450 EXPEEIMENT STATION KECOED. 



life history of the citrus root parasite Tyleuchulus semipenetrans. presiously 

 described (E. S. R., 30, p. 648.) 



This nematode was first noted in California (E. S. R., 28, p. 850). The 

 author, from material received from many of the citrus-producing countries, 

 has found that this organism Is widely spread and that it seems to be con- 

 fined to plants belonging to the citrus family. It is believed that T. semipene- 

 trans is an injurious parasite that kills the feeding roots of citrus trees, the 

 extent of the damage varying in different regions and under different condi- 

 tions. In the progress of the life history studies it was discovered that hot 

 water was fatal to the nematode and that citrus roots would survive tempera- 

 tures required to kill it. This fact, it is thought, would indicate that a hot 

 water treatment may prove more or less efficient in controlling the spread of 

 the pest. 



The poor nitrifying power of soils a possible cause of die-back (exan- 

 thema) in lemons, C. B. Lipman (Science, n. ser., 39 (1914), No. 1011, pp. 

 728-730). — A preliminary account is given of observations and experiments 

 made on several citrus soils, in which were trees affected with die-back. 



The author is led to believe from his investigations that a poor nitrifying 

 power on the part of the soil, with the ammonifying power remaining normal, 

 may be the cause of the peculiar manifestations which are characteristic of 

 the disease. Samples of these soils were examined, and in every case found 

 to have a vei"y slight nitrifying power or none at all. When dried blood or 

 sulphate of ammonia was added to them there was only a slight increase or 

 none of nitrates, while the ammoniflcation proceeded very rapidly. The au- 

 thor believes, and his hypothesis is confirmed by results given by Florida in- 

 vestigators (E. S. R., 23, p. 447) relative to the increased amount of die-back 

 where organic manures were used in citrus groves, that not only die-back 

 is to be accounted for in this way. but that the equally destructive and much 

 more widely spread di.sease, mottled leaf, is capable of being explained in a 

 similar manner. 



Pellicularia koleroga on coffee in Porto Rico, G. L. Fawcett (U. 8. Dept. 

 Agr., Jour. Affr. Research. 2 {191^), No. 3, pp. 231-233, figs. 3).— As the result 

 of a study of the leaf blight of coffee in Porto Rico, the author has concluded 

 that it is due to the fungus P. koleroga. originally described from India, but 

 which, it has been claimed by mycologists, does not occur in Porto Rico. In 

 connection with this investigation a study was made of a disease known as 

 candelillo in Venezuela. This disease has been formerly identified as being 

 caused by P. koleroga, but the author believes it is not due to that fungus. 



A destructive nematode introduced into the United States, L. P. Btabs 

 (Abs. in Phytopathology. 4 (1914), No. 1, pp. 45, 46). — The author reports 

 observing in hyacinths, in the bulb garden of the I^. S. Department of Agri- 

 culture at Bellingham. Wash., the nematode TyJenchus dipsaci. This nematode 

 not only attacks the bulbs but also the aerial portion of its host, abandoning 

 the leaves toward the end of the season and returning to the bulb. The infec- 

 tion is said to be readily carried by the bulbs, and on account of the destructive 

 nature of the parasite it is considered important to eradicate any bulbs that 

 may be found infected and to make rigid inspection of all imported hyacinth 

 bulbs. 



Spheeropsis canker of Quercus prinus, W. H. Rankin (Ahs. in Phyto- 

 pathology, 4 (1914), No. 1, pp. 44, 45). — This disease of chestnut oaks is said 

 to have been very prevalent at Yonkers, N. Y., in July, 1912. The foliage was 

 destroyed, and on the older limbs numerous cankers were found. Isolations 

 were made of the above fungus, and inoculations produced cankers in 47 days. 

 The organism agrees morphologically with the description of S. vialorum. and 



