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.
Tomato Spotted Wilt Virus. The tomato spotted wilt virus (TSWV) causes dark brown, purple or black spots on leaves. The spots can spread to the stems, causing cankers and streaks. The foliage begins to wilt once the disease spreads, and the leaves become stiff.
Problems on tomato leaves can mean the onset of a disease, an attack from a tomato pest, a nutrient deficiency, or conditions that can lead to trouble. Healthy tomato plants have leaves that are green and evenly-colored. Look for these red flags on your tomato leaves to quickly identify problems. Black, brown, dark, or water-soaked spots.