The best type of heater for almond orchards has not been thoroughly worked out as yet, but the reservoir heaters of the Bolton or Hamilton type have been commonly and successfully used. The former are commonly known as “pots.” At least 75 one or two-gallon heaters per acre are necessary to control temperatures as low as 27 or 28 degrees F. Probably not over 100 pots to an acre would be needed at most. Double the number of pots should be placed around the outside row of the orchard to afford the necessary protection. The gravity of oil best suited for orchard heating is between 20 and 25 degrees Beaumé. It is essential that it be as free from impurities, such as sulphur, as possible. During the spring of 1917, orchard heating was done very extensively in some districts of the state while the trees were approaching full bloom. As the season progressed it became apparent that some serious injury had been done by the heating, for the bulk of the blossoms fell off and the leaves turned yellow in streaks as if burned by an acid. The appearance was exactly as if the particles of soot settling on the pistils of the flowers and on the young leaves had absorbed sulphur dioxide gas (a product of oil combustion where sulphur is contained in the oil) and that the dews uniting with it to form sulphurous acid had done the damage. Had the heating been done later and only after the trees had passed full bloom, it is possible that a much heavier set of nuts might have been secured, since the small fruits, where they had formed, seemed to have been uninjured, only the pistils of the flowers having been affected, probably preventing pollination and fertilization of the ovules. The time of heating is therefore a very important point. Almond blossoms become progressively more tender to frost as they advance in development. With their petals on they are not nearly as tender as they are after the petals have fallen. They reach their most tender stage after the calyx shucks have fallen from the young expanding fruits before they are the size of a pea. Ordinarily, orchard heating before the trees have passed full bloom is a waste of time and material and is often injurious. The most needed time is for a period of two or three weeks after the bulk of the petals have fallen, unless temperatures below 28 or 29 degrees are encountered before that time. CROP HANDLING