SOME EFFECTS OF FUEL OIL ON PLANTS

the leaves of plants when applied as a spray (see among others Ginsberg (2), Knight et al. (4), Kelley (3), de Ong (1), and Rohrbaugh (5)), no investigation regarding their effects upon roots is known to the writers. The fuel oil used was purchased from the Consumers Petroleum Company, Chicago, Illinois. It is described commercially as 3236 Baume gravity gas oil, consisting principally of saturated hydrocarbons. It is obtained in the refining of petroleum as one of the heavier fractions of distillation. The viscosity is about 55 seconds Saybolt. In appearance it is medium thin, of a greenish amber color, and is similar to the "medium oils'7 which spray investigators have found most useful. The experiments were carried on with four plants : the tomato, Lycopersicum esculentum; the peach, Prunus persica; the apple, Pyrus mains; and Ageratum houstonianum. The four were chosen for their availability rather than for any scientific reason, but they proved suitable material for the investigation because none of them contained natural oil in sufficient quantities to interfere with the recognition of the introduced oil in the plant body, and they gave an interesting variety of reactions. As the most extensive experiments were with tomatoes and peaches, the reactions of these two species only are being reported. The tomatoes were from greenhouse stock, all from the same planting, carbohydrate high and tending to reproduction. The peaches and apples were year-old seedlings obtained through the courtesy of Dr. M. J. Dorsey, Chief in Pomology at the University of Illinois. They were planted in good potting loam, the tomatoes being in 5-inch pots and the peaches in 6-inch. Two lots of 12 plants each were used for each species divided into sets of two pots each. One of these sets, without oil, served as the control ; the other five sets had one application of oil applied to the surface of the soil in amounts of 1, 2, 3, 4, and 5 per cent, by volume of the soil content of the respective pots. In one lot of each species the soil was heaped about the stems of the plant so that there was no surface contact of the oil with the stems. This was designated as the M series ; the others constituted the 8 series. All plants were watered regularly to maintain proper moisture conditions for good growth and the plants were kept under observation for 51 days.