The volume of flame, however, is increased by inert gas, and there is a proportionate diminution of the heating effect. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 Various. Nitrogen by itself is an inert gas, colorless and uninflammable. Scientific American Supplement No. 819 Various.
There are two primary fungus diseases that can produce black spots on tomato plant leaves: Septoria leaf spot and Alternaria leaf spot, also known as early blight. Septoria and Alternaria differ slightly in appearance and prefer slightly different weather climates.
Like Septorialeaf spot, early blight is common in Iowa tomatoplantings, and the two diseases may attack the sameplants. Premature loss of lower leaves is the most obvioussymptom of the disease (Figure 3). Brown to black spots, 1 â 4 to 1 â 2 inch in diameter with dark edges, appear on lowerleaves (Figure 4).