206 MASS. EXPERIMENT STATION BULLETIN 280 



Monograph of the Genus Pestalofia. (E. F. Guba, Waltham). This in- 

 teresting but taxononiically difficult group of fungi has been the subject of 

 critical study for several years. Part I, published in 1929, embraced a study of 

 46 species of which 30 were found to be distinct. Part II, of which manuscript 

 for publication is now complete, embraces a study of 52 described species of which 

 38 are distinct. A key to 68 species is appended. 



In general the species are saprophytes or very weak parasites, capable of 

 infecting their suscepts only through injuries. In the absence of biologic studies, 

 no importance can be attached to published reports crediting species of Pestalotia 

 as being true parasites. 



Forcing Gladiolus with the Aid of Artificial Light. (L. H. Jones). 

 Four greenhouse plots were planted with Crimson Glow gladiolus on September 

 6, 1930. The corms had been in cold storage since the previous March and 

 germinated perfectly. They were planted 6 inches apart each way with a total 

 of 70 corms in each plot. Two alternating plots were illuminated from twilight 

 to dawn with 500-watt lights and were curtained off from the non-illununated 

 check plots. One check plot produced 3 spikes of blooms; the other check plot 

 produced none. In the illuminated plots, 81 per cent and 69 per cent of the 

 plants produced flowering spikes. The blooms in the check plot appeared three 

 weeks before blooms in the lighted areas. The best spikes in any plot were the 

 first to bloom. These occurred in the illuminated plots during the first 10 days 

 of January. 



Eradication of Nematodes in Greenhouse Soils by the Use of Chem- 

 icals. (L. H. Jones). Progress has been made in substituting the liquid ortho- 

 dichlorobenzene for the dry paradichlorobenzene. By adsorbing the orthodichlo- 

 robenzene with diatomaceous earth, this chemical may be mixed with cyanogas 

 and this mixture applied to the soil in a dry state. In preliminary tests, this 

 mixture eradicated nematodes from a soil inoculated with large nematode galls. 

 It appears that orthodichlorobenzene has the property of aiding the soil in the 

 retention of hydrocyanic acid gas. 



Plant Containers. (L. H. Jones). Non-porous containers made of paper, 

 glass, rubber, or metal will grow plants equal to those grown in standard clay 

 flower pots. Paper pots should have the fibers thoroughly impregnated and 

 bound together with some waterproofing material to prevent decomposition of 

 the container and consequent nitrogen deficiency in the soil. Non-porous con- 

 tainers lose soil moisture about half as fast as do clay pots. If a clay pot is kept 

 on a dry surface, it develops an uneven distribution of soil moisture, the lower 

 portion of the soil gradually becoming too dry for root action even though the 

 upper layer is moist. This condition is caused by the excessive evaporation of 

 soil moisture through the wall of the pot, for this loss of moisture is seldom 

 made up by the daily watering of the plants. However, if the clay pot is kept 

 on a moist surface, the evaporated water is replaced from without the pot and 

 not from the soil moisture. The practice of employing a moist bench for clay 

 flower pots, therefore, assures an even distribution of soil moisture. A non- 

 porous container cannot evaporate moisture through the wall of the container, 

 and, therefore, the moisture is conserved uniformly throughout the soil mass. 

 A full report of this work is given in Bulletin 277. 



The conunon belief that aeration of the soil takes place through the wall of 

 the clay pot may possibly be true when the pot itself is dry; but if the pore 

 spaces are filled with moisture, which is the usual condition in greenhouse prac- 



