Penetration and Accumulation of Petroleum Spray Oils in the Leaves, Twigs, and Fruit of Citrus Trees

Herbicidal properties of benzene and certain methyl derivatives

“…Entry is both through the cuticle and through stomata, and the oil moves into the intercellular spaces, replacing some of the air. Rohrbaugh (1934) could detect no spray oil within citrus leaf or stem cells, this in contradiction to the results of Knight et al (1929) and Young (1935& ). As Rohrbaugh points out, it is necessary to distinguish clearly between naturally occurring oils and applied petroleum oils, however it does not seem unlikely that some oil constituents would be able to penetrate the cell wall and enter the protoplasm.…”

“…Once in the intercellular spaces, the oil moves by surface activity, facili tated by the lipophilic cell wall surfaces (emphasized by Scott, 1950) exposed to intercellular air. Movement for only short distances was detected in citrus leaves (Rohrbaugh, 1934) ; it seems quite well established, however, that in many kinds of plants the oil may move from organ to organ, up or down (Knight et al, 1929;Young, 1935α, b;Minshall and Helson, 1949). In dan delions, carrots, and parsnips, kerosene-like oils moved downward when ap- [Vol.…”

Factors Affecting Reductions in Photosynthesis Caused by Applying Horticultural Oil to Grapevine Leaves

“…Photosynthesis was appreciably depressed by oil application only when the undersides of leaves were treated. Grape leaves are hy-postomatous (Mullins et al, 1992), and it has been shown repeatedly that application of oils to leaf surfaces with stomata leads to greater leaf penetration as well as more visible injury (Dallyn, 1953;Kelley, 1930a;Rohrbaugh, 1934) and greater depression of transpiration (Kelley, 1930b) and photosynthesis (Dallyn, 1953;Kelley, 1930a;Rohrbaugh, 1934) than application to surfaces without stomata. Several authors have shown that oils of viscosities similar to JMS Stylet-Oil can also slowly penetrate through intact cuticles without stomatal openings (Ginsburg, 1931;Knight et al, 1929;Külps and Hein, 1972), but if penetration through the upper surface took place in our grape leaves, it was not enough to affect photosynthesis.…”

Quantification of mineral oil accumulation and movement in potato plants and its significance in potato virus Y management

“…It is widely believed that mineral oil forms a film at the surface of the leaves. However, Rohrbaugh reported that mineral oil may penetrate under the epidermis to a depth of more than half a dozen plant cells in leaves, stems or fruit in citrus. Tan et al used fluorescence and confocal laser scanning microscopy to examine the localisation and movement of mineral oils in citrus and reported that mineral oil moves through intercellular spaces and plasmodesmata.…”