Influence of Foliage Sprays on Drought Resistance of Conifers.

Periodic drought is one of the most serious hazards to young conifer plantations in several regions of this country. In the Lake States region, for example, droughts have occurred in four years of the past seven. Biologists have suggested that repellent substances sprayed on leaves of conifers to prevent rodent damage might, in addition, have a beneficial effect on survival during droughts. It seemed desirable to make a careful test of a few sprays to determine if they were of any real use in increasing resistance to drought. The present paper describes experiments designed to test the protective value of various sprays that have been suggested as useful agents in lowering transpiration. Review of literature