452 EXPERIMENT STATION RECORD. 



brought to the hiboratory in 1!X)T that were covered with numerous black 

 Itustules. A uiieroscoiJical examiuation of the material sh<nved that the spores 

 were those which characterize the geuus Pestalozzia, and further studies indi- 

 cated that the species was P. uvicola, of which no record of occurrence in 

 America had been previously reported. 



Arsenical poisoning of fruit trees, W. P. Headden {Colorado Sta. Bui. J.il, 

 pp. 3-27, pis. 7). — The author was called upon to investigate some shade and 

 ornamental trees, the bad condition of which was claimed to be due to arsenic 

 and lead. Subsequently other investigations were carried on to determine 

 whether the arsenic used so extensively as calcic arsenite and lead arsenate 

 for the control of insect pests is responsible for the rapid destruction of trees 

 in a number of the principal fruit districts of the State. 



The author made analyses of soils, different parts of trees, etc., and in 

 samples of trees he found present from 1.25 to 12,77 parts of arsenic per 

 million of woody tissue. While the arsenic is generally in an insoluble form, 

 soluble arsenic was found present in the soil in amounts that are believed 

 dangerous to the life of the tree. 



In addition to arsenical poisoning, the author discusses briefly lead poisoning 

 and the effect of lime, which in some regions seems to have an unquestionably 

 injurious influence on the trees. In one instance, where the sap had exuded 

 from the tree and dried, he found that the air-dry material contained 24.1)3 

 per cent of lime. 



In conclusion, the author states that there are a large number of fruit trees 

 in the State suffering from an affection of the trunk and root, the trouble 

 beginning in the greater number of cases at the crown of the tree and subse- 

 (juently involving both trunk and roots. The first marked symptom is an early 

 ripening of the foliage, usually followed by the death of the tree about mid- 

 summer of the ensuing year. The crown of the tree is found to be girdled, the 

 bark on portions of the trunk dead and sunken, and most of the roots dead, 

 the bark destroyed, and the woody tissue discolored. Experiments showed that 

 soluble arsenical compounds will effect the destruction of the bark, the staining 

 of the wood, the production of the so-called blackheart, and the speedy death 

 of the tree. 



Arsenical poisons have been extensively used in the orchards under investiga- 

 tion and these compounds have accumulated in the soil. While the accumula- 

 tion of arsenic in the soil is usually in an insoluble form, it has probably passed 

 beyond the limit of danger in a soluble form, the alkalis, such as sodium car- 

 bonate, sodium sulphate, and sodium chlorid rendering the arsenic soluble. 

 The lime salts do not appear to protect effectively the arsenical compounds 

 from the solvent action of the alkalis. It is thought that systematic poisoning 

 may take place, and probably does, by the absorption of the arsenic with the 

 nutritive solutions taken up by the feeding roots, but the greater portion of the 

 trouble appears to be due to local irritant poisoning. 



The arsenic in the arsenate of lime is more readily brought into solution than 

 that of the lead arsenate. Arsenical poisoning it is believed is in many cases 

 ccmiplicated by lime poisoning, the lime or marl in the soil and subsoil acting 

 conjointly with the arsenic in producing some of the injury. 



The Fusicladium disease of the pear and apple, C. P. Lounsbury (Agr. Jour. 

 Cape Good Hope, 33 {1908), No. 1, pp. 16-32, figs. 10). — An account is given of 

 the disease of apples and pears known in this country as apple and pear scab, 

 due to Fusieladimii dendritieum and 7^. pyrinuni. Both these diseases have 

 made their appearance in South Africa and are causing considerable injury. 

 The effect of the fungus on the host plants and the conditions which favor the 

 spread of the disease are described, and suggestions given for pi-eveuting the 



