed bitter pit, while those from the un- 

 sprayed portion were free from this disease. It is claimed that the poison 

 enters the stoma or lenticel and is carried through the intercellular canals. 

 where it penetrates into the interior of one of the cells. All the cells in the 

 young fruit, being meristematic, are in process of extremely rapid growth, 

 and the cells surrounding that containing the poison divide actively on all 

 sides, thus leaving the poison in the interior of the fruit without any apparent 

 connection with the exterior. 



Water core of apple, J. B. S. Norton {Phytopathology, 1 {1911), No. ^, pp. 

 126-12S). — From a historical study of the diseased fruit and from the conditions 

 affecting the diseased trees the author holds that water core of the apple is 

 probably due to sap forced into the seed cavities and intercellular spaces by 

 excessive sap pressure under conditions of reduce<i transpiration. 



Peach and plum troubles, R. D. Whitmarsh {Massachusetts Sta. Rpt. 1910, 

 pt. 1, pp. 161-116, pis. 2). — Notes are given on a number of diseases of the 

 peach and plum, among them brown rot, scab, leaf curl, and black knot, and 



